Lactobacillus

J Appl Microbiol, 2000 Jan, 88(1), 176 - 82
Effect of pH control on lactic acid fermentation of starch by Lactobacillus manihotivorans LMG 18010T; Guyot JP et al.; Lactic acid fermentation of starch by Lactobacillus manihotivorans LMG 18010T, a new amylolytic L(+) lactic acid producer, was investigated and compared with starch fermentation by Lact . plantarum A6 . At non-controlled pH, growth and lactic acid production from starch by Lact . manihotivorans LMG 18010T lasted 25 h . Specific growth and lactic acid production rates continuously decreased from the onset of the fermentation, unlike Lact . plantarum A6 which was able to grow and convert starch product hydrolysis into lactic acid more rapidly and efficiently at a constant rate up to pH 4.5 . In spite of complete and rapid starch hydrolysis by Lact . manihotivorans LMG 18010T during the first 6 h, only 45% of starch hydrolysis products were converted to lactic acid . When pH was maintained at 6.0, lactic acid, amylase and final biomass production by Lact . manihotivorans LMG 18010T increased markedly and the fermentation time was reduced by half . Under the same conditions, an increase only in amylase production was observed with Lact . plantarum A6 . When grown on glucose or starch at pH 6.0, Lact . manihotivorans LMG 18010T had an identical maximum specific growth rate (0.35 h(-1)), whereas the maximum rate of specific lactic acid production was three times higher with glucose as substrate . Lactobacillus manihotivorans LMG 18010T did not produce amylase when grown on glucose . Based on the differences in the physiology between the two species and other amylolytic lactic acid bacteria, different applications may be expected.

J Appl Microbiol, 2000 Jan, 88(1), 142 - 53
Effect of some nutritional and environmental parameters on the production of diacetyl and on starch consumption by Pediococcus pentosaceus and Lactobacillus acidophilus in submerged cultures; Escamilla ML et al.; Three series of 5-day submerged cultures with Pediococcus pentosaceus MITJ-10 and Lactobacillus acidophilus Hansen 1748 were carried out in starch-based media, and the effect of cultural factors on the changes of starch, diacetyl and amylase activity determined . In axenic cultures, Ped . pentosaceus MITJ-10 produced more diacetyl (63.27 mg l(-1)) by adding glucose, yeast extract and CaCO3 (P < 0.01), at 28 degrees C (P < 0.05); but more starch was consumed (18.4 g l(-1)) in the absence of glucose (P < 0.01) . Lact . acidophilus Hansen 1748 consumed more starch (26.56 g l(-1)) at 28 degrees C, with CaCO3, glucose (P < 0.01) and yeast extract (P < 0.05); however, the amylolytic activity (10077U l(-1)) was favoured at 35 degrees C (P < 0.01) . Little starch was consumed in mixed cultures due to the low pH; nevertheless, diacetyl content rose to 135.76 mg l(-1) at 32 degrees C (P < 0.01) . Therefore, both studied strains might be useful to produce aromatic extensors from starchy substrates . These natural aromatic extensors are of interest to the food industry.

J Appl Microbiol, 2000 Jan, 88(1), 81 - 9
Purification and some characteristics of enterocin ON-157, a bacteriocin produced by Enterococcus faecium NIAI 157; Ohmomo S et al.; Bacteriocin-like activity (BLA) was screened in 690 strains of lactic acid bacteria isolated from plant materials such as silages and fermented vegetables . Among them, a strain identified as Enterococcus faecium NIAI 157 showed a clear BLA against the indicator strain, Ent . faecium IFO 13712 . The proteinaceous nature and antimicrobial activity against closely related species strongly indicated that this BLA was a bacteriocin and was designated enterocin ON-157 . The bacteriocin activity of this strain was extracellularly produced in the logarithmic growth phase in MRS broth and purified by ultrafiltration, ammonium sulphate precipitation and cation-exchange chromatography . Purified enterocin ON-157 had a molecular weight of approximately 2500 Da in SDS-PAGE analysis and was easily inhibited by treatment with alpha-amylase and proteolytic enzymes . Enterocin ON-157 had a bactericidal mode of action and inhibited the growth of the enterococci, Lactobacillus sake and Listeria monocytogenes . Enterococcus faecium NIAI 157 harboured two plasmids, 49.0 kb and 43.7 kb, and a variant missing a larger plasmid by curing with novobiocin lost the bactriocin activity.

J Appl Microbiol, 2000 Jan, 88(1), 58 - 68
The microbial association of Greek taverna sausage stored at 4 and 10 degrees C in air, vacuum or 100% carbon dioxide, and its spoilage potential; Samelis J et al.; Strains of the Lactobacillus sakei/curvatus group, mainly non-slime-producing Lact . sakei, dominated the microbial flora of industrially manufactured taverna sausage, a traditional Greek cooked meat, stored at 4 degrees C and 10 degrees C in air, vacuum and 100% CO2 . Atypical, arginine-positive and melibiose-negative strains of this group were isolated . The isolation frequency of Lact . sakei/curvatus from sausages stored anaerobically was as high as 92-96%, while other meat spoilage organisms were practically absent . Conversely, in air-stored sausages, leuconostocs, mainly Leuconostoc mesenteroides ssp . mesenteroides, had a considerable presence (14-21%), whereas Brochothrix thermosphacta, pseudomonads and Micrococcaceae grew, but failed to increase above 10(5) cfu g(-1) in all samples during storage . Only yeasts were able to compete against LAB and reached almost 10(7) cfu g(-1) after 30 d of aerobic storage at 10 degrees C . The great dominance (> 10(8) cfu g(-1)) of LAB caused a progressive decrease of pH and an increase of the concentration of L-lactate, D-lactate and acetate in all sausage packs . The growth of LAB and its associated chemical changes were more pronounced at 10 degrees C than 4 degrees C . At both storage temperatures, L-lactate and acetate increased more rapidly and to a higher concentration aerobically, unlike D-lactate, which formed in higher amounts anaerobically . Storage in air was the worst packaging method, resulting in greening and unpleasant off-odours associated with the high acetate content of the sausages . Carbon dioxide had no significant effect on extending shelf-life . The factors affecting the natural selection of Lact . sakei/curvatus in taverna sausage are discussed . Moreover, it was attempted to correlate the metabolic activity of this group with the physicochemical changes and the spoilage phenomena occurring in taverna sausage under the different storage conditions.

J Appl Microbiol, 2000 Jan, 88(1), 52 - 7
The growth of Listeria monocytogenes in cheese packed under a modified atmosphere; Whitley E et al.; The effect of modified atmosphere Packaging (MAP) on the growth of Listeria monocytogenes in mould ripened cheeses was studied at refrigeration temperatures (2-8.3 degrees C) over a storage period of 6 weeks . Control experiments in cling film with no atmospheric modification produced a lag time before growth of up to 1 week and rapid subsequent growth . MAP with a CO2 concentration of less than 20% allowed growth to occur but when O2 was incorporated; the lag time was reduced from 3 to 2 weeks and subsequent growth was also faster, producing an increase in cell numbers of 1.4 log cycles over the incubation period . N2-MAP in the absence of O2 increased the lag time to 3 weeks and slowed growth, while the inclusion of CO2 extended the lag to 3 weeks and slowed subsequent growth even more . In MAP with 80:10:10 (v/v/v) N2:CO2:O2, there was a lag period of 2-3 weeks before growth of L . monocytogenes occurred, while the total viable aerobic count (TVAC) decreased by 2-3 log cycles and the total Lactobacillus count showed little change . It was concluded that MAP was not suitable for preventing the growth of L . monocytogenes in such cheeses.

J Appl Microbiol, 2000 Jan, 88(1), 44 - 51
Bacteriocin production by lactic acid bacteria isolated from Rioja red wines; Navarro L et al.; Forty-two lactic acid bacteria (LAB) of the genera Lactobacillus (32), Leuconostoc (6), Pediococcus (3) and Lactococcus (1), isolated from Rioja red wines, were tested for antimicrobial activity . All these strains, as well as 18 Leuconostoc oenos and 19 yeast strains were used as indicators . Only nine strains showed antimicrobial activity, and all were of the species Lactobacillus plantarum, which constitutes the predominant microflora in Rioja red wines after alcoholic fermentation . Lact . plantarum strain J-51 showed the widest range of action, inhibiting the growth of 31 strains of the four studied LAB genera . Lact . plantarum J-51 antimicrobial activity was lost after treatment with proteases, suggesting a proteinaceous nature for this activity . It was found to be stable between pH 3 and 9 and under strong heating conditions (100 degrees C for 60 min) . Polymerase chain reaction (PCR) analysis of Lact . plantarum J-51 genome revealed the presence of the plnA gene that encodes the plantaricin precursor PlnA . A 366-bp fragment was sequenced and showed 95% identity with pln locus of Lact . plantarum C-11 . The deduced precursor peptide sequence showed one mutation (Gly7 to Ser7) at the double glycine leader peptide, and the three putative 26-, 23- and 22-residue active peptides remain identical to those of Lact . plantarum C-11 . Therefore, antimicrobial peptides constitute a potent adaptation advantage for those strains that dominate in a medium such as wine, and can play an important role in the ecology of wine microflora.

Acta Microbiol Immunol Hung, 2000, 47(1), 53 - 61
Microbial study of farmhouse ewe cheese during storage in olive oil; Gomez R et al.; The effect of storing farmhouse ewe cheese in oil and in vacuo over long periods of time on physicochemical properties (water activity and pH) and the microbiota of the cheese was investigated . The storage conditions were found to scarcely influence the sample pH . Also, the initial water activity (a(w) = 0.961) and its value after 9 months of storage (0.927) were both very similar to those for naturally ripened cheese . The incidence of pathogenic microbial groups was found to decrease with storage time (counts fell below 1 log CFU/g) . The flora that effects proteolytic changes in cheese consisted of lactic microorganisms (viz . lactococci and lactobacilli), in addition, after 6 months of storage, of enterococci . The last are responsible for the formation of large amounts of soluble nitrogen (SN), non-protein nitrogen (NPN) and aminoacid nitrogen (NH2-N), which provide this type of cheese with very special sensory features while preventing dehydration and thus lengthening its shelf life.

Bioseparation, 1999, 8(1-5), 229 - 35
On-line monitoring of glucose and/or lactate in a fermentation process using an expanded micro-bed flow injection analyser; Nandakumar MP et al.; A novel flow injection biosensor system for monitoring fermentation processes has been developed using an expanded micro bed as the enzyme reactor . An expanded bed reactor is capable of handling a mobile phase containing suspended matter like cells and cell debris . Thus, while the analyte is free to interact with the adsorbent, the suspended particulate matter passes through unhindered . With the use of a scaled down expanded bed in the flow injection analysis (FIA) system, it was possible to analyse samples directly from a fermentor without the pretreatment otherwise required to extract the analyte or remove the suspended cells . This technique, therefore, provides a means to determine the true concentrations of the metabolites in a fermentor, with more ease than possible with other techniques . Glucose oxidase immobilised on STREAMLINE was used to measure glucose concentration in a suspension of dead yeast cells . There was no interference from the cell particles even at high cell densities such as 15 gm dry weight per litre . The assay time was about 6 min . Accuracy and reproducibility of the system was found to be good . In another scheme, lactate oxidase was covalently coupled to STREAMLINE for expanded bed operation . With the on-line expanded micro bed FIA it was possible to follow the fermentation with Lactobacillus casei.

Bioseparation, 1999, 8(1-5), 159 - 68
Expanded bed adsorption as a unique unit operation for the isolation of bacteriocins from fermentation media; Callewaert R et al.; Expanded bed adsorption using a strong cation exchanger allowed the direct isolation of amylovorin L471, a bacteriocin from Lactobacillus amylovorus DCE 471, from the fermentation medium . The pH of the loading and elution buffer were optimised in a packed bed with cell-free culture supernatant . Bound bacteriocin was eluted with 1.0 M NaCl . The highest recovery (30%) was obtained at the lowest pH (3.6) . At higher pH values the recovery was lower, namely 12%, 15% and 7% at pH 4.5, 6.5 and 8.0, respectively . In expanded bed mode, direct isolation of the bacteriocin from the fermentation medium at pH 3.6 (loading and elution) initially resulted in a recovery of 12% . After optimisation of the pH (loading and elution at pH 3.6 and 6.5, respectively), the recovery for amylovorin L471 increased up to 30% and higher . Recovery of enterocin A from Enterococcus faecium CTC 492 fermentation medium averaged 15% (loading and elution at pH 3.6 and 6.0, respectively) . With pediocin, produced by Pediococcus acidilactici ATCC 8042, 26% recovery was obtained at a pH of 6.5 during loading and elution . Low recoveries can be ascribed to non-optimal operation conditions (pH of loading and elution buffer), inactivation of the bacteriocin on a cationic resin, and the formation of more insoluble and less active, strongly hydrophobic bacteriocin aggregates upon further purification.

Int J Food Microbiol, 1999 Nov 15, 52(3), 155 - 61
Arginine, citrulline and ornithine metabolism by lactic acid bacteria from wine; Arena ME et al.; The catabolism of arginine, an amino acid found in grape juice and wine, citrulline and ornithine was investigated in four lactic acid bacteria . Only Lactobacillus hilgardii X1B catabolized arginine and excreted citrulline into the medium . The recovery of arginine as ornithine was lower than the expected theoretical value . The arginase-urease pathway was not detected indicating that the amino acid degradation was carried out only by the arginine dihydrolase pathway . Oenococcus oeni m, a strain not able to utilize arginine, degraded citrulline that was completely recovered as ornithine, ammonia and CO2 . Lactobacillus hilgardii X1B catabolized citrulline but it was only 44% recovered as ornithine . The citrulline utilization by Oenococcus oeni m may be important for two reasons: it can gain extra energy for growth from citrulline metabolism, and the amino-acid diminution could avoid the possibility of ethyl carbamate formation from the citrulline naturally present in wine.

FEMS Microbiol Lett, 2000 Apr 1, 185(1), 1 - 7
Enterococcal-type glycopeptide resistance genes in non-enterococcal organisms; Patel R; Although the emergence of vancomycin-resistant enterococci can be attributed, in part, to the increasing use of vancomycin in clinical practice, and glycopeptide use in animal husbandry, the origins of the enterococcal vancomycin resistance genes are not clear . The vancomycin resistance-associated genes in Enterococcus gallinarum, Enterococcus casseliflavus/flavescens, Lactobacillus spp., Leuconostoc spp., Pediococcus spp., and Erysipelothrix rhusiopathiae, are not the source of the high-level vancomycin resistance-associated genes in enterococci . There are, however, environmental organisms which have been found to have gene clusters homologous to the enterococcal vanA, vanB and vanC gene clusters; these include the biopesticide Paenibacillus popilliae, and, to a lesser extent, the glycopeptide-producing organisms Amycolatopsis orientalis and Streptomyces toyocaensis . Still, the exact sources of the enterococcal vancomycin resistance genes remain a mystery.

Akush Ginekol (Sofiia), 1999, 38(2), 21 - 3
{Streptococcus group B isolated in 3 microscopic displays from the vaginal secretions of pregnant women}; Shopova E et al.; Over a period of 20 months we investigated 1366 vaginal specimens from pregnant women for GBS (group B streptococci) carrier in three microscopic patterns, evaluated by Nugent score system . More frequently we isolated GBS in group I intermedia (score 4-6)--20.8%, (when Lactobacillus spp . is missing--67.4%, without or associated with other nonanaerobic microorganisms (60.5%) . All isolated GBS strains showed sensitivity to ampicillin and carbenicillin . Good sensitivity was found to cefazolin (92.4%) ant to cefuroxim (94.9%) . The strains showed 13.7% resistance to erythromycin and 4.1% to clindamycin.

Arch Gynecol Obstet, 1999 Nov, 263(1-2), 34 - 6
Accuracy of rapid antigen detection test for group B streptococci in the indigenous vaginal bacterial flora; Donders GG et al.; OBJECTIVE: To test the sensitivity of the rapid group B streptococci (GBS) antigen test ICONR and compare its accuracy in women with vaginal enterococci or with non-specific disturbance of the lactobacillary flora . STUDY DESIGN: The ICONR, aerobic culture and a microscopic wet mount evaluation were done on a vaginal sample in 254 unselected women presenting for routine gynecologic care in an academic hospital in Flanders, Belgium and tested by Chi2 {diagnostic odds ratio (DOR) and its 95 percent confidence limits} . RESULTS: Sensitivity of the test was 70%, specificity 99.5% . Prevalence of GBS was 10.6% overall, 23% in the group with abnormal vaginal flora and 7% in the normal group (p=0.002) . Accuracy of the ICONR was not affected by abnormal vaginal flora, but was significantly lower in the presence of enterococci: the DOR decreased from 490 to 58, and the positive predictive value from 94 to 80% . CONCLUSION: With a sensitivity of 70% the enzyme immunoassay ICONR does not appear to be suitable as a practical screening tool for detecting GBS carriage in normal or preterm laboring women . In the presence of enterococci the test performed less well, with a DOR falling by 8 to 9 fold . We presume this is due to lower specificity in vivo in the presence of enterococci, as non-specific disturbance of the lactobacillary flora did not interfere with test results.

Int J STD AIDS, 2000 Mar, 11(3), 150 - 5
Diagnosis of bacterial vaginosis by wet mount identification of bacterial morphotypes in vaginal fluid; Schmidt H et al.; In order to develop a more practical way of diagnosing bacterial vaginosis (BV), we evaluated a scoring system, weighting small bacterial morphotypes versus lactobacillary morphotypes in wet mounts, assessed criteria for BV and normalcy from this scoring, and then evaluated their reproducibility and accuracy . We examined 754 women for pH, homogeneous vaginal discharge, amine odour, clue cells and the composite clinical diagnosis . We also examined wet mounts for small bacterial morphotypes and lactobacillary morphotypes, and weighted their quantitative presence as a bacterial morphotype score . The term 'small bacterial morphotypes' denotes a group of small bacillary forms comprising coccobacilli, tiny rods, and mobile curved rods . The different characteristics of BV were all gradually associated with increased bacterial morphotype scoring . We deemed a score of 0-1 as normal, 2-4 as intermediate phase, grade I, 5-6 as intermediate phase, grade II, and 7-8 indicative of BV . Reproducibility of the interpretation was high, both for the new grading system (weighted Kappa 0.90 in women perceiving and 0.81 in women not perceiving abnormal vaginal discharge) and for the new criterion for BV (non-weighted Kappa 0.91 and 0.84 in the 2 groups of women) . The new criterion also proved highly concurrent with the composite clinical diagnosis (Kappa 0.91 and 0.81 in the 2 groups) . In conclusion, the wet mount bacterial morphotype scoring is valid for grading of the disorder of the vaginal microbial ecosystem, and the new criterion for BV a more practical option than existing diagnostic methods.

J Immunol, 2000 Apr 1, 164(7), 3733 - 40
Lactobacilli and Streptococci activate NF-kappa B and STAT signaling pathways in human macrophages; Miettinen M et al.; Gram-positive bacteria induce the production of several cytokines in human leukocytes . The molecular mechanisms involved in Gram-positive bacteria-induced cytokine production have been poorly characterized . In this work we demonstrate that both nonpathogenic Lactobacillus rhamnosus GG and pathogenic Streptococcus pyogenes (group A streptococci) induce NF-kappa B and STAT DNA-binding activity in human primary macrophages as analyzed by EMSA . NF-kappa B activation was rapid and was not inhibited by a protein synthesis inhibitor cycloheximide, suggesting that these bacteria could directly activate NF-kappa B . STAT1, STAT3, and IFN regulatory factor-1 DNA binding was induced by both bacteria with delayed kinetics compared with NF-kappa B . In addition, streptococci induced the formation of IFN-alpha-specific transcription factor complex and IFN-stimulated gene factor-3 (ISGF3) . STAT1 and STAT3 activation and ISGF3 complex formation were inhibited by cycloheximide or by neutralization with IFN-alpha/beta-specific Abs . Streptococci were more potent than lactobacilli in inducing STAT1, ISGF3, and IFN regulatory factor-1 DNA binding . Accordingly, only streptococci induced IFN-alpha production . The activation of the IFN-alpha signaling pathway by streptococci could play a role in the pathogenesis of these bacteria . These results indicate that extracellular Gram-positive bacteria activate transcription factors involved in cytokine signaling by two mechanisms: directly, leading to NF-kappa B activation, and indirectly via cytokines, leading to STAT activation.

Gene, 2000 Jan 25, 242(1-2), 155 - 66
The genetic switch for the regulatory pathway of Lactobacillus plantarum phage (phi)g1e: characterization of the promoter P(L), the repressor gene cpg, and the cpg-encoded protein Cpg in Escherichia coli; Kakikawa M et al.; The structural and functional features of the approximately 530 bp P(L)/Gb5-Gb6-cpg-Gb7 region (P(L) overlaps Gb5) for the lysogenic pathway of L . plantarum phage (phi)gle were investigated using the cat gene of E . coli plasmid pKK232-8 as a reporter . In E . coli XL1-Blue, a recombinant plasmid pKPL2 (cat under P(L)/Gb5-Gb6) exhibited distinct CAT activity, whereas the activity of pKPLCP1 (cat under P(L)/Gb5-Gb6-cpg) was only marginal . When pKPL2 was coexistent with a compatible derivative of plasmid pACYC177 carrying P(L)/Gb5-Gb6-cpg, the CAT activity was declined to the level of pKPLCP1 . On the other hand, the cpg-encoded protein Cpg was overproduced in E . coli under P(T7) . The molecular mass of the purified Cpg (14.5 kDa on a SDS gel) corresponded well with that (15.1 kDa) predicted from the DNA sequence . Gel-shift and footprinting assays demonstrated that Cpg selectively binds to about 25 bp bases centered around the GATAC-box (from 1 to 7) . Moreover, protein crosslinking experiments using glutaraldehyde showed that Cpg most likely functions as a dimeric form . Thus, the present results indicate that Cpg probably represses P(L) through binding to the operator GATAC-box(es), and the P(L)/cpg region might participate in the lysogenic pathway.

J Food Prot, 2000 Mar, 63(3), 412 - 4
Binding of aflatoxin B1 alters the adhesion properties of Lactobacillus rhamnosus strain GG in a Caco-2 model; Kankaanpaa P et al.; Lactic acid bacteria have been previously reported to possess antimycotoxigenic activities both in vitro and in vivo . The objective of this study was to investigate the effect of aflatoxin B1 on adhesion capability of Lactobacillus rhamnosus strain GG using a Caco-2 adhesion model . Removal of aflatoxin B1 by L . rhamnosus strain GG reduced the adhesion capability of this strain from 30% to 5% . It is therefore concluded that aflatoxins may influence the adhesion properties of probiotics able to sequester them, and subsequently these bacteria may reduce the accumulation of aflatoxins in the intestine via increased excretion of an aflatoxin-bacteria complex.

Plant Foods Hum Nutr, 1999, 54(3), 239 - 50
Effect of process improvement on the physico-chemical properties of infant weaning food from fermented composite blends of cereal and soybeans; Onilude AA et al.; Saccharomyces cerevisiae and Lactobacillus plantarum ATCC 10776 were used as starters to ferment various composite blends of cereals and legumes produced through malting and toasting of two varieties of maize--Zea mays (DMR-LSR white & DMR-ESR yellow), sorghum--Sorghum bicolor (Dawa white & Dawa red) and one variety of soybeans (Glycine ax) . Compared to the untoasted and unmalted fermented blends, a relatively lower pH (3.6), highly sour product was obtained with 12 h of fermentation . Results also showed that cereal and soybean toasting brought about a better reconstitution indices (B25, 84 ml; B45, 87 ml), water holding capacities (B25, 0.68 ml/g; B45, 0.62 ml/g), bulk densities (C15, 11.6; C35, 10.8) and gross energy (B15, 501.5 k cal/100g; B45, 508.5 kcal/100g) at the end of fermentation . Furthermore, reductions in total polyphenol and tannin contents were observed with fermentation of toasted and malted cereal blends supplemented with toasted and malted soybeans while porridges from the same blends displayed desirable starch stability and consistent gelling tendency, although B15 (a ferment of malted, toasted white maize supplemented with toasted and malted soybean) fell within acceptable limits . In all, the physical characteristics were affected by varieties of cereal and soybeans.

Enzyme Microb Technol, 2000 Mar 1, 26(5-6), 431 - 445
Comparison of simple neural networks and nonlinear regression models for descriptive modeling of Lactobacillus helveticus growth in pH-controlled batch cultures; Schepers AW et al.; A set of 20 Lactobacillus helveticus growth curves was obtained from pH-controlled batch cultures with different pH setpoints, whey permeate and yeast extract concentrations . To find the best descriptive model of the biomass concentration versus time (y = X(t)) growth curve, fitting results of a large number of models were compared with statistical and approximate methods . Models studied included simple neural networks, reparameterized Logistic, Gompertz, Richards, Schnute, Weibull, and Morgan-Mercier-Flodin models, Amrane-Prigent model, and four new models based on autonomous growth functions . Simple neural networks with only four weights were good descriptive models of the growth curves and fitting qualities were similar to those of the best existing four-parameter models, such as the Logistic model . However, meaningful parameters had to be calculated numerically and use of simple neural networks yielded no distinctive advantages over other models . A new five-parameter model, based on an autonomous growth function, yielded the best fitting results, even when the number of model parameters was accounted for in the comparisons . However, the maximum specific growth rate was not always well estimated . Therefore the five-parameter Richards model was chosen as the best descriptive model of the growth curve.

J Reprod Med, 2000 Feb, 45(2), 131 - 4
Trichomonas vaginalis and bacterial vaginosis . Coexistence in vaginal wet mount preparations from pregnant women; Franklin TL et al.; OBJECTIVE: To identify how frequently trichomoniasis and characteristics of bacterial vaginosis (BV) occur concomitantly in wet mount preparations from pregnant women . STUDY DESIGN: Diagnosis of trichomoniasis was predicted on visualization of the organism . Diagnosis of BV required a positive volatile (whiff) test, presence of "clue cells" and one of two minor criteria: (1) absence of lactobacilli, or (2) a pH > 4.5 . Pregnant women from January 1995 to July 1997 at our clinic had wet mount/KOH preparations performed as standard prenatal care . Corresponding medical charts were analyzed for symptoms, race, BV, sexually transmitted diseases, urinary tract infections and other infections . RESULTS: Of 191 pregnant women identified, 69 had trichomoniasis . Seventy-nine percent of the 69 were African American . Fifteen percent of pregnant women (17) had concomitant trichomoniasis and BV . Irrespective of race, 35-38% of pregnant women with trichomoniasis had another sexually transmitted disease or a urinary tract infection diagnosed in that pregnancy . CONCLUSION: BV, or bacteria excess syndrome, is a frequent coinfection in pregnant women harboring Trichomonas vaginalis.

Appl Microbiol Biotechnol, 2000 Feb, 53(2), 159 - 66
Influence of complex nutrients, temperature and pH on bacteriocin production by Lactobacillus sakei CCUG 42687; Aasen IM et al.; The effects of process conditions and growth kinetics on the production of the bacteriocin sakacin P by Lactobacillus sakei CCUG 42687 have been studied in pH-controlled fermentations . The fermentations could be divided into phases based on the growth kinetics, phase one being a short period of exponential growth, and three subsequent ones being phases of with decreasing specific growth rate . Sakacin P production was maximal at 20 degrees C . At higher temperatures (25-30 degrees C) the production ceased at lower cell masses, when less glucose was consumed, resulting in much lower sakacin P concentrations . With similar media and pH, the maximum sakacin P concentration at 20 degrees C was seven times higher than that at 30 degrees C . The growth rate increased with increasing concentrations of yeast extract, and the maximum concentration and specific production rate of sakacin P increased concomitantly . Increasing tryptone concentrations also had a positive influence upon sakacin P production, though the effect was significantly lower than that of yeast extract . The maximum sakacin P concentration obtained in this study was 20.5 mg l(-1) . On the basis of the growth and production kinetics, possible metabolic regulation of bacteriocin synthesis is discussed, e.g . the effects of availability of essential amino acids, other nutrients, and energy.

J Otolaryngol, 2000 Feb, 29(1), 28 - 34
Clinical evaluation of a commercially available oral moisturizer in relieving signs and symptoms of xerostomia in postirradiation head and neck cancer patients and patients with Sjögren's syndrome; Rhodus NL et al.; A major complication of irradiation therapy for head and neck cancer is salivary gland dysfunction and xerostomia . The purpose of this clinical investigation was to evaluate the effects of a commercially available oral moisturizer (Optimoist) on salivary flow rate, symptoms of xerostomia, oral pH, oral microflora, and swallowing in postirradiation head and neck cancer patients (XRT) and patients with Sjogren's syndrome (SS) . Subjects who were post-XRT and subjects with SS (n = 24; mean age = 54.1) discontinued their use of any salivary substitute or moisturizer for 2 weeks prior to entering the study . Baseline whole unstimulated saliva was collected for 5 minutes using a standard sialometric technique . Candida albicans and Lactobacillus cultures were performed using kits from Orion Diagnostica, Inc., and a pH analysis was performed on the salivary sample using a Markson (model 00663) pH meter . Swallowing was assessed by clinical measures by videofluoroscopic techniques . Several subjective assessments were performed to evaluate symptoms of xerostomia . Subjects were instructed in the use of a daily diary and to use only the provided article ad libitum for a period of 2 weeks . After the 2-week period, the results indicated significant subjective and objective improvements in signs and symptoms of xerostomia . Whole unstimulated salivary flow rate improved from (mean +/- SEM) 0.1150 +/- 0.02 to 0.2373 +/- 0.09 mL/min . Salivary pH did not change . Global subjective improvement in xerostomia improved in 58% of the subjects . Candida colonization decreased in 43% of the subjects . There was no change in Lactobacilli colonization . Swallowing objectively improved in 75% of subjects . These results indicate significant improvement in both signs of hyposalivation and symptoms of xerostomia with the use of Optimoist in postirradiation head and neck cancer patients and patients with SS.

Mikrobiol Z, 1999 Nov-Dec, 61(6), 42 - 50
{The bacteriocinogenic and lysozyme-synthesizing activity of lactobacilli}; Kovalenko NK et al.; It was shown that lactic acid bacteria isolated from different sources produced along with lactic acid the bacteriocine substances . Strains producing bacteriocines were mainly isolated from digestive tract of people and calves . Bacteriogenic properties have been shown more frequently in the case of lactobacilli (7.8%) more rarely--in coccoid forms of lactic acid bacteria (4.5%) . At the same time bacteriocine activity was higher in the case of Enterococcus and depended both on the strain type and cultivation conditions . Synthesis of bacteriocines started from the hours of phase of the culture growth and reached maximum at the beginning of stationary phase . The bacteriocine accumulation rate depended on composition of the growth medium.

Eur J Clin Microbiol Infect Dis, 2000 Jan, 19(1), 33 - 8
Comparison of a commercial disk test with vancomycin and colimycin susceptibility testing for identification of bacteria with abnormal gram staining reactions; Fenollar F et al.; In an effort to identify bacteria that fail to give the expected Gram reaction, thus leading to misidentification, two nonstaining tests for Gram reaction, vancomycin and colimycin susceptibility testing and the Gram-Sure test (Remel, USA), were employed on 145 strains from 42 gram-negative and gram-positive genera with contradictory Gram stain results . The Gram-Sure test is a commercially available disk that detects the presence of L-alanine-aminopeptidase, an enzyme usually found only in the cell wall of gram-negative bacteria . In this test, aminopeptidase activity is detected using a substrate that can be hydrolyzed to produce a fluorescent compound under long-wave UV light . The commercial disk test and vancomycin plus colimycin susceptibility testing appeared to perform equally well except in the identification of Erysipelothrix and Lactobacillus, for which the commercial disk test was better, and Moraxella, for which vancomycin and colimycin susceptibility testing was more helpful . An advantage of the commercial disk test is that it can be performed in 10 min, whereas vancomycin and colimycin susceptibility testing requires at least 18 h . The commercial disk test is also less expensive than vancomycin and colimycin susceptibility testing . However, since the same results can be obtained with the 5 microg and 30 microg vancomycin disks, it is possible to use only one vancomycin disk, with the cost then being equivalent to that of the commercial disk test . The major inconvenience of the commercial disk test is the requirement of a UV ray . However, this test could be a useful tool for the identification of unusual organisms.

Biochemistry, 2000 Mar 14, 39(10), 2429 - 35
Effects of subunit occupancy on partitioning of an intermediate in thymidylate synthase mutants; Variath P et al.; Experimental evidence for a 5-exocyclic methylene-dUMP intermediate in the thymidylate synthase reaction was recently obtained by demonstrating that tryptophan 82 mutants of the Lactobacillus casei enzyme produced 5-(2-hydroxyethyl)thiomethyl-dUMP (HETM-dUMP) (Barret, J . E., Maltby, D . A., Santi, D . V., and Schultz, P . G . (1998) J . Am . Chem . Soc . 120, 449-450) . The unusual product was proposed to emanate from trapping of the intermediate with beta-mercaptoethanol in competition with hydride transfer from H(4)folate to form dTMP . Using mutants of the C-terminal residue of thymidylate synthase, we found that the ratio of HETM-dUMP to dTMP varies as a function of CH(2)H(4)folate concentration . This observation seemed inconsistent with the conclusion that both products arose from a common intermediate in which CH(2)H(4)folate was already bound to the enzyme . The enigma was resolved by a kinetic model that allowed for differential partitioning of the intermediate formed on each of the two subunits of the homodimeric enzyme in forming the two different products . With three C-terminal mutants of L . casei TS, HETM-dUMP formation was consistent with a model in which product formation occurs upon occupancy of the first completely bound subunit, the rate of which is unaffected by occupancy of the second subunit . With one analogous E . coli TS mutant, HETM-dUMP formation occurred upon occupancy of the first subunit, but was inhibited when both subunits were occupied . With all mutants, dTMP formation occurs from occupied forms of both subunits at different rates; here, binding of cofactor to the first subunit decreased affinity for the second, but the reaction occurred faster in the enzyme form with both subunits bound to dUMP and CH(2)H(4)folate . The model resolves the apparent enigma of the cofactor-dependent product distribution and supports the conclusion that the exocyclic methylene intermediate is common to both HETM-dUMP and dTMP formation.

Toxicol In Vitro, 2000 Feb, 14(1), 53 - 9
Inhibition of dihydrofolate reductase and cell growth activity by the phenanthroindolizidine alkaloids pergularinine and tylophorinidine: the in vitro cytotoxicity of these plant alkaloids and their potential as antimicrobial and anticancer agents; Rao KN et al.; The phenanthroindolizidine plant alkaloids pergularinine (PGL) and tylophorinidine (TPD) isolated from the Indian medicinal herb Pergularia pallida have been evaluated for their biological activity and assessed for the first time employing dihydrofolate reductase (DHFR) (5,6,7,8-THF: NADP(+) oxidoreductase, EC 1.5.1.3) as the probe in the present investigations . The enzyme is a key target in cancer chemotherapy and has been purified from Lactobacillus leichmannii . Cytotoxicity studies showed that both PGL and TPD are potently toxic and inhibited the growth of L . leichmannii cells (IC(50)=45 and 40 microM, respectively) . Both the alkaloids significantly inhibited DHFR activity (IC(50)=40 and 32 microM for PGL and TPD, respectively) . Alkaloid concentrations greater than 75-95 microM resulted in a complete loss of DHFR activity . Our results are suggestive of the alkaloids as potential antimicrobial and antitumour compounds . Alkaloid binding to DHFR is slow and reversible . Inhibition kinetics revealed K(i) values of 9x10(-6) M and 7x10(-6) M for PGL and TPD, respectively for the enzyme and inhibition in both the cases was a simple linear 'non-competitive' type.

J Clin Microbiol, 2000 Mar, 38(3), 1302 - 4
Potential errors in recognition of Erysipelothrix rhusiopathiae; Dunbar SA et al.; Here we describe four isolations of Erysipelothrix rhusiopathiae associated with polyarthralgia and renal failure, septic arthritis, classic erysipeloid, and peritonitis . Although the biochemical identification was straightforward in each case, recognition presented a challenge to the clinical microbiologist, since in three cases E . rhusiopathiae was not initially considered due to unusual clinical presentations, in two cases the significance might not have been appreciated because growth was in broth only, and in one case the infection was thought to be polymicrobic . Because the Gram stain can be confusing, abbreviated identification schemes that do not include testing for H(2)S production could allow E . rhusiopathiae isolates to be misidentified as Lactobacillus spp . or Enterococcus spp . in atypical infections.

Appl Environ Microbiol, 2000 Mar, 66(3), 1152 - 7
Antagonistic activity of Lactobacillus acidophilus LB against intracellular Salmonella enterica serovar Typhimurium infecting human enterocyte-like Caco-2/TC-7 cells; Coconnier MH et al.; To gain further insight into the mechanism by which lactobacilli develop antimicrobial activity, we have examined how Lactobacillus acidophilus LB inhibits the promoted cellular injuries and intracellular lifestyle of Salmonella enterica serovar Typhimurium SL1344 infecting the cultured, fully differentiated human intestinal cell line Caco-2/TC-7 . We showed that the spent culture supernatant of strain LB (LB-SCS) decreases the number of apical serovar Typhimurium-induced F-actin rearrangements in infected cells . LB-SCS treatment efficiently decreased transcellular passage of S . enterica serovar Typhimurium . Moreover, LB-SCS treatment inhibited intracellular growth of serovar Typhimurium, since treated intracellular bacteria displayed a small, rounded morphology resembling that of resting bacteria . We also showed that LB-SCS treatment inhibits adhesion-dependent serovar Typhimurium-induced interleukin-8 production.

Appl Environ Microbiol, 2000 Mar, 66(3), 1084 - 92
Characterization and determination of origin of lactic acid bacteria from a sorghum-based fermented weaning food by analysis of soluble proteins and amplified fragment length polymorphism fingerprinting; Kunene NF et al.; The group that includes the lactic acid bacteria is one of the most diverse groups of bacteria known, and these organisms have been characterized extensively by using different techniques . In this study, 180 lactic acid bacterial strains isolated from sorghum powder (44 strains) and from corresponding fermented (93 strains) and cooked fermented (43 strains) porridge samples that were prepared in 15 households were characterized by using biochemical and physiological methods, as well as by analyzing the electrophoretic profiles of total soluble proteins . A total of 58 of the 180 strains were Lactobacillus plantarum strains, 47 were Leuconostoc mesenteroides strains, 25 were Lactobacillus sake-Lactobacillus curvatus strains, 17 were Pediococcus pentosaceus strains, 13 were Pediococcus acidilactici strains, and 7 were Lactococcus lactis strains . L . plantarum and L . mesenteroides strains were the dominant strains during the fermentation process and were recovered from 87 and 73% of the households, respectively . The potential origins of these groups of lactic acid bacteria were assessed by amplified fragment length polymorphism fingerprint analysis.

Can J Microbiol, 1999 Dec, 45(12), 981 - 7
Some probiotic properties of chicken lactobacilli; Gusils C et al.; The beneficial effect of lactobacilli has been attributed to their ability to colonize human and animal gastrointestinal tracts . In this work, adhesion assays with three lactobacillus strains and intestinal fragments obtained from chickens were assessed . Lactobacillus animalis and L . fermentum were able to adhere to three kinds of epithelial cells (crop, small and large intestines) with predominance to small intestine . Among the strains considered, L . fermentum subsp . cellobiosus showed the lowest and L . animalis the highest adhesion ability . Scanning electron microphotographs showing L . animalis and L . fermentum adhering to intestinal cells were obtained . The characterization of L . animalis adhesion indicated that lectin-like structure of this strain has glucose/mannose as specific sugars of binding . However, a calcium requirement was not observed . The adhesion of L . fermentum was reduced by addition of sialic acid or mannose (P < 0.01) . These carbohydrates can be involved in the interaction between adhesin and epithelial surface . In this case, the dependence on bivalent cations was demonstrated . Lactobacillus fermentum was effective in reducing the attachment of Salmonella pullorum by 77%, while L . animalis was able to inhibit (90%, 88%, and 78%) the adhesion of S . pullorum, S . enteritidis, and S . gallinarum to host-specific epithelial fragments respectively . Our results from this in vitro model suggest that these lactobacilli are able to block the binding sites for Salmonella adhesion.

J Food Prot, 2000 Feb, 63(2), 237 - 43
Reduction of biogenic amine formation using a negative amino acid-decarboxylase starter culture for fermentation of Fuet sausages; Bover-Cid S et al.; The ability of Lactobacillus sakei CTC494, a negative amino acid-decarboxylase starter culture, to reduce biogenic amine accumulation during sausage fermentation and storage at 4 and 19 degrees C was studied . The effect on the amine formation of the tyramine producer Lactobacillus curvatus CTC371, as a positive strain, was also examined in comparison to a spontaneous fermentation process without starter culture (control batch) . The polyamines spermine, spermidine, and diaminopropane were not influenced by the ripening, and their levels slightly decreased in all the batches throughout the storage . Tyramine, cadaverine, and putrescine were the main amines formed during the ripening . The addition of starter culture resulted in a decrease on the biogenic amine formation, depending on the strain inoculated . A great reduction in tyramine content was achieved when L . sakei CTC494 was inoculated, whereas L . curvatus CTC371 only attenuated tyramine accumulation compared with the control batch . Both starters were able to significantly limit the production of putrescine and cadaverine, and they inhibited tryptamine and phenylethylamine formation by the wild microbial flora . Tyramine levels of the control sausages rose during the storage at both temperatures, whereas those of cadaverine only increased at 19 degrees C . On the contrary, sausages manufactured through the starter controlled fermentation did not show changes of amine contents during the storage . The addition of a proper selected starter culture is advisable to produce safer sausages with low contents of biogenic amines.

J Food Prot, 2000 Feb, 63(2), 202 - 9
The antimicrobial properties of chitosan in mayonnaise and mayonnaise-based shrimp salads; Roller S et al.; The potential for using chitosan glutamate as a natural food preservative in mayonnaise and mayonnaise-based shrimp salad was investigated . Mayonnaise containing 3 g/liter of chitosan combined with acetic acid (0.16%) or lemon juice (1.2 and 2.6%) was inoculated with log 5 to 6 CFU/g of Salmonella Enteritidis, Zygosaccharomyces bailii, or Lactobacillus fructivorans and stored at 5 and 25 degrees C for 8 days . In mayonnaise containing chitosan and 0.16% acetic acid, 5 log CFU/g of L . fructivorans were inactivated, and numbers remained below the sensitivity limit of the plate counting technique for the duration of the experiment . Z . bailii counts were also reduced by approximately 1 to 2 log CFU/g within the first day of incubation at 25 degrees C, but this was followed by growth on subsequent days, giving an overall growth delay of 2 days . No differences in counts of Z . bailii in mayonnaise stored at 5 degrees C or of Salmonella Enteritidis stored at either temperature were observed . In mayonnaise containing lemon juice at both 1.2 and 2.6%, no substantial differences were observed between the controls and the samples containing chitosan . In shrimp salads stored at 5 degrees C, the presence of a coating of chitosan (9 mg/g of shrimp) inhibited growth of the spoilage flora from approximately log 8 CFU/g in the controls to log 4 CFU/g throughout 4 weeks . However, at 25 degrees C, chitosan was ineffective as a preservative . The results demonstrated that chitosan may be useful as a preservative when combined with acetic acid and chill storage in specific food applications.

J Agric Food Chem, 2000 Feb, 48(2), 239 - 44
Use of two-dimensional electrophoresis to evaluate proteolysis in salmon (Salmo salar) muscle as affected by a lactic fermentation; Morzel M et al.; Two-dimensional electrophoresis was used to study proteolysis in salmon fillets inoculated or not with the starter culture Lactobacillus sake LAD . Protein fragments appeared increasingly with time in both samples, indicating that the main quantitative changes were due to endogenous enzymes . In the most acidic zone (pI = 4-6 . 20) particularly, proteolysis was overall independent from processing . In contrast, fermentation had a significant effect in the pH range 6.20-8.35, suggesting a specificity of the bacterial proteases of L . sake toward alkaline to slightly acidic proteins . Furthermore, fragments surrounding tropomyosin (apparent pI = 4.70) appeared in fermented samples, indicating that the protein may be a suitable substrate for the metabolism of L . sake LAD.

Med Microbiol Immunol (Berl), 1999 Aug, 188(1), 9 - 14
The role of tumor necrosis factor (TNF)-alpha in the antitumor effect of intrapleural injection of Lactobacillus casei strain Shirota in mice; Yasutake N et al.; The involvement of several cytokines in the antitumor effect induced by intrapleural (i.pl.) injection of heat-killed cells of Lactobacillus casei strain Shirota (LC 9018) in mice was investigated . Injection of LC 9018 i.pl . into Meth A fibrosarcoma (Meth A)-bearing mice not only significantly prolonged the survival of the mice, but also effectively inhibited the accumulation of malignant pleural fluid in the thoracic cavity . In the thoracic cavity of tumor-bearing mice treated with LC 9018, we observed large amounts of several cytokines including interleukin (IL)-1beta, interferon (IFN)-gamma, IL-12 and tumor necrosis factor (TNF)-alpha . Both anti-IFN-gamma and anti-IL-12 monoclonal antibody (mAb) treatments partially diminished the antitumor activity of LC 9018 in vivo, while the treatment of anti-IL-1beta mAb did not influence the survival of the mice . However, anti-TNF-alpha mAb treatment completely abolished the antitumor effect of LC 9018 in vivo, suggesting that in this model LC 9018 has a survival-prolonging effect involving certain cytokines . Moreover, i.pl . injection of mouse recombinant TNF-alpha into Meth A-bearing mice pretreated with anti-TNF-alpha mAb partially restored the survival-enhancing effect of LC 9018 . These results led us to conclude that TNF-alpha induced by i.pl . injection of LC 9018 plays an important role in the antitumor effect of LC 9018 in vivo.

Enzyme Microb Technol, 2000 Feb 1, 26(2-4), 209 - 215
Production of lactic acid by Lactobacillus rhamnosus with vitamin-supplemented soybean hydrolysate; Kwon S et al.; Batch fermentation studies were performed to evaluate the potentials of a complex nitrogen source, soybean, as an alternative to yeast extract for the economical production of lactic acid by Lactobacillus rhamnosus . An enzyme-hydrolysate of soybean meal, Soytone, with an adequate supplementation of vitamins was found to be highly effective in supporting lactic acid production from glucose and lactose . The effects of seven selected vitamins: d-biotin, pyridoxine, p-aminobenzoic acid, nicotinic acid, thiamine, pantothenic acid, and riboflavin, on cell growth and lactic acid production were investigated to provide the basis for the optimization of vitamin supplementation to minimize the cost . Pantothenic acid was the most required compound while the other six vitamins were also essential for high lactic acid productivity . As a result of the optimization, 15 g/l yeast extract could be successfully replaced with 19.3 g/l Soytone supplemented with the vitamins, resulting in a production of 125 g/l lactic acid from 150 g/l glucose . The volumetric productivity and lactate yield were 2.27 g/l/h and 92%, respectively, which were higher than those with 15 g/l yeast extract . The raw material cost was estimated to be 21.4 cent/kg lactic acid, which was only approximately 41% of that with yeast extract.

Curr Microbiol, 2000 Apr, 40(4), 245 - 9
Genetic organization and polymorphism of the guaA gene encoding the GMP synthetase in Lactobacillus rhamnosus; Grimaldi C et al.; The guaA gene encoding GMP synthetase was cloned from a potential probiotic strain of Lactobacillus rhamnosus . DNA sequence and Northern blot analysis indicated that (i) guaA did not belong to an guaAB operonic structure, conversely to enteric bacteria, (ii) L . rhamnosus guaA seemed to be highly expressed, and (iii) genetic regulation might differ from Bacillus subtilis . Moreover, differences in the genetic organization of guaA allowed discrimination of some closely related L . rhamnosus strains, with a rapid screening by PCR.

Gerodontology, 1999 Jul, 16(1), 47 - 58
Caries activity and associated risk factors in elderly hospitalised population--15-months follow-up in French institutions; Guivante-Nabet C et al.; Only a few studies have been published concerning hospitalised elderly disabled people . OBJECTIVES: 1) to investigate the oral health status of elderly French patients hospitalised in the two main geriatric hospitals of Paris . 2) to describe the respective influences of general parameters (type of hospitalisation, pathologies and medication) on oral environment parameters . 3) to analyse the influences of these oral parameters on caries activity in Long-Term Care (LTCF) and in rehabilitation facilities (RF) patients and to study the incidence and the time-course of caries in these specific population . SUBJECTS: 117 subjects (mean age = 83.0 years, SD = 7.8, range = 64 to 102 years) were examined at baseline and 32 of the 50 LTCF subjects were reexamined 15-months later . METHODS: The general parameters recorded were age, gender, type of hospitalisation, period of stay, removable prosthesis, general diseases, number of diagnoses, medications with hyposalivary side-effects . The oral environment parameters recorded were flow rate, buffer capacity, mutans streptococci and lactobacilli counts, measured at baseline by tests on stimulated saliva, and plaque index . Crown and root surfaces were recorded according to a modified caries activity index . RESULTS: Among the polypathological subjects (85.5% of the population), the number of diseases ranged from 2 to 8 . The LTCF patients had a significantly higher mean number of diagnoses (3.5; SD = 1.5) than the RF patients (2.8; SD = 1.4) . 76.9% of patients were taking medications with hyposalivary side-effects . The stimulated flow rate ranged from 0.02 ml/min to 5 ml/min . Its mean was significantly lower for LTCF patients (0.67 ml/min; SD = 0.51) than for RF patients (1.12 ml/min; SD = 0.89) . The plaque index was significantly higher in LTCF subjects and in patients with mental diseases . At baseline, 17,442 crown and root surfaces were examined . Flow rate was related to crown caries and buffer capacity to root caries . During the 15-months follow-up, the mean number of active root surfaces was significantly increased: from 0.148 (SD = 0.116) at baseline vs . 0.250 (SD = 0.174) at the second examination . CONCLUSIONS: The strongest relationship in the present study between oral parameters and caries activity was the negative relationship between buffer capacity and active root caries . This study confirms an association between the type of hospitalisation and both salivary parameters flow rate and plaque index . This investigation illustrates the critical need for hygiene and oral care, in this elderly disabled population.

Gerodontology, 1999 Jul, 16(1), 37 - 46
Factors which are associated with dental decay in the older individual; Loesche WJ et al.; OBJECTIVES: To improve reliability of salivary bacterial cultures as a surrogate for plaque levels of cariogenic bacterial species by reporting the salivary CFUs of these organisms as a function of the number of teeth . DESIGN: Cross-sectional collection of data in a convenience sample of adults over 60 years of age . SETTING: Hospital Dental clinic, University bacteriology laboratory . SUBJECTS: 523 older dentate subjects, average age 70, including 412 subjects who were in an independent living status and 111 in a dependent-living situation . MAIN OUTCOME MEASURES: Subjects were examined for decay and the presence of salivary factors including the levels of S . mutans, lactobacilli, yeast and other bacteria . The salivary levels of the bacteria were adjusted for the number of teeth in the mouth, and the resultant values were entered into multivariable logistic regression models along with clinical and other salivary parameters . RESULTS: Mutans streptococci levels reported as CFUs/ml saliva per tooth were significantly associated with coronal surface decay, and lactobacilli, reported in a similar way, were significantly associated with root surface decay . Salivary levels of yeasts, which had previously been associated with decay in this population, were no longer significant using this construct . CONCLUSIONS: This construct of reporting salivary bacteriological data as a function of tooth number and per ml saliva could improve the reliability of bacteriological data obtained in epidemiological studies investigating the role of bacteria in dental decay in the elderly.

Plasmid, 2000 Mar, 43(2), 130 - 6
Nucleotide sequence analysis of the lactococcal EPS plasmid pNZ4000; van Kranenburg R et al.; The complete 42180-bp nucleotide sequence of the mobilization plasmid pNZ4000, coding for exopolysaccharide (EPS) production in Lactococcus lactis, was determined . This plasmid contains a region involved in EPS biosynthesis, four functional replicons, a region containing mobilization genes, and three origin of transfer (oriT) sequences . Sequences identical to these oriT sequences were also found on two other lactococcal plasmids and a plasmid from Lactobacillus helveticus . Several complete and partial IS elements were identified on pNZ4000, including iso-ISS1, iso-IS946, and iso-IS982 sequences . Furthermore, pNZ4000 contains a gene cluster that may encode a cobalt transport system and a gene that encodes a CorA homologue which may function as a magnesium transporter .

Poult Sci, 2000 Jan, 79(1), 7 - 11
Lactobacillus flora in the cloaca and vagina of hens and its inhibitory activity against Salmonella enteritidis in vitro; Miyamoto T et al.; Lactobacilli in the cloaca and vagina of 40 normal laying hens were investigated quantitatively and qualitatively, and their ability to inhibit growth of Salmonella enteritidis (SE) was examined using a spot-the-lawn technique . All samples of cloacal contents and half the samples of vaginal mucus were positive for lactobacilli . The means +/- SD of total Lactobacillus counts in the cloaca and those in the vagina were log10 5.5 +/- 1.1 and 2.5 +/- 2.6 cfu/g, respectively . In the cloaca, Lactobacillus acidophilus was isolated from 92.5% of hens, and Lactobacillus salivarius was isolated from 85.0% of hens, whereas Lactobacillus fermentum was isolated from only one hen . In the vagina, L . acidophilus and L . salivarius were isolated from 42.5% of hens . In the inhibition assay in vitro, all strains of Lactobacillus from cloacal contents and vaginal mucus inhibited growth of SE . There was a wide range of the inhibitory activity even in the same species . No difference of the growth inhibition zone was observed between lactobacilli from cloaca and those from vagina . The present study suggested that lactobacilli in the cloaca and vagina of hens might have a protective effect against SE colonization.

Biochim Biophys Acta, 2000 Feb 29, 1490(3), 355 - 61
A gene cluster encoding plantaricin 1.25beta and other bacteriocin-like peptides in Lactobacillus plantarum TMW1.25; Ehrmann MA et al.; Plantaricin 1.25beta is a thermostable class two bacteriocin produced by Lactobacillus plantarum TMW1.25 isolated from sausage fermentation . It is co-produced with several other bacteriocin-like peptides . Using oligonucleotides derived from previously determined peptide sequences, a 3.8 kb DNA fragment could be amplified . A neighboring 1.8 kb fragment was amplified using ligation-anchored single-specific-primer PCR . Sequencing of the complete 5.6 kb stretch revealed that the structural gene for plantaricin 1.25beta, plnB, was located downstream of another bacteriocin gene, plnC . Seven other open reading frames were detected, including plnK encoding a bacteriocin-like peptide, but not including any putative immunity genes . Interestingly, the gene cluster contained an IS30-like insertion sequence, designated IS125, as well as an ISS1 homolog.

Hua Xi Yi Ke Da Xue Xue Bao, 1998 Mar, 29(1), 33 - 7
{The effect of removable partial denture on the composition of bacteria on the apt-to-decay site of abutment teeth}; Gao N et al.; This study was aimed at the composition of plaques which were on the base teeth's carious sensitive sites, just after the insertion of the removable partial denture (RPD) . The results showed that the ratios of bacterial detection in different teeth at the same period and those on the different sites of same teeth at different periods were not significantly different . There was a tendency that the detection ratio of the stomatococcus at the early period was higher than that of other bacteria, but at the middle period the ratios declined, and at the late period it was higher again . The detection ratio of the bacillus was on the contrary in the study . At the same time, the composition of the plaques changed significantly after the dentures had been used for 7, 14, and 21 days and 3 months . After 3 months, the ratios of the stomatococcus and the bacillas returned to their normal levels . The 3 main cariogenic bacteria were all detected in this study . The Streptococcus mutant was the dominant bacterium in the plaques and its ratio went up with the time duration . The ratio for the lower second molar was higher than that for the mandibular second premolar (P < 0.05) . The detection ratios of the Actinomyces viscosus and lactobacillus were lower . In conclusion, after the insertion of RPD, the oral microbial ecosystem would be changed and the cariogenic bacteria began to implant on the surface of the base teeth . So RPD is a potential factor to cause the caries.

Rinsho Biseibutshu Jinsoku Shindan Kenkyukai Shi, 1999 Dec, 10(2), 77 - 82
Identification of Lactobacillus species of human origin by a commercial kit, API50CHL; Song YL et al.; The efficacy of a biochemical kit, API50CHL kit, for identification of intestinal and vaginal lactobacilli from humans was evaluated by comparing with the results of DNA-DNA hybridization assay . The results showed that in total only 52 of the 172 strains (30.2%) tested were identified correctly by the kit at species level . Especially all strains of some species, such as Lactobacillus gasseri and Lactobacillus crispatus, were misidentified as Lactobacillus acidophilus by the kit . However, the kit was found to be reliable for identification of Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus rhamnosus, and Lactobacillus salivarius . This suggests that the exact identification of Lactobacillus isolates from human stool and vaginal specimens by API50CHL kit is difficult without the support of modern genotypic technique.

Sex Transm Dis, 2000 Feb, 27(2), 74 - 8
Effect of chlorhexidine on genital microflora, Neisseria gonorrhoeae, and Trichomonas vaginalis in vitro; Rabe LK et al.; BACKGROUND: Chlorhexidine is a disinfectant that has been used in skin and mouth washes and as a preservative in some vaginal lubricants . A gel containing 0.25% chlorhexidine gluconate has been found to be effective against Chlamydia trachomatis in vitro and in animal models . Applied vaginally, 5 g of this gel could achieve vaginal fluid concentrations of < or = 1250 microg/ml . GOAL: To test the in vitro activity of chlorhexidine in a gel over a pH range of 4 to 8 in the presence or absence of blood . STUDY DESIGN: Organisms were exposed to chlorhexidine for 30 minutes to 2 hours, and the minimum cidal concentration (MCC) was calculated . RESULTS: The MCC for Neisseria gonorrhoeae was 25 microg/ml at 30 minutes and 12.5 microg/ml at 1 to 2 hours of exposure, whereas the MCC for Trichomonas vaginalis was 1250 microg/ml . Chlorhexidine was more active at pH 8 than pH 4, and less active in the presence of blood . The MCC for Lactobacillus crispatus was 1250 microg/ml at pH 4 and only 125 microg/ml at pH 8 . CONCLUSIONS: Based on its in vitro activity, chlorhexidine may be an appropriate topical microbicide for prevention of gonorrhea, but not for prevention of trichomoniasis . This study suggests that the presence of blood and pH affect the activity of chlorhexidine against genital pathogens and commensals.

Zentralbl Veterinarmed B, 1999 Dec, 46(10), 683 - 7
Aggregation of sow lactobacilli with diarrhoeagenic Escherichia coli; Kmet V et al.; A total of 20 strains of lactobacilli were isolated from the oesophagus and vagina of 20 sows at the time of partus . Aggregation activity was seen between six homofermentative autoaggregative lactobacilli and three strains of pathogenic Escherichia coli with F4, F5 and F6 fimbriae . The highest aggregation activity was observed between vaginal Lactobacillus acidophilus PV 32 or oesophageal OE 2/1 and E . coli with F4 (K88) . The presence of aggregation-promoting factor (APF) was confirmed by polymerase chain reaction (PCR) with primers of a specific fragment the apf gene derived from human L . gasseri 4B2 in one oesophageal L . acidophilus strain OE 2/1 . We propose that autoaggregative lactobacilli that aggregate with diarrhoeagenic E . coli can express a class of APF proteins that exhibit the function of an aggregation mediator.

J Infect Dis, 2000 Feb, 181(2), 595 - 601
Effects of contraceptive method on the vaginal microbial flora: a prospective evaluation; Gupta K et al.; A prospective evaluation of 331 university women who were initiating use of oral contraceptive pills (OCPs), a cervical cap, diaphragm-spermicide, or other spermicidal methods was done to assess the effects of commonly used contraceptive methods on the vaginal flora . Vaginal introital cultures were performed at baseline and then weekly for 1 month . The prevalence of Escherichia coli vaginal colonization and of abnormal vaginal Gram stain scores (Nugent criteria) increased significantly among women using a cervical cap or diaphragm-spermicide but not among women using OCPs . Women with E . coli colonization were significantly more likely to have an abnormal Nugent score and an absence of lactobacilli . In a multivariate model, use of spermicidal contraception in the preceding week was associated with an abnormal Nugent score and with colonization with E . coli, Enterococcus species, and anaerobic gram-negative rods . Thus, spermicidal methods of contraception are associated with alterations of the vaginal microflora that consequently may predispose women to genitourinary infections.

J Infect Dis, 2000 Feb, 181(2), 587 - 94
Intravaginal practices, vaginal flora disturbances, and acquisition of sexually transmitted diseases in Zimbabwean women; van De Wijgert JH et al.; One hundred sixty-nine Zimbabwean women were studied to determine whether the use of intravaginal practices (cleaning with the fingers, wiping the vagina, and inserting traditional substances) are associated with disturbances of vaginal flora and acquisition of sexually transmitted diseases (STDs) . Subjects were interviewed and received counseling and a pelvic examination at enrollment, 1 month, and 6 months, and vaginal specimens were collected at enrollment and at 6 months . Users were more likely than nonusers to have vaginal flora disturbances but were not more likely to acquire an STD (relative risk {RR}, 2.15; P=.188) . Certain vaginal flora disturbances were associated with increased STD incidence and HIV prevalence . The absence of lactobacilli from the vaginal flora was associated with being positive for human immunodeficiency virus in baseline (odds ratio {OR}, 0.24; P=.001) and 6-month transition multivariate models (OR, 0.39; P=.025) . The presence of clue cells at baseline was associated with a higher incidence of STDs (RR, 1 . 94; P=.025).

J Dent, 2000 Feb, 28(2), 111 - 6
A five-year clinical evaluation of Class II composite resin restorations; Kohler B et al.; OBJECTIVES: To study the clinical efficacy of posterior composite resin restorations placed in general practice after five years . METHODS: Two commercial composite resin systems were used . Three general practitioners placed the restorations at a Public Dental Health Service Office . The patients were not selected specifically for this study . Class II cavities were restored with Superlux Molar and P-50 APC composite systems on an alternate basis . At baseline, 63 restorations were placed in molars and premolars in 45 patients . For primary caries, generally a conservative cavity design was used (n = 23), while replacements of amalgams resulted in the larger conventional Class II design (n = 40) . The restorations were assessed using a modified USPHS criteria . Wear measurements were determined by the Leinfelder method . Photographs and bite-wing radiographs were taken to supplement the clinical evaluation of colour match, marginal adaptation and recurrent caries . Saliva sampling was performed to determine the rate of secretion and the level of mutans streptococci and lactobacilli . RESULTS: At the five-year review 51 restorations were available for examination, of which nine restorations were rated clinically unacceptable . Including the failed restorations (n = 7), at the three-year review, a total of 16 restorations had failed (27.6%) over a five-year period . The most common reasons for failure were recurrent caries (n = 7) and marginal defects (n = 4) . The mean wear of Superlux Molar was 167 microns and of P-50 APC 158 microns . Eight of the 11 patients with failed restorations due to caries and marginal defects had high counts of mutans streptococci at baseline . CONCLUSIONS: The failures in the present group of patients did not specifically relate to material, tooth type or cavity design . However, it is suggested that patient factors such as caries activity should be monitored and managed.

Acta Crystallogr D Biol Crystallogr, 1999 Dec, 55 ( Pt 12), 1978 - 85
Three-dimensional structure of the Gly121Tyr dimeric form of ornithine decarboxylase from Lactobacillus 30a; Vitali J et al.; Ornithine decarboxylases catalyze the conversion of ornithine to putrescine at the beginning of the polyamine pathway . Ornithine decarboxylase (ODC) from Lactobacillus 30a is a 990612 Da dodecamer composed of six homodimers . A single point mutation (Gly121Tyr) was found to prevent association of dimers into dodecamers . The dimeric protein has been crystallized at pH 7.0 in the presence of guanosine triphosphate (GTP) . Crystals belong to space group P3(2)21, with unit-cell parameters a = 111.8, c = 135.9 A and one monomer in the asymmetric unit . The structure was determined by molecular replacement and refined using simulated annealing to R = 0.211 at 2 . 7 A resolution . The GTP-binding site was analyzed in detail . The protein exhibits a novel binding mode for GTP which is different from that seen in most G-proteins or GTPases . Central to this binding scheme appear to be three lysines, Lys190, Lys374 and Lys382, which form salt bridges with the three phosphates, and Thr191, which hydrogen bonds with the guanine base . Furthermore, the structure suggests that there is some flexibility in the wing domain, which can change its orientation as the protein adapts to its environment . The active site is similar to that of the native enzyme, consistent with the observation that the enzyme activity does not depend on its dodecameric state.

Int J Clin Pract, 1999 Apr-May, 53(3), 179 - 84
The effect of supplementation with milk fermented by Lactobacillus casei (strain DN-114 001) on acute diarrhoea in children attending day care centres; Pedone CA et al.; The objective of this study was to determine if supplementation with milk fermented by yogurt cultures and Lactobacillus casei (strain DN-114 001) could lessen acute diarrhoea in healthy children . The study was conducted over six months, with 287 children aged 18.9 (SD 6.0) months, comprising three periods of one month supplementation, each month being followed by one month without supplementation . Subjects were supplemented daily with either 125 g or 250 g (according to age) of one of three tested dairy products: standard yogurt, milk fermented by yogurt cultures and Lactobacillus casei (10(8) cfu/ml), or a jellied milk (control product) . A daily record was kept of the number and type of stools . Although the incidence of diarrhoea was not shown to be different between the groups, the severity of diarrhoea over the six-month study was significantly decreased (4.3 days) with the supplementation of L . casei fermented milk compared with the jellied milk (8.0 days) (p = 0.009).

Biotechnol Prog, 2000 Jan-Feb, 16(1), 59 - 63
Characterization of Lactobacillus carbohydrate fermentation activity using immobilized cell technique; Corton E et al.; A microbial bioreactor based on calcium alginate immobilized Lactobacillus cells coupled to a pH electrode was developed for quantitative determination of carbohydrate fermentation activity . A high biomass (10(10) cfu mL(-)(1)) and particular pregrowth conditions were needed . Reduction of catabolite repression by monosaccharides was achieved by pregrowth in lactose . The evolution of acid production in a continuous flow-stopped flow bioreactor was monitored for different sugar solutions in contact with the immobilized bacteria . The resulting slopes (DeltamV/Deltat) were used to quantify the fermentation capability for a defined sugar related to that of glucose, which was taken as 100% . The procedure is simple, being based on pH variation that can give quantitative results compared to other reported techniques for carbohydrate fermentation pattern from which only qualitative results are obtained . In addition, it offers reduction in time and costs and is a suitable tool for the rapid analysis of isolated strains and in studies of modifications of sugar metabolism in mutants.

J Appl Microbiol, 1999 Dec, 87(6), 923 - 31
Purification and characterization of a bacteriocin produced by Lactobacillus acidophilus IBB 801; Zamfir M et al.; Lactobacillus acidophilus IBB 801 produces a small bacteriocin, designated acidophilin 801, with an estimated molecular mass of less than 6.5 kDa . It displays a narrow inhibitory spectrum (only related lactobacilli but including the Gram-negative pathogenic bacteria Escherichia coli Row and Salmonella panama 1467) with a bactericidal activity . The antimicrobial activity of cell-free culture supernatant fluid was insensitive to catalase but sensitive to proteolytic enzymes such as trypsin, proteinase K and pronase, heat-stable (30 min at 121 degrees C), and maintained in a wide pH range . The proteinaceous compound was isolated from cell-free culture supernatant fluid and purified . Crude bacteriocin was isolated as a floating pellicle after ammonium sulphate precipitation (40% saturation) and partially purified by extraction/precipitation with chloroform/methanol (2/1, v/v) . Further purification to homogeneity was performed by reversed phase Fast Performance Liquid Chromatography . The amino acid composition was determined . Amino acid sequencing revealed that the N-terminal end was blocked.

Int J Gynaecol Obstet, 1999 Nov, 67 Suppl 1, S35 - 8
The future of bacterial vaginosis-related research; Taylor-Robinson D; Various ways and criteria are used to diagnose BV . Guidelines should be redrawn and they should embody greater uniformity . The etiology of BV remains enigmatic . However, various observations suggest that host factors, possibly hormonal, cause an imbalance in the vaginal microflora . Exogenous factors, such as semen and antibiotics, may then help to bring about a more prolonged change . This forms a working hypothesis for further exploration . The role of the lactobacillus phage in the development of BV also needs to be determined . Various conditions may occur as a consequence of BV in non-pregnant and pregnant women and BV may also affect men . A subjective assessment of the extent to which these associations occur or are likely to be shown to occur by further investigations is presented in Table 1 . The ability to cure acute BV needs to be improved as does the treatment of chronic BV, for which vaginal recolonization with exogenous lactobacilli is an approach to be evaluated further.

Cancer Lett, 1999 Dec 1, 147(1-2), 125 - 37
Inhibitory effects of freeze-dried milk fermented by selected Lactobacillus bulgaricus strains on carcinogenesis induced by 1,2-dimethylhydrazine in rats and by diethylnitrosamine in hamsters; Balansky R et al.; Fermented milk products might be used for cancer chemoprevention due to their putative anticarcinogenic and antitumor activities . The diet was supplemented with freeze-dried milk fermented by Lactobacillus bulgaricus strain LBB.B 144 (product FFM.B 144) added throughout the experiment at doses of 1.3 g and 2.5 g per rat, 5 times a week starting 3 weeks before the first carcinogen injection . This treatment significantly inhibited, by 26.2-28.6% and by 34.2%, the total intestinal carcinogenesis induced by 1,2-dimethylhydrazine (DMH, 21 mg/kg, s.c., once per week for 20 weeks) in male and female BD6 rats, respectively . FFM.B144 decreased the tumor incidence and multiplicity in large bowel, caecum, and duodenum . Protective effects were better expressed in female animals, with exception of that observed in duodenum . Supplementation of diet with freeze-dried milk fermented by Lactobacillus bulgaricus strain LBB.B5 (product FFM.B5) inhibited DMH-induced carcinogenesis only in the large bowel, but had no significant protective effect when all intestinal tumors were taken into account . However, both freeze-dried products favorably shifted the differentiation of large bowel tumors by increasing the proportion of benign and highly differentiated malignant tumors and decreasing in parallel the number of poorly differentiated carcinomas without influencing the tumor size . A lower number of cases with visible mesenterial metastasis was also observed in FFM-treated rats . In addition, both FFM.B 144 and FFM.B5 significantly inhibited, by 26-33%, the induction in the same rats of ear-duct tumors . FFM.B144 but not FFM.B5 was also effective in inhibiting the tracheal carcinogenesis induced in Syrian golden hamsters by diethylnitrosamine (DEN, 100 mg/kg, two s.c . injections), the protective effect being better expressed in female animals . The anticarcinogenic potential of some fermented milk products might be exploited in chemoprevention of cancer in humans.

Adv Exp Med Biol, 1999, 473, 185 - 90
Potentiation of the effectiveness of Lactobacillus casei in the prevention of E . coli induced diarrhea in conventional and gnotobiotic pigs; Bomba A et al.; The influence of preventive administration of Lactobacillus casei subsp . casei and maltodextrin KMS X-70 on Escherichia coli 08: K88 adhesion in the gastrointestinal tract of 11 conventional and 6 gnotobiotic piglets was investigated . The preventive administration of L . casei alone had almost no inhibitory effect on the adherence of E . coli to the jejunal mucosa of gnotobiotic and conventional piglets while the lactobacilli administered together with maltodextrin decreased the number of E . coli colonising jejunal mucosa of gnotobiotic piglets by 1 logarithm (4.95 log 10/cm2) in comparison with the control group (5.96 log 10/cm2) . L . casei administered in combination with maltodextrin decreased the number of E . coli colonising the jejunum of conventional piglets by more than two and half logarithm (4.75 log 10/cm2, p < 0.05) in comparison with the control (7.42 log 10/cm2) . The inhibitory effect of Lactobacillus casei and maltodextrin KMS X-70 on the adhesion of E . coli to the intestinal mucosa of conventional and gnotobiotic pigs was probably mediated by Lactobacillus--produced antibacterial substances and stimulation of immunity.

Appl Environ Microbiol, 2000 Feb, 66(2), 606 - 13
Bacteriocin production with Lactobacillus amylovorus DCE 471 is improved and stabilized by fed-batch fermentation; Callewaert R et al.; Amylovorin L471 is a small, heat-stable, and hydrophobic bacteriocin produced by Lactobacillus amylovorus DCE 471 . The nutritional requirements for amylovorin L471 production were studied with fed-batch fermentations . A twofold increase in bacteriocin titer was obtained when substrate addition was controlled by the acidification rate of the culture, compared with the titers reached with constant substrate addition or pH-controlled batch cultures carried out under the same conditions . An interesting feature of fed-batch cultures observed under certain culture conditions (constant feed rate) is the apparent stabilization of bacteriocin activity after obtaining maximum production . Finally, a mathematical model was set up to simulate cell growth, glucose and complex nitrogen source consumption, and lactic acid and bacteriocin production kinetics . The model showed that bacterial growth was dependent on both the energy and the complex nitrogen source . Bacteriocin production was growth associated, with a simultaneous bacteriocin adsorption on the producer cells dependent on the lactic acid accumulated and hence the viability of the cells . Both bacteriocin production and adsorption were inhibited by high concentrations of the complex nitrogen source.

Immunol Cell Biol, 2000 Feb, 78(1), 55 - 66
Immune response to orally consumed antigens and probiotic bacteria; Chin J et al.; The gut mucosal system must fulfil conflicting roles in suppressing immune responses against orally fed antigens (tolerance) while still retaining the ability to respond to potential enteric pathogens . It must also, to a large degree, not mount an immune response against commensal enteric bacteria and the administration of large numbers of probiotic bacteria formulated as dietary supplements in food products . Contrary to this dogma, it has been found that feeding ovalbumin as a marker antigen, in association with selected probiotic bacteria, appears to prime for an intestinal immune response that is further augmented by skin vaccination . Skin immunization is known to stimulate a strong innate, humoral and cellular immune response . Such dominant immunogenic signals appear to override tolerogenic signals engendered by oral feeding of antigen . High-dose antigen feeding stimulated a strong Th2-dependent antibody response to skin vaccination but completely suppressed cytotoxic T cell responses . This was true even when ovalbumin was administered in conjunction with various selected probiotic bacteria . However, while yeast appeared to be better at priming for an enhanced humoral response, Lactobacillus fermentum and Staphylococcus carnosus were more effective in enhancing the postvaccinal lymphoproliferative response against ovalbumin.

Appl Microbiol Biotechnol, 1999 Dec, 53(1), 69 - 74
Isolation and characterisation of a ropy Lactobacillus strain producing the exopolysaccharide kefiran; Micheli L et al.; A capsular-polysaccharide-producing strain, LM-17, was isolated from kefir grains and was identified as a slime-forming, rod-shaped Lactobacillus . According to 1H- and 13C-NMR spectral data, the exopolysaccharide produced by the isolated bacterial strain is identical to the glucogalactan extracted from kefir grains and therefore known as kefiran . The kefiran produced was characterised by means of viscosity, optical rotatory power, circular dichroism and IR spectral measurements . A batch procedure was set up for the culture and extraction of the exopolysaccharide in laboratory conditions, resulting in a yield of 2 g/l purified kefiran from the culture supernatant of the LM-17 strain.

J Inorg Biochem, 1999 Nov-Dec, 77(3-4), 185 - 95
Thermolysis of coenzymes B12 at physiological temperatures: activation parameters for cobalt-carbon bond homolysis and a quantitative analysis of the perturbation of the homolysis equilibrium by the ribonucleoside triphosphate reductase from Lactobacillus leichmannii; Brown KL et al.; The kinetics of the thermolysis of 5'-deoxyadenosylcobalamin (AdoCbl, coenzyme B12) in aqueous solution, pH 7.5, have been studied in the temperature range 30-85 degrees C using AdoCbl tritiated at the adenine C2 position and the method of initial rates . Combined with a careful analysis of the distribution of adenine-containing products, the results permit the dissection of the competing rate constants for carbon-cobalt bond homolysis and heterolysis . After correction for the temperature-dependent occurrence of the much less reactive base-off species of AdoCbl, the activation parameters for homolysis of the base-on species were found to be delta H++homo,on = 33.8 +/- 0.2 kcal mol-1 and delta S++homo,on = 13.5 +/- 0.7 cal mol-1 K-1, values not significantly different from those determined by Hay and Finke (J . Am . Chem . Soc . 108 (1986) 4820), in the temperature range 85-115 degrees C . In contrast, the heterolysis of base-on AdoCbl was characterized by a much smaller enthalpy of activation (delta H++het,on = 18.5 +/- 0.2 kcal mol-1) and a negative entropy of activation (delta S++het,on = -34.0 +/- 0.7 cal mol-1 K-1) so that heterolysis, which is minor pathway at elevated temperatures, is the dominant pathway for AdoCbl decomposition at physiological temperatures . Using literature values for the rate constant for the reverse reaction, the equilibrium constant for AdoCbl homolysis at 37 degrees C was calculated to be 7.9 x 10(-18) . Comparison with the equilibrium constant for this homolysis at the active site of the ribonucleoside triphosphate reductase from Lactobacillus leichmannii shows that the enzymes shifts the equilibrium constant towards homolysis products by a factor of 2.9 x 10(12) (17.7 kcal mol-1) by binding the thermolysis products with an equilibrium constant of 7.1 x 10(16) M-2, compared to the bonding constant for AdoCbl of 2.4 x 10(4) M-1.

Eur J Cancer Prev, 1999 Dec, 8(6), 533 - 7
Effects of intestinal bacteria on the development of colonic neoplasm II . Changes in the immunological environment; Horie H et al.; To study the effects of intestinal bacteria on the development of colonic neoplasm, we have established gnotobiotic mice with a single species of intestinal bacteria . In the previous study, the incidence of colonic adenoma induced with 1,2-dimethylhydrazine (DMH) in the gnotobiotic mice with Lactobacillus acidophilus, gnotobiotic mice with Escherichia coli and germ-free mice were 30, 50 and 74%, respectively . In this study, 7-week-old mice in each group were sacrificed without the administration of DMH to examine the constituents of immuno-competent cells in various mouse organs using flow cytometry . In the gnotobiotic mice, CD3 intermediate interleukin (IL)-2Rbeta positive cells were observed predominantly in the liver . In the gnotobiotic mice with L . acidophilus, Mac-1 positive Gr-1 positive cells were observed predominantly in the colonic lamina propria . The activation of extrathymic T cells in the liver and granulocytes in the colonic mucosa may be related to anti-neoplastic effects of L . acidophilus in this experimental model.

Microbios, 1999, 100(397), 135 - 44
Prevalence and persistence of amoxycillin-resistant bacteria in the dental plaques of adults; Packer S et al.; The prevalence and persistence of amoxycillin-resistant organisms (ARO) in the dental plaque of adults was determined . Plaque samples from ten adults, who had not taken antibiotics during the previous 6 months, were screened for ARO on three occasions at intervals of 3 months . The ARO were tested for their susceptibility to amoxycillin and to amoxycillin plus clavulanic acid as well as their ability to produce beta-lactamases . The ARO were found in all subjects on at least one sampling occasion and in 87% of the 30 samples examined . Of the 36 ARO isolated, 33% were yeasts, 19% were staphylococci, 19% Actinomycetes spp . and 14% lactobacilli, whilst seventeen of the isolates produced a beta-lactamase and seven of these were sensitive to coamoxiclav . The proportion of ARO in an individual fluctuated widely over the study period . It is suggested that the ARO are frequently, though transiently, present in low numbers in the plaque of individuals who have not recently received antibiotics.

Infect Immun, 2000 Feb, 68(2), 752 - 9
Activation of human peripheral blood mononuclear cells by nonpathogenic bacteria in vitro: evidence of NK cells as primary targets; Haller D et al.; The interaction of commensal bacteria with immunocompetent cells may occur in definite compartments of the mucosal immune system, as limited translocation through the epithelial barrier cannot be excluded . In this study the stimulation of human peripheral blood mononuclear cells and purified lymphocyte subsets by nonpathogenic gram-positive lactobacilli (Lactobacillus johnsonii and Lactobacillus sakei) and gram-negative Escherichia coli was investigated . The various bacterial strains induced a differential cytokine pattern . Whereas L . johnsonii and L . sakei strongly induced gamma interferon (IFN-gamma) and interleukin-12 (IL-12), E . coli and lipopolysaccharide (LPS) preferentially induced IL-10 after 16 h of stimulation . Expression of activation antigens CD69 and CD25 was observed on (CD3(-) CD56(+)) natural killer (NK) cells after stimulation of total human peripheral blood mononuclear cells . All bacteria mediated the proliferation of human peripheral blood mononuclear cells, and the strongest proliferative response was observed with L . johnsonii . Purified CD4(+), CD8(+), and CD19(+) lymphocyte subsets were not activated upon bacterial stimulation but showed normal response to a mitogenic stimulus . In contrast, purified NK cells upregulated the IL-2Ralpha chain (CD25) and underwent proliferation when stimulated by L . johnsonii . E . coli and LPS were less effective in inducing proliferation . Expression of CD25 or secretion of IFN-gamma from purified NK cells was significantly increased in the presence of bacterially primed macrophages, indicating that full activation required both bacterium- and cell contact-based signals derived from accessory cells.

Int J Food Microbiol, 1999 Dec 15, 53(2-3), 115 - 25
Hydrolysis of muscle myofibrillar proteins by Lactobacillus curvatus and Lactobacillus sake; Sanz Y et al.; Proteolytic enzyme activities of whole cells and cell free extracts (CFE) of Lactobacillus curvatus CECT 904 and Lactobacillus sake CECT 4808 were characterised using synthetic chromogenic compounds and myofibrillar proteins as substrates . The hydrolytic action was monitored by SDS-PAGE and reverse phase-HPLC analyses . The CFE of L . sake partially contributed, together with muscle enzymes, to the initial hydrolysis of myofibrillar proteins . Whole-cells of both L . curvatus and L . sake generated peptides considered important for cured-meat taste . The peptide mapping, resulting from the action on the substrates assayed, revealed a profile of extra and intracellular enzymes . Both strains expressed strong amino acid metabolism.

Am J Gastroenterol, 2000 Jan, 95(1 Suppl), S22 - 5
Probiotics and immune response; Cunningham-Rundles S et al.; Current evidence supports the concept that oral administration of probiotic lactobacilli may be therapeutic in preventing antibiotic-associated diarrhea in children and in reestablishing normal flora in the gastrointestinal tract . Children with human immunodeficiency virus (HIV) infections may have episodes of diarrhea and frequently experience malabsorption associated with possible bacterial overgrowth; together these may interact to produce the growth abnormalities characteristic of this group . The overall objective of this investigation has been to determine whether oral administration of the probiotic Lactobacillus plantarum 299v could improve nutrient status and promote growth in children congenitally exposed to HIV . In addition, the possible beneficial effect of Lactobacillus plantarum 299v in modulating immune response was evaluated . In preliminary results described here, we report on the ability of Lactobacillus plantarum 299v to colonize children with HIV and to elicit specific systemic immune response after oral supplementation.

Am J Gastroenterol, 2000 Jan, 95(1 Suppl), S19 - 21
Probiotics and inflammatory bowel diseases; Schultz M et al.; The pathogenesis of inflammatory bowel diseases remains elusive . However, the resident luminal bacteria seem to be an important factor in their development and chronicity . There is evidence to suggest that inflammatory bowel diseases may represent an aggressive immunological response to the resident luminal flora, rather than an alteration in the normal flora . In prior research, probiotic bacteria were effective in managing certain acute diarrheal diseases, and investigators reported that certain Lactobacilli strains seem to have protective immunomodulating and bowel flora manipulating properties . We report the results of recent studies with probiotics in animal models, in which promising effects for the treatment of chronic inflammatory bowel disease, pouchitis, and ulcerative colitis were observed . Future research may clarify a precise role for probiotic bacteria in managing chronic inflammatory bowel diseases.

Am J Gastroenterol, 2000 Jan, 95(1 Suppl), S8 - 10
The effects of antibiotic use on gastrointestinal function; Levy J; The bacterial flora of the gastrointestinal (GI) tract plays an important role in maintaining the integrity of the enterocyte, modulating metabolic and immunologic processes, and protecting against colonization by invasive pathogens . Disruption of this finely tuned and stable gut flora by antibiotics, infection, chemotherapy, or radiation has profound effects on the protective barrier and results in overgrowth by pathogens, invasion and translocation of toxins, and life-threatening infections . Use of antibiotics promotes the emergence of resistant organisms, and multiple-antibiotic resistance has become a major public health issue . Preservation of protective species or recolonization with nonpathogenic yeasts or lactobacilli during periods of stress (infections, drugs) has begun to show promise in the management of patients receiving multiple antibiotics, particularly in hospital-acquired infections.

J Pediatr Gastroenterol Nutr, 2000 Jan, 30(1), 68 - 72
Clinical evaluation of the addition of lyophilized, heat-killed Lactobacillus acidophilus LB to oral rehydration therapy in the treatment of acute diarrhea in children; Simakachorn N et al.; BACKGROUND: Addition of a medication to the World Health Organization protocol for treatment of acute diarrhea in children is controversial . In this trial, the clinical efficacy of a medication (Lacteol Fort sachets; Laboratoire du Lacteol du Docteur Boucard, Houdan France) containing lyophilized heat-killed Lactobacillus acidophilus LB was assessed as an adjunct to oral rehydration therapy . METHODS: Children aged 3 to 24 months with acute diarrhea and mild or moderate dehydration were enrolled in the study . Children received oral rehydration therapy for the first 4 hours . After this first rehydration phase, undiluted milk formula or breast milk was fed alternately with oral rehydration solution . Children were fed rice gruel as tolerated . They received either one sachet containing 10 billion of lyophilized heat-killed L . acidophilus LB or placebo at admission and at 12-hour intervals for five doses . RESULTS: Seventy-three children (37 L . acidophilus LB, 36 placebo) were enrolled, of whom 40 (17 L . acidophilus LB, 23 placebo) received an antibiotic before inclusion . Rotavirus was identified in approximately 50% of the children in each group . After 24 hours of treatment, the number of rotavirus-positive children with watery stools was significantly lower (p = 0.012) in the L . acidophilus LB group . Mean duration of diarrhea was decreased (p = 0.034) with L . acidophilus LB (43.4 hours) versus placebo (57.0 hours) . This decreased duration was particularly marked in children with no antibiotic therapy before inclusion (31.1 hours): 42.9 hours for the L . acidophilus LB group versus 74.0 hours for the placebo group (p = 0.016) . CONCLUSIONS: Addition of L . acidophilus LB to oral rehydration therapy was effective in the treatment of children with acute diarrhea by decreasing the duration of diarrhea.

J Pediatr Gastroenterol Nutr, 2000 Jan, 30(1), 54 - 60
Lactobacillus GG administered in oral rehydration solution to children with acute diarrhea: a multicenter European trial; Guandalini S et al.; BACKGROUND: The probiotic Lactobacillus GG is effective in promoting a more rapid recovery of acute, watery diarrhea in children with rotavirus enteritis . Very limited information is available, however, on the potential role of such agents in non-rotaviral diarrheal episodes . Furthermore, no evidence is available concerning the efficacy of Lactobacillus GG administered in the oral rehydration solution during oral rehydration therapy . A multicenter trial was conducted to evaluate the efficacy of Lactobacillus GG administered in the oral rehydration solution to patients with acute-onset diarrhea of all causes . METHODS: Children 1 month to 3 years of age with acute-onset diarrhea were enrolled in a double-blind, placebo-controlled investigation . Patients were randomly allocated to group A, receiving oral rehydration solution plus placebo, or group B, receiving the same preparation but with a live preparation of Lactobacillus GG (at least 10(10) CFU/250 ml) . After rehydration in the first 4 to 6 hours, patients were offered their usual feedings plus free access to the same solution until diarrhea stopped . RESULTS: One hundred forty children were enrolled in group A, and 147 in group B . There were no differences at admission between the groups in age, sex, previous types of feeding, previous duration of diarrhea, use of antibiotics, weight, height, weight-height percentile, prevalence of fever, overall status, degree of dehydration, and percentage of in- versus outpatients . Duration of diarrhea after enrollment was 71.9 +/- 35.8 hours in group A versus 58.3 +/- 27.6 hours in group B (mean +/- SD; P = 0.03) . In rotavirus-positive children, diarrhea lasted 76.6 +/- 41.6 hours in group A versus 56.2 +/- 16.9 hours in groups B (P < 0.008) . Diarrhea lasted longer than 7 days in 10.7% of group A versus 2.7% of group B patients (P < 0.01) . Hospital stays were significantly shorter in group B than in group A . CONCLUSIONS: Administering oral rehydration solution containing Lactobacillus GG to children with acute diarrhea is safe and results in shorter duration of diarrhea, less chance of a protracted course, and faster discharge from the hospital.

J Dairy Sci, 1999 Dec, 82(12), 2536 - 42
Viability of Lactobacillus gasseri and its cholesterol-binding and antimutagenic activities during subsequent refrigerated storage in nonfermented milk; Usman et al.; The effect storage at 4 degrees C on the viability of Lactobacillus gasseri and its sodium taurocholate-deconjugating and cholesterol-binding abilities as well as desmutagenic activity was investigated . Unfermented milks containing L . gasseri strains SBT0274 and SBT0270 at 10(9) cfu/ml were prepared using 10% skim milk . Total and bile-tolerant lactobacilli for strains SBT0274 and SBT0270 generally decreased after 14 d of storage at 4 degrees C; however, viable cells of these strains were still at 10(8) cfu/ml after 28 d of storage . The amounts of cholic acid released and of cholesterol bound by strains SBT0274 and SBT0270 declined over time, especially at 21 d of storage . Antimutagenic activity of unfermented milk made from both strains was attributed to the bacterial cells, and the activity was stable during storage at 4 degrees C for 28 d.

J Dairy Sci, 1999 Dec, 82(12), 2525 - 9
New binding assay and preparative trial of cell-surface lectin from Lactobacillus acidophilus group lactic acid bacteria; Matsumura A et al.; To select Lactobacillus acidophilus group bacteria as a probiotic yogurt starter, we designed a new screening method that measures the binding activity of surface layer protein to rat colonic mucin, which contains sugar chains similar to those in human colonic mucin . The B1 subgroup (Lactobacillus gasseri), which is the dominant strain in the human intestinal tract, showed the highest binding activity to rat colonic mucin among all the subgroups of L . acidophilus . The binding activity of the surface layer protein was also shown to be significantly reduced after periodate oxidation of the rat colonic mucin . This new screening method is useful for rapid selection of L . acidophilus strains that have high adhesion to the human intestinal tract . Lectin-like proteins that were bound to rat colonic mucin were isolated from the surface layer proteins with a rat colonic mucin-coated membrane and were analyzed by SDS-PAGE . A few main bands together with several minor bands were observed on the electrophoretograms obtained from the strains tested . It is possible that those lectin-like proteins contribute to adhesion of the bacterial cell to human colonic mucosa by binding specifically to carbohydrate portions.

Int J Food Sci Nutr, 1999 May, 50(3), 203 - 11
Processing of quinoa (Chenopodium quinoa, Willd): effects on in vitro iron availability and phytate hydrolysis; Valencia S et al.; The effect of different processing techniques was studied on in vitro iron availability and phytate hydrolysis in high and low saponin content quinoa (Chenopodium quinoa, Willd) seeds . Water slurries of ungerminated and germinated quinoa flour were processed by cooking, soaking, and fermentation using Lactobacillus plantarum as starter . Iron solubility under physiological conditions (in vitro) was measured and used as an estimation of iron availability . Phytate (inositol hexaphosphate/IP6) and its degradation products were analysed by an HPLC method . The IP6 + IP5 content was reduced by cooking with 4 to 8%, germination with 35 to 39%, soaking with 61 to 76% and by fermentation with 82 to 98% . The highest reduction, about 98%, was obtained after fermentation of the germinated flour . Cooking had no effect on the amount of soluble iron . Iron solubility increased, however, two to four times after soaking and germination, three to five times after fermentation and five to eight times after fermentation of the germinated flour samples and was highly correlated to the reduction of IP6 + IP5 (P < 0.001) . There was no difference between the quinoa varieties with regard to phytate reduction and iron solubility . The pH in fermented samples was reduced from 6.5 to about 3.5, due to lactic acid formation.

Int J Food Sci Nutr, 1999 May, 50(3), 159 - 64
Formation of biogenic amine in mayonnaise, herring and tuna fish salad by lactobacilli; Leuschner RG et al.; The effect of amino acid decarboxylase-positive lactobacilli in mayonnaise, herring and tuna fish salads on formation of biogenic amines (BA) was investigated . Commercial mayonnaise was inoculated with either of five amine-forming lactobacilli which were selected as model contaminants: Lactobacillus curvatus LTH 975 and LTH 1859 (cadaverine, putrescine, tyramine and phenylethylamine producing), L . delbrueckii LTH 1260 (tyramine and phenylethylamine forming) and L . buchneri LTH 1388 and LTH 661 (histamine forming) . Low concentrations of tyramine (4.5 ppm) were detected and an addition of precursor amino acids resulted in an increase of amine concentrations to 40 ppm putrescine, 16.5 ppm tyramine and 5.5 ppm cadaverine . Herring and tuna fish salads were inoculated either with L . curvatus LTH 975 or L . Buchneri LTH 1388 . In tuna fish salad 1 ppm putrescine, 3 ppm cadaverine, 7 ppm histamine and 28 ppm tyramine were found after 4 days when L . curvatus was added . In the corresponding herring salad putrescine (14 ppm), cadaverine (11.5 ppm), histamine (17 ppm) and tyramine (72 ppm) were detected . Fish salads containing L . buchneri displayed histamine concentrations of 900 ppm in tuna and 670 ppm in herring salad, respectively . Eight lactic acid bacteria and five yeasts, isolates from spoiled delicatessen salads and ingredients, were not able to form putrescine, cadaverine, histamine, tyramine or phenylethylamine.

Biochemistry, 1999 Nov 30, 38(48), 15962 - 9
Characterization of rates of ring-flipping in trimethoprim in its ternary complexes with Lactobacillus casei dihydrofolate reductase and coenzyme analogues; Polshakov VI et al.; NMR measurements have been used to investigate rates of ring-flipping and the activation parameters for the trimethoxybenzyl ring of the antibacterial drug trimethoprim (TMP) bound to Lactobacillus casei dihydrofolate reductase (DHFR) for a series of ternary complexes formed with analogues of the coenzyme NADPH . Rates were obtained at several temperatures from line shape analyses ((13)C-edited HSQC (1)H spectra) and transfer of magnetization measurements (zz-HSQC) on complexes containing 3'-O-{(13)C}trimethoprim . Examination of the structures of the complexes indicates that ring-flipping can only be achieved following major conformational changes and transient fluctuations of the protein and coenzyme structure around the trimethoxybenzyl ring . There is no simple correlation between rates of ring-flipping and binding constants . The presence of the coenzyme nicotinamide ring (in either its reduced or its oxidized forms) in the binding site close to the trimethoxybenzyl ring moiety is the major factor reducing the ring-flipping on coenzyme binding . Thus, the ternary complex with NADPH shows the largest reduction in the rate of ring-flipping (11 +/- 3 s(-)(1) at 298 K) as compared with the binary complex (793 +/- 80 s(-)(1) at 298 K) . Complexes with NADPH analogues that either have no nicotinamide ring or are known to have their nicotinamide rings removed from the binding site show the smallest reductions . For the DHFR.TMP.NADP(+) complex where there are two conformations present, very different rates of ring-flipping were observed for the two forms . The activation parameters (DeltaH() and DeltaS()) for the ring-flipping in all the complexes are discussed in terms of the protein-ligand interactions and the possible constraints on the pathway through the transition state.

Appl Environ Microbiol, 2000 Jan, 66(1), 383 - 91
Use of green fluorescent protein to tag lactic acid bacterium strains under development as live vaccine vectors; Geoffroy MC et al.; The lactic acid bacteria (LAB) are safe microorganisms which are mainly used for the preparation of fermented foods and for probiotic applications . The potential of LAB as live vehicles for the production and delivery of therapeutic molecules such as antigens is also being actively investigated today . However, very little is known about the fate of live LAB when administered in vivo and about the interaction of these microorganisms with the nasal or gastrointestinal ecosystem . For future applications, it is essential to be able to discriminate the biotherapeutic strain from the endogenous microflora and to unravel the mechanisms underlying the postulated health-beneficial effect . We therefore started to investigate both aspects in a mouse model with two LAB species presently under development as live vaccine vectors, i.e., Lactococcus lactis and Lactobacillus plantarum . We have constructed different expression vectors carrying the gfp (green fluorescent protein {GFP}) gene from the jellyfish Aequoria victoria, and we found that this visible marker was best expressed when placed under the control of the inducible strong nisA promoter from L . lactis . Notably, a threshold amount of GFP was necessary to obtain a bright fluorescent phenotype . We further demonstrated that fluorescent L . plantarum NCIMB8826 can be enumerated and sorted by flow cytometry . Moreover, tagging of this strain with GFP allowed us to visualize its phagocytosis by macrophages in vitro and ex vivo and to trace it in the gastrointestinal tract of mice upon oral administration.

Appl Environ Microbiol, 2000 Jan, 66(1), 310 - 9
An explosive antisense RNA strategy for inhibition of a lactococcal bacteriophage; Walker SA et al.; The coding regions of six putative open reading frames (ORFs) identified near the phage phi31 late promoter and the right cohesive end (cos) of lactococcal bacteriophage phi31 were used to develop antisense constructs to inhibit the proliferation of phage phi31 . Two middle-expressed ORFs (ORF 1 and ORF 2) and four late-expressed ORFs (ORF 3 through ORF 6) were cloned individually between the strong Lactobacillus P6 promoter and the T7 terminator (T(T7)) to yield a series of antisense RNA transcripts . When expressed on a high-copy-number vector from a strong promoter, the constructs had no effect on the efficiency of plaquing (EOP) or the plaque size of phage phi31 . To increase the ratio of antisense RNA to the targeted sense mRNA appearing during a phage infection, the antisense cassettes containing the late-expressed ORFs (ORF 3 through ORF 6) were subcloned to pTRK360, a low-copy-number vector containing the phage phi31 origin of replication, ori31 . ori31 allows for explosive amplification of the low-copy-number vector upon phage infection, thereby increasing levels of antisense RNA transcripts later in the lytic cycle . In addition, the presence of ori31 also lowers the burst size of phage phi31 fourfold, resulting in fewer sense, target mRNAs being expressed from the phage genome . The combination of ori31 and P6::anti-ORF 4H::T(T7) resulted in a threefold decrease in the EOP of phage phi31 (EOP = 0.11 +/- 0.03 {mean +/- standard deviation}) compared to the presence of ori31 alone (EOP = 0.36) . One-step growth curves showed that expression of anti-ORF 4H RNA decreased the percentage of successful centers of infection (75 to 80% for ori31 compared to 35 to 45% for ori31 plus anti-ORF 4H), with no further reduction in burst size . Growth curves performed in the presence of varying levels of phage phi31 showed that ori31 plus anti-ORF 4H offered significant protection to Lactococcus lactis, even at multiplicities of infection of 0.01 and 0.1 . These results illustrate a successful application of an antisense strategy to inhibit phage replication in the wake of recent unsuccessful reports.

Appl Environ Microbiol, 2000 Jan, 66(1), 297 - 303
Detection and identification of gastrointestinal Lactobacillus species by using denaturing gradient gel electrophoresis and species-specific PCR primers; Walter J et al.; Denaturing gradient gel electrophoresis (DGGE) of DNA fragments obtained by PCR amplification of the V2-V3 region of the 16S rRNA gene was used to detect the presence of Lactobacillus species in the stomach contents of mice . Lactobacillus isolates cultured from human and porcine gastrointestinal samples were identified to the species level by using a combination of DGGE and species-specific PCR primers that targeted 16S-23S rRNA intergenic spacer region or 16S rRNA gene sequences . The identifications obtained by this approach were confirmed by sequencing the V2-V3 region of the 16S rRNA gene and by a BLAST search of the GenBank database.

Appl Environ Microbiol, 2000 Jan, 66(1), 277 - 83
Carbon catabolite repression in Lactobacillus pentosus: analysis of the ccpA region; Mahr K et al.; The catabolite control protein CcpA is a central regulator in low-G+C-content gram-positive bacteria . It confers carbon catabolite repression to numerous genes required for carbon utilization . It also operates as a transcriptional activator of genes involved in diverse phenomena, such as glycolysis and ammonium fixation . We have cloned the ccpA region of Lactobacillus pentosus . ccpA encodes a protein of 336 amino acids exhibiting similarity to CcpA proteins of other bacteria and to proteins of the LacI/GalR family of transcriptional regulators . Upstream of ccpA was found an open reading frame with similarity to the pepQ gene, encoding a prolidase . Primer extension experiments revealed two start sites of transcription for ccpA . In wild-type cells grown on glucose, mRNA synthesis occurred only from the promoter proximal to ccpA . In a ccpA mutant strain, both promoters were used, with increased transcription from the distant promoter, which overlaps a presumptive CcpA binding site called cre (for catabolite responsive element) . This suggests that expression of ccpA is autoregulated . Determination of the expression levels of CcpA in cells grown on repressing and nonrepressing carbon sources revealed that the amounts of CcpA produced did not change significantly, leading to the conclusion that the arrangement of two promoters may ensure constant expression of ccpA under various environmental conditions . A comparison of the genetic structures of ccpA regions revealed that lactic acid bacteria possess the gene order pepQ-ccpA-variable while the genetic structure in bacilli and Staphylococcus xylosus is aroA-ccpA-variable-acuC.

Appl Environ Microbiol, 2000 Jan, 66(1), 262 - 7
Increased production of hydrogen peroxide by Lactobacillus delbrueckii subsp . bulgaricus upon aeration: involvement of an NADH oxidase in oxidative stress; Marty-Teysset C et al.; The growth of Lactobacillus delbrueckii subsp . bulgaricus (L . delbrueckii subsp . bulgaricus) on lactose was altered upon aerating the cultures by agitation . Aeration caused the bacteria to enter early into stationary phase, thus reducing markedly the biomass production but without modifying the maximum growth rate . The early entry into stationary phase of aerated cultures was probably related to the accumulation of hydrogen peroxide in the medium . Indeed, the concentration of hydrogen peroxide in aerated cultures was two to three times higher than in unaerated ones . Also, a similar shift from exponential to stationary phase could be induced in unaerated cultures by adding increasing concentrations of hydrogen peroxide . A significant fraction of the hydrogen peroxide produced by L . delbrueckii subsp . bulgaricus originated from the reduction of molecular oxygen by NADH catalyzed by an NADH:H(2)O(2) oxidase . The specific activity of this NADH oxidase was the same in aerated and unaerated cultures, suggesting that the amount of this enzyme was not directly regulated by oxygen . Aeration did not change the homolactic character of lactose fermentation by L . delbrueckii subsp . bulgaricus and most of the NADH was reoxidized by lactate dehydrogenase with pyruvate . This indicated that NADH oxidase had no (or a very small) energetic role and could be involved in eliminating oxygen.

J Biol Chem, 2000 Jan 7, 275(1), 297 - 302
Crystal versus solution structures of thiamine diphosphate-dependent enzymes; Svergun DI et al.; The quaternary structures of the thiamine diphosphate-dependent enzymes transketolase (EC 2.2.1.1; from Saccharomyces cerevisiae), pyruvate oxidase (EC 1.2.3.3; from Lactobacillus plantarum), and pyruvate decarboxylase (EC 4.1.1.1; from Zymomonas mobilis and brewers' yeast, the latter in the native and pyruvamide-activated forms) were examined by synchrotron x-ray solution scattering . The experimental scattering data were compared with the curves calculated from the crystallographic models of these multisubunit enzymes . For all enzymes noted above, except the very compact pyruvate decarboxylase from Z . mobilis, there were significant differences between the experimental and calculated profiles . The changes in relative positions of the subunits in solution were determined by rigid body refinement . For pyruvate oxidase and transketolase, which have tight intersubunit contacts in the crystal, relatively small modifications of the quaternary structure (root mean square displacements of 0.23 and 0.27 nm, respectively) sufficed to fit the experimental data . For the enzymes with looser contacts (the native and activated forms of yeast pyruvate decarboxylase), large modifications of the crystallographic models (root mean square displacements of 0.58 and 1.53 nm, respectively) were required . A clear correlation was observed between the magnitude of the distortions induced by the crystal environment and the interfacial area between subunits.

J Bacteriol, 2000 Jan, 182(1), 155 - 63
Genetics of L-sorbose transport and metabolism in Lactobacillus casei; Yebra MJ et al.; Genes encoding L-sorbose metabolism of Lactobacillus casei ATCC 393 have been identified on a 6.8-kb chromosomal DNA fragment . Sequence analysis revealed seven complete genes and a partial open reading frame transcribed as two units . The deduced amino acid sequences of the first transcriptional unit (sorRE) showed high similarity to the transcriptional regulator and the L-sorbose-1-phosphate reductase of the sorbose (sor) operon from Klebsiella pneumoniae . The other genes are transcribed as one unit (sorFABCDG) in opposite direction to sorRE . The deduced peptide sequence of sorF showed homology with the D-sorbitol-6-phosphate dehydrogenase encoded in the sor operon from K . pneumoniae and sorABCD to components of the mannose phosphotransferase system (PTS) family but especially to domains EIIA, EIIB, EIIC and EIID of the phosphoenolpyruvate-dependent L-sorbose PTS from K . pneumoniae . Finally, the deduced amino acid sequence of a truncated gene (sorG) located downstream of sorD presented high similarity with ketose-1,6-bisphosphate aldolases . Results of studies on enzyme activities and transcriptional analysis revealed that the two gene clusters, sorRE and sorFABCDG, are induced by L-sorbose and subject to catabolite repression by D-glucose . Data indicating that the catabolite repression is mediated by components of the PTS elements and by CcpA, are presented . Results of sugar uptake assays in L . casei wild-type and sorBC mutant strains indicated that L-sorbose is taken up by L-sorbose-specific enzyme II and that L . casei contains an inducible D-fructose-specific PTS . Results of growth analysis of those strains and a man sorBC double mutant suggested that L-sorbose is probably also transported by the D-mannose PTS . We also present evidence, from studies on a sorR mutant, suggesting that the sorR gene encodes a positive regulator of the two sor operons . Sequence alignment of SorR, SorC (K . pneumoniae), and DeoR (Bacillus subtilis) revealed that they might constitute a new group of transcriptional regulators.

J Bacteriol, 2000 Jan, 182(1), 146 - 54
X-prolyl dipeptidyl aminopeptidase gene (pepX) is part of the glnRA operon in Lactobacillus rhamnosus; Varmanen P et al.; A peptidase gene expressing X-prolyl dipeptidyl aminopeptidase (PepX) activity was cloned from Lactobacillus rhamnosus 1/6 by using the chromogenic substrate L-glycyl-L-prolyl-beta-naphthylamide for screening of a genomic library in Escherichia coli . The nucleotide sequence of a 3.5-kb HindIII fragment expressing the peptidase activity revealed one complete open reading frame (ORF) of 2,391 nucleotides . The 797-amino-acid protein encoded by this ORF was shown to be 40, 39, and 36% identical with PepXs from Lactobacillus helveticus, Lactobacillus delbrueckii, and Lactococcus lactis, respectively . By Northern analysis with a pepX-specific probe, transcripts of 4.5 and 7.0 kb were detected, indicating that pepX is part of a polycistronic operon in L . rhamnosus . Cloning and sequencing of the upstream region of pepX revealed the presence of two ORFs of 360 and 1,338 bp that were shown to be able to encode proteins with high homology to GlnR and GlnA proteins, respectively . By multiple primer extension analyses, the only functional promoter in the pepX region was located 25 nucleotides upstream of glnR . Northern analysis with glnA- and pepX-specific probes indicated that transcription from glnR promoter results in a 2.0-kb dicistronic glnR-glnA transcript and also in a longer read-through polycistronic transcript of 7.0 kb that was detected with both probes in samples from cells in exponential growth phase . The glnA gene was disrupted by a single-crossover recombinant event using a nonreplicative plasmid carrying an internal part of glnA . In the disruption mutant, glnRA-specific transcription was derepressed 10-fold compared to the wild type, but the 7.0-kb transcript was no longer detectable with either the glnA- or pepX-specific probe, demonstrating that pepX is indeed part of glnRA operon in L . rhamnosus . Reverse transcription-PCR analysis further supported this operon structure . An extended stem-loop structure was identified immediately upstream of pepX in the glnA-pepX intergenic region, a sequence that showed homology to a 23S-5S intergenic spacer and to several other L . rhamnosus-related entries in data banks.

Microbes Infect, 1999 Apr, 1(4), 285 - 92
Microbial interactions in the vaginal ecosystem, with emphasis on the pathogenesis of bacterial vaginosis; Pybus V et al.; During bacterial vaginosis (BV), populations of lactobacilli which are generally dominant in the vagina of overtly healthy women are replaced by other facultative and anaerobic microorganisms . Some Lactobacillus strains produce hydrogen peroxide and all produce lactic acid; however, the antagonistic role of these metabolites in vivo remains controversial . Positive interactions among BV-associated organisms may contribute to the pathogenesis of BV and its sequelae.

J Food Prot, 1999 Dec, 62(12), 1430 - 4
Study of adhesion of Lactobacillus casei CRL 431 to ileal intestinal cells of mice; Morata de Ambrosini VI et al.; It is well known that the cell wall of Lactobacillus casei CRL 431, a strain present in probiotics, presents lectinlike surface molecules . Presence of these molecules stimulates the immune system . Given the role that lectins and lectinlike substances play in the adhesion phenomenon, it is probable that this is an initial stage in the immunostimulation produced by this bacterium . To confirm this, adhesion of this microorganism to exfoliated mouse ileal epithelial cells was studied in vitro . Other L . casei strains isolated from adult human intestines and one of dairy origin were also examined for their ability to adhere to ileal epithelial cells . Another strain, which was included in the present study, was Lactobacillus acidophilus CRL 730 . L . casei strains isolated from humans showed good ability to adhere to ileal epithelial cells, whereas L . casei isolated from dairy origin did not . Adhesion was only observed at 37 degrees C and at a pH between 6 and 7.5 . The exposure time needed for highest adhesion was 30 min . Presence of lectinlike substances on the surface of L . casei CRL 431 is important to this adhesion phenomenon, since adherence capacity was lost after removal of these substances.

J Food Prot, 1999 Dec, 62(12), 1416 - 29
On the microbiological profile of traditional Portuguese sourdough; Rocha JM et al.; Traditional manufacture of bread from maize has been noted to play important roles from both economic and social standpoints; however, enforcement of increasingly strict hygiene standards requires thorough knowledge of the adventitious microbiota of the departing dough . To this goal, sourdough as well as maize and rye flours from several geographic locations and in two different periods within the agricultural year were assayed for their microbiota in sequential steps of quantification and identification . More than 400 strains were isolated and taxonomic differentiation between them was via Biomerieux API galleries (375 of which were successfully identified) following preliminary biochemical and morphological screening . The dominant groups were yeasts and lactic acid bacteria (LAB) . The most frequently isolated yeasts were Saccharomyces cerevisiae and Candida pelliculosa . The most frequently isolated LAB were (heterofermentative) Leuconostoc spp . and (homofermentative) Lactobacillus spp.; L . brevis, L . curvatus, and L . lactis ssp . lactis were the dominant species for the Lactobacillus genera; Lactococcus lactis ssp . lactis for lactococci; Enterococcus casseliflavus, E . durans, and E . faecium for enterococci; and Streptococcus constellantus and S . equinus for streptococci.

Caries Res, 2000 Jan-Feb, 34(1), 70 - 4
Effect of four dental varnishes on the colonization of cariogenic bacteria on exposed sound root surfaces; Ekenback SB et al.; The aim of this study was to evaluate the effect of four different dental varnishes on the colonization of mutans streptococci, total streptococci and lactobacilli on exposed sound root surfaces . Sixty-five individuals were randomly allotted to one of four groups for treatment with Cervitec((R) ) varnish containing 1% chlorhexidine and 1% thymol, a thymol varnish or one of two different fluoride varnishes, Fluor Protector and Duraphat . The varnish was applied to three buccal root surfaces in each patient at baseline and after 1 week . Dental plaque from the root surfaces was collected and analysed on four different occasions: at baseline, after 1 week, 1 month and 6 months . The Cervitec varnish caused a statistically significant reduction in the number of mutans streptococci over time . The reduction was significant at 1 week and 1 month relative to baseline . The numbers of total streptococci and lactobacilli were not significantly affected by treatment with Cervitec . No statistically significant difference over time was found for mutans streptococci, lactobacilli or total streptococci after treatment with the fluoride varnishes or the thymol varnish.

Int J Food Microbiol, 1999 Dec 1, 53(1), 43 - 52
Protective cultures inhibit growth of Listeria monocytogenes and Escherichia coli O157:H7 in cooked, sliced, vacuum- and gas-packaged meat; Bredholt S et al.; Contamination of cooked meat products with Listeria monocytogenes poses a constant threat to the meat industry . The aim of this study was therefore to investigate the use of indigenous lactic acid bacteria (LAB) as protective cultures in cooked meat products . Cooked, sliced, vacuum- or gas-packaged ham and servelat sausage from nine meat factories in Norway were inoculated with 10(3) cfu/g of a mixture of three rifampicin resistant (rif-mutant) strains of L . monocytogenes and stored at 8 degrees C for four weeks . Growth of L . monocytogenes and indigenous lactic acid flora was followed throughout the storage period . LAB were isolated from samples where L . monocytogenes failed to grow . Five different strains growing well at 3 degrees C . pH 6.2, with 3% NaCl, and producing moderate amounts of acid were selected for challenge experiments with the rif-resistant strains of L . monocytogenes . a nalidixic acid/streptomycin sulphate-resistant strain of Escherichia coli O157:H7 and a mixture of three rif-resistant strains of Yersinia enterocolitica O:3 . All five LAB strains inhibited growth of both L . monocytogenes and E . coli O157:H7 . No inhibition of Y . enterocolitica O:3 was observed . A professional taste panel evaluated cooked, sliced, vacuum-packaged ham inoculated with each of the five test strains after storage for 21 days at 8 degrees C . All samples had acceptable sensory properties . The five LAB strains hybridised to a 23S rRNA oligonucleotide probe specific for Lactobacillus sakei . These indigenous LAB may be used as protective cultures to inhibit growth of L . monocytogenes and E . coli O157:H7 in cooked meat products.

Int J Food Microbiol, 1999 Dec 1, 53(1), 13 - 20
Influence of sodium chloride concentration on the controlled lactic acid fermentation of "Almagro" eggplants; Ballesteros C et al.; The effect of a commercial Lactobacillus starter and sodium chloride concentration on the fermentation of "Almagro" eggplants (Solanum melongena L . var . esculentum depressum) was studied . The results of fermentation using added starter and varying salt concentrations (4, 6, and 10% w/v) in brine were compared with the results of spontaneous fermentation taking place in brine with a salt concentration of 4% . Fresh fruits, medium in size (34-44 g), were used in all cases; all fruits were blanched under identical conditions . Temperature in the fermenters was 32+/-2 degrees C . The results obtained indicate that addition of a suitable starter shortened the fermentation process, provided the salt concentration in the brine did not exceed 6% . In the conditions tested, the eggplants obtained after fermentation were found to be of good quality though somewhat bitter which may explained by the starter employed.

J Agric Food Chem, 1999 Sep, 47(9), 3854 - 7
Pesticides in fermentative processes of wine; Cabras P et al.; The influence of six fungicides (azoxystrobin, cyprodinil, fludioxonil, mepanipyrim, pyrimethanil, and tetraconazole) on the fermentative activity of two yeasts (Saccharomyces cerevisiae and Kloeckeraapiculata) and two lactic bacteria (Leuconostoc oenos and Lactobacillus plantarum) was studied . The possibility of their being degraded by these yeasts and bacteria was also investigated . The presence of the pesticides did not affect alcoholic fermentation, not even with levels higher than those normally found in grapes in field experiments . On the contrary, their presence stimulated the yeast, especially K . apiculata, to produce more alcohol . The fermentative process did not affect the amount of pesticides either by degradation or by adsorption . During malolactic fermentation by Le . oenos, malic acid decreased slightly less (by approximately 15%) in the presence of all pesticides, except mepanipyrim . A lower effect ( approximately 5%) was found during the fermentative process with La . plantarum . The bacteria studied did not show a degradative effect on pesticides during malolactic fermentation.

J Agric Food Chem, 1999 Aug, 47(8), 3441 - 8
Hydrolytic action of Lactobacillus casei CRL 705 on pork muscle sarcoplasmic and myofibrillar proteins; Sanz Y et al.; Lactobacillus casei CRL 705 was screened, among other meat isolates, for its proteinase and aminopeptidase activities toward synthetic substrates and, according to that, selected for specific assays on muscle proteins . The hydrolytic effects of whole cells, cell free extracts (CFE), and the combination of both on muscle sarcoplasmic and myofibrillar protein extracts was evaluated by SDS-PAGE and reverse phase HPLC analyses . The proteinase activity of whole cells caused the degradation of a great number of sarcoplasmic protein bands . A partial hydrolysis was also associated with CFE that when combined with whole cells showed an important additional degradation . Peptide profiles from sarcoplasmic protein extracts were greatly modified regardless of the addition of whole cells or CFE, although their combination intensified these changes . The generation of free amino acids was remarkable when whole cells and CFE were incorporated together to sarcoplasmic protein extracts.

J Agric Food Chem, 1999 Mar, 47(3), 1156 - 61
Contribution of the microbial and meat endogenous enzymes to the free amino acid and amine contents of dry fermented sausages; Hierro E et al.; The role of the starter culture and meat endogenous enzymes on the free amino acid and amine contents of dry fermented sausages was studied . Five batches of sausages were prepared . The control batch was manufactured with aseptic ingredients without microbial inoculation . The other four experimental batches were manufactured with aseptic ingredients inoculated with Lactobacillus plantarum 4045 or Micrococcus-12 or L . plantarum 4045 and Micrococcus-12 or L . plantarum 4045 and Staphylococcus sp . Their effects on pH, a(w), myofibrillar proteins, and free amino acid and amine contents were studied . Sausages inoculated only with L . plantarum 4045 or with this starter combined with a Micrococcaceae had the lowest pH as a result of carbohydrate fermentation . In all batches similar patterns were observed for myofibrillar proteins and free amino acids which could indicate that meat endogenous proteases play an important role in proteolytic phenomena . No changes were observed in the amine fraction, indicating that the strains used as starter cultures did not show amino acid decarboxylase activity.

Syst Appl Microbiol, 1999 Sep, 22(3), 354 - 9
Lactobacillus perolens sp . nov., a soft drink spoilage bacterium; Back W et al.; Lactic acid bacteria that are able to spoil soft drinks with low pH comprise a limited number of acidotolerant or acidophilic species of the genera Lactobacillus, Leuconostoc and Weissella . Various Gram-positive rods causing turbidity and off-flavour were isolated from orange lemonades . Physiological and biochemical studies including SDS-PAGE whole-cell protein analysis showed a homogeneous group of organisms . The 16S rRNA gene sequence analysis of two representatives revealed that they formed a phylogenetically distinct line within the genus Lactobacillus . All strains were facultatively heterofermentative, producing L-lactic acid . Based on the data presented a new species L . perolens is proposed . The name refers to the off-flavour caused by high amounts of diacetyl . The type strain of L . perolens is DSM 12744 (LMG 18936) . A rRNA targeted oligonucleotide probe was designed that allows a fast and reliable identification of L . perolens.

J Agric Food Chem, 1999 Nov, 47(11), 4736 - 41
Pseudovitamin B(12) is the predominant cobamide of an algal health food, spirulina tablets; Watanabe F et al.; The vitamin B(12) concentration of an algal health food, spirulina (Spirulina sp.) tablets, was determined by both Lactobacillus leichmannii ATCC 7830 microbiological and intrinsic factor chemiluminescence methods . The values determined with the microbiological method were approximately 6-9-fold greater in the spirulina tablets than the values determined with the chemiluminescence method . Although most of the vitamin B(12) determined with the microbiological method was derived from various vitamin B(12) substitutive compounds and/or inactive vitamin B(12) analogues, the spirulina contained a small amount of vitamin B(12) active in the binding of the intrinsic factor . Two intrinsic factor active vitamin B(12) analogues (major and minor) were purified from the spirulina tablets and partially characterized . The major (83%) and minor (17%) analogues were identified as pseudovitamin B(12) and vitamin B(12), respectively, as judged from data of TLC, reversed-phase HPLC, (1)H NMR spectroscopy, ultraviolet-visible spectroscopy, and biological activity using L . leichmannii as a test organism and the binding of vitamin B(12) to the intrinsic factor.

J Appl Microbiol, 1999 Nov, 87(5), 743 - 9
Differentiation of Lactobacillus isolates from infant faeces by SDS-PAGE and rRNA-targeted oligonucleotide probes; Xanthopoulos V et al.; Isolates of lactobacilli from infant faeces phenotypically characterized as Lactobacillus paracasei subsp . paracasei (six strains), Lact . rhamnosus (six strains), Lact . gasseri (three strains), Lact . acidophilus (one strain) and Lact . fermentum/reuteri (three strains) according to recent classification systems were subjected to SDS-PAGE of whole cell proteins and rRNA-targeted oligonucleotide probe hybridization, in order to confirm the phenotypic characterization and elucidate the exact taxonomic position of the three strains that had properties between fermentum and reuteri . Results suggested a good agreement between the phenotypic characterization, SDS-PAGE and rRNA-targeted oligonucleotide probe hybridization for strains of all species except for the Lact . fermentum/reuteri strains . Results obtained by rRNA probes suggested a possible phylogenetic relatedness of the strains to Lact . reuteri . Isolates from infant faeces with interesting probiotic properties could be used as components of fermented milk products.

Acta Odontol Scand, 1999 Aug, 57(4), 181 - 4
Simplified sampling methods for estimating levels of lactobacilli in saliva in dental clinical practice; Gabre P et al.; The aim of the present study was to evaluate whether estimation of lactobacilli was possible with simplified saliva sampling methods . Dentocult LB (Orion Diagnostica AB, Trosa, Sweden) was used to estimate the number of lactobacilli in saliva sampled by 3 different methods from 96 individuals: (i) Collecting and pouring stimulated saliva over a Dentocult dip-slide; (ii) direct licking of the Dentocult LB dip-slide; (iii) contaminating a wooden spatula with saliva and pressing against the Dentocult dip-slide . The first method was in accordance with the manufacturer's instructions and selected as the 'gold standard'; the other 2 methods were compared with this result . The 2 simplified methods for estimating levels of lactobacilli in saliva showed good reliability and specificity . Sensitivity, defined as the ability to detect individuals with a high number of lactabacilli in saliva, was sufficient for the licking method (85%), but significantly reduced for the wooden spatula method (52%).

J Appl Microbiol, 1999 Sep, 87(3), 345 - 52
Bile salt deconjugation by lactobacillus plantarum 80 and its implication for bacterial toxicity
De Boever P, Verstraete W.
The effects of bile salts on the survival of lactobacilli were investigated using glycocholic acid, cholic acid and deoxycholic acid as model compounds and the bile salt hydrolase active Lactobacillus plantarum 80 (BSH+) and its BSH negative mutant . The detrimental effects of cholic acid, i.e . growth inhibition and cytotoxicity at a concentration of 1 and 5 mmol l-1, respectively, were considered to be due to the hydrophobic protonated form of the molecule, which brings about membrane damage . The conversion of glycocholic acid to cholic acid by the BSH active L . plantarum 80 caused a growth inhibition which was comparable with the inhibition observed in the broth supplemented with 1 mmol l-1 cholic acid . Deoxycholic acid caused toxicity through membrane damage when the compound was in solution . Its toxicity disappeared in the culture broth as the molecule precipitated . In case of cholic acid, the toxicity could be removed by buffering the solution at pH 7.0 . It was calculated that at this pH most of the cholic acid molecules were ionized . The results led to the formulation of an extended hypothesis about the ecological significance of bile salt transformations . Primary deconjugation is carried out to counteract intracellular acidification . Yet, the deconjugated molecule can be harmful at moderately acidic pH-values . In this case, the BSH+ strains could effectively profit from their activity in case they are associated with 7alpha-dehydroxylating bacteria which dehydroxylate the deconjugated bile salts . The dehydroxylated molecule has a low solubility and precipitates at moderately acidic pH.

Biotechnol Bioeng, 2000 Jan 20, 67(2), 147 - 56
Enhanced production of L-(+)-lactic acid in chemostat by Lactobacillus casei DSM 20011 using ion-exchange resins and cross-flow filtration in a fully automated pilot plant controlled via NIR; Gonzalez-Vara Y R A et al.; Due to the lack of suitable in-process sensors, on-line monitoring of fermentation processes is restricted almost exclusively to the measurement of physical parameters only indirectly related to key process variables, i.e., substrate, product, and biomass concentration . This obstacle can be overcome by near infrared (NIR) spectroscopy, which allows not only real-time process monitoring, but also automated process control, provided that NIR-generated information is fed to a suitable computerized bioreactor control system . Once the relevant calibrations have been obtained, substrate, biomass and product concentration can be evaluated on-line and used by the bioreactor control system to manage the fermentation . In this work, an NIR-based control system allowed the full automation of a small-scale pilot plant for lactic acid production and provided an excellent tool for process optimization . The growth-inhibiting effect of lactic acid present in the culture broth is enhanced when the growth-limiting substrate, glucose, is also present at relatively high concentrations . Both combined factors can result in a severe reduction of the performance of the lactate production process . A dedicated software enabling on-line NIR data acquisition and reduction, and automated process management through feed addition, culture removal and/or product recovery by microfiltration was developed in order to allow the implementation of continuous fermentation processes with recycling of culture medium and cell recycling . Both operation modes were tested at different dilution rates and the respective cultivation parameters observed were compared with those obtained in a conventional continuous fermentation . Steady states were obtained in both modes with high performance on lactate production . The highest lactate volumetric productivity, 138 g L(-1) h(-1), was obtained in continuous fermentation with cell recycling .

Microbiology, 1999 Nov, 145 ( Pt 11), 3147 - 54
PepR1, a CcpA-like transcription regulator of Lactobacillus delbrueckii subsp . lactis; Schick J et al.; The PepR1 protein from Lactobacillus delbrueckii subsp . lactis DSM 7290 shares extensive homology with catabolite-control proteins from various Gram-positive bacteria . Expression of the subcloned pepR1 gene allowed for partial complementation of a ccpA defect in Staphylococcus xylosus . The influence of PepR1 on transcription of the prolidase gene pepQ, which is located adjacent to pepR1, was examined by use of lacZ reporter gene fusions in Escherichia coli . PepR1 stimulated transcription initiation at the pepQ promoter about twofold, and this effect required the integrity of a 14 bp palindromic cre-like sequence located 74 nt upstream of pepQ . In gel-mobility-shift assays, PepR1 specifically interacted with the pepQ promoter region and also with DNA fragments covering the promoters of the pepX, pepl and brnQ genes of Lb . delbrueckii subsp . lactis, which encode two additional peptidases and a branched-chain amino acid transporter, respectively . cre-like elements were identified in each of these DNA fragments . Catabolite control of PepQ was demonstrated in Lb . delbrueckii subsp . lactis . During growth with lactose the enzyme activity was twofold higher than in the presence of glucose, and corresponding differences were also detected in the level of pepQ transcription.

Can J Microbiol, 1999 Nov, 45(11), 891 - 7
Effect of ultrafiltration of yeast extracts on their ability to promote lactic acid bacteria growth; Gaudreau H et al.; Five yeast extracts (YE) were fractionated by ultrafiltration (UF) with 1, 3, and 10 kDa molecular weight cutoff membranes, concentrated by freeze-drying, and the resulting powders of yeast extract filtrates (YEF) were evaluated for their growth-promoting properties on nine cultures of lactic acid bacteria (LAB) . There was an increase in alpha-amino nitrogen content of the YEF powders as the pore size of the UF membranes used to filter the YE solutions decreased . The source of YE had a much greater effect than UF on the growth of LAB . This was also the case for the YEF contents in total and alpha-amino nitrogen . Growth curves of the LAB showed that maximum growth rate (mumax) data were on average 30% higher with bakers' YE than with brewers' YE, while maximum optical density (ODmax) values were on average 16% higher with bakers' YE . This could be related to the higher nitrogen content of the bakers' YE used in this study . Modification by UF of the YE had no significant influence on the growth of 4 of the 9 LAB strains . The three strains of Lactobacillus casei were negatively influenced by UF, as they did not grow as well in the media containing the YEF obtained after filtering with 1 and 3 kDa membranes . On a total solids basis, the 2.5 x retentates from the 10 kDa membrane gave, on average, 4% lower mumax and 5% lower ODmax values as compared to cultures where the corresponding YEF was used as medium supplement . This could also be partially related to the different nitrogen contents of the filtrates and retentates.

Appl Environ Microbiol, 1999 Dec, 65(12), 5597 - 9
Growth of facultatively heterofermentative lactobacilli on starter cell suspensions; Rapposch S et al.; The growth of facultatively heterofermentative lactobacilli (FHL) on cell suspensions of the homofermentative Lactobacillus helveticus was investigated . Osmotic lysis of L . helveticus led to a significant increase of ribose . It decreased steadily in parallel with the growth of FHL, strongly suggesting that the bacteria used ribose as a growth substrate.

Appl Environ Microbiol, 1999 Dec, 65(12), 5590 - 3
Involvement of manganese in conversion of phenylalanine to benzaldehyde by lactic acid bacteria; Nierop Groot MN et al.; We examined the involvement of Mn(II) in the conversion of phenylalanine to benzaldehyde in cell extracts of lactic acid bacteria . Experiments performed with Lactobacillus plantarum demonstrated that Mn(II), present at high levels in this strain, is involved in benzaldehyde formation by catalyzing the conversion of phenylpyruvic acid . Experiments performed with various lactic acid bacterial strains belonging to different genera revealed that benzaldehyde formation in a strain was related to a high Mn(II) level.

Appl Environ Microbiol, 1999 Dec, 65(12), 5378 - 85
Influence of different functional elements of plasmid pGT232 on maintenance of recombinant plasmids in Lactobacillus reuteri populations in vitro and in vivo; Heng NC et al.; Plasmid pGT232 (5.1 kb), an indigenous plasmid of Lactobacillus reuteri 100-23, was determined, on the basis of nucleotide and deduced protein sequence data, to belong to the pC194-pUB110 family of plasmids that replicate via the rolling-circle mechanism . The minimal replicon of pGT232 was located on a 1.7-kb sequence consisting of a double-strand origin of replication and a gene encoding the replication initiation protein, repA . An erythromycin-selectable recombinant plasmid containing this minimal replicon was stably maintained (>97% erythromycin-resistant cells) without antibiotic selection in an L . reuteri population under laboratory growth conditions but was poorly maintained (<33% resistant cells) in the L . reuteri population inhabiting the murine gastrointestinal tract . Stable maintenance (>90% resistant cells) of pGT232-derived plasmids in the lactobacillus population in vivo required an additional 1.0-kb sequence which contained a putative single-strand replication origin (SSO) . The SSO of pGT232 is believed to be novel and functions in an orientation-specific manner.

Appl Environ Microbiol, 1999 Dec, 65(12), 5350 - 6
The presence of salt and a curing agent reduces bacteriocin production by Lactobacillus sakei CTC 494, a potential starter culture for sausage fermentation; Leroy F et al.; The specific conditions in the batter of raw fermented sausages may reduce the efficiency of bacteriocin-producing starter cultures . In this work, using in vitro fermentation, we found that sodium chloride and sodium nitrite interfere with the growth of Lactobacillus sakei CTC 494, an organism which produces the antilisterial bacteriocin sakacin K . Because sakacin K production follows primary metabolite kinetics, a decrease in cell formation resulted in a decrease in sakacin K production as well . Sodium chloride dramatically influenced bacteriocin production by decreasing both biomass production and specific bacteriocin production . Sodium nitrite, however, had no effect on specific bacteriocin production and decreased bacteriocin production only because of its effect on cell growth . Moreover, sodium nitrite enhanced the toxic effect of lactic acid on bacterial growth.

J Appl Microbiol, 1999 Oct, 87(4), 611 - 9
Influence of growth phases and desiccation on the degrees of unsaturation of fatty acids and the survival rates of rhizobia
Boumahdi M, Mary P, Hornez J.
The influence of growth phase on the evolution of cellular fatty acids (CFA) and survival of Sinorhizobium and Bradyrhizobium during desiccation and storage at different levels of relative humidity (R . H.) was studied . Lactobacillic, cis vaccenic and palmitic acids were the major fatty acids of S . meliloti RCR 2011, B . elkanii USDA 120 and B . japonicum 3.2, whatever the growth phase . An exchange of cis vaccenic with lactobacillic acid was observed during the course of growth . The degree of unsaturation (% unsaturated CFA/% saturated CFA = u/s ratio) was significantly higher during the mid logarithmic phase of growth . Survival rates immediately after desiccation were unaffected by the growth phase and the R.H . Furthermore, no correlation was found between survival rate and u/s ratio . During the course of desiccation, the u/s ratio of rhizobia decreased but the decrease was largely independent of the R.H . Optimum R.H . values for storage were in the range 22-67.8%, and S . meliloti was significantly more tolerant than the bradyrhizobia . Cells of rhizobia harvested in the lag phase of growth were more resistant to protracted storage than cells at other growth phases . Again, no correlation was found between u/s ratio and survival rates, despite the expected practical significance for screening for drought-tolerant micro-organisms.

J Appl Microbiol, 1999 Oct, 87(4), 583 - 94
Anaerobic lactic acid degradation during ensilage of whole crop maize inoculated with lactobacillus buchneri inhibits yeast growth and improves aerobic stability
Driehuis F, Elferink SJ, Spoelstra SF.
Aerobic deterioration of silages is initiated by (facultative) aerobic micro-organisms, usually yeasts, that oxidize the preserving organic acids . In this study, a Lactobacillus buchneri strain isolated from maize silage was evaluated for its potential as a bacterial inoculant that enhances aerobic stability of silages . In four experiments, chopped whole crop maize (30-43% dry matter (DM)) was inoculated with Lact . buchneri and ensiled in laboratory silos . Uninoculated silages served as controls . Analysis of silages treated with Lact . buchneri at levels of 103-106 cfu g-1 after about 3 months of anaerobic storage showedthat acetic acid and 1-propanol contents increased with inoculum levels above 104 cfu g-1,whereas lactic acid decreased . Propionic acid, silage pH and DM loss increased withinoculum levels above 105 cfu g-1 . Time course experiments with maize inoculated with Lact . buchneri at 4 x 104-2 x 105 cfu g-1 showed that up to 7-14 d after ensiling, Lact . buchneri had no effect on silage characteristics . Thereafter, the lactic acid content of the inoculated silages declined and, simultaneously, acetic acid and, to a lesser extent, propionic acid and 1-propanol, accumulated . Inoculation reduced survival of yeasts during the anaerobic storage phase and inhibited yeast growth when the silage was exposed to O2, resulting in a substantial improvement in aerobic stability . The results indicate that the use of Lact . buchneri as a silage inoculant can enhance aerobic stability by inhibition of yeasts . The ability of the organism to ferment lactic acid to acetic acid appears to be an important underlying principle of this effect.

Antimicrob Agents Chemother, 1999 Dec, 43(12), 3039 - 41
In vitro activities of ketolide HMR3647, macrolides, and other antibiotics against Lactobacillus, Leuconostoc, and Pediococcus isolates; Zarazaga M et al.; Testing of susceptibility to 13 antibiotics was performed with 90 isolates of Lactobacillus, Leuconostoc, and Pediococcus . MICs at which 90% of the isolates tested were inhibited by HMR3647, erythromycin, and ciprofloxacin were 0.015, 0.125 and 32 microg/ml, respectively . The penicillin MIC was > or = 16 microg/ml against 26.2% of the studied Lactobacillus sp . isolates and 50% of Lactobacillus plantarum . HMR3647 showed excellent activity against these genera.

Int J Food Microbiol, 1999 Oct 15, 51(2-3), 133 - 43
Establishment of conditions for green table olive fermentation at low temperature; Duran Quintana MC et al.; Four Lactobacillus plantarum strains were isolated from table olive cold fermentation brines . Their specific growth rate and acidification in MRS broth and in green table olive brines were studied by means of a mixed 2 pH (4.5 and 5.0) x 3 salt (3, 4 and 5%, w/v, NaCl) x 3 incubation temperature (9, 12 and 15 degrees C) levels factorial design . In MRS broth, the greatest effect (linear) on acidification was due to temperature . In brine, the effects were considerably less, pH (linear) being the most important for specific growth rate, and temperature (linear) for acidification . In both media, an initial pH of 5.0 led to good acidification at 12-15 degrees C . The effectiveness of the conditions found (initial pH of 5.0; 3%,w/v, NaCl; and incubation at 12 degrees C) was confirmed in simulated green olive fermentations with three of the strains, which proved especially robust . Behaviour in terms of growth and acidification rates was similar for these strains, and comparable to that observed in traditional processes, although mannitol and sucrose were not metabolised and fructose was only partially used . This leads to the possibility of obtaining normal fermentation processes of table olives in cold regions when appropriate initial conditions and starter cultures are used.

J Nutr, 1999 Dec, 129(12), 2231 - 5
Prolonged intake of fructo-oligosaccharides induces a short-term elevation of lactic acid-producing bacteria and a persistent increase in cecal butyrate in rats; Le Blay G et al.; While the prebiotic effects of fructo-oligosaccharides (FOS), short-chain polymers of fructose, have been thoroughly described after 2-3 wk of ingestion, effects after intake for several months are unknown . We tested the hypothesis that these effects would differ after ingestion for short and long periods in rats . Rats were fed a basal low-fiber diet (Basal) or the same diet containing 9 g/100 g of FOS for 2, 8 or 27 wk, and cecal contents were collected at the end of each time period . Cecal short-chain fatty acid concentration was higher in rats fed FOS than in those fed Basal, and this effect persisted over time: 83.8 +/- 4.1 vs . 62.4 +/- 6.5 micromol/g at 2 wk and 103.5 +/- 5.8 vs . 73.2 +/- 7.4 micromol/g at 27 wk (P < 0.05) . The molar butyrate ratio was higher in rats fed FOS regardless of the time period (14.8 +/- 0.6% vs . 6.7 +/- 1.1% at 27 wk, P < 0.05) . Lactate concentration in rats fed FOS was elevated after 2 wk and then decreased: 63.5 +/- 21.6 micromol/g at 2 wk vs . 8.8 +/- 3.3 micromol/g at 8 wk (P < 0.05) . After 2 wk, FOS increased the concentrations of total lactic acid-producing bacteria, and Lactobacillus sp . (P < 0.05), without modifying total anaerobes . However, most of these effects were abolished after 8 and 27 wk of FOS consumption . In the long term, the FOS-induced increase in intestinal lactic acid-producing bacteria was lost, but the butyrogenic properties of FOS were maintained.

Int J Food Microbiol, 1999 Nov 1, 52(1-2), 105 - 8
Effects of water activity, NaCl and smoke concentrations on the growth of Lactobacillus plantarum ATCC 12315; Catte M et al.; The effect of water activity (a(w)), NaCl and liquid smoke concentrations on the growth of Lactobacillus plantarum, was studied in MRS broth under anaerobic conditions . A complete 2(3) factorial design was used to determine influential factors and interactions among these factors . NaCl concentration and a(w) had a major effect on the maximum biomass obtained but no interaction influenced this response . Smoke did not affect either biomass nor acidifying capacities.

Int J Food Microbiol, 1999 Nov 1, 52(1-2), 77 - 84
Characterisation of lactic acid bacteria from spoiled, vacuum-packaged, cold-smoked rainbow trout using ribotyping; Lyhs U et al.; A total of 405 lactic acid bacteria (LAB) isolated from spoiled, vacuum-packaged, salted, sodium nitrite- or potassium nitrate-treated, cold-smoked rainbow trout stored at 4 degrees C or 8 degrees C were characterised and identified using a molecular method . The isolates were initially classified according to their restriction endonuclease profiles using HindIII and EcoRI restriction endonucleases and further characterised by rRNA gene restriction patterns (ribotypes) . Numerical analysis of these ribopatterns was performed together with 19 reference LAB strain patterns in order to identify the isolates to species level . The strains were divided with HindIII and EcoRI ribopatterns into ten and nine clusters at the similarity level of 65% and 50%, respectively . The Leuconostoc-clusters and the Lb . sakei/Lb . curvatus-clusters formed the two main groups . Only one isolate was identified as Lactobacillus plantarum and no Carnobacterium strains were discovered . For both enzymes, the 35 isolates possessing six individual ribotypes and forming five clusters could not be identified further with the reference strains used . The relative proportion of Leuconostoc mesenteroides subsp . mesenteroides was higher in all samples stored at 4 degrees C . Most of the Leuconostoc citreum were found in the samples stored at 8 degrees C, and particularly in the nitrite-treated samples.

J Bacteriol, 1999 Dec, 181(23), 7385 - 9
Unusual structure of the attB site of the site-specific recombination system of Lactobacillus delbrueckii bacteriophage mv4; Auvray F et al.; The temperate phage mv4 integrates its genome into the chromosome of Lactobacillus delbrueckii subsp . bulgaricus by site-specific recombination within the 3' end of a tRNA(Ser) gene . Recombination is catalyzed by the phage-encoded integrase and occurs between the phage attP site and the bacterial attB site . In this study, we show that the mv4 integrase functions in vivo in Escherichia coli and we characterize the bacterial attB site with a site-specific recombination test involving compatible plasmids carrying the recombination sites . The importance of particular nucleotides within the attB sequence was determined by site-directed mutagenesis . The structure of the attB site was found to be simple but rather unusual . A 16-bp DNA fragment was sufficient for function . Unlike most genetic elements that integrate their DNA into tRNA genes, none of the dyad symmetry elements of the tRNA(Ser) gene were present within the minimal attB site . No inverted repeats were detected within this site either, in contrast to the lambda site-specific recombination model.

J Food Prot, 1999 Nov, 62(11), 1336 - 40
Antagonistic action of Lactobacillus lactis toward Salmonella spp . and Escherichia coli O157:H7 during growth and refrigerated storage; Brashears MM et al.; Cells of Lactobacillus lactis were added to trypticase soy broth that contained cells of Escherichia coli O157:H7 or cells of Salmonella spp . in order to determine if L . lactis inhibited the pathogens . The inhibition of all pathogens was examined during growth at 37 degrees C for 24 h . Inhibition of Salmonella spp . was also examined at refrigeration temperatures (6 degrees C) for 5 days . One strain each of E . coli O157:H7, Salmonella Typhimurium, and Salmonella Enteritidis was examined . E . coli was enumerated on violet red bile agar, and Salmonella spp . were enumerated on brilliant green agar . In all experiments at 37 degrees C, the L . lactis completely inhibited all pathogens, producing numbers that were not detectable after 24 h of incubation . There were significant (P > 0.05) increases in numbers of the pathogens in the control samples containing no L . lactis . There were significant (P < 0.05) declines in the pH of both control and L . lactis inoculated samples . There was a significantly (P < 0.05) larger decline in the pH of samples inoculated with L.lactis . Interaction studies with pH-neutralized broth indicated that acid production by L lactis was primarily responsible for the inhibition . Numbers of Salmonella spp . incubated at 6 degrees C did not decline significantly (P > 0.05) for control or inoculated samples, which suggests that this strain of L . lactis does not inhibit Salmonella spp . at refrigeration temperatures . Additionally, there were no significant (P > 0.05) changes in pH or in numbers of L . lactis during refrigerated storage.

J Food Prot, 1999 Nov, 62(11), 1243 - 7
Survival of Escherichia coli O157:H7 in ground-beef patties during storage at 2, -2, 15 and then -2 degrees C, and -20 degrees C; Ansay SE et al.; The survival of Escherichia coli O157:H7 and of a nonpathogenic control strain of E . coli was monitored in raw ground beef that was stored at 2 degrees C for 4 weeks, -2 degrees C for 4 weeks, 15 degrees C for 4 h and then -2 degrees C for 4 weeks, and -20 degrees C . Irradiated ground beef was inoculated with one E . coli control strain or with a four-strain cocktail of E . coli O157:H7 (ca . 10(5) CFU/g), formed into patties (30 to 45 g), and stored at the appropriate temperature . The numbers of the E . coli control strain decreased by 1.4 log 10 CFU/g, and pathogen numbers declined 1.9 log 10 CFU/g when patties were stored for 4 weeks at 20 degrees C . When patties were stored at -2 degrees C for 4 weeks, the numbers of the E . coli control strain and the serotype O157:H7 strains decreased 2.8 and 1.5 log 10 CFU/g, respectively . Patties stored at 15 degrees C for 4 h prior to storage at -2 degrees C for 4 weeks resulted in 1.6 and 2.7 log 10-CFU/g reduction in the numbers of E . coli and E . coli O157:H7, respectively . Storage of retail ground beef at 15 degrees C for 4 h (tempering) did not result in increased numbers of colony forming units per gram, as determined with violet red bile, MRS lactobacilli, and plate-count agars . Frozen storage (-20 degrees C) of ground-beef patties that had been inoculated with a single strain of E . coli resulted in approximately a 1 to 2 log 10-CFU/g reduction in the numbers of the control strain and individual serotype O157:H7 strains after 1 year . There was no significant difference between the survival of the control strain and the O157:H7 strains, nor was there a difference between O157:H7 strains . These data demonstrate that tempering of ground-beef patties prior to low-temperature storage accelerated the decline in the numbers of E . coli O157:H7.

J Infect Dis, 1999 Dec, 180(6), 1950 - 6
The identification of vaginal Lactobacillus species and the demographic and microbiologic characteristics of women colonized by these species; Antonio MA et al.; Lactobacillus acidophilus has been reported to be the predominant vaginal species . Vaginal lactobacilli isolated from 215 sexually active women were identified using whole-chromosomal DNA probes to 20 American Type Culture Collection Lactobacillus strains . Most women were colonized by L . crispatus (32%), followed by L . jensenii (23%), a previously undescribed species designated L . 1086V (15%), L . gasseri (5%), L . fermentum (0.3%), L . oris (0.3%), L . reuteri (0.3%), L . ruminis (0.3%), and L . vaginalis (0.3%) . H2O2 was produced by 95% of L . crispatus and 94% of L . jensenii isolates, compared with only 9% of L . 1086V . Colonization by L . crispatus or L . jensenii was positively associated with being white (P<.001), age >/=20 years (P=.05), barrier contraceptive usage (P=.008), and lower frequency of bacterial vaginosis (P<.001) and gonorrhea (P=.03) . L . crispatus and L . jensenii, not L . acidophilus, are the most common species of vaginal lactobacilli.

J Infect Dis, 1999 Dec, 180(6), 1863 - 8
Vaginal lactobacilli, microbial flora, and risk of human immunodeficiency virus type 1 and sexually transmitted disease acquisition; Martin HL et al.; A prospective cohort study was conducted to examine the relationship between vaginal colonization with lactobacilli, bacterial vaginosis (BV), and acquisition of human immunodeficiency virus type 1 (HIV-1) and sexually transmitted diseases in a population of sex workers in Mombasa, Kenya . In total, 657 HIV-1-seronegative women were enrolled and followed at monthly intervals . At baseline, only 26% of women were colonized with Lactobacillus species . During follow-up, absence of vaginal lactobacilli on culture was associated with an increased risk of acquiring HIV-1 infection (hazard ratio {HR}, 2.0; 95% confidence interval {CI}, 1.2-3.5) and gonorrhea (HR, 1.7; 95% CI, 1.1-2.6), after controlling for other identified risk factors in separate multivariate models . Presence of abnormal vaginal flora on Gram's stain was associated with increased risk of both HIV-1 acquisition (HR, 1.9; 95% CI, 1.1-3.1) and Trichomonas infection (HR, 1.8; 95% CI, 1.3-2.4) . Treatment of BV and promotion of vaginal colonization with lactobacilli should be evaluated as potential interventions to reduce a woman's risk of acquiring HIV-1, gonorrhea, and trichomoniasis.

Curr Microbiol, 2000 Jan, 40(1), 40 - 6
Molecular identification of potentially probiotic lactobacilli; Roy D et al.; The rRNA-targeted oligonucleotide probes are useful for the identification of Lactobacillus acidophilus, L . gasseri, L . johnsonii, L . crispatus, and L . amylovorus . However, the oligonucleotide probe designed for L . helveticus hybridized with nucleic acids of type strains of L . gallinarum and L . helveticus . Hence, the similarity among the 73 strains of lactobacilli was evaluated on the basis of their randomly amplified polymorphic DNA (RAPD) profiles derived from five single-primer reactions . These strains were grouped into seven clusters at a similarity level of 30%, which corresponded to six separate species of the L . acidophilus complex (L . johnsonii, L . gallinarum, L . amylovorus, L . crispatus, L . acidophilus, and L . gasseri, respectively) and L . helveticus . For the first time, strains of L . gallinarum were characterized by RAPD and PFGE analyses . The genome length in that species was estimated to be near 1.45 Mb with the summation of ApaI fragments, and near 1.95 Mb with the summation of SmaI fragments.

J Anim Sci, 1999 Nov, 77(11), 3084 - 95
Feasibility of using total purines as a marker for ruminal bacteria; Obispo NE et al.; A procedure for measuring total purine content of mixed ruminal bacteria was adapted for use in the determination of purines in pure cultures of ruminal bacteria . Recovery of adenine and guanine, alone or in mixture, was quite variable . The problem was traced to solubility of the silver salt of adenine in the acid wash solution . When the precipitating solution was used as the wash, recovery of the purines was over 97% . Recovery of a 1:1 mixture of adenine and guanine added to yeast RNA was 100.6+/-3.2% . Purine, protein, and bacterial concentrations were determined for 10 pure cultures of ruminal bacteria: Butyrivibrio fibrisolvens, D16f, H10b, and H17c; Fibrobacter succinogenes B21a; Lachnospira multiparus D25e; Lactobacillus lactis ARD26e; Prevotella ruminicola H15a; Ruminococcus albus 7; Ruminococcus flavefaciens B34b; and Streptococcus bovis ARD5d . The CV for the most-probable-number (MPN) assay (bacterial concentrations), purine analysis, and protein analysis were 55.86, 5.25 and 6.52%, respectively . Considerable variation was found among bacterial species and strains when purine and protein concentrations were compared as the amount per individual cell . More consistent values were obtained when these components were expressed on a dry matter basis . Purine:protein ratios for the 10 pure cultures ranged from .023 to .1299, with a mean value of .0883 . For samples of mixed bacteria separated from ruminal fluid, this ratio was found to average .0306, which is approximately one-third of the value for the pure cultures . The value determined for the mixed bacterial sample is similar to previously reported values . Based on the ratio obtained with the pure cultures, the microbial protein flow out of the rumen has probably been overestimated in most previous reports . Limited studies suggest that the samples of mixed ruminal bacteria used as a standard are probably contaminated with feed particles containing protein, which results in lower purine:protein ratios.

FEMS Microbiol Lett, 1999 Dec 1, 181(1), 109 - 12
Evidence of a glucose proton motive force-dependent permease and a fructose phosphoenolpyruvate:phosphotransferase transport system in Lactobacillus reuteri CRL 1098; Taranto MP et al.; Sugar uptake and phosphoenolpyruvate phosphorylation assays have shown that the heterofermentative strain Lactobacillus reuteri CRL 1098, of likely probiotic value, can transport D-fructose through an inducible fructose-specific phosphotransferase system (K(m) 95 microM) and D-glucose mainly through a proton motive force-driven permease . These data open new perspectives for metabolic and regulatory studies in this bacterium.

Chin J Dent Res, 1999 Feb, 2(1), 34 - 7
A study of the relationship between caries activity and the status of dental caries: application of the Dentocult LB method; Shi S et al.; OBJECTIVE: To clarify the relationship between caries activity and the status of caries of primary teeth and the relationship between the quantity of Lactobacillus in the oral cavity and the status of dental caries . METHODS: The status of caries of primary teeth in 164 children ages 3 to 5 was examined . Caries incidence, mean DFT, and Caries Severity Index (CSI) were calculated . Based on the quantity of Lactobacilli in the saliva of preschool children detected with the Dentocult LB method of caries activity, four grades were classified: Grade 0 = 10(3) CFU/mL, Grade I = 10(4) CFU/mL, Grade II = 10(5) CFU/mL, and Grade III = 10(6) CFU/mL . RESULTS: The results showed that 34.15% of the children had caries status beyond Grade I . There were significant differences of caries status, DFT, and CSI among different grades, all of which increased with grades . There was a high correlation between grades and caries incidence, DFT, and CSI in the 164 preschool children . CONCLUSION: As a Caries Activity Test (CAT), detection of Lactobacilli may reveal the status of dental caries and provide valuable information for the prevention and treatment of dental caries.

FEMS Microbiol Lett, 1999 Nov 15, 180(2), 297 - 304
Relationships between arginine degradation, pH and survival in Lactobacillus sakei; Champomier Verges MC et al.; Lactobacillus sakei is one of the most important lactic acid bacteria of meat and fermented meat products . It is able to degrade arginine with ammonia and ATP production by the arginine deiminase pathway (ADI) . This pathway is composed of three enzymes: arginine deiminase, ornithine transcarbamoylase and carbamate kinase, and an arginine transport system . The transcription of the ADI pathway is induced by arginine and subjected to catabolite repression . In order to understand the physiological role of the degradation of this amino acid we investigated the growth of bacteria under various conditions . We show that arginine degradation is responsible for an enhanced viability during the stationary phase when cells are grown under anaerobiosis . Arginine is necessary for the induction of the ADI pathway but in association with another environmental signal . Using a mutant of the L-lactate dehydrogenase unable to lower the pH we could clearly demonstrate that (i) low pH is not responsible for cell death during the stationary phase, so survival is due to another factor than elevated pH, (ii) neither low pH nor oxygen limitation is responsible for the induction of the ADI pathway together with arginine since the ldhL mutant is able to degrade arginine under aerobiosis.

Int J Syst Bacteriol, 1999 Oct, 49 Pt 4, 1451 - 5
Lactobacillus paralimentarius sp . nov., isolated from sourdough; Cai Y et al.; Six strains of lactic acid bacteria isolated from sourdough were characterized taxonomically . They were Gram-positive, catalase-negative, facultatively anaerobic rods that did not produce gas from glucose . Morphological and physiological data indicated that the strains belong to the genus Lactobacillus and they were similar to Lactobacillus alimentarius in phenotypic characteristics . These strains shared the same phenotypic characteristics and exhibited intragroup DNA homology values of over 89.8%, indicating that they comprised a single species . The G + C content of the DNA for the strains was 37.2-38.0 mol% . The 16S rRNA sequence of representative strain TB 1T was determined and aligned with that of other Lactobacillus species . This strain was placed in the genus Lactobacillus on the basis of phylogenetic analysis . L . alimentarius was the most closely related species in the phylogenetic tree and this species also showed the highest sequence homology value (96%) with strain TB 1T . DNA-DNA hybridization indicated that strain TB 1T did not belong to L . alimentarius . It is proposed that these strains are placed in the genus Lactobacillus as a new species, Lactobacillus paralimentarius sp . nov . The type strain of L . paralimentarius is TB 1T, which has been deposited in the Japan Collection of Microorganisms (JCM) as strain JCM 10415T.

Int J Syst Bacteriol, 1999 Oct, 49 Pt 4, 1417 - 28
Comparison of partial malolactic enzyme gene sequences for phylogenetic analysis of some lactic acid bacteria species and relationships with the malic enzyme; Groisillier A et al.; DNA sequences covering 36% of the mle gene that encodes the malolactic enzyme were determined for 13 strains of lactic acid bacteria, representing Pediococcus, Leuconostoc, Lactobacillus and Oenococcus genera . The sequences were aligned with the corresponding region of mleS in Lactococcus lactis . The phylogenetic distance matrix tree of all mle sequences was compared with the 16S rRNA phylogenetic tree . The analysis showed that the mle fragment evolved more rapidly than the 16S gene and differently . Pediococcus and Lactobacillus species were intermixed in the 16S rRNA tree whereas they were separated in the mle tree . Leuconostoc mesenteroides and Oenococcus oeni were distinct from other species in the 16S rRNA tree, whereas they were intermixed with Lactobacillus species and Lactococcus lactis in the mle tree . The amino acid sequences deduced from partial mle genes were aligned with 22 malic enzyme sequences and the corresponding phylogenetic tree was constructed . Malic and malolactic enzymes were distinct at the phylogenetic level, except for malic enzymes of yeast and Escherichia coli which were nearer the malolactic enzymes than the other malic enzymes . The analysis of conserved sites showed several interesting amino acids specific to either malic enzyme or malolactic enzyme.

Oral Microbiol Immunol, 1999 Aug, 14(4), 238 - 43
Mutans streptococci and other caries-associated acidogenic bacteria in five-year-old children in South Africa; Toi CS et al.; Correlations between mutans streptococci and caries are inconsistent; some studies show that early caries may occur with other bacterial species possessing the ability to survive, interact and compete with mutans streptococci . This study looked at the relationship between mutans streptococci, Lactobacillus, Actinomyces and Veillonella in saliva and plaque collected from four tooth sites in two ethnic groups, with and without caries . All samples were collected and cultured onto selective media . Colonies were enumerated and identified using biochemical tests . Pearson correlations showed low yet statistically significant correlations between plaque mutans streptococci counts and the number of decayed surfaces (ds) and decayed, missing and filled surfaces (dmfs) of primary teeth in blacks and in coloreds (historical race classification) . Salivary mutans streptococci counts correlated with ds and dmfs in coloreds . No relationship was found between ds, dmfs and Lactobacillus, Actinomyces or Veillonella numbers . Significant associations were evident between plaque mutans streptococci and Veillonella and Lactobacillus in black children with caries and between plaque mutans streptococci and Actinomyces and Lactobacillus and Veillonella in colored children . Hence, oral microbes are in constant flux but have interrelationships in children with caries.

Oral Microbiol Immunol, 1999 Oct, 14(5), 316 - 20
Impaired secretory immunity in dystrophic epidermolysis bullosa; Sweet SP et al.; Dystrophic epidermolysis bullosa is a congenital disorder characterized by blistering of the skin and oral mucosa . This study investigated the hypothesis that children with dystrophic epidermolysis bullosa have impaired oral secretory immunity . Immunoglobulin A (IgA), secretory IgA and IgG concentrations, and IgA and secretory IgA antibody levels to Candida albicans, Lactobacillus casei and Streptococcus mutans were measured in whole saliva from 22 children with dystrophic epidermolysis bullosa and 22 matched controls . Salivary total IgA and total IgG concentrations were significantly raised in dystrophic epidermolysis bullosa due to serum leakage from oral blistering, but the converse was seen with secretory IgA . This suggestion of a mucosal immune defect was supported by decreased secretory IgA antibody responses to all three microorganisms tested . This apparent defect in secretory immunity in dystrophic epidermolysis bullosa may be due to mucosal involvement and damage resulting in impaired antigen sampling in mucosal associated lymphoid tissue or to impaired transport of secretory IgA across the salivary gland mucosa.

Clin Diagn Lab Immunol, 1999 Nov, 6(6), 799 - 802
Effects of orally administered viable Lactobacillus rhamnosus GG and Propionibacterium freudenreichii subsp . shermanii JS on mouse lymphocyte proliferation; Kirjavainen PV et al.; Immunomodulation by probiotics is a subject of growing interest, but the knowledge of dose response and time profile relationships is minimal . In this study we examined the effects of Lactobacillus rhamnosus GG (LGG) and Propionibacterium freudenreichii subsp . shermanii JS (PJS) on the proliferative activity of murine lymphocytes ex vivo . Dose dependency was assessed by treating animals perorally with a low or a high dose (i.e., 10(9) or 10(12) viable bacteria/kg of body weight) for 7 days . The lower dose levels of each strain appeared to enhance T-cell proliferation at the optimal concanavalin A (ConA) concentration (by 69 to 84%) and B-cell proliferation at the optimal and supraoptimal concentrations of lipopolysaccharide (by 57 to 82%) . B-cell proliferation was also enhanced by the high LGG dose (by 32 to 39%) but was accompanied by a marginal decrease in T-cell proliferation (by 8%) at the optimal ConA concentration . The time profiles of the immune responses were assessed after daily treatment with the higher dose for 3, 7, and 14 days . A significant decrease in basal lymphoproliferation (by 32 to 42%) was observed with PJS treatment after the 3- and 7-day periods; however, this activity returned to control levels after 14 days of treatment, which also resulted in significantly enhanced T-cell proliferation at optimal and supraoptimal ConA concentrations (by 24 to 80%) . The 14-day LGG treatment also enhanced the latter activity (by 119%) . In conclusion, LGG and PJS have specific dose- and duration-dependent immunomodulatory effects on the proliferative activity of B and T lymphocytes and may also reduce lymphocyte sensitivity to the cytotoxic effects of lectin mitogens.

Plasmid, 1999 Nov, 42(3), 221 - 35
Complete sequence of plasmid pLH1 from lactobacillus helveticus ATCC15009: analysis reveals the presence of regions homologous to other native plasmids from the host strain; Thompson JK et al.; The complete sequence for plasmid pLH1 from Lactobacillus helveticus ATCC15009 has been determined . Analysis of the 19,360-bp primary sequence revealed a putative replication origin and initiation protein, information that could provide the basis for the construction of cloning vectors for L . helveticus . Evidence that pLH1 is theta-replicating could be deduced from the plasmid size, from the homology to the replication protein of the Bacillus natto theta-replicating plasmid pLS32, and from the identification of a putative resolvase gene (orf-195) . Although 14 open reading frames capable of encoding polypeptides longer than 100 amino acids were identified, none, on the basis of homology with known sequences, appeared to encode a well-characterized trait relevant to milk fermentation . Plasmid pLH1 revealed regions of identity with the smaller cryptic plasmids (pLH2 and pLH3) from the same strain and with other tracts of DNA, including insertion sequence elements, from a variety of other lactic acid bacteria . The presence of such regions provides a basis for developing an explanation of the phenotypic variability observed in these bacteria . The plasmid also appears to possess a number of genetic elements present in other lactic acid bacterial plasmids, conservation of which would be consistent with an important functional or evolutionary role . It could be argued that the plasmid complement of L . helveticus ATCC15009 consists of parasitic entities concerned only with their own replication and survival .

Appl Environ Microbiol, 1999 Nov, 65(11), 4729 - 33
Introduction of peptidase genes from Lactobacillus delbrueckii subsp . lactis into Lactococcus lactis and controlled expression; Wegmann U et al.; Peptidases PepI, PepL, PepW, and PepG from Lactobacillus delbrueckii subsp . lactis, which have no counterparts in Lactococcus lactis, and peptidase PepQ were examined to determine their potential to confer new peptidolytic properties to lactococci . Controllable expression of the corresponding genes (pep genes) was achieved by constructing translational fusions with the promoter of the nisA gene (P(nisA)) . A suitable host strain, UKLc10, was constructed by chromosomal integration of the genes encoding the NisRK two-component system into the fivefold peptidase-deficient mutant IM16 of L . lactis . Recombinants of this strain were used to analyze growth, peptidase activities, peptide utilization, and intracellular protein cleavage products . After nisin induction of P(nisA)::pep fusions, all of the peptidases were visible as distinct bands in protein gels . Despite the fact that identical transcription and translation signals were used to express the pep genes, the relative amounts of individual peptidases varied considerably . All of the peptidases exhibited activities in extracts of recombinant UKLc10 clones, but only PepL and PepG allowed the clones to utilize specific peptide substrates as sources of essential amino acids . In milk medium, induction of pepG and induction of pepW resulted in growth acceleration . The activities of all five peptidases during growth in milk medium were revealed by high-performance liquid chromatography analyses of intracellular amino acid and peptide pools.

FEMS Microbiol Lett, 1999 Nov 1, 180(1), 55 - 60
Tyrosine decarboxylase activity of Lactobacillus brevis IOEB 9809 isolated from wine and L . brevis ATCC 367; Moreno-Arribas V et al.; Tyramine, a frequent amine in wines, is produced from tyrosine by the tyrosine decarboxylase (TDC) activity of bacteria . The tyramine-producing strain Lactobacillus brevis IOEB 9809 isolated from wine and the reference strain L . brevis ATCC 367 were studied . At the optimum pH, 5.0, K(m) values of IOEB 9809 and ATCC 367 crude extracts for L-tyrosine were 0.58 mM and 0.67 mM, and V(max) was higher for the wine strain (115 U) than the ATCC 367 (66 U) . TDC exhibited a preference for L-tyrosine over L-DOPA as substrate . Enzyme activity was pyridoxal-5'-phosphate (PLP)-dependent and it was stabilized by the substrate and coenzyme . In contrast, glycerol and beta-mercaptoethanol strongly inhibited TDC . Tyramine competitively inhibited TDC for both strains . Citric acid, lactic acid and ethanol had an inhibitory effect on cells and crude extracts, but none could inhibit TDC at the usual concentrations in wines.

J Pediatr, 1999 Nov, 135(5), 564 - 8
Lactobacillus GG in the prevention of antibiotic-associated diarrhea in children; Vanderhoof JA et al.; OBJECTIVE: The objective of this study was to determine the efficacy of Lactobacillus casei sps . rhamnosus (Lactobacillus GG) (LGG) in reducing the incidence of antibiotic-associated diarrhea when coadministered with an oral antibiotic in children with acute infectious disorders . STUDY DESIGN: Two hundred two children between 6 months and 10 years of age were enrolled; 188 completed all phases of the protocol . LGG, 1 x 10(10) - 2 x 10(10) colony forming units per day, or comparable placebo was administered in a double-blind randomized trial to children receiving oral antibiotic therapy in an outpatient setting . The primary caregiver was questioned every 3 days regarding the incidence of gastrointestinal symptoms, predominantly stool frequency and consistency, through telephone contact by blinded investigators . RESULTS: Twenty-five placebo-treated but only 7 LGG-treated patients had diarrhea as defined by liquid stools numbering 2 or greater per day . Lactobacillus GG overall significantly reduced stool frequency and increased stool consistency during antibiotic therapy by the tenth day compared with the placebo group . CONCLUSION: Lactobacillus GG reduces the incidence of antibiotic-associated diarrhea in children treated with oral antibiotics for common childhood infections.

Appl Environ Microbiol, 1999 Nov, 65(11), 4981 - 6
Lactobacillus salivarius CTC2197 prevents Salmonella enteritidis colonization in chickens; Pascual M et al.; A rifampin-resistant Lactobacillus salivarius strain, CTC2197, was assessed as a probiotic in poultry, by studying its ability to prevent Salmonella enteritidis C-114 colonization in chickens . When the probiotic strain was dosed by oral gavage together with S . enteritidis C-114 directly into the proventriculus in 1-day-old Leghorn chickens, the pathogen was completely removed from the birds after 21 days . The same results were obtained when the probiotic strain was also administered through the feed and the drinking water apart from direct inoculation into the proventriculus . The inclusion of L . salivarius CTC2197 in the first day chicken feed revealed that a concentration of 10(5) CFU g(-1) was enough to ensure the colonization of the gastrointestinal tract of the birds after 1 week . However, between 21 and 28 days, L . salivarius CTC2197 was undetectable in the gastrointestinal tract of some birds, showing that more than one dose would be necessary to ensure its presence till the end of the rearing time . Freeze-drying and freezing with glycerol or skim milk as cryoprotective agents, appeared to be suitable methods to preserve the probiotic strain . The inclusion of the L . salivarius CTC2197 in a commercial feed mixture seemed to be a good way to supply it on the farm, although the strain showed sensitivity to the temperatures used during the feed mixture storage and in the chicken incubator rooms . Moreover, survival had been improved after several reinoculations in chicken feed mixture.

Appl Environ Microbiol, 1999 Nov, 65(11), 4746 - 52
Cloning, expression, and characterization of cadmium and manganese uptake genes from Lactobacillus plantarum; Hao Z et al.; An Mn(2+) and Cd(2+) uptake gene, mntA, was cloned from Lactobacillus plantarum ATCC 14917 into Escherichia coli . Its expression conferred on E . coli cells increased Cd(2+) sensitivity as well as energy-dependent Cd(2+) uptake activity . Both transcription and translation of mntA were induced by Mn(2+) starvation in L . plantarum, as indicated by reverse transcriptase PCR and immunoblotting . Two Cd(2+) uptake systems have been identified in L . plantarum: one is a high-affinity Mn(2+) and Cd(2+) uptake system that is expressed in Mn(2+)-starved cells, and the other is a nonsaturable Cd(2+) uptake system that is expressed in Cd(2+)-sufficient cells (Z . Hao, H . R . Reiske, and D . B . Wilson, Appl . Environ . Microbiol . 65:592-99, 1999) . MntA was not detected in an Mn(2+)-dependent mutant of L . plantarum which had lost high-affinity Mn(2+) and Cd(2+) uptake activity . The results suggest that mntA is the gene encoding the high-affinity Mn(2+) and Cd(2+) transporter . On the basis of its predicted amino acid sequence, MntA belongs to the family of P-type cation-translocating ATPases . The topology and potential Mn(2+)- and Cd(2+)-binding sites of MntA are discussed . A second clone containing a low-affinity Cd(2+) transport system was also isolated.

Appl Environ Microbiol, 1999 Nov, 65(11), 4741 - 5
Characterization of cadmium uptake in Lactobacillus plantarum and isolation of cadmium and manganese uptake mutants; Hao Z et al.; Two different Cd(2+) uptake systems were identified in Lactobacillus plantarum . One is a high-affinity, high-velocity Mn(2+) uptake system which also takes up Cd(2+) and is induced by Mn(2+) starvation . The calculated K(m) and V(max) are 0.26 microM and 3.6 micromol g of dry cell(-1) min(-1), respectively . Unlike Mn(2+) uptake, which is facilitated by citrate and related tricarboxylic acids, Cd(2+) uptake is weakly inhibited by citrate . Cd(2+) and Mn(2+) are competitive inhibitors of each other, and the affinity of the system for Cd(2+) is higher than that for Mn(2+) . The other Cd(2+) uptake system is expressed in Mn(2+)-sufficient cells, and no K(m) can be calculated for it because uptake is nonsaturable . Mn(2+) does not compete for transport through this system, nor does any other tested cation, i.e., Zn(2+), Cu(2+), Co(2+), Mg(2+), Ca(2+), Fe(2+), or Ni(2+) . Both systems require energy, since uncouplers completely inhibit their activities . Two Mn(2+)-dependent L . plantarum mutants were isolated by chemical mutagenesis and ampicillin enrichment . They required more than 5,000 times as much Mn(2+) for growth as the parental strain . Mn(2+) starvation-induced Cd(2+) uptake in both mutants was less than 5% the wild-type rate . The low level of long-term Mn(2+) or Cd(2+) accumulation by the mutant strains also shows that the mutations eliminate the high-affinity Mn(2+) and Cd(2+) uptake system.

FEMS Immunol Med Microbiol, 1999 Nov, 26(2), 153 - 8
Immunological cross-reactivity between the vaccine and other isolates of Streptococcus bovis and Lactobacillus; Shu Q et al.; Recent studies have showed that immunisation with Streptococcus bovis (Sb-5) and Lactobacillus (LB-27) may confer protection against lactic acidosis in sheep and cattle . The present study was designed to determine the degree of immunological cross-reactivity between Sb-5 and eight other strains of Streptococcus bovis; and between LB-27 and four other isolates of Lactobacillus . The cross-reactivity index (CRI, a low CRI indicates a high degree of immunological cross-reactivity) ranged from 7.3 to 56.1% between the strains of S . bovis (the encapsulated strains with CRIs ranging from 7.3 to 12.4%) . For isolates of Lactobacillus the CRIs ranged from 11.5 to 72.2% . The results indicate that all the isolates tested have a certain degree of immunological homology with Sb-5 and LB-27, and suggest that the vaccine may cross-react with a large number of strains of S . bovis and Lactobacillus which may cause lactic acidosis . As most of the S . bovis strains in the rumen are encapsulated, the high degree of homology between Sb-5 and encapsulated S . bovis strains further suggests that the vaccine containing Sb-5 may be effective against a wide range of strains of S . bovis in sheep and cattle.

FEMS Immunol Med Microbiol, 1999 Nov, 26(2), 137 - 42
The effect of probiotic bacteria on the adhesion of pathogens to human intestinal mucus; Tuomola EM et al.; Human intestinal glycoproteins extracted from faeces were used as a model for intestinal mucus to investigate adhesion of pathogenic Escherichia coli and Salmonella strains, and the effect of probiotics on this adhesion . S-fimbriated E . coli expressed relatively high adhesion in the mucus model, but the other tested pathogens adhered less effectively . Probiotic strains Lactobacillus GG and L . rhamnosus LC-705 as well as a L . rhamnosus isolated from human faeces were able to slightly reduce S-fimbria-mediated adhesion . Adhesion of S . typhimurium was significantly inhibited by probiotic L . johnsonii LJ1 and L . casei Shirota . Lactobacillus GG and L . rhamnosus (human isolate) increased the adhesion of S . typhimurium suggesting that the pathogen interacts with the probiotic.

FEMS Immunol Med Microbiol, 1999 Nov, 26(2), 131 - 5
The effect of orally administered viable probiotic and dairy lactobacilli on mouse lymphocyte proliferation; Kirjavainen PV et al.; Four common Lactobacillus strains were screened for their effects on proliferation of mouse splenic lymphocytes . Mice received perorally 10(9) viable bacteria kg(-1) body weight for 7 days . Lactobacillus acidophilus treatment enhanced ex vivo basal proliferation (by 43%) and B-cell response at suboptimal and optimal concentrations of lipopolysaccharide (LPS) (by 27-28%) . Conversely, Lactobacillus casei, Lactobacillus gasseri and Lactobacillus rhamnosus inhibited both basal proliferation (by 14-51%) and mitogen-stimulated lymphoproliferation, particularly at supra-optimal concentrations of concanavalin A (by 43-68%) and LPS (by 23-62%) . Therefore, these Lactobacillus strains demonstrate strain-specific effects on B- and T-cells and may also alter the splenocyte sensitivity to the cytotoxic effects of mitogens.

Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 403 - 11
Non-dairy lactic fermentations: the cereal world; Vogel RF et al.; Sourdough is the foremost cereal fermentation performed in a variety of technologies with almost any cereal . The lactobacilli studied most intensely include Lactobacillus sanfranciscensis, L . reuteri and L . pontis isolated from traditional and modern rye and wheat fermentations . Molecular biology tools are available for their rapid identification and monitoring throughout a process . The currently available insight on their metabolism can be used to explain their prevalence in this environment and their interactions . Key genes of the sugar degradation pathway were cloned and characterised from L . sanfranciscensis . In addition some strains were found to have special properties including the production of antagonistic compounds or the adhesion to human intestinal cells.

Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 317 - 31
Lactic acid bacteria in the quality improvement and depreciation of wine; Lonvaud-Funel A; The winemaking process includes two main steps: lactic acid bacteria are responsible for the malolactic fermentation which follows the alcoholic fermentation by yeasts . Both types of microorganisms are present on grapes and on cellar equipment . Yeasts are better adapted to growth in grape must than lactic acid bacteria, so the alcoholic fermentation starts quickly . In must, up to ten lactic acid bacteria species can be identified . They belong to the Lactobacillus, Pediococcus, Leuconostoc and Oenococcus genera . Throughout alcoholic fermentation, a natural selection occurs and finally the dominant species is O . oeni, due to interactions between yeasts and bacteria and between bacteria themselves . After bacterial growth, when the population is over 10(6) CFU/ml, malolactic transformation is the obvious change in wine composition . However, many other substrates can be metabolized . Some like remaining sugars and citric acid are always assimilated by lactic acid bacteria, thus providing them with energy and carbon . Other substrates such as some amino acids may be used following pathways restricted to strains carrying the adequate enzymes . Some strains can also produce exopolysaccharides . All these transformations greatly influence the sensory and hygienic quality of wine . Malic acid transformation is encouraged because it induces deacidification . Diacetyl produced from citric acid is also helpful to some extent . Sensory analyses show that many other reactions change the aromas and make malolactic fermentation beneficial, but they are as yet unknown . On the contrary, an excess of acetic acid, the synthesis of glucane, biogenic amines and precursors of ethylcarbamate are undesirable . Fortunately, lactic acid bacteria normally multiply in dry wines; moreover some of these activities are not widespread . Moreover, the most striking trait of wine lactic acid bacteria is their capacity to adapt to a hostile environment . The mechanisms for this are not yet completely elucidated . Molecular biology has provided some explanations for the behaviour and the metabolism of bacteria in wine . New tools are now available to detect the presence of desirable and undesirable strains . Even if much remains unknown, winemakers and oenologists can nowadays better control the process . By acting upon the diverse microflora and grape musts, they are more able to produce healthy and pleasant wines.

Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 217 - 46
Peptidases and amino acid catabolism in lactic acid bacteria; Christensen JE et al.; The conversion of peptides to free amino acids and their subsequent utilization is a central metabolic activity in prokaryotes . At least 16 peptidases from lactic acid bacteria (LAB) have been characterized biochemically and/or genetically . Among LAB, the peptidase systems of Lactobacillus helveticus and Lactococcus lactis have been examined in greatest detail . While there are homologous enzymes common to both systems, significant differences exist in the peptidase complement of these organisms . The characterization of single and multiple peptidase mutants indicate that these strains generally exhibit reduced specific growth rates in milk compared to the parental strains . LAB can also catabolize amino acids produced by peptide hydrolysis . While the catabolism of amino acids such as Arg, Thr, and His is well understood, few other amino acid catabolic pathways from lactic acid bacteria have been characterized in significant detail . Increasing research attention is being directed toward elucidating these pathways as well as characterizing their physiological and industrial significance.

Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 159 - 84
The biosynthesis and functionality of the cell-wall of lactic acid bacteria; Delcour J et al.; The cell wall of lactic acid bacteria has the typical gram-positive structure made of a thick, multilayered peptidoglycan sacculus decorated with proteins, teichoic acids and polysaccharides, and surrounded in some species by an outer shell of proteins packed in a paracrystalline layer (S-layer) . Specific biochemical or genetic data on the biosynthesis pathways of the cell wall constituents are scarce in lactic acid bacteria, but together with genomics information they indicate close similarities with those described in Escherichia coli and Bacillus subtilis, with one notable exception regarding the peptidoglycan precursor . In several species or strains of enterococci and lactobacilli, the terminal D-alanine residue of the muramyl pentapeptide is replaced by D-lactate or D-serine, which entails resistance to the glycopeptide antibiotic vancomycin . Diverse physiological functions may be assigned to the cell wall, which contribute to the technological and health-related attributes of lactic acid bacteria . For instance, phage receptor activity relates to the presence of specific substituents on teichoic acids and polysaccharides; resistance to stress (UV radiation, acidic pH) depends on genes involved in peptidoglycan and teichoic acid biosynthesis; autolysis is controlled by the degree of esterification of teichoic acids with D-alanine; mucosal immunostimulation may result from interactions between epithelial cells and peptidoglycan or teichoic acids.

Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 139 - 55
Multi-domain, cell-envelope proteinases of lactic acid bacteria; Siezen RJ; The multi-domain, cell-envelope proteinases encoded by the genes prtB of Lactobacillus delbrueckii subsp . bulgaricus, prtH of Lactobacillus helveticus, prtP of Lactococcus lactis, scpA of Streptococcus pyogenes and csp of Streptococcus agalactiae have been compared using multiple sequence alignment, secondary structure prediction and database homology searching methods . This comparative analysis has led to the prediction of a number of different domains in these cell-envelope proteinases, and their homology, characteristics and putative function are described . These domains include, starting from the N-terminus, a pre-pro-domain for secretion and activation, a serine protease domain (with a smaller inserted domain), two large middle domains A and B of unknown but possibly regulatory function, a helical spacer domain, a hydrophilic cell-wall spacer or attachment domain, and a cell-wall anchor domain . Not all domains are present in each cell-envelope proteinase, suggesting that these multi-domain proteins are the result of gene shuffling and domain swapping during evolution.

Int J Paediatr Dent, 1999 Jun, 9(2), 93 - 8
Pre- and post-treatment levels of salivary mutans streptococci and lactobacilli in pre-school children; Twetman S et al.; OBJECTIVES: To examine the effect of operative and restorative treatment of dental caries on the levels of caries associated microorganisms in saliva and to relate alterations to the type and extent of treatment . DESIGN: Longitudinal . SETTING: Paediatric Dentistry Department at a central hospital in Sweden . SUBJECTS AND METHODS: One hundred and eight pre-school children with severe dental caries scheduled for treatment under general anaesthesia . Chair-side tests were used to estimate the levels of salivary mutans streptococci, lactobacilli and buffer capacity before the surgery and at recall appointments 1 and 6 months after treatment . Caries were assessed according to WHO guidelines and the number of extracted teeth and filled surfaces during surgery were recorded . RESULTS: The results demonstrate that the post-treatment levels of mutans streptococci and lactobacilli were significantly reduced (P < 0.001) compared to pretreatment levels . Lactobacilli levels were more dramatically reduced than mutans streptococci . The reduction of mutans streptococci was positively correlated to the number of extracted teeth (P < 0.01), but not to the number of restored or ground surfaces . Lactobacilli reduction was not significantly related to the type of treatment . CONCLUSION: The findings suggest that extensive operative and restorative dental care effectively reduces the levels of caries associated with microorganisms during a period of at least 6 months.

Indian J Dent Res, 1998 Jul-Sep, 9(3), 91 - 7
Salivary counts of mutans streptococci and lactobacilli in children ageing 6-8 year old having a socioeconomic background in Brazil; Hofling JF et al.; Saliva samples from students aged 6 to 8 year-old were analysed in order to determine the incidence of Streptococcus group mutans and Lactobacillus . Two hundred children were examined, distributed in five socioeconomic categories (A to E) . Stimulated saliva samples were collected and inoculated into the SB20 and Rogsa agar culture medium for the Streptococcus and Lactobacillus cultivation . After growth, the number of these microorganisms (CUF/mL) was determined after identification of the representative colonies by biochemical methods on the basis of carbohydrate fermentation . A significative part of the population, particularly among the lower socioeconomic categories (D/E) was considered a high risk group in developing dental caries because of the high number of Streptococcus group mutans and Lactobacillus.

Cryobiology, 1999 Sep, 39(2), 144 - 9
The effect of suboptimal growth temperature and growth phase on resistance of lactobacillus acidophilus to environmental stress
Lorca GL, de Valdez GF.
This paper describes the effect of growth temperature and the physiological age of Lactobacillus acidophilus CRL 639 on the development of cross resistance to different kinds of environmental stress . Exponential-phase cells growing at 25 degrees C and stationary-phase cells (8- and 11-h-old cultures at the optimal temperature of 37 degrees C) showed the highest survival and metabolic activity after challenge by freezing, heating, osmotic stress, and exposure to ethanol, peroxide, or acid . One-dimensional SDS-PAGE gels showed overexpression of three proteins (22.5, 39.6, and 49.2 kDa) at 25 degrees C, of two proteins (40.9 and 48.3 kDa) in 8-h-old cultures, and of one protein (30.3 kDa) after glucose depletion in 11-h-old cultures . These results strongly suggest the involvement of different sets of protein in the cellular processes of adaptation to environmental changes .

J Food Prot, 1999 Oct, 62(10), 1150 - 6
A 23S rDNA-targeted polymerase chain reaction-based system for detection of Staphylococcus aureus in meat starter cultures and dairy products; Straub JA et al.; A polymerase chain reaction-based system for detection of Staphylococcus aureus was developed . The system consisted of the following components: (i) selective enrichment, (ii) DNA isolation, (iii) amplification of DNA with primers targeted against the 23S rRNA gene, and (iv) evaluation of the specificity of the polymerase chain reaction by Southern hybridization and nested polymerase chain reaction . The method achieved a high degree of sensitivity and unambiguity as required for the detection of contaminants in food starter preparations . The method permitted detection of Staphylococcus aureus in preparations of meat starter cultures containing Staphylococcus carnosus either alone or in combination with lactobacilli, pediococci, and/or Kocuria varians . Detection limits were sufficiently low to show within 12 h the presence of 10(0) CFU of S . aureus in starter preparations containing 10(10) CFU of S . carnosus . The system was also applied to dried skim milk and cream . For detection without selective enrichment, a protocol was developed and permitted detection of 120 CFU of S . aureus in 1 ml of cream within 6 h . With nested polymerase chain reaction, the detection limit was decreased by one order of magnitude.

Microbiol Res, 1999 Sep, 154(2), 199 - 204
Purification and amino acid sequence of lactocin 705, a bacteriocin produced by Lactobacillus casei CRL 705; Palacios J et al.; Lactobacillus casei CRL 705, isolated from a dry fermented sausage, produces an antibacterial peptide which is active against Listeria monocytogenes . Previous studies have shown that this compound is potentially useful to control food-borne pathogens in ground meat . In view of the potential application of this antimicrobial substance in food fermentation, a detailed biochemical analysis of this peptide is required . In this work, the purification and amino acid sequence of this bacteriocin is presented . The adsorption-desorption pH-dependent property of lactocin 705 was exploited for purification . The active extract was further subjected to RP-HPLC and SDS-PAGE . The active antimicrobial band was electroeluted from an SDS-PAGE gel and its amino acid sequence determined . Lactocin 705 had an estimated molecular weight of 3357.80 and an isoelectric point of 10.03 . The peptide contains a high ratio of glycine residues and does not show any modified amino acids, like lanthionine or beta-methyllanthionine . The sequence was unique when compared to several databases.

Clin Oral Investig, 1999 Mar, 3(1), 7 - 10
Salivary mutans streptococci and lactobacilli in 9- and 13-year-old Italian schoolchildren and the relation to oral health; Brambilla E et al.; The prevalence and levels of mutans streptococci (MS) and lactobacilli (LB) in saliva and its possible correlation with dental caries and periodontal conditions was investigated in 473 Italian schoolchildren, 9 and 13 years of age . A clinical examination and sampling of stimulated whole saliva was carried out in the school and oral health was assessed as DMFT and CPITN using the WHO criteria . The saliva samples were frozen in liquid nitrogen and after thawing, cultivated on selective media . To test the influence of cryopreservation, fresh samples from 20 subjects were cultivated . Thirty-five percent of the children were caries-free with a mean DMFT of 1.9 at the age of 13 . The majority exhibited healthy periodontal conditions . Salivary MS and LB were identified in 52% and 21% of the children, respectively . The prevalence of MS was higher among the 13-year-olds than the 9-year-olds while no such difference was found regarding LB . There was a statistically positive relationship (P < 0.01) between the levels of MS and LB and both were significantly correlated to caries (P < 0.01) . The correlation coefficient of microbial recovery between frozen and unfrozen samples was 0.99 . In conclusion, the data provided cross-sectional information of a clear positive relationship between selected micro-organisms in saliva and caries in 9- and 13-year-old children in spite of a relatively low prevalence of the disease . The findings are discussed in a risk selection perspective.

J Dent Res, 1999 Oct, 78(10), 1640 - 6
Saliva, salivary micro-organisms, and oral health in the home-dwelling old elderly--a five-year longitudinal study; Narhi TO et al.; High scores of chair-side salivary microbial tests have been found to be related to an increased prevalence and incidence of coronal and root caries . Many elderly face an increased risk of the growth of oral microbes, and previous studies have reported high salivary microbial counts in elderly populations . The aim of this follow-up study was to compare, at five-year intervals, stimulated salivary flow rates with the numbers of selected salivary micro-organisms (mutans streptococci, lactobacilli, and yeasts) in a group of home-dwelling elderly in Helsinki . A further aim was to study the influence of baseline microbial counts on five-year root caries increments and rates of tooth loss . The baseline study population was comprised of 270 subjects who were all participants in the population-based Helsinki Aging Study . Salivary flow rates and microbial conditions were determined as part of their dental examination at the Institute of Dentistry, University of Helsinki, in 1990-1991 . Of these subjects, 110 underwent a follow-up examination in 1995-1996 . Commercially available kits (Dentocult SM strip mutans for mutans streptococci, Dentocult LB for lactobacilli, and Oricult N for yeasts) were used for the enumeration of micro-organisms, after the collection of paraffin-wax-stimulated whole saliva . The stimulated whole saliva flow rates of the subjects were significantly lower at the follow-up than at baseline (paired t test, difference -0.16 mL/min; p < 0.05), whereas buffer capacity was higher (paired t test, difference 0.19 on a three-unit scale; p < 0.05) . Apart from lower salivary lactobacilli counts at follow-up (paired t test, difference -0.44 CFUs/mL of saliva; p < 0.001), no changes were found in salivary microbial levels . Salivary microbial counts were clearly associated with the subjects' dentition types: More denture-wearers had high microbial counts than persons with natural dentitions . None of the salivary factors correlated with the root caries incidence or the number of teeth lost during the five-year follow-up.

Neurogastroenterol Motil, 1999 Oct, 11(5), 365 - 74
Motility in the Roux-Y limb after distal gastrectomy: relation to the length of the limb and the afferent duodenojejunal segment--an experimental study; Le Blanc-Louvry I et al.; Following gastrectomy, the longer is a Roux-Y limb constructed to restore digestive continuity the higher the frequency of postoperative symptoms . The aim of this experimental study was to test how the level of the jejunal transection and the length of the Roux limb affect the motility of the constructed limb and in particular the onset and the propagation of activity fronts (AFs) . Three months after a distal Roux-en-Y gastrectomy, electromyographic tracings were recorded in six groups of rats grouped according to the level of the transection (20 or 40 cm from the pylorus) and the length of the limb (10, 20 or 30 cm) . Animals in which a simple laparotomy or laparotomy + jejunal transection was performed, served as controls . During the interdigestive period, all animals had AFs in the limb which were independent from those recorded in the duodenum . In the limb, the mean time interval between two AFs was shorter (P < 0.01) and more irregular than in controls . An increase in limb length was associated with a lower incidence of completely propagated AFs (P < 0.05) and a higher incidence of irregularly propagated AFs (P < 0.01) . When propagation of the AFs was analysed both in the limb and in the jejunum distal to the anastomosis, propagation abnormalities were more frequent . Below the gastrojejunal anastomosis, for an intestinal length of either 20 or 30 cm, the frequency of abnormal AFs was not different when this length was either only a limb or a limb with the 10 cm of distal jejunum below the jejuno-jejunal anastomosis . Interruption of AFs by a meal was irregular in the limb and more rarely observed in the 30-cm than in 10-cm limbs (P < 0.05) . Interruption of AFs was shorter than in controls (P < 0.01) . In the duodenum and the jejunum proximal to the limb, the interval between AFs was higher than in controls and in the Roux-Y limbs (P < 0.001) . Intraluminal concentrations of bacterial strains were not different in the different types of limb while lactobacillus concentrations and pooled concentrations of bacteria were higher than in controls (P < 0.05) . No relationship was found between the incidence of myoelectric abnormalities and intraluminal bacterial concentrations . Increasing the length of a Roux-Y limb resulted in more frequent disturbances in AFs in the limb but had no significant consequence on the overall rate of abnormal AFs in the jejunum distal to the transection . Motor response to food intake was also reduced . Motor changes were not related to intraluminal bacterial concentrations.

FEMS Microbiol Lett, 1999 Oct 15, 179(2), 375 - 83
Characterization of pFR18, a small cryptic plasmid from Leuconostoc mesenteroides ssp . mesenteroides FR52, and its use as a food grade vector; Biet F et al.; A 1.8-kb cryptic plasmid pFR18 was isolated from Leuconostoc mesenteroides ssp . mesenteroides FR52 and characterized . The identification of single-stranded DNA intermediate (ssDNA) in Leuconostoc demonstrated that the replication of pFR18 is directed by a rolling-circle mechanism (RCR) . Sequence analysis revealed a single open reading frame (rep18) encoding a putative 335-amino acid protein homologous to the pT181 replicase . Furthermore, a putative double strand origin similar to that of the pT181 plasmid family was identified . A cloning vector was developed on the basis of the pFR18 replicon by inserting an erythromycin resistance cassette within a non-essential region of the plasmid . The resulting construction was able to transform Lactobacillus sake and various species of Leuconostoc . It was stable in L . mesenteroides, however, the segregational stability of a pFR18 derivative containing large Escherichia coli DNA fragments was affected . Nevertheless, the new RCR plasmid pFR18 may be useful for the construction of food grade vectors.

Microbiology, 1999 Sep, 145 ( Pt 9), 2559 - 68
Characterization and production of amylovorin L471, a bacteriocin purified from Lactobacillus amylovorus DCE 471 by a novel three-step method; Callewaert R et al.; The strongly hydrophobic bacteriocin amylovorin L471 from Lactobacillus amylovorus DCE 471 was isolated and purified to homogeneity from complex culture broth by a novel, rapid and simple three-step protocol including (i) ammonium sulphate precipitation, (ii) chloroform/methanol extraction/precipitation and (iii) reversed-phase HPLC, the only chromatographic step involved . The molecular mass of the peptide was determined to be 4876.9 Da by electrospray mass spectrometric analysis . N-terminal amino acid sequencing identified 35 amino acid residues as being identical to the N-terminal sequence of lactobin A, a bacteriocin from another L . amylovorus strain . These non-identical strains produce bacteriocins that display small differences in molecular mass and inhibitory spectrum . The amino acid sequence of amylovorin L471 shared significant homology with lactacin X, one of the two bactericidal peptides produced by Lactobacillus johnsonii VPI11088 . A purified amylovorin L471 preparation permitted confirmation of the inhibitory spectrum previously established with a crude extract . It displayed a bactericidal mode of action on lactobacilli after an extremely rapid adsorption to the target cells . Two Listeria spp . were only weakly sensitive . Amylovorin L471 appears to be produced constitutively . Ethanol not only stimulated specific bacteriocin production but also prevented adsorption of the bacteriocin molecules to the producer cells upon prolonged fermentation . The latter result supports the hypothesis that the apparent inactivation of bacteriocin observed during the stationary phase of batch fermentations is due to adsorption.

Mol Gen Genet, 1999 Sep, 262(2), 355 - 66
Integrative recombination of Lactobacillus delbrueckii bacteriophage mv4: functional analysis of the reaction and structure of the attP site; Auvray F et al.; The integrase of the temperate bacteriophage mv4 catalyzes site-specific recombination between the phage attP site and the attB site of the host during lysogenization of Lactobaccillus delbrueckii subsp . bulgaricus . The mv4 integrase also functions in a wide variety of gram-positive bacteria and in Escherichia coli . In this report, in vitro and in vivo recombination assays were developed and the integrase was purified in order to study in greater detail the mv4 attP x attB recombination event . In a cell-free extract of E . coli at 42 degrees C, the mv4 integrase promotes efficient in vitro recombination between a supercoiled attP-containing plasmid and a linear attB fragment . The integrase, which was purified to apparent homogeneity, showed no absolute requirement for accessory factors, unlike the majority of the lambda Int family of recombinases . Deletion derivatives of the attP site were constructed and tested for recombination with the attB site in vitro . A 234-bp DNA fragment containing five scattered putative mv4 Int-binding sites was sufficient for function of the attP site . In contrast to the right arm of attP, most of the left arm could be deleted without drastically reducing the recombination efficiency . In vivo in E . coli, mv4 Int catalyzed recombination in trains between attP and attB sites present on two separate plasmids . This property was used to confirm in vivo the results of the deletion analysis of the attP site performed in vitro.

J Infect Dis, 1999 Nov, 180(5), 1632 - 6
Correlation of behaviors with microbiological changes in vaginal flora; Schwebke JR et al.; Bacterial vaginosis (BV) is characterized by dramatic changes in the vaginal ecosystem . Women without evidence of vaginal infection may exhibit transient changes in their flora . We prospectively followed up women by using diaries and self-obtained vaginal smears to correlate behaviors with changes in flora . The majority of women (38/51, 78%) had significant, although transient, changes . Behaviors associated with unstable flora were a history of BV, a greater number of partners, and more frequent episodes of receptive oral sex . Only the latter remained significantly associated in the multivariate analysis . Variables that were associated with day-to-day variability in the flora included use of vaginal medication, menses, greater number of partners, spermicide use, more frequent vaginal intercourse, and less frequent use of condoms . Only a minority of women (11/51, 22%) maintained a "normal" lactobacillus-predominant flora . Factors associated with instability of the flora are similar to those epidemiologically associated with BV.

J Bacteriol, 1999 Oct, 181(20), 6569 - 72
Efficiency of transcription from promoter sequence variants in Lactobacillus is both strain and context dependent; McCracken A et al.; The introduction of consensus -35 (TTGACA) and -10 (TATAAT) hexamers and a TG motif into the Lactobacillus acidophilus ATCC 4356 wild-type slpA promoter resulted in significant improvements (4.3-, 4.1-, and 10.7-fold, respectively) in transcriptional activity in Lactobacillus fermentum BR11 . In contrast, the same changes resulted in decreased transcription in Lactobacillus rhamnosus GG . The TG motif was shown to be important in the context of weak -35 and -10 hexamers (L . fermentum BR11) or a consensus -10 hexamer (L . rhamnosus GG) . Thus, both strain- and context-dependent effects are critical factors influencing transcription in Lactobacillus.

Obstet Gynecol, 1999 Oct, 94(4), 630 - 1
The great douching debate: to douche, or not to douche; Monif GR; It has been implied douching causes chlamydial infection, acute salpingitis, ectopic pregnancy, and reduced fertility . However, the incriminating articles do not represent a vast accumulation of data from diverging sources; rather, most reflect repetitive analysis of data from a limited population base by an institutionally interrelated group of investigators . The conclusions reached were reintroduced periodically into the literature in different journals . An equally plausible alternate hypothesis is that douching is a marker for increased probability of one or more sexually transmitted diseases and their sequelae . Review of microbiologic rather than epidemiologic data published on douching revealed that douching with a preparation containing acetic acid caused a small reduction in total bacterial counts . Most of that change was attributable to washing . When povidone-iodine was present, significant reductions occurred, but these were short-lived . The first bacteria to recover are usually the lactobacilli, which might explain partial efficacy of prolonged douching with commercial preparations of povidone-iodine.

Antonie Van Leeuwenhoek, 1999 May, 75(4), 309 - 20
A study on growth characteristics and nutrient consumption of Lactobacillus plantarum in A-stat culture; Kask S et al.; Lactobacillus plantarum was grown in complex media containing glucose and yeast extract . The maximum growth yield based on yeast extract consumption was 0.5 g dwt g-1 . Growth yield YATP 15-17 g dwt mol ATP-1 was almost constant in the glucose limited A-stat experiment whereas in the yeast extract limited culture it increased with dilution rate . The maximum specific growth rate observed, 0.5 h-1, was similar for both A-stat and batch cultures . Specific oxygen consumption, QO2, reached the value of 1.8 mmol O2 h-1 g dwt-1 . It was shown that Val, Ile, Leu, Tyr and Phe, were consumed mainly as free amino acids, while Asp, Pro, Lys and Arg were derived from peptides . Significantly more Asp, Ser, Glu, Val, Ile, Leu and Phe were consumed than needed to build up cell protein whereas some Pro, Gly, Ala and Lys was synthesized . A network of metabolic reactions in L . plantarum was proposed on the basis of the experimental data.

J Ind Microbiol Biotechnol, 1999 Aug, 23(2), 79 - 85
Survival of Lactobacillus helveticus entrapped in Ca-alginate in relation to water content, storage and rehydration; Selmer-Olsen E et al.; Lactobacillus helveticus CNRZ 303 entrapped in Ca-alginate gel beads was investigated for improved survival and stability during fluidized-bed drying, storage and rehydration . Addition of protective solutes was very important . Studies of the conditions showed that inactivation of entrapped L . helveticus started when the water content exceeded 0.3-0.4 g H2O (g dry wt)-1 for adonitol, glycerol and reconstituted non fat milk solids (NFSM) . With Ringer's solution (control) and betaine, the fall in viability was evident above 1 g H2O (g dry wt)-1 . Drying down to 0.2 g H2O (g dry wt)-1 required the removal of 98.5-98.9% of the water . The best survival rate with the least injured cells among survivors was experienced with adonitol and NFMS, respectively, 71% and 57% (compared to the initial) immediately after dehydration . Adonitol and NFMS were also best for survival during storage . The highest cell recovery was obtained by rehydrating the cells in cheese whey permeate between 20-30 degrees C done at pH 6.0-7.0, satisfying the demands for cell survival, repair and slow swelling (adaptions).

Mol Microbiol, 1999 Sep, 33(6), 1152 - 61
Identification of the pH-inducible, proton-translocating F1F0-ATPase (atpBEFHAGDC) operon of Lactobacillus acidophilus by differential display: gene structure, cloning and characterization; Kullen MJ et al.; The influence of low pH on inducible gene expression in Lactobacillus acidophilus was investigated by the use of differential display . Logarithmic phase cultures were exposed to pH 3.5 for various intervals, and RNA was isolated and reverse transcribed . The resultant cDNAs were subjected to PCR and the products were resolved by electrophoresis . Several cDNA products were induced after exposure to pH 3.5 . One of these products, a 0.7 kb fragment, showed sequence similarity to bacterial atpBEF genes of the atp operon, whose genes encode the various subunits of the F1F0-ATPase . With the 0.7 kb differential display product as a probe, hybridizations with total RNA from untreated and acid-treated L . acidophilus verified the acid inducibility of this operon . The increase in atp mRNA induced by low pH was accompanied by an increase in the activity of the enzyme in membrane extracts . The full-length atp operon was sequenced, and its genes were in the order of atpBEFHAGDC, coding for the a, c, b, delta, alpha, gamma, beta and epsilon subunits respectively . The operon contained no i gene, but was preceded by a 122 bp intergenic space, which contained putative extended -10 and -35 promoter regions . Primer extension analysis of RNA from cultures that were shifted from pH 5.6 to pH 3 . 5, and held for 0, 30 or 45 min, revealed that the transcriptional start site did not change position as a function of culture pH or time after exposure to pH 3.5 . The primary structure and genetic organization indicated that the H+-ATPase of L . acidophilus is a typical F1F0-type ATPase . The similarity to streptococcal ATPases and the acid inducibility of this operon suggest that it may function in the ATP-dependent extrusion of protons and maintenance of cytoplasmic pH . Finally, the use of differential display RT-PCR was an effective approach to identify genes in L . acidophilus induced by an environmental stimulus.

J Reprod Med, 1999 Sep, 44(9), 807 - 14
Cost of bacterial vaginosis in pregnancy . Decision analysis and cost evaluation of a clinical study in Germany; Muller E et al.; OBJECTIVE: To estimate the economic impact of screening for and treatment of bacterial vaginosis during early pregnancy . STUDY DESIGN: Data from a clinical study that aligned two screening and treatment strategies and a no-screening or treatment strategy with three gynecologic practices in Berlin were used in decision tree analysis . Costs applied to the clinical outcomes were determined from standard German references and the charges from university clinics . RESULTS: Practices A and B screened all 600 patients in the early second trimester and treated the positive cases with clindamycin 2% vaginal cream (A) or a Lactobacillus preparation (B), which incurred lower total costs, $493,159 and $497,619, as compared to practice C (total costs, $534,926), which did not screen or treat for bacterial vaginosis . Including costs of screening and treatment, the net savings of practice A as compared to practice C was estimated to be $47,316 . CONCLUSION: The presence of more preterm, premature and low-birth-weight infants added costs for practice C . The estimated cost savings lend support to the value of screening and treatment for bacterial vaginosis in early pregnancy.

Curr Opin Biotechnol, 1999 Oct, 10(5), 505 - 10
Functionality of probiotics and intestinal lactobacilli: light in the intestinal tract tunnel; Vaughan EE et al.; The commercial interest in functional foods that contain live microorganisms, also termed probiotics, is paralleled by increasing scientific attention to their functionality in the digestive tract . Most studies are focused on intestinal Lactobacillus species, which are part of the natural gastro-intestinal microbiota, and include analysis of colonisation factors and other interactions with the host, the design of novel or improved strains with specific health benefits, and the application of sophisticated molecular tools to determine their fate and activity in situ.

Appl Environ Microbiol, 1999 Oct, 65(10), 4351 - 6
Use of PCR-based methods for rapid differentiation of Lactobacillus delbrueckii subsp . bulgaricus and L . delbrueckii subsp . lactis; Torriani S et al.; Two PCR-based methods, specific PCR and randomly amplified polymorphic DNA PCR (RAPD-PCR), were used for rapid and reliable differentiation of Lactobacillus delbrueckii subsp . bulgaricus and L . delbrueckii subsp . lactis . PCR with a single combination of primers which targeted the proline iminopeptidase (pepIP) gene of L . delbrueckii subsp . bulgaricus allowed amplification of genomic fragments specific for the two subspecies when either DNA from a single colony or cells extracted from dairy products were used . A numerical analysis of the RAPD-PCR patterns obtained with primer M13 gave results that were consistent with the results of specific PCR for all strains except L . delbrueckii subsp . delbrueckii LMG 6412(T), which clustered with L . delbrueckii subsp . lactis strains . In addition, RAPD-PCR performed with primer 1254 provided highly polymorphic profiles and thus was superior for distinguishing individual L . delbrueckii strains.

Gastrointest Endosc, 1999 Oct, 50(4), 475 - 9
The effect of oral decontamination with clindamycin palmitate on the incidence of bacteremia after esophageal dilation: a prospective trial; Hirota WK et al.; BACKGROUND: Antibiotic prophylaxis to prevent bacterial endocarditis is recommended in high-risk patients undergoing esophageal dilation, a high-risk procedure . Some studies suggest that the oropharynx is the source of bacteremia . A topical antibiotic mouthwash, which reduces bacterial colonization of the oral flora, might decrease bacteremia rates and would be an attractive alternative to systemic administration of antibiotics . METHODS: Adults undergoing outpatient bougienage for a benign or malignant esophageal stricture were randomized in a clinician-blinded fashion to either pre-procedure clindamycin mouthwash or no treatment . Subjects were stratified by type of dilator used . Blood cultures were obtained immediately after the first esophageal dilation and 5 minutes after the last dilation . RESULTS: Fifty-nine patients were enrolled: 30 in the treatment arm and 29 in the no-treatment arm . There were 7 positive blood cultures: 5 in the treatment arm and 2 in the no-treatment arm . The identified organisms were Streptococcus viridans (2), Staphylococcus mucilaginous (2), Lactobacillus (2), and Actinomyces odontolyticus (1) . Patients with bacteremia reported greater subjective difficulty with dysphagia (p = 0.01) irrespective of stricture diameter, procurement of biopsies, or dilator type . CONCLUSIONS: The percentage of cases with bacteremia for all dilations performed in this manner was 12% (95% CI {5.3, 23.6}), much lower than previously cited . All organisms in this study were oral commensals . There appears to be no effect of a clindamycin mouthwash on reducing bacteremia after esophageal dilation.

Lett Appl Microbiol, 1999 Aug, 29(2), 136 - 40
Heat resistance of Lactobacillus spp . isolated from Cheddar cheese; Jordan KN et al.; Mesophilic Lactobacillus spp . are the dominant organisms in mature Cheddar cheese . The heat resistance of broth grown cultures of Lactobacillus plantarum DPC1919 at temperatures between 50 and 57.5 degrees C, Lact . plantarum DPC2102 at temperatures between 48 and 56 degrees C and Lact . paracasei DPC2103 at temperatures between 50 and 67.5 degrees C was determined . The z-values for Lact . plantarum DPC1919, Lact . Plantarum DPC2102 and Lact . paracasei DPC2103 were 6.7 degrees C, 6.2 degrees C and 5.3 degrees C, respectively . Lactobacillus paracasei DPC2103 showed evidence of injury and recovery, especially at higher temperatures . Milk grown cultures of strains DPC2102 and DPC2103 showed greater heat resistance than broth grown cultures, tailing of the death curves and a nonlinear z-curve . Of the three strains, Lact . paracasei DPC2103 had the potential to survive pasteurization temperatures, whether grown in milk or broth.

Lett Appl Microbiol, 1999 Aug, 29(2), 90 - 2
Differentiation of Lactobacillus casei, Lactobacillus paracasei and Lactobacillus rhamnosus by polymerase chain reaction; Ward LJ et al.; Lactobacillus casei, Lact . paracasei and Lact . rhamnosus form a closely related taxonomic group within the heterofermentative lactobacilli . These three species are difficult to differentiate using traditional fermentation profiles . We have developed polymerase chain reaction primers which are specific for each of these species based on differences in the V1 region of the 16S rRNA gene . Sixty-three Lactobacillus isolates from cheese were identified using these primers . The 12 Lact . rhamnosus and 51 Lact . paracasei identified in this way were also differentiated using a randomly amplified polymorphic DNA (RAPD) primer.

Infect Immun, 1999 Oct, 67(10), 5486 - 9
Expression of Chlamydia psittaci- and human immunodeficiency virus-derived antigens on the cell surface of Lactobacillus fermentum BR11 as fusions to bspA; Turner MS et al.; The basic surface protein, BspA, has been used as a fusion partner to direct peptide antigens from the human immunodeficiency virus gp41 protein and the Chlamydia psittaci OmpA protein to the cell surface of Lactobacillus fermentum BR11 . BspA has potential utility in the construction of live vaccines and diagnostic reagents.

Infect Immun, 1999 Oct, 67(10), 5170 - 5
Acid production by vaginal flora in vitro is consistent with the rate and extent of vaginal acidification; Boskey ER et al.; Perinatally, and between menarche and menopause, increased levels of estrogen cause large amounts of glycogen to be deposited in the vaginal epithelium . During these times, the anaerobic metabolism of the glycogen, by the epithelial cells themselves and/or by vaginal flora, causes the vagina to become acidic (pH approximately 4) . This study was designed to test whether the characteristics of acid production by vaginal flora in vitro can account for vaginal acidity . Eight vaginal Lactobacillus isolates from four species-L . gasseri, L . vaginalis, L . crispatus, and L . jensenii-acidified their growth medium to an asymptotic pH (3.2 to 4.8) that matches the range seen in the Lactobacillus-dominated human vagina (pH 3.6 to 4.5 in most women) (B . Andersch, L . Forssman, K . Lincoln, and P . Torstensson, Gynecol . Obstet . Investig . 21:19-25, 1986; L . Cohen, Br . J . Vener . Dis . 45:241-246, 1969; J . Paavonen, Scand . J . Infect . Dis . Suppl . 40:31-35, 1983; C . Tevi-Benissan, L . Belec, M . Levy, V . Schneider-Fauveau, A . Si Mohamed, M.-C . Hallouin, M . Matta, and G . Gresenguet, Clin . Diagn . Lab . Immunol . 4:367-374, 1997) . During exponential growth, all of these Lactobacillus species acidified their growth medium at rates on the order of 10(6) protons/bacterium/s . Such rates, combined with an estimate of the total number of lactobacilli in the vagina, suggest that vaginal lactobacilli could reacidify the vagina at the rate observed postcoitally following neutralization by the male ejaculate (W . H . Masters and V . E . Johnson, Human sexual response, p . 93, 1966) . During bacterial vaginosis (BV), there is a loss of vaginal acidity, and the vaginal pH rises to >4.5 . This correlates with a loss of lactobacilli and an overgrowth of diverse bacteria . Three BV-associated bacteria, Gardnerella vaginalis, Prevotella bivia, and Peptostreptococcus anaerobius, acidified their growth medium to an asymptotic pH (4.7 to 6.0) consistent with the characteristic elevated vaginal pH associated with BV . Together, these observations are consistent with vaginal flora, rather than epithelial cells, playing a primary role in creating the acidity of the vagina.

J Food Prot, 1999 Sep, 62(9), 1004 - 10
Effective use of nisin to control lactic acid bacterial spoilage in vacuum-packed bologna-type sausage; Davies EA et al.; Lactic acid bacteria (LAB) commonly cause spoilage in minimal heat-treated vacuum-packed cured delicatessen meats . Predominant species are Lactobacillus sake and L . curvatus . LAB strains isolated from spoiled products of this type (liver sausage, ham and bologna sausage) were found to be sensitive to low nisin concentrations (maximum of 1.25 microg g(-1)) . Addition of 25 microg g(-1) nisin (as Nisaplin) inhibited the growth of LAB spoilage organisms inoculated into vacuum-packed pasteurized bologna-type sausages stored at 8 degrees C . Control sausages became spoiled (>10(8) LAB CFU g(-1)) by day 7, whereas sausages containing nisin remained unspoiled for >50 days . The effect of three types of phosphates (used as emulsifiers) on nisin activity in the sausages was compared . LAB growth rate was fastest in samples containing orthophosphate, and slowest in sausages containing diphosphate . The shelf life was also greatly extended in the latter . Fat content also affected nisin activity . Nisin activity (as indicated by LAB inhibition) was greatest in samples containing 15% > 25% > 37% (wt/wt) fat . In a sausage formulation containing 37% fat and incorporating diphosphate as emulsifier, levels of nisin as low as 2.5 microg g(-1) showed antibacterial effects . A nisin level of 6.25 microg g(-1) totally inhibited LAB growth for over 4 weeks and 25 microg g(-1) for 5 weeks . Spoilage control was achieved in the same sausage formulation but with 25% (wt/wt) fat; 12.5 microg g(-1) nisin prevented LAB growth for 5 weeks.

Eur J Biochem, 1999 Sep, 264(3), 833 - 9
Solution structure of plantaricin C, a novel lantibiotic; Turner DL et al.; Plantaricin C, a bacteriocin produced by a Lactobacillus plantarum strain of dairy origin, is a lantibiotic . One dehydroalanine, one lanthionine and three beta-methyl-lanthionine residues were found in its 27 amino acid sequence . The plantaricin C structure has two parts: the first comprises the six NH2-terminal residues, four of which are lysines, which confer a strong positive charge to this stretch . The amino acids in positions 7 and 27 form the lanthionine bridge, giving a globular conformation to the rest of the molecule . The beta-methyl-lanthionine bridges are established between residues 12-15, 13-18 and 23-26 . This central region has a charge distribution compatible with an amphipathic alpha-helix, through which plantaricin C would become inserted into the membrane matrix of sensitive organisms, provoking the opening of pores and leakage of the cytoplasmic content.

Virology, 1999 Sep 15, 262(1), 220 - 9
A2 cro, the lysogenic cycle repressor, specifically binds to the genetic switch region of Lactobacillus casei bacteriophage A2; Ladero V et al.; Lysogenic induction of temperate bacteriophage A2 of Lactobacillus casei is controlled by the action of its cI and cro products at the phage operator region . Three 20-bp inverted repeated DNA segments (subsites O1, O2, and O3) and the two divergent (PL and PR) promoters were mapped within the 153-bp operator region . The A2-encoded Cro product is shown to be the functional homolog of lambda Cro . The binding of Cro to the three operator subsites is noncooperative and yields two discrete protein-DNA complexes of retarded migration in mobility shift assays . The Kapp value for the Cro-PL-PR DNA complex was estimated to be 6 nM . Cro shows a slightly higher affinity for O3 than for O1 and O2 subsites . The O3 subsite overlaps the -35 hexamer of the PL promoter, which directs cI expression . A Cro mutant protein, devoid of the last 12 residues (Cro*), allowed the assignment of the DNA-binding domain to the NH2 end of Cro . The C end enhances its affinity for the DNA and probably stabilizes bending induced by Cro .

Berl Munch Tierarztl Wochenschr, 1999 Aug, 112(8), 301 - 4
Collagen (Cn-I) binding by gut lactobacilli; Styriak I et al.; Four gut Lactobacillus strains displaying the features which make them particularly promising for the preparation of probiotic products were investigated together with 5 fresh isolates and one collection strain of Lactobacillus plantarum for their ability to bind type I collagen (Cn-I) . Immobilised Cn-I in microtitre plates was bound only by 3 strains of gut lactobacilli from piglets and the collection strain Lactobacillus plantarum LHI 10 from Prague in range of A570nm readings 0.114-0.221 . Six strains (isolates from turkeys and a calf) did not bind Cn-I (A570nm < 0.1) in this assay . An influence of cultivation medium on Cn-I binding was significant (P < 0.001) in all four adherent strains . Significantly higher (P < 0.001) binding of Cn-I was observed for Lactobacillus casei L 81 and Lactobacillus plantarum LHI 10 grown on solid medium (MRS agar) than for MRS broth-grown cells, however, Lactobacillus plantarum L 5 and Lactobacillus fermentum L 435 expressed significantly (P < 0.001) higher Cn-I binding during cultivation in MRS broth . The specificity of the binding was confirmed because the Cn-I binding by lactobacilli after their preincubation with this protein was completely abolished . Three selected inhibitors (fucoidan, heparan sulphate and hyaluronic acid) significantly (P < 0.001) reduced Cn-I binding by the Lactobacillus plantarum L 5 strain . Following up on some earlier strain characteristics, these results suggest that the selected piglets lactobacilli are also able to bind Cn-I and therefore should antagonize collagen niche colonization by various enteropathogens when used for probiotic purposes.

Arch Virol, 1999, 144(8), 1503 - 12
Physical mapping and partial genetic characterization of the Lactobacillus delbrueckii subsp . bulgaricus bacteriophage lb539; Auad L et al.; A restriction map was constructed of the 37 kb genome of the temperate Lactobacillus delbrueckii subsp . bulgaricus bacteriophage lb539 . Restriction analysis and Southern hybridization experiments detected variable levels of homologous regions among the genomes of lb539 and the L . delbrueckii reference phages LL-H (virulent) and mv4 (temperate) . The principal homology was observed at the regions encoding the structural proteins . These studies allowed us to construct a partial genetic map of phage lb539 for lysin, the main structural tail protein and the packaging region genes . Furthermore, a short 1.5 kb DNA fragment of the prolate-headed JCL1032 phage genome was observed to be highly homologous with the DNA of the isometric-headed lb539, mv4 and LL-H phages . The described distribution of the homologous regions between the genomes of the phages lb539, LL-H, mv4 and JCL1032 presented here supports the modular evolution theory of the bacteriophages.

Extremophiles, 1999 Aug, 3(3), 175 - 83
Molecular cloning, expression, and characterization of a thermostable glutamate racemase from a hyperthermophilic bacterium, Aquifex pyrophilus; Kim SS et al.; A gene encoding glutamate racemase has been cloned from Aquifex pyrophilus, a hyperthermophilic bacterium, and expressed in Escherichia coli . The A . pyrophilus glutamate racemase is composed of 254 amino acids and shows high homology with glutamate racemase from Escherichia coli, Bacillus subtilis, or Lactobacillus brevis . This racemase converts L- or D-glutamate to D- or L-glutamate, respectively, but not other amino acids such as alanine, aspartate, and glutamine . The cloned gene was expressed and the protein was purified to homogeneity . The A . pyrophilus racemase is present as a dimer but it oligomerizes as the concentration of salt is increased . The Km and k(cat) values of the overexpressed A . pyrophilus glutamate racemase for the racemization of L-glutamate to the D-form and the conversion of D-glutamate to the L-form were measured as 1.8 +/- 0.4mM and 0.79 +/- 0.06s(-1) or 0.50 +/- 0.07mM and 0.25 +/- 0.01s(-1), respectively . Complete inactivation of the racemase activity by treatment with cysteine-modifying reagents suggests that cysteine residues may be important for activity . The protein shows strong thermostability in the presence of phosphate ion, and it retains more than 50% of its activity after incubation at 85 degrees C for 90 min.

FEMS Microbiol Lett, 1999 Sep 1, 178(1), 47 - 53
The broad host range plasmid pLF1311 from Lactobacillus fermentum VKM1311; Aleshin VV et al.; The complete nucleotide sequence (2389 bp) of the cryptic plasmid pLF1311 from Lactobacillus fermentum VKM1311 was determined . DNA sequence analysis revealed the putative coding regions for a replicative protein (RepB), its repressor (RepA) and double-stranded (dso) and single-stranded (sso) origins . pLF1311 belongs to the pE194 family of rolling circle-replicating plasmids . A derivative of pLF1311 that contains the cat gene of plasmid pC194 of Staphylococcus aureus and the oriT of RP4 was constructed and transferred by conjugative mobilization from Escherichia coli to various Gram-positive bacteria . The stable maintenance of this derivative was shown in some strains of Lactobacillus, Lactococcus, Enterococcus and Bacillus under non-selective conditions.

J Biotechnol, 1999 Jul 30, 73(1), 61 - 70
Lactic acid production by immobilized Lactobacillus casei in recycle batch reactor: a step towards optimization; Senthuran A et al.; Different nutritional and process parameters influencing lactic acid production by Lactobacillus casei, adsorbed to Poraver beads in a recycle batch reactor system, were studied in an attempt to set up a system having a long operational lifetime and permitting use of high substrate concentrations for maximal conversion to the product . The presence of lactose, even as a minor fraction of the total sugar amount, was necessary for complete utilization by the organism for growth and conversion to lactate . Hydrolysed whey protein constituted a richer source of nitrogen compared to yeast extract . Addition of lactate to the medium at the start of the process resulted in severe inhibition compared with the normal process . For a homofermentative process, pH 6.0 was found to be optimal . The overall productivity of the recycle system was higher under all conditions studied in comparison with the batch process using free cells . Enhancement in productivity in the recycle batch reactor was also accompanied by an increase in density of suspended cells . However, the contribution of the suspended cells to the overall reactor productivity was not noticeable . The bead size of the matrix was found to be important for operational stability of the reactor.

J Dairy Sci, 1999 Aug, 82(8), 1612 - 7
Purification and identification of potentially bioactive peptides from enzyme-modified cheese; Haileselassie SS et al.; Antihypertensive peptides inhibiting angiotensin I-converting enzyme have been isolated from enzymatic hydrolysates of various food materials, but no information is available on the isolation of antihypertensive peptides from enzyme-modified cheese . In this study, several bioactive peptides, mainly potential antihypertensive peptides from enzyme-modified cheese prepared by commercial and Lactobacillus casei enzymes, were purified and identified . Enzyme-modified cheese samples were prepared by combination of Neutrase (1883.0 U/ml), L . casei enzymes (amino peptidase activity 86.4 leucine aminopeptidase U/g), and Debitrase (22.0 leucine aminopeptidase U/g) . The water-soluble fractions of the enzyme-modified cheeses that were prepared by different enzymes were subjected to reverse-phase HPLC on a Delta Pak C18 column . Each peak was purified on the same column using a binary gradient . One peak from the Neutrase digest, five peaks from the Neutrase-Debitrase digest, and two peaks from the Neutrase-Lactobacillus enzyme digest were purified and identified by API mass spectrometry . On the basis of their molecular masses, amino acid sequences of purified peptides were identified . beta-Casomorphin with a sequence like that of beta-casein (YPFPGPI f 60-66) was found after the Neutrase digest . All of the peptides purified from the digests with combination of Neutrase and Debitrase or Neutrase and L . casei enzymes contained active sites in their sequences . The presence of sites containing potential antihypertensive peptides suggests that the purified peptides may have antihypertensive properties . Thus, the enzyme-modified cheese process, mainly designed to produce flavor ingredients, may simultaneously produce bioactive peptides, which are considered to be of physiological importance.

Dent Update, 1998 Oct, 25(8), 319 - 24
Microbiology of carious lesions; de Soet JJ et al.; Dental caries is a process in which the enamel, and later the dentine, is demineralized by acids produced by bacterial fermentation of carbohydrates . The main indicator bacteria in this process are mutans streptococci and lactobacilli . This article discusses how monitoring of patients' salivary levels of these organisms can help in prevention and treatment of caries in different patient populations.

Biochem J, 1999 Sep 15, 342 Pt 3, 509 - 12
Ornithine and glutamate decarboxylases catalyse an oxidative deamination of their alpha-methyl substrates; Bertoldi M et al.; Ornithine decarboxylase (ODC) from Lactobacillus 30a catalyses the cleavage of alpha-methylornithine into ammonia and 2-methyl-1-pyrroline; glutamate decarboxylase (GAD) from Escherichia coli catalyses the cleavage of alpha-methylglutamate into ammonia and laevulinic acid . In our analyses, 2-methyl-1-pyrroline and laevulinic acid were identified by HPLC and mass spectroscopic analysis, and ammonia was identified by means of glutamate dehydrogenase . Molecular oxygen was consumed during these reactions in a 1:2 molar ratio with respect to the products . The catalytic efficiencies (k(cat)/K(m)) of the reactions catalysed by ODC and GAD were determined as 12500 and 9163 M(-1).min(-1) respectively . When the reactions were performed under anaerobic conditions, no ammonia, 2-methyl-1-pyrroline or laevulinic acid was produced to a significant extent . The formation of ammonia and O(2) consumption (in a 1:2 molar ratio with respect to ammonia) were also detected during the reaction of ODC and GAD with putrescine and gamma-aminobutyrate respectively . Taken together, these findings clearly indicate that ODC and GAD catalyse an oxidative deamination of their decarboxylation products, a reaction similar to that catalysed by dopa decarboxylase (DDC) with alpha-methyldopa {Bertoldi, Dominici, Moore, Maras and Borri Voltattorni (1998) Biochemistry 37, 6552-6561} . Furthermore, this reaction was accompanied by a decarboxylation-dependent transamination occurring for GAD, DDC and ODC with a frequency of approx . 0.24%, 1% and 9% respectively compared with that of oxidative deamination.

Appl Environ Microbiol, 1999 Sep, 65(9), 4264 - 7
Identification of Lactobacillus isolates from the gastrointestinal tract, silage, and yoghurt by 16S-23S rRNA gene intergenic spacer region sequence comparisons; Tannock GW et al.; Lactobacillus isolates were identified by PCR amplification and sequencing of the region between the 16S and 23S rRNA genes (spacer region) . The sequences obtained from the isolates were compared to those of reference strains held in GenBank . A similarity of 97.5% or greater was considered to provide identification . To check the reliability of the method, the V2-V3 region of the 16S rRNA gene was amplified and sequenced in the case of isolates whose spacer region sequences were less than 99% similar to that of a reference strain . Confirmation of identity was obtained in all instances . Spacer region sequencing provided rapid and accurate identification of Lactobacillus isolates obtained from gastrointestinal, yoghurt, and silage samples . It had an advantage over 16S V2-V3 sequence comparisons because it distinguished between isolates of Lactobacillus casei and Lactobacillus rhamnosus.

Appl Environ Microbiol, 1999 Sep, 65(9), 4148 - 54
Synergistic actions of nisin, sublethal ultrahigh pressure, and reduced temperature on bacteria and yeast; ter Steeg PF et al.; Nisin in combination with ultrahigh-pressure treatment (UHP) showed strong synergistic effects against Lactobacillus plantarum and Escherichia coli at reduced temperatures (<15 degrees C) . The strongest inactivation effects were observed when nisin was present during pressure treatment and in the recovery medium . Elimination (>6-log reductions) of L . plantarum was achieved at 10 degrees C with synergistic combinations of 0.5 microg of nisin per ml at 150 MPa and 0.1 microg of nisin per ml at 200 MPa for 10 min . Additive effects of nisin and UHP accounted for only 1.2- and 3.7-log reductions, respectively . Elimination was also achieved for E . coli at 10 degrees C with nisin present at 2 microg/ml, and 10 min of pressure at 200 MPa, whereas the additive effect accounted for only 2.6-log reductions . Slight effects were observed even against the yeast Saccharomyces cerevisiae with nisin present at 5 microg/ml and with 200 MPa of pressure . Combining nisin, UHP, and lowered temperature may allow considerable reduction in time and/or pressure of UHP treatments . Kill can be complete without the frequently encountered survival tails in UHP processing . The slightly enhanced synergistic kill with UHP at reduced temperatures was also observed for other antimicrobials, the synthetic peptides MB21 and histatin 5 . The postulated mode of action was that the reduced temperature and the binding of peptides to the membrane increased the efficacy of UHP treatment . The increases in fatty acid saturation or diphosphatidylglycerol content and the lysylphosphatidyl content of the cytoplasm membrane of L . plantarum were correlated with increased susceptibility to UHP and nisin, respectively.

Appl Environ Microbiol, 1999 Sep, 65(9), 4002 - 7
D-Lactate dehydrogenase gene (ldhD) inactivation and resulting metabolic effects in the Lactobacillus johnsonii strains La1 and N312; Lapierre L et al.; Lactobacillus johnsonii La1, a probiotic bacterium with demonstrated health effects, grows in milk, where it ferments lactose to D- and L-lactate in a 60:40% ratio . The D-lactate dehydrogenase (D-LDH) gene (ldhD) of this strain was isolated, and an in vitro-truncated copy of that gene was used to inactivate the genomic copy in two strains, La1 and N312, by gene replacement . For that, an 8-bp deletion was generated within the cloned ldhD gene to inactivate its function . The plasmid containing the altered ldhD was transferred to L . johnsonii via conjugative comobilization with Lactococcus lactis carrying pAMbeta1 . Crossover integrations of the plasmid at the genomic ldhD site were selected, and appropriate resolution of the cointegrate structures resulted in mutants that had lost the plasmid and in which the original ldhD was replaced by the truncated copy . These mutants completely lacked D-LDH activity . Nevertheless, the lower remaining L-LDH activity of the cells was sufficient to reroute most of the accumulating pyruvate to L-lactate . Only a marginal increase in production of the secondary end products acetaldehyde, diacetyl, and acetoin was observed . It can be concluded that in L . johnsonii D- and L-LDH are present in substantial excess for their role to eliminate pyruvate and regenerate NAD(+) and that accumulated pyruvate is therefore not easily redirected in high amounts to secondary metabolic routes.

Appl Environ Microbiol, 1999 Sep, 65(9), 3908 - 14
Comparison of ribotyping, randomly amplified polymorphic DNA analysis, and pulsed-field gel electrophoresis in typing of Lactobacillus rhamnosus and L . casei strains; Tynkkynen S et al.; A total of 24 strains, biochemically identified as members of the Lactobacillus casei group, were identified by PCR with species-specific primers . The same set of strains was typed by randomly amplified polymorphic DNA (RAPD) analysis, ribotyping, and pulsed-field gel electrophoresis (PFGE) in order to compare the discriminatory power of the methods . Species-specific primers for L . rhamnosus and L . casei identified the type strain L . rhamnosus ATCC 7469 and the neotype strain L . casei ATCC 334, respectively, but did not give any signal with the recently revived species L . zeae, which contains the type strain ATCC 15820 and the strain ATCC 393, which was previously classified as L . casei . Our results are in accordance with the suggested new classification of the L . casei group . Altogether, 21 of the 24 strains studied were identified with the species-specific primers . In strain typing, PFGE was the most discriminatory method, revealing 17 genotypes for the 24 strains studied . Ribotyping and RAPD analysis yielded 15 and 12 genotypes, respectively.

J Hosp Infect, 1999 Aug, 42(4), 275 - 82
Intrinsically vancomycin-resistant gram-positive organisms: clinical relevance and implications for infection control; Nelson RR; Intrinsic resistance to vancomycin in gram-positive bacteria presumably predates acquired vancomycin resistance in enterococci but it has only recently generated interest . Intrinsically resistant enterococci possessing the vanC gene and the non-enterococcal genera Leuconostoc, Lactobacillus, Pediococcus and Erysipelothrix are known to cause human infection . This review examines the available data on their identification, resistance mechanisms, epidemiology, clinical infections and antimicrobial susceptibility . Intrinsically vancomycin-resistant gram-positives are usually opportunistic pathogens . Although serious infections may occur, treatment options remain available . No additional infection control measures for the intrinsically resistant genera appear justified with currently available evidence, although vigilance should be maintained to detect future changes in susceptibility patterns.

Microbios, 1999, 98(391), 159 - 74
Purification and characterization of an arylamine N-acetyltransferase from Lactobacillus acidophilus; Chen GW et al.; N-acetyltransferase from Lactobacillus acidophilus was purified by ultrafiltration, DEAE-Sephacel, gel filtration chromatography on Sephadex G-100, and DEAE-5pw on high performance liquid chromatography, as judged by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) on a 12% (w/v) slab gel . The purified enzyme was thermostable at 37 degrees C for 1 h with a half-life of 32 min at 37 degrees C, and displayed optimum activity at 37 degrees C and pH 7.0 . The K(m) and Vmax values for 2-aminofluorene were 0.842 mM and 2.406 nmol/min/mg protein, respectively . Among a series of divalent cations and salts, Zn2+, Ca2+, Fe2+, Mg2+, and Cu2+ were demonstrated to be the most potent inhibitors . The enzyme had a molecular mass of 44.9 kD . The three chemical modification agents, iodoacetamide, phenylglyoxal, and diethylpyrocarbonate, all exhibited dose-, time-, and temperature-dependent inhibition effects . Preincubation of purified N-acetyltransferase with acetyl coenzyme A (AcCoA) provided significant protection against the inhibition of iodoacetamide and diethylpyrocarbonate, but only partial protection against the inhibition of phenylglyoxal . These results indicate that cysteine, histidine, and arginine residues are essential for this bacterial activity, and the first two are likely to reside on the AcCoA binding site, but the arginine residue may be located close to the AcCoA binding site . This report is the first demonstration of acetyl CoA:arylamine N-acetyltransferase in L . acidophilus.

Mem Inst Oswaldo Cruz, 1999 Sep-Oct, 94(5), 701 - 7
Microbial flora variations in the respiratory tract of mice; Cangemi de Gutierrez R et al.; A stable microbial system in the respiratory tract acts as an important defense mechanism against pathogenic microorganisms . Perturbations in this system may allow pathogens to establish . In an ecological environment such as the respiratory tract, there are many diverse factors that play a role in the establishment of the indigenous flora . In the present work we studied the normal microbial flora of different areas of the respiratory tract of mice and their evolution from the time the mice were born . Our interest was to know which were the dominant groups of microorganisms in each area, which were the first capable of colonizing and which dominated over time to be used as probiotic microorganisms . Our results show that Gram negative facultatively anaerobic bacilli and strict anaerobic microorganisms were the last ones to appear in the bronchia, while aerobic and Gram positive cocci were present in all the areas of the respiratory tract . The number of facultative aerobes and strict anaerobes were similar in the nasal passage, pharynx instilled and trachea, but lower in bronchia . The dominant species were Streptococcus viridans and Staphylococcus saprophyticcus, followed by S . epidermidis, Lactobacilli and S . cohnii I which were present on every studied days but at different proportions . This paper is the first part of a research topic investigating the protective effect of the indigenous flora against pathogens using the mice as an experimental model.

J Anim Sci, 1999 Aug, 77(8), 2259 - 68
Effect of virginiamycin on ruminal fermentation in cattle during adaptation to a high concentrate diet and during an induced acidosis; Coe ML et al.; The objective of Exp . 1 was to compare the effects of virginiamycin (VM; 0, 175, or 250 mg x animal(-1) x d(-1)) and monensin/tylosin (MT; 250/ 90 mg x animal(-1) x d(-1)) on ruminal fermentation products and microbial populations in cattle during adaptation to an all-concentrate diet . Four ruminally cannulated, Holstein steers were used in a 4x4 Williams square design with 21-d periods . Steers were stepped up to an all-concentrate diet fed at 2.5% of BW once daily . Ruminal pH, protozoal counts, and NH3-N and VFA concentrations generally were unaffected by VM or MT . Mean counts of Lactobacillus and Streptococcus bovis were lower (P<.05) for VM-treated compared with control or MT-treated steers . Both VM and MT prevented the increase in Fusobacterium necrophorum counts associated with increasing intake of the high-concentrate diet observed in the control . The objective of Exp . 2 was to compare the effects of VM and MT on ruminal pH, L(+) lactate and VFA concentrations, and F . necrophorum numbers during carbohydrate overload . Six ruminally cannulated Holstein steers were assigned randomly to either the control, VM (175 mg/d), or MT (250 + 90 mg/d) treatments . Acidosis was induced with intraruminal administration of a slurry of ground corn and corn starch . The VM and MT premixes were added directly to the slurry before administration . Carbohydrate challenge induced acute ruminal acidosis (pH was 4.36 and L (+) lactate was 19.4 mM) in controls by 36 h . Compared with the controls, steers receiving VM or MT had higher (P<.05) ruminal pH, and the VM group had a lower (P<.05) L (+) lactate concentration . Fusobacterium necrophorum numbers initially increased in VM- and MT-administered steers . In the control steers, F . necrophorum was undetectable by 36 h . Virginiamycin seemed to control the growth of ruminal lactic acid-producing bacteria and, therefore, has the potential to moderate ruminal fermentation in situations that could lead to rapid production of lactic acid.

Caries Res, 1999 Sep-Oct, 33(5), 357 - 65
Distribution of three cariogenic bacteria in secondary carious lesions around amalgam restorations; Gonzalez-Cabezas C et al.; Secondary dental caries remains an unresolved problem in dentistry and little is known of its microbial etiology . The purpose of this study was to compare the distribution of the three most suspected cariogenic groups of bacteria, mutans streptococci . Actinomyces naeslundii genospecies 2 and lactobacilli, in natural secondary caries around amalgam restorations . Extracted teeth with secondary caries were sectioned to obtain three samples that were randomly distributed to three different groups . Each group was immunolabeled with antibodies to either Streptococcus mutans, A . naeslundii genospecies 2 or Lactobacillus casei and subsequently labeled with secondary fluorescent antibodies . All samples were analyzed three-dimensionally using confocal microscopy . The results indicated that the three different bacteria were widely present and could have an important role in the development of secondary caries around amalgam restorations.

J Food Prot, 1999 Aug, 62(8), 894 - 8
Inactivation of Lactobacillus helveticus bacteriophages by thermal and chemical treatments; Quiberoni A et al.; The effect of several biocides and thermal treatments on the viability of four Lactobacillus helveticus phages was investigated . Times to achieve 99% inactivation of phages at 63 degrees C and 72 degrees C in three suspension media were calculated . The three suspension media were tris magnesium gelatin buffer (10 mM Tris-HCl, 10 mM MgSO4, and 0.1% wt/vol gelatin), reconstituted skim milk sterile reconstituted commercial nonfat dry skim milk, and Man Rogosa Sharpe broth . The thermal resistance depended on the phage considered, but a treatment of 5 min at 90 degrees C produced a total inactivation of high titer suspensions of all phages studied . The results obtained for the three tested media did not allow us to establish a clear difference among them, since some phages were more heat resistant in Man Rogosa Sharpe broth and others in tris magnesium gelatin buffer . From the investigation on biocides, we established that sodium hypochlorite at a concentration of 100 ppm was very effective in inactivating phages . The suitability of ethanol 75%, commonly used to disinfect utensils and laboratory equipment, was confirmed . Isopropanol turned out to be, in general, less effective than ethanol at the assayed concentrations . In contrast, peracetic acid (0.15%) was found to be an effective biocide for the complete inactivation of all phages studied after 5 min of exposure . The results allowed us to establish a basis for adopting the most effective thermal and chemical treatments for inactivating phages in dairy plant and laboratory environments.

J Ind Microbiol Biotechnol, 1999 Jun, 22(6), 617 - 621
Pullulan production from deproteinized whey by Aureobasidium pullulans; Roukas T; The production of pullulan from deproteinized whey by Aureobasidium pullulans P56 was investigated using an adaptation technique and a mixed culture system . The adaptation of A . pullulans and the mixed cultures of A . pullulans and/or Lactobacillus brevisX20, Debaryomyces hansenii 194 and Aspergillus niger did not increase the production of polysaccharide . Enzymic hydrolysis of lactose in deproteinized whey gave a higher polysaccharide concentration and polysaccharide yield than acidic hydrolysed lactose . Maximum polysaccharide concentration (11.0 +/- 0.5 g L-1), biomass dry weight (10.5 +/- 0.4 g L-1), polysaccharide yield (47.2 +/- 1.8%) and sugar utilization (93.2 +/- 2.8%) were achieved using enzyme-hydrolysed whey (pH 6.5) containing 25 g L-1 lactose and supplemented with K2HPO4 0.5%, L-glutamic acid 1%, olive oil 2.5%, and Tween 80 0.5% . In this case the pullulan content of the crude polysaccharide was 40%.

Gene, 1999 Aug 20, 236(2), 333 - 46
Primary structure and features of the genome of the Lactobacillus gasseri temperate bacteriophage (phi)adh; Altermann E et al.; The complete DNA sequence of the Lactobacillus (Lb.) gasseri temperate phage (phi)adh was determined . The linear and double-stranded genome consists of 43.785bp with a G+C content of 35 . 3% and 3' protruding cohesive ends of 12nt . Sixty-two possible ORFs were identified . On the basis of homology comparisons, some of them could be assigned to possible functions, such as a helicase, a nucleic acid polymerase and a protease . In a non-coding area of the (phi)adh genome, structural features of a potential replication origin were detected . After subcloning, this region was functional as a replicon in Lb . gasseri and Lactococcus lactis . N-terminal aa sequencing and electron microscopic analysis of intact and defective phage particles enabled the identification of two capsid protein genes . One of their products, the major head protein, seems to be processed on the posttranslational level.

Clin Exp Immunol, 1999 Aug, 117(2), 368 - 75
Prevention of B220+ T cell expansion and prolongation of lifespan induced by Lactobacillus casei in MRL/lpr mice; Mike A et al.; We examined the therapeutic effect of heat-killed Lactobacillus casei (LC) on MRL/lpr mice . Ingestion of a diet containing 0.05% (w/w) LC from the weaning period prolonged the lifespan and tended to reduce the proportion of B220+ T cells in the spleen and mesenteric lymph nodes (MLN) of MRL/lpr mice . When LC was intraperitoneally injected once a week after the age of 8 weeks, I-A- macrophages accumulated in the spleen as well as the peritoneum and macrophage progenitors increased in the bone marrow . Moreover, the amount of IL-6 mRNA in peritoneal macrophages was reduced by LC injection . Splenocytes from LC-injected MRL/lpr mice exhibited lower proliferative responses to mitogens than those from control MRL/lpr mice and the increase in number of B220+ T cells in the spleen and MLN was prevented by LC injection . However, LC injection affected neither expression of interferon-gamma (IFN-gamma) and IL-4 mRNAs nor proliferative capacities of splenic T cells . Our findings demonstrate that LC injection accelerates macrophage recruitment and prevents the expansion of B220+ T cells without affecting the functions of T cells in MRL/lpr mice . These immunological modulations induced by LC may lead to prolongation of the lifespan of MRL/lpr mice.

Psychosom Med, 1999 Jul-Aug, 61(4), 508 - 12
Depressive symptoms favor abundant growth of salivary lactobacilli; Anttila SS et al.; OBJECTIVE: The purpose was to study the growth of lactobacilli in subjects with depressive symptoms in the total 55-year-old population of Oulu (a medium-sized town in Finland); 780 people participated . METHODS: The dental examination included measurements of salivary lactobacillus growth with the Dentocult-LB method; measurements of salivary flow rate, pH, and buffering capacity; and assessment of oral health status . Depressive symptoms were determined with the Zung Self-Rating Depression Scale (ZSDS) . Participants were also asked about their health, medication, smoking, and dietary habits . RESULTS: The prevalence of high lactobacillus counts (> or =100,000 CFU/ml) was 22% among women and 31% among men (p = .02) . Thirty-seven percent of the subjects with a high rate of depressive symptoms (ZSDS score of > or = 40) and 23% of those with an ZSDS score of < or = 39 had high counts of lactobacilli (p = .003) . A logistic regression analysis with improvement of goodness of fit was made to confirm the relation between abundant lactobacilli and a high rate of depressive symptoms . After the confounding factors had been added stepwise into the logistic regression model, depressive symptoms were still significantly associated with abundant lactobacillus growth . CONCLUSIONS: The association between high lactobacillus counts and depressive symptoms suggests that depressed subjects are at risk of having caries and possibly other dental diseases that should be recognized in the treatment of these patients.

Int J Food Microbiol, 1999 Jun 1, 48(3), 167 - 77
Detection and characterization of a novel antibacterial substance produced by Lactobacillus plantarum ST 31 isolated from sourdough; Todorov S et al.; Lactobacillus plantarum ST31 isolated from sourdough produced an antimicrobial substance inhibiting other strains of the genera Lactobacillus, Leuconostoc, Pediococcus, Streptococcus, Bacillus and some foodborne pathogens including Staphylococcus aureus . This antimicrobial substance was inactivated by proteolytic enzymes . Consequently, it was characterized as a bacteriocin and was designated plantaricin ST31 . This bacteriocin was stable in the pH range 3-8 and it was not affected by amylolytic enzymes . Production of plantaricin was pH and temperature dependent, and maximum yields were obtained in MRS broth cultures maintained at pH 6 and incubated at 30 degrees C in the exponential phase to the early stationary growth phase of the producer organism . This bacteriocin was purified by using consecutive ammonium sulfate and reversed-phase chromatography . It is a peptide of 20 amino acid residues with a mass of 2755+/-0.3 Da, as determined by electrospray mass spectrometry . The sequence of Plantaricin ST31 showed no similarity to those of other bacteriocins . Plantaricin ST31 production appeared to be chromosomally encoded.

Przegl Lek, 1999, 56(3), 211 - 5
{Probiotics and their therapeutic properties}; Ochmanski W et al.; Probiotics are specific products of microorganisms, and by being biologically active positively act on stabilizing the bacteriological flora of the gastrointestinal tract . They are live or lyophilized bacterial cultures, especially those derived from lactic fermentation (Lactobacillacea and Streptococcacea) . The first to use the term probiotics were Lilly and Stillwell in 1965 when referring to substances produced by protozoa, which in turn stimulated the growth of other organisms . Probiotics are devoid of side affects and do not cause accumulation of toxic substances in the body . They are administered for therapeutic, prophylactic and nutritional purposes both in humans and in animals . Interest into probiotics has been spurred on by the growing abundance of civilization disorders such as neoplasms, atherosclerosis, heart disease, hypertension and HIV infection . Probiotics are potentially capable of annihilating these disorders . Starter cultures are pure mixed bacterial, fungal or mold cultures which by transformation of their metabolism faciliate favourable changes in apperance, aroma, consistency, and durability of foodstuffs . Contemporary knowledge concerning probiotics and their action is derived from many years of tradition in consumption of fermented milk products and the documentation of much research into strains of lactic bacteria, their harmless action on health and overall beneficial effect.

Mikrobiol Z, 1999 Mar-Apr, 61(2), 74 - 9
{The microbial cenosis of the tonsils in healthy children and in those frequently ill}; Marushko IuV et al.; The microbial cenosis of tonsils has been studied in healthy and ailing children . It has been found out that Staphylococcus aureus and S . epidermidis, beta-hemolytic streptococcus, rarely gram-negative flora and candidae were most often isolated in the ailing children . Normal microflora of healthy children mainly included lactic acid bacteria whose level considerably decreased in ailing children that is most distinctly expressed in children with decompensated tonsillitis . To correct the disturbances in microbial cenosis during complex therapy we used lactobacteria to treat the nasopharynx with the suspension of these bacteria . Positive clinical effect with following positive results of bacteriological investigation has been obtained in all patients.

Biologicals, 1999 Mar, 27(1), 11 - 21
Design of a "microbicide" for prevention of sexually transmitted diseases using "inactive" pharmaceutical excipients; Neurath AR et al.; The human immunodeficiency virus (HIV-1) pandemic has been driven primarily by the sexual transmission of the virus, and facilitated by prior infections with other sexually transmitted disease (STD) pathogens . Although treatment of these STDs has been proposed as a means to decrease the rate of HIV-1 sexual transmission, preventive measures effective against both HIV-1 and other STD pathogens are expected to have a larger impact . These measures include topically applied mechanical and chemical (i.e . microbicidal) barriers . Microbicides of preference should have a broad specificity against diverse STD pathogens and a well established safety record, considering their repeated use over decades . Here, we report that cellulose acetate phthalate (CAP), an "inactive" pharmaceutical excipient, commonly used in the production of enteric tablets and capsules: (1) has antiviral activity against HIV-1 and several herpesviruses (HSV); and (2) when appropriately formulated, in micronized form, inactivates HIV-1, HSV-1, HSV-2, cytomegalovirus, Neisseria gonorrhoeae, Trichomonas vaginalis, Haemophilus ducreyi and Chlamydia trachomatis but does not affect Lactobacilli, components of the natural vaginal flora contributing to resistance against STDs . Thus, the CAP formulations meet the criteria for preferred microbicides and warrant further evaluation in vivo in humans .

Microbiology, 1999 Jul, 145 ( Pt 7), 1703 - 9
Use of fluorescence ratio imaging for intracellular pH determination of individual bacterial cells in mixed cultures; Siegumfeldt H et al.; The development of a rapid method for measuring intracellular pH (pHi) in single bacterial cells is described . Lactobacillus delbrueckii subsp . bulgaricus and Listeria innocua were used as test organisms . The method is based upon fluorescence microscopy and ratio imaging of cells stained with carboxyfluorescein succinimidyl ester . After staining, the bacteria were immobilized on a membrane filter and transferred to a closed perfusion chamber, allowing control of the cell environment during analysis . The set-up was optimized with regard to the use of neutral-density filters and background subtraction, for determining the excitation ratio 490 nm/435 nm (R490/435) independent of the excitation light intensity, and to reduce photobleaching . This allowed for time-lapse studies with multiple exposures . To study the pHi of Lb . delbrueckii subsp . bulgaricus and L . innocua in response to different extracellular pH (pHex) values, an in vivo calibration curve was constructed in the pHi range 5.0-8.5 . Distinct differences between the two cultures were observed . L . innocua maintained a near-neutral pHi almost independently of pHex (5.0-8.0), whereas the pHi of Lb . delbrueckii subsp . bulgaricus decreased with decreasing pHex . In pure and mixed cultures at pHex 5.0, the pHi values of Lb . delbrueckii subsp . bulgaricus and L . innocua were 6.1 +/- 0.2 and 7.5 +/- 0.2, respectively . This difference in pHi may explain how Lb . delbrueckii subsp . bulgaricus obtains a competitive advantage over L . innocua at low pHex.

J Dent Res, 1999 Aug, 78(8), 1410 - 6
Oral microflora in subjects with reduced salivary secretion; Almstahl A et al.; It is generally assumed that a decreased salivary secretion rate will promote plaque accumulation and increase the risk for caries, gingival inflammation, and mucosal infections . In this study, the effect of hyposalivation on the oral microflora was examined . The following micro-organisms were analyzed in rinsing samples from 14 subjects with hyposalivation: the total number of anaerobically growing micro-organisms, alpha-hemolytic streptococci, mutans streptococci, lactobacilli, Fusobacterium nucleatum, Prevotella intermedia/Prevotella nigrescens, Staphylococcus aureus, Candida albicans, and enterics . The study group, age 53 +/- 7 years, had no history of radiation therapy and showed no signs of inflammation in their salivary glands on biopsy . All were dentate with a mean of 24 +/- 3 teeth . Their salivary secretion rates were 0.03 +/- 0.02 mL/min (unstimulated) and 0.84 +/- 0.65 mL/min (stimulated) . The control group was matched to the hyposalivation group according to age, sex, and number of teeth . There was a significantly increased number of lactobacilli, and a tendency, not statistically significant and with large variations within the groups, toward a higher proportion of mutans streptococci and a lower proportion of alpha-hemolytic streptococci in the hyposalivation group . The presence of micro-organisms associated with gingival inflammation and mucosal infections was comparable with that in the healthy controls . The results indicated that a low salivary secretion rate mainly promotes a flora associated with the development of caries.

J Bacteriol, 1999 Aug, 181(16), 4848 - 52
Complementary and overlapping selectivity of the two-peptide bacteriocins plantaricin EF and JK; Moll GN et al.; Plantaricin EF and JK are both two-peptide bacteriocins produced by Lactobacillus plantarum C11 . The mechanism of plantaricin EF and JK action was studied on L . plantarum 965 cells . Both plantaricins form pores in the membranes of target cells and dissipate the transmembrane electrical potential (Deltapsi) and pH gradient (DeltapH) . The plantaricin EF pores efficiently conduct small monovalent cations, but conductivity for anions is low or absent . Plantaricin JK pores show high conductivity for specific anions but low conductivity for cations . These data indicate that L . plantarum C11 produces bacteriocins with complementary ion selectivity, thereby ensuring efficient killing of target bacteria.

J Bacteriol, 1999 Aug, 181(16), 4768 - 73
Transport of D-xylose in Lactobacillus pentosus, Lactobacillus casei, and Lactobacillus plantarum: evidence for a mechanism of facilitated diffusion via the phosphoenolpyruvate:mannose phosphotransferase system; Chaillou S et al.; We have identified and characterized the D-xylose transport system of Lactobacillus pentosus . Uptake of D-xylose was not driven by the proton motive force generated by malolactic fermentation and required D-xylose metabolism . The kinetics of D-xylose transport were indicative of a low-affinity facilitated-diffusion system with an apparent K(m) of 8.5 mM and a V(max) of 23 nmol min(-1) mg of dry weight(-1) . In two mutants of L . pentosus defective in the phosphoenolpyruvate:mannose phosphotransferase system, growth on D-xylose was absent due to the lack of D-xylose transport . However, transport of the pentose was not totally abolished in a third mutant, which could be complemented after expression of the L . curvatus manB gene encoding the cytoplasmic EIIB(Man) component of the EII(Man) complex . The EII(Man) complex is also involved in D-xylose transport in L . casei ATCC 393 and L . plantarum 80 . These two species could transport and metabolize D-xylose after transformation with plasmids which expressed the D-xylose-catabolizing genes of L . pentosus, xylAB . L . casei and L . plantarum mutants resistant to 2-deoxy-D-glucose were defective in EII(Man) activity and were unable to transport D-xylose when transformed with plasmids containing the xylAB genes . Finally, transport of D-xylose was found to be the rate-limiting step in the growth of L . pentosus and of L . plantarum and L . casei ATCC 393 containing plasmids coding for the D-xylose-catabolic enzymes, since the doubling time of these bacteria on D-xylose was proportional to the level of EII(Man) activity.

J Appl Microbiol, 1999 Jul, 87(1), 49 - 61
A fast method for monitoring the colonization rate of lactobacilli in a meat model system; Veyrat A et al.; A random amplified polymorphic DNA (RAPD) assay coupled to a fast and reproducible cell lysis method from Lactobacillus colonies were developed to type lactobacilli of different strains and species, with the aim of precisely enumerating each of the different Lactobacillus strains inoculated in a nutrient-rich environment, such as sausage meat batter . Colonization assays were carried out in an aseptic meat fermentation system for up to 14 d and the inoculated strains were challenged with mixtures of wild lactobacilli . The proportion of inoculated strains remaining at different times was compared with the total number of lactobacilli grown on MRS agar by RAPD . The colonization rate of the different strains tested was very different . The RAPD-fast lysis method developed is simple and, with a low cost per assay, could also be applied to other food fermentations.

Prep Biochem Biotechnol, 1999 Aug, 29(3), 273 - 309
Adenosylcobalamin-dependent ribonucleoside triphosphate reductase from Lactobacillus leichmannii . Rapid, improved purification involving dGTP-based affinity chromatography plus biophysical characterization studies demonstrating enhanced, "crystallographic level" purity; Suto RK et al.; Ribonucleoside triphosphate reductase (RTPR, EC 1.17.4.2) from Lactobacillus leichmannii is a 5'-deoxyadenosylcobalamin-dependent (AdoCbl; Coenzyme B12) enzyme . RTPR is also a prototypical adenosylcobalamin-dependent ribonucleotide reductase, one that, as its name indicates, converts ribonucleoside triphosphates (NTP) to deoxyribonucleoside triphosphates (dNTP) . Upon substrate binding to RTPR, AdoCbl's cobalt-carbon bond is cleaved to generate cob(II)alamin, 5'-deoxyadenosine, and the cysteine (C408) derived thiyl radical . Five key cysteines (Cys 119, 408, 419, 731, and 736), from among the ten total cysteines, are involved in RTPR's catalytic mechanism . A critical examination of the RTPR isolation and purification literature suggested that the purification protocol currently used results in RTPR which contains 2040% microheterogeneity, along with minor contamination by other proteins . In addition, no report of crystalline RTPR has ever appeared . The literature indicates that irreversible cysteine oxidation (e.g., to -SO2H or -SO3H) is one highly plausible reason for the microheterogeneity of RTPR . The literature also indicates that improvement in the level of enzyme purity is the most effective next step in coaxing enzymes to crystallize that have previously failed to do so . A shortened, improved purification of RTPR has been developed, one involving a shorter purification time, a lower pH, a higher concentration of the more effective reductant DTT (all designed to help protect the cysteines from oxidation), and a final step utilizing our recently reported, improved dGTP-based affinity chromatography resin . The resultant RTPR is approximately 20-30% higher in both specific activity and in its ability to undergo single turnovers, and is homogeneous by mass spectrometry and dynamic light scattering . Additionally, the revised purification procedure eliminates > 30 proteins present in 2-3% amounts along with damaged RTPR that does not bind properly (i.e . tightly) to the dGTP-affinity resin . Finally, dGTP-based affinity chromatography purified RTPR has yielded the first reported, albeit small, single crystals of RTPR.

Bioorg Med Chem, 1999 Jun, 7(6), 1105 - 10
Dihydrofolate reductase and cell growth activity inhibition by the beta-carboline-benzoquinolizidine plant alkaloid deoxytubulosine from Alangium lamarckii: its potential as an antimicrobial and anticancer agent; Rao KN et al.; Beta-carboline-benzoquinolizidine plant alkaloid deoxytubulosine (DTB) was evaluated and assessed for the first time for its biochemical and biological activity employing the biomarker dihydrofolate reductase (DHFR) (5,6,7,8-tetrahydrofolate: NADP+ oxidoreductase, EC 1.5.1.3) as the probe enzyme, a key target in cancer chemotherapy . DHFR, employed in the present investigations was purified from Lactobacillus leichmannii . DTB, isolated from the Indian medicinal plant Alangium lamarckii was demonstrated to exhibit potent cytotoxicity . The alkaloid potently inhibited the cell growth of L . leichmannii and the cellular enzyme activity of DHFR (IC50=40 and 30 microM for the cell growth and enzyme inhibitions, respectively) . DTB concentrations >75 microM resulted in a total loss of the DHFR activity, thus suggesting that the beta-carboline-benzoquinolizidine plant alkaloid is a promising potential antitumor agent . Our results are also suggestive of its potential antimicrobial activity . DTB binding to DHFR appears to be slow and reversible . Inhibition kinetics revealed that DHFR has a Ki value of 5x10(-6) M for DTB and that the enzyme inhibition is a simple linear 'non-competitive' type.

FEMS Microbiol Lett, 1999 Jul 15, 176(2), 483 - 7
Processing of extracellular lipase of Lactobacillus plantarum: involvement of a metalloprotease; Silva Lopes Mde F et al.; The hypothesis of a proteolytic involvement in the extracellular lipase processing of a strain of Lactobacillus plantarum was considered and tested, in vitro assays with acid proteases, cathepsin D and renin revealed that both did affect lipolytic activity positively . In vivo assays with growth in the presence of the protease inhibitors pepstatin, phenylmethylsulfonyl fluoride, transepoxysuccinyl-L-leucylamido-(4-guanidino)butane and ethylenediaminetetraacetic acid showed that ethylenediaminetetraacetic acid did affect the pattern of the proteins that possess lipolytic activity . Therefore, it is suggested that a metalloprotease is involved in the processing of the extracellular lipases of L . plantarum, although other proteases can also be important.

Antonie Van Leeuwenhoek, 1999 Apr, 75(3), 217 - 23
Heterofermentative metabolism of glucose and ribose and utilisation of citrate by the smooth biotype of Lactobacillus amylovorus NCFB 2745; Whitley K et al.; Lactobacillus amylovorus NCFB 2745 exhibits a rough colony morphology, ferments glucose homofermentatively and cannot utilise ribose . After five transfers in de Man Rogosa and Sharpe media (containing glucose and citrate) Lb . amylovorus 2745 appears smooth on agar plates; smooth cultures reverted to rough by culturing in aerobic conditions . The smooth type shows patterns of fermentation that are typical of a heterofermentative lactobacillus . Thus, the smooth morphotype produces CO2 and ethanol in addition to lactate and is able to ferment ribose . The switch in metabolism to the smooth form is accompanied by an increase in phosphoketolase and a reduction in aldolase enzyme activities . Citrate also has effects on growth rates and end-metabolites.

Appl Environ Microbiol, 1999 Aug, 65(8), 3540 - 6
Characterization of muscle sarcoplasmic and myofibrillar protein hydrolysis caused by Lactobacillus plantarum; Fadda S et al.; Strains of Lactobacillus plantarum originally isolated from sausages were screened for proteinase and aminopeptidase activities toward synthetic substrates; on the basis of that screening, L . plantarum CRL 681 was selected for further assays on muscle proteins . The activities of whole cells, cell extracts (CE), and a combination of both on sarcoplasmic and myofibrillar protein extracts were determined by protein, peptide, and free-amino-acid analyses . Proteinase from whole cells initiated the hydrolysis of sarcoplasmic proteins . The addition of CE intensified the proteolysis . Whole cells generated hydrophilic peptides from both sarcoplasmic and myofibrillar proteins . Other peptides of a hydrophobic nature resulted from the combination of whole cells and CE . The action of both enzymatic sources on myofibrillar proteins caused maximal increases in lysine, arginine, and leucine, while the action of those on sarcoplasmic proteins mainly released alanine . In general, pronounced hydrolysis of muscle proteins required enzyme activities from whole cells in addition to those supplied by CE.

Appl Environ Microbiol, 1999 Aug, 65(8), 3418 - 26
Phenotypic and genotypic characterization of non-starter lactic acid bacteria in mature cheddar cheese; Fitzsimons NA et al.; Non-starter lactic acid bacteria were isolated from 14 premium-quality and 3 sensorially defective mature Irish Cheddar cheeses, obtained from six manufacturers . From countable plates of Lactobacillus-selective agar, 20 single isolated colonies were randomly picked per cheese . All 331 viable isolates were biochemically characterized as mesophilic (i.e., group II) Lactobacillus spp . Phenotypically, the isolates comprised 96.4% L . paracasei, 2.1% L . plantarum, 0.3% L . curvatus, 0.3% L . brevis, and 0.9% unidentified species . Randomly amplified polymorphic DNA (RAPD) analysis was used to rapidly identify the dominant strain groups in nine cheeses from three of the factories, and through clustering by the unweighted pair group method with arithmetic averages, an average of seven strains were found per cheese . In general, strains isolated from cheese produced at the same factory clustered together . The majority of isolates associated with premium-quality cheese grouped together and apart from clusters of strains from defective-quality cheese . No correlation was found between the isomer of lactate produced and RAPD profiles, although isolates which did not ferment ribose clustered together . The phenotypic and genotypic methods employed were validated with a selection of 31 type and reference strains of mesophilic Lactobacillus spp . commonly found in Cheddar cheese . RAPD analysis was found to be a useful and rapid method for identifying isolates to the species level . The low homology exhibited between RAPD banding profiles for cheese isolates and collection strains demonstrated the heterogeneity of the L . paracasei complex.

Appl Environ Microbiol, 1999 Aug, 65(8), 3360 - 3
Kinetics, stereospecificity, and expression of the malolactic enzyme; Arthurs CE et al.; Mass spectrometric measurement of carbon dioxide production was used to study malolactic fermentation (MLF) in Lactobacillus collinoides isolated from cider . The kinetics and stereospecificity of the malolactic enzyme (MLE) were studied, and the stoichiometry of the reaction sequence was investigated . The optimum pH for activity of the MLE was 4.9 . MLF was more rapid (in both intact cells and cell extracts) when L-malic acid was used than when D-malic acid or the racemic mixture was added . The enzyme was found to be constitutively present in L . collinoides . Addition of L-malic acid (37 mM) to the growth medium resulted in increased MLE activity; addition of the D isomer alone or the racemic mixture resulted in lower activities . Addition of the main sugars in apple juice (fructose, sucrose, and glucose) to the growth medium in the presence of malic acid repressed production of MLE to similar extents in all three cases; in the absence of malic acid, instead of inhibiting MLF, addition of sugars to the growth medium somewhat increased the residual MLE activity.

Int J Food Microbiol, 1999 May 1, 48(2), 113 - 23
Duplication of the beta-galactosidase gene in some Lactobacillus plantarum strains; Fernandez M et al.; Curing of a plasmid that encoded a beta-galactosidase gene (beta-gal) from the Lactobacillus plantarum strain of dairy origin LL441 was not accompanied by complete loss of the lactose utilization phenotype . DNA-DNA hybridization, using an internal fragment of the beta-gal gene as a probe, revealed a second determinant located on the chromosome of the cured derivatives . The chromosomal copy was present in all of a series of beta-Gal+ L . plantarum and Lactobacillus pentosus strains from different origins . In addition, four other L . plantarum strains harboured plasmid encoded beta-gal genes as well . Since both sequences cross-hybridized and present a similar genetic organization, it is postulated that the plasmid copy was generated through gene duplication and, probably, selected by growth of the strains in lactose rich environments.

Int J Syst Bacteriol, 1999 Jul, 49 Pt 3, 1075 - 81
Molecular identification of Lactobacillus hilgardii and genetic relatedness with Lactobacillus brevis; Sohier D et al.; Conventional phenotypic methods lead to misidentification of the lactic acid bacteria Lactobacillus hilgardii and Lactobacillus brevis . Random amplified polymorphic DNA (RAPD) and repetitive element PCR (REP-PCR) techniques were developed for a molecular study of these two species . The taxonomic relationships were confirmed by analysis of the ribosomal operon . Amplified DNA fragments were chosen to isolate L . hilgardii-specific probes . In addition to rapid molecular methods for identification of L . hilgardii, these results convincingly proved that some strains first identified as L . brevis must be reclassified as L . hilgardii . The data clearly showed that these molecular methods are more efficient than phenotypic or biochemical studies for bacterial identification at the species level.

Int J Syst Bacteriol, 1999 Jul, 49 Pt 3, 997 - 1007
Genetic diversity within Lactobacillus sakei and Lactobacillus curvatus and design of PCR primers for its detection using randomly amplified polymorphic DNA; Berthier F et al.; The genotypic and phenotypic diversity among isolates of the Lactobacillus curvatus/Lactobacillus graminis/Lactobacillus sakei group was evaluated by comparing RAPD data and results of biochemical tests, such as hydrolysis of arginine, D-lactate production, melibiose and xylose fermentation, and the presence of haem-dependent catalase . Analyses were applied to five type strains and to a collection of 165 isolates previously assigned to L . sakei or L . curvatus . Phenotypic and RAPD data were compared with each other and with previous DNA-DNA hybridization data . The phenotypic and genotypic separation between L . sakei, L . curvatus and L . graminis was clear, and new insights into the detailed structure within L . sakei and L . curvatus were obtained . Individual strains could be typed by RAPD and, after the elimination of similar or identical isolates, two sub-groups in both L . curvatus and L . sakei were defined . The presence or absence of catalase activity further distinguished the two L . curvatus sub-groups . By cloning and sequencing specific RAPD products, pairs of PCR primers were developed that can be used to specifically detect L . curvatus, L . sakei and each of the L . sakei sub-groups.

Res Vet Sci, 1999 Aug, 67(1), 65 - 71
Immunisation against lactic acidosis in cattle; Shu Q et al.; The present study was designed to investigate the efficacy of control of lactic acidosis by immunisation against lactic acid-producing bacteria, Streptococcus bovis and Lactobacillus . Ten steers were allocated to two treatment groups . One group was immunised with a vaccine containing S . bovis (strain Sb-5) and Lactobacillus (LB-27) cells, and the other was a non-immunised control group . The vaccine, using Freund's complete adjuvant for primary immunisation and Freund's incomplete adjuvant for boosters, was administered intramuscularly . After primary immunisation, boosters were given at 2 to 4 week intervals . Both anti- S . bovis and anti- Lactobacillus IgG levels in saliva increased significantly (P < 0.01) after the 1st booster which were lower (P < 0.05) than the IgG levels after the 2nd and 3rd boosters, but were not significantly different (P > 0.05) from the IgG levels prior to a grain challenge (after the 4th booster) . There were positive correlations between the anti- S.bovis and anti- Lactobacillus IgG in serum and saliva . Compared with the control group, steers in the immunised group had higher (P < 0.05) feed intakes, lower (P < 0.05) rumen concentrations of lactate and lower numbers of S . bovis and Lactobacillus . Three of the control animals were withdrawn from the grain challenge due to their rumen pH persisting below 5.2, while only one animal in the immunised group was withdrawn . These results suggest that the risk of lactic acidosis can be reduced by immunisation against S . bovis and Lactobacillus .

Eur J Oral Sci, 1999 Jun, 107(3), 157 - 63
Oral status of 81 subjects with eating disorders; Ohrn R et al.; The aim was to explore possible correlations between the oral status of patients undergoing treatment at a special outpatient psychiatric clinic for eating disorders and such variables as psychiatric diagnosis and duration of illness, oral hygiene habits, salivary function, and dietary habits . Healthy volunteers of a similar age were recruited for comparison . The material comprised 100 consecutive referrals, of whom 79 were women and 2 were men (age range 17 to 47, median 25 yr) participated . The eating disorders were diagnosed according to the American Psychiatric Association's DSM III-R criteria . The clinical and radiographic examinations were supplemented by standardized intraoral photographs, study models and salivary analysis . The decayed, missing, filled surfaces (DMFS) index was 15.3+/-10.9, a significantly higher caries frequency than for the reference group . More than half the subjects had erosive tooth wear involving the dentine, and about one-third had very low unstimulated salivary flow rates and very high counts of mutans streptococci and lactobacilli . Erosive tooth wear was significantly correlated to the number of years of binge-eating . Compared to age-matched individuals, subjects with diagnosed eating disorders are more susceptible to both dental caries and erosion . They should be encouraged to adopt appropriately tailored preventive programmes and to have regular dental check-ups.

J Formos Med Assoc, 1999 May, 98(5), 356 - 60
Clones of Lactobacillus casei and Torulopsis glabrata associated with recurrent abdominal wall abscess; Lu PL et al.; Infectious disease caused by Lactobacillus sp has not been previously reported in Taiwan . We present a case of recurrent abdominal wall abscess in a chronically ill 36-year-old woman, and review the literature on Lactobacillus infection . Five isolates of L . casei were recovered from blood and pus samples, and two isolates of Torulopsis glabrata were isolated from two blood specimens 3 months apart . Two clones of L . casei and T . glabrata were identified by means of antibiotyping with the E test and molecular methods . The abscess was surgically removed because of poor response to 7 months of antimicrobial therapy for the second infectious episode . Recurrent Lactobacillus infection can occur in chronically ill or immunosuppressed patients . Treatment of these infections may require a longer duration of antibiotic therapy, or surgical intervention.

Indian J Pathol Microbiol, 1999 Jan, 42(1), 25 - 9
Polymicrobial etiology of dental caries; Saini S et al.; The present study was carried out to establish the normal bacterial oral flora and the aerobic and anaerobic bacterial flora from deep seated dental caries, and to determine the antimicrobial sensitivity of the clinical isolates so obtained Streptococcus mutans (48%) and Streptococcus sanguis (20%) were the main aerobic isolates whereas Lactobacillus spp . (52%), Veillonella spp . (24%) and Actinomyces spp . (12%) were the major anaerobic isolates . Hundred percent of the samples from dental caries yielded polymicrobial isolates while in two samples from healthy individuals S . mutans was the sole isolate . As the flora changed from healthy tooth to dental caries it changed from one predominated by anaerobic gram-positive cocci to anaerobic gram-positive bacilli . All the anaerobes isolated were sensitive to metronidazole and cefotaxime, whereas all the isolated streptococci were sensitive to penicillin, erythromycin and clindamycin . Incorporation of the antibiotics in baseline restoration, if technically feasible, has been advocated.

J Bacteriol, 1999 Aug, 181(15), 4592 - 7
Genetic characterization of a cell envelope-associated proteinase from Lactobacillus helveticus CNRZ32; Pederson JA et al.; A cell envelope-associated proteinase gene (prtH) was identified in Lactobacillus helveticus CNRZ32 . The prtH gene encodes a protein of 1,849 amino acids and with a predicted molecular mass of 204 kDa . The deduced amino acid sequence of the prtH product has significant identity (45%) to that of the lactococcal PrtP proteinases . Southern blot analysis indicates that prtH is not broadly distributed within L . helveticus . A prtH deletion mutant of CNRZ32 was constructed to evaluate the physiological role of PrtH . PrtH is not required for rapid growth or fast acid production in milk by CNRZ32 . Cell surface proteinase activity and specificity were determined by hydrolysis of alpha(s1)-casein fragment 1-23 by whole cells . A comparison of CNRZ32 and its prtH deletion mutant indicates that CNRZ32 has at least two cell surface proteinases that differ in substrate specificity.

J Food Prot, 1999 Jul, 62(7), 773 - 7
Spray-drying of bacteriocin-producing lactic acid bacteria; Mauriello G et al.; Cell survival, cellular damage, and antagonistic activity were investigated after spray-drying of four bacteriocin-producing strains of lactic acid bacteria: Lactococcus lactis subsp . lactis 140, isolated from natural whey culture and producing a narrow-inhibitory spectrum bacteriocin); L . lactis subsp . lactis G35, isolated from pizza dough and producing nisin; Lactobacillus curvatus 32Y and Lactobacillus sp . 8Z, isolated from dry sausages . Trials were performed with bacteria suspended in skimmed milk or directly grown in whey . Three air temperatures at the inlet of the drier (160, 180, and 200 degrees C) and three flow rates (10, 13, and 17 ml/min) were assayed . Cell viability and bacteriocin activity of the dried materials were determined immediately after the process and after 5, 15, 30, and 60 days of storage at 4 degrees C . There was no significant difference between the two feeding suspensions in cell survival, always decreasing with the increase of inlet-air temperature . No loss of bacteriocin activity was detected in reconstituted powders, nor was any loss of ability to produce bacteriocin found after drying . Investigations of sensitivity to NaCl revealed only temporary damage to dried bacteria . During storage for 2 months at 4 degrees C, all samples, but mainly the lactococcal strains, displayed a gradual decrease in cell survival . Bacteriocin activity remained at the same level, allowing powders to be considered as effective biopreservatives.

J Food Prot, 1999 Apr, 62(4), 336 - 42
Growth control of Listeria monocytogenes on cold-smoked salmon using a competitive lactic acid bacteria flora; Nilsson L et al.; A Lactobacillus sake strain LKE5 and four strains of Carnobacterium piscicola were evaluated as biopreservation cultures to control the growth of Listeria monocytogenes on vacuum-packed, cold-smoked salmon stored at 5 degrees C . All five strains were antilisterial as live cultures in an agar diffusion assay . Cell-free supernatants of two strains of C . piscicola and L . sake LKE5 were also antilisterial because of the production of bacteriocins . The presence of high cell numbers of strains of C . piscicola had no influence on the sensory quality of cold-smoked salmon stored at 5 degrees C, but L . sake LKE5 caused strong sulfurous off-flavors and was rejected as a culture for biopreservation of cold-smoked salmon . A bacteriocin-producing strain of C . piscicola (A9b) initially caused a 7-day lag phase of L . monocytogenes, followed by a reduction in numbers of L . monocytogenes from 10(3) CFU/ml to below 10 CFU/ml after 32 days of incubation, coinciding with the detection of antilisterial compounds . The presence of a nonbacteriocin-producing strain of C . piscicola (A10a) prevented the growth of L . monocytogenes during the 32-day incubation . The growth of L . monocytogenes was strongly repressed on cold-smoked salmon in the presence of C . piscicola A9b and A 10a, respectively . The initial cell numbers of L . monocytogenes that were found on Oxford plates incubated at 25 degrees C reached low maximum cell counts of 10(4) and 2 x 10(3) after 14 and 20 days of storage in mixed culture with C . piscicola A9b and A10a.

Br J Surg, 1999 Jul, 86(7), 961 - 5
Experimental study of the influence of intestinal flora on the healing of intestinal anastomoses; Okada M et al.; BACKGROUND: The beneficial effects of the normal intestinal flora on wound healing in the skin have already been confirmed, and this study attempted to elucidate the influence of the intestinal flora on the healing process in intestinal anastomoses . METHODS: Five groups of rats were studied: germ-free, conventional, monocontaminated with Lactobacillus acidophilus La5 or Escherichia coli X7 and ex-germ-free (conventionalized) . All animals underwent ileal and colonic resections followed by anastomoses . Seven days later they were killed and the bursting pressure and hydroxyproline concentration of the anastomoses were measured . The microbiological status of the animals was confirmed weekly . RESULTS: No bacteria were detected in the germ-free rats and no other bacteria were found in the monocontaminated animals . Conventional rats had a significantly higher anastomotic bursting pressure both in the ileum compared with rats monocontaminated with L . acidophilus, and in the colon compared with germ-free rats . The ex-germ-free rats also showed a significantly higher bursting pressure than germ-free animals and rats monocontaminated with either L . acidophilus or E . coli in the ileum and colon . CONCLUSION: The presence of the intestinal flora enhanced the healing of intestinal anastomoses . The data suggest that this effect depends on differences in the types of bacteria in the intestine.

J Dairy Sci, 1999 Jul, 82(7), 1388 - 93
Purification and characterization of an antihypertensive peptide from a yogurt-like product fermented by Lactobacillus helveticus CPN4; Yamamoto N et al.; Whey peptides in a yogurt-like product fermented by Lactobacillus helveticus CPN4 were fractionated by a Sep-pak C-18 cartridge followed by two-step reverse-phase HPLC . The antihypertensive activity was measured by systolic blood pressure in spontaneously hypertensive rats after oral administration of each fraction . Five major peptides in the final fraction were further purified by reverse-phase HPLC and were measured for these antihypertensive activities in spontaneously hypertensive rats . The only peptide in the final fraction that showed strong antihypertensive activity had a sequence of Tyr-Pro, which is found in alpha s1-casein (CN), beta-CN, and kappa-CN . The synthetic peptide Tyr-Pro yielded significant antihypertensive activity from 2 to 8 h after oral administration of 1 mg of peptide/kg of body weight, and the effect was maximal at 6 h after oral administration . The antihypertensive effect of the peptide was dependent on the peptide dosage from 0.1 to 10 mg of peptide/kg of body weight . The concentration of Tyr-Pro peptide increased during fermentation and reached about 8.1 micrograms/ml of whey in the pH 4.3 yogurt-like product . The antihypertensive peptide had a low inhibitory activity against angiotensin I-converting enzyme . The inhibition of 50% of the angiotensin I-converting enzyme (IC50) was 720 microM.

Plasmid, 1999 Jul, 42(1), 31 - 41
Cloning of erythromycin-resistance determinants and replication origins from indigenous plasmids of Lactobacillus reuteri for potential use in construction of cloning vectors; Lin CF et al.; Lactobacillus reuteri L1 and N16 strains contain a 7.0-kb plasmid (pTE80) and a 15-kb plasmid (pTE15), respectively, encoding resistance to erythromycin (Em(r)) . Physical maps of both plasmids were established . Nucleotide sequences of the genetic determinants encoding Em(r) on pTE80 and pTE15 revealed the existence of a very similar (ca . 99% nucleotide sequence and ca . 98% amino acid sequence identity) open reading frame for an Em(r) transmethylase gene (erm) in both plasmids . These structural erm genes, 753 and 750 bp in length, respectively, were highly related (ca . 98% nucleotide sequence and ca . 97% amino acid sequence identity) to the erm gene of L . fermentum plasmid pLEM3 . Sequence analysis showed that these two erm genes from pTE80 and pTE15 could be categorized under the ermB (ermAM) class . These are the first members of the ermB (ermAM) class of Em(r) determinant from L . reuteri to be characterized at the nucleotide sequence level . The Em(r) gene from pTE80 (erm80) was then ligated into pUC18/19 to construct replication origin (RO)-screening vectors pUE80(+) and pUE80(-) (pUE80(+/-)) . These plasmids contain the pUC18/19-derived multiple cloning site, ampicillin-resistance trait, and the LacZ' gene, which enable direct screening for recombinants in Escherichia coli . Once the recombinant contains a RO from L . reuteri, the Em(r) trait of erm80 is used as a selection marker for the replication of the chimeric plasmid as it is transformed into L . reuteri using the cloned RO as a replicon . Replication regions from pTE80 and pTE15 were successfully cloned into the constructed vector pUE80(-) . The RO cloned from pTE80 was further identified as being highly stable in L . reuteri and also bearing a relatively narrow host range compared with that of pTE15 . The Em(r) determinant (erm80) and RO cloned from pTE80 could be used in the future construction of derivatives of cloning vectors for this microbe . Moreover, the pUE80(+/-) and pTE80-RO constructed in this study have the potential to be developed as a suicide vector and an E . coli-L . reuteri shuttle vector, respectively .

Klin Padiatr, 1999 Mar-Apr, 211(2), 53 - 6
{Persistent Lactobacillus casei subspecies rhamnosus bacteremia in a 14 year old girl with acute myeloid leukemia . A case report}; Majcher-Peszynska J et al.; The present clinical observation is related to a 14-year-old girl suffering from acute myeloid leukemia . The clinical course was complicated by episodes of severe enterocolitis, E . coli- septicemia, pancreatitis and pneumonia . In the course of continued cytostatic and antibiotic treatment a persistent asymptomatic Lactobacillus casei subsp . rhamnosus-bacteremia became detectable by a total of 18 blood cultures . Microbial cultures of the faeces revealed colony-forming unites of this germ in orders of 10(9)/g . Antibiotic eradication attempts according to the resistogram were not successful . The Lactobacillus-bacteremia disappeared only after 13 months when the cytostatic therapy was terminated . An adjuvant influence of the Lactobacillus infection on the outcome of the underlying disease cannot be excluded.

Br Poult Sci, 1999 Mar, 40(1), 91 - 4
Effect of Lactobacillus acidophilus and zinc bacitracin as dietary additives for broiler chickens; Abdulrahim SM et al.; The influence of Lactobacillus acidophilus and zinc bacitracin alone, or in combination, on the growth of broiler chickens was monitored over a period of 8 weeks . 2 . The maximum improvement in body weight over the controls was 10.8% with both additives in the diet but the use of bacitracin alone induced a 9.1% improvement . 3 . Food conversion was reduced by zinc bacitracin alone but was improved by the use of L . acidophilus and bacitracin in combination . 4 . The combination treatment increased abdominal fat deposition in the female chickens by 31%.

J Infect Dis, 1999 Aug, 180(2), 426 - 37
The effects of three nonoxynol-9 preparations on vaginal flora and epithelium; Watts DH et al.; To evaluate the effects of nonoxynol-9 (N-9) on the vaginal flora and epithelium, 48 women (16 in each group) were evaluated by use of quantitative vaginal cultures and colposcopy . at baseline and at 0.5, 4, 24, 48, and 72 h after insertion of one of three N-9 preparations (4% gel {Conceptrol}, 3.5% gel {Advantage-24}, or a 28% vaginal contraceptive film) . The proportion positive for H2O2+ or H2O2- lactobacilli did not change significantly with any of the preparations, but lactobacilli concentrations decreased transiently . Both the proportion of women with Gardnerella vaginalis and the concentration of G . vaginalis decreased transiently . The proportion of women with Escherichia coli increased with the 4% gel, and the concentration increased with all preparations . The number with anaerobic gram-negative rods increased, although the concentrations decreased . Symptoms and colposcopic abnormalities were rare . Changes in levels of vaginal bacteria were transient after single applications of N-9, but adverse effects may be enhanced with frequent, chronic use.

Appl Environ Microbiol, 1999 Jul, 65(7), 3008 - 14
Biochemical and structural characterization of the glucan and fructan exopolysaccharides synthesized by the lactobacillus reuteri wild-type strain and by mutant strains
Van Geel-Schutten GH, Faber EJ, Smit E, Bonting K, Smith MR, Ten Brink B, Kamerling JP, Vliegenthart JF, Dijkhuizen L.
Lactobacillus reuteri LB 121 cells growing on sucrose synthesize large amounts of a glucan (D-glucose) and a fructan (D-fructose) with molecular masses of 3,500 and 150 kDa, respectively . Methylation studies and 13C or 1H nuclear magnetic resonance analysis showed that the glucan has a unique structure consisting of terminal, 4-substituted, 6-substituted, and 4,6-disubstituted alpha-glucose in a molar ratio of 1.1:2.7:1.5:1.0 . The fructan was identified as a (2-->6)-beta-D-fructofuranan or levan, the first example of levan synthesis by a Lactobacillus species . Strain LB 121 possesses glucansucrase and levansucrase enzymes that occur in a cell-associated and a cell-free state after growth on sucrose, raffinose, or maltose but remain cell associated during growth on glucose . Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of sucrose culture supernatants, followed by staining of gels for polysaccharide synthesizing activity with sucrose as a substrate, revealed the presence of a single glucansucrase protein of 146 kDa . Growth of strain LB 121 in chemostat cultures resulted in rapid accumulation of spontaneous exopolysaccharide-negative mutants that had lost both glucansucrase and levansucrase (e.g., strain K-24) . Mutants lacking all levansucrase activity specifically emerged following a pH shiftdown (e.g., strain 35-5) . Strain 35-5 still possessed glucansucrase and synthesized wild-type glucan.

Lett Appl Microbiol, 1999 Jun, 28(6), 419 - 22
Secretion of lysine in a broth medium by lactic bacteria and yeasts associated with garri production using a synthetic gene; Okafor N et al.; Although cassava is an important food in the tropics, it has two major deficiencies which are carried over into those foods made from it: its content of toxic cyanogenic glucosides and its low content of protein and amino acids . Garri, a fermented cassava food, has previously been ameliorated using organisms which simultaneously secrete linamarase (to reduce the residual cyanide in the food), amylase (to contribute to the growth of fermenting organisms and increase the flavour) and lysine (to improve the amino-acid content of the food) . Some of the organisms fermenting cassava for garri production produce appreciable quantities of linamarase and amylase, but they are low in lysine production . It was therefore decided to improve these organisms by transforming them with a synthetic lysine gene coding for an 8-lysine peptide cloned in pBluescript II SK phagemid vector under the control of lac promoter . The synthetic lysine polypeptide gene was successfully introduced into Escherichia coli DH5 alpha and several strains of Lactobacillus spp . and Saccharomyces spp . There was a dramatic increase in lysine secretion in the organisms, ranging from about 2.5 to sixfold, following transformation with the synthetic gene.

J Appl Microbiol, 1999 Jun, 86(6), 1053 - 8
Purification and partial amino acid sequence of plantaricin 1.25 alpha and 1.25 beta, two bacteriocins produced by Lactobacillus plantarum TMW1.25; Remiger A et al.; Two bacteriocins produced by Lactobacillus plantarum TMW1.25 have been purified by a four-step purification procedure, including ammonium sulphate precipitation and cation-exchange chromatography followed by hydrophobic-interaction chromatography on octyl sepharose . The final purification was performed by repeated reversed-phase chromatography steps which yielded two bacteriocin fractions designated plantaricin 1.25 alpha and plantaricin 1.25 beta . The molecular masses of the peptides in these fractions were 5979 and 5203 Da, respectively . Combination of the fractions did not have any synergistic effects on bacteriocin activity, indicating that they each contain a one-peptide bacteriocin . The major peptide in the alpha fraction was blocked at its N-terminus, and a partial sequence (25 residues) could only be obtained after cleavage with CNBr . This sequence did not show clear homologies with known bacteriocins . The beta peptide has been sequenced almost completely and consists, presumably, of 53 residues . This peptide displayed strong homology to the known N-terminal part of brevicin 27 produced by Lactobacillus brevis SB27 . The results showed that the beta peptide contains as many as six consecutive lysine residues at the N-terminus.

Appl Environ Microbiol, 1999 Jul, 65(7), 3213 - 21
Use of conserved randomly amplified polymorphic DNA (RAPD) fragments and RAPD pattern for characterization of Lactobacillus fermentum in Ghanaian fermented maize dough; Hayford AE et al.; The present work describes the use of randomly amplified polymorphic DNA (RAPD) for the characterization of 172 dominant Lactobacillus isolates from present and previous studies of Ghanaian maize fermentation . Heterofermentative lactobacilli dominate the fermentation flora, since approximately 85% of the isolates belong to this group . Cluster analysis of the RAPD profiles obtained showed the presence of two main clusters . Cluster 1 included Lactobacillus fermentum, whereas cluster 2 comprised the remaining Lactobacillus spp . The two distinct clusters emerged at the similarity level of <50% . All isolates in cluster 1 showed similarity in their RAPD profile to the reference strains of L . fermentum included in the study . These isolates, yielding two distinct bands of approximately 695 and 773 bp with the primers used, were divided into four subclusters, indicating that several strains are involved in the fermentation and remain dominant throughout the process . The two distinct RAPD fragments were cloned, sequenced, and used as probes in Southern hybridization experiments . With one exception, Lactobacillus reuteri LMG 13045, the probes hybridized only to fragments of different sizes in EcoRI-digested chromosomal DNA of L . fermentum strains, thus indicating the specificity of the probes and variation within the L . fermentum isolates.

Appl Environ Microbiol, 1999 Jul, 65(7), 3033 - 41
The groESL chaperone operon of Lactobacillus johnsonii; Walker DC et al.; The Lactobacillus johnsonii VPI 11088 groESL operon was localized on the chromosome near the insertion element IS1223 . The operon was initially cloned as a series of three overlapping PCR fragments, which were sequenced and used to design primers to amplify the entire operon . The amplified fragment was used as a probe to recover the chromosomal copy of the groESL operon from a partial library of L . johnsonii VPI 11088 (NCK88) DNA, cloned in the shuttle vector pTRKH2 . The 2,253-bp groESL fragment contained three putative open reading frames, two of which encoded the ubiquitous GroES and GroEL chaperone proteins . Analysis of the groESL promoter region revealed three transcription initiation sites, as well as three sets of inverted repeats (IR) positioned between the transcription and translation start sites . Two of the three IR sets bore significant homology to the CIRCE elements, implicated in negative regulation of the heat shock response in many bacteria . Northern analysis and primer extension revealed that multiple temperature-sensitive promoters preceded the groESL chaperone operon, suggesting that stress protein production in L . johnsonii is strongly regulated . Maximum groESL transcription activity was observed following a shift to 55 degrees C, and a 15 to 30-min exposure of log-phase cells to this temperature increased the recovery of freeze-thawed L . johnsonii VPI 11088 . These results suggest that a brief, preconditioning heat shock can be used to trigger increased chaperone production and provide significant cross-protection from the stresses imposed during the production of frozen culture concentrates.

Appl Environ Microbiol, 1999 Jul, 65(7), 2901 - 6
Characterization and identification of Pediococcus species isolated from forage crops and their application for silage preparation; Cai Y et al.; Pediococcus species isolated from forage crops were characterized, and their application to silage preparation was studied . Most isolates were distributed on forage crops at low frequency . These isolates could be divided into three (A, B, and C) groups by their sugar fermentation patterns . Strains LA 3, LA 35, and LS 5 are representative isolates from groups A, B, and C, respectively . Strains LA 3 and LA 35 had intragroup DNA homology values above 93.6%, showing that they belong to the species Pediococcus acidilactici . Strain LS 5 belonged to Pediococcus pentosaceus on the basis of DNA-DNA relatedness . All three of these strains and strain SL 1 (Lactobacillus casei, isolated from a commercial inoculant) were used as additives to alfalfa and Italian ryegrass silage preparation at two temperatures (25 and 48 degrees C) . When stored at 25 degrees C, all of the inoculated silages were well preserved and exhibited significantly (P < 0.05) reduced fermentation losses compared to that of their control in alfalfa and Italian ryegrass silages . When stored at 48 degrees C, silages inoculated with strains LA 3 and LA 35 were also well preserved, with a significantly (P < 0.05) lower pH, butyric acid and ammonia-nitrogen content, gas production, and dry matter loss and significantly (P < 0.05) higher lactate content than the control, but silages inoculated with LS 5 and SL 1 were of poor quality . P . acidilactici LA 3 and LA 35 are considered suitable as potential silage inoculants.

Biochemistry, 1999 Jun 22, 38(25), 8038 - 44
Direct measurement of the pKa of aspartic acid 26 in Lactobacillus casei dihydrofolate reductase: implications for the catalytic mechanism; Casarotto MG et al.; The ionization state of aspartate 26 in Lactobacillus casei dihydrofolate reductase has been investigated by selectively labeling the enzyme with {13Cgamma} aspartic acid and measuring the 13C chemical shifts in the apo, folate-enzyme, and dihydrofolate-enzyme complexes . Our results indicate that no aspartate residue has a pKa greater than approximately 4.8 in any of the three complexes studied . The resonance of aspartate 26 in the dihydrofolate-enzyme complex has been assigned by site-directed mutagenesis; aspartate 26 is found to have a pKa value of less than 4 in this complex . Such a low pKa value makes it most unlikely that the ionization of this residue is responsible for the observed pH profile of hydride ion transfer {apparent pKa = 6.0; Andrews, J., Fierke, C . A., Birdsall, B., Ostler, G., Feeney, J., Roberts, G . C . K., and Benkovic, S . J . (1989) Biochemistry 28, 5743-5750} . Furthermore, the downfield chemical shift of the Asp 26 (13)Cgamma resonance in the dihydrofolate-enzyme complex provides experimental evidence that the pteridine ring of dihydrofolate is polarized when bound to the enzyme . We propose that this polarization of dihydrofolate acts as the driving force for protonation of the electron-rich O4 atom which occurs in the presence of NADPH . After this protonation of the substrate, a network of hydrogen bonds between O4, N5 and a bound water molecule facilitates transfer of the proton to N5 and transfer of a hydride ion from NADPH to the C6 atom to complete the reduction process.

J Dairy Sci, 1999 Jun, 82(6), 1099 - 107
Sensitivity of Staphylococcus aureus and Lactobacillus helveticus in ovine milk subjected to high hydrostatic pressure; Gervilla R et al.; Ovine milk, standardized to 6% fat, was inoculated with Staphylococcus aureus CECT 534 and Lactobacillus helveticus CECT 414 at a concentration of 10(7) cfu/ml and treated by high hydrostatic pressure . Treatments consisted of combinations of pressure (200, 300, 400, 450, and 500 MPa), temperature (2, 10, 25, and 50 degrees C), and time (5, 10, and 15 min) . Staphylococcus aureus was highly resistant to pressure; only pressurizations at 50 degrees C of 500 MPa for 15 min achieved reductions of > or = 7.3 log units . For L . helveticus, the number of surviving cells was reduced considerably at pressures of 400 MPa or more (up to 4.5 log units at 50 degrees C for 15 min), and pressure was more effective at low (2 and 10 degrees C) and moderately high (50 degrees C) temperatures than at room temperature (25 degrees C) . Both species showed first-order kinetics of destruction in the range 0 to 60 min . The D values for S . aureus were 20 min (2 degrees C at 450 MPa) and 16.7 min (25 degrees C at 450 MPa), and D values for L . helveticus were 7.1 min (2 degrees C at 450 MPa) and 9.1 min (25 degrees C at 450 MPa) . Lactobacillus helveticus showed higher rates of survival of pressure than those reported in previous studies for other Lactobacillus spp.

Kansenshogaku Zasshi, 1999 May, 73(5), 451 - 6
{Detection of bactericidal antibody in the breast milk of a mother infected with enterohemorrhagic Escherichia coli O157:H7}; Adachi E et al.; A 21 years-old pregnant woman developed diarrhea, fresh bloody stools and abdominal pain on April 6th 1997 at 32 weeks of gestation, and was admitted to the hospital on April 11th . The stool culture on admission was positive for enterohemorrhagic Escherichia coli (EHEC) O157:H7 (Stx1 and 2) . Clinical laboratory data during admission showed only slight elevation of beta-microglobulin and N-acetyl glucosaminidase in the urine, and no neurological or hemolytic symptoms were seen . After the antibiotic and lactobacillus administration, all her symptoms were relieved and no abnormal findings in pregnancy were observed . She delivered a baby girl normally on May 30th . Serum (between 41 and 120 days from the onset) and milk (between 4 and 64 days post partum) samples from the mother, and serum (64 days of age) from a baby and cord blood were obtained to monitor the immune status against EHEC O157:H7 and against Shiga toxins (Stx) . Anti-E . coli O157 LPS antibodies (IgA, G and M) were assayed by the ELISA method . Neutralizing anti-Stx antibodies were measured by using ACHN cell cytotoxicity assay . In the colostrum and mature milk, high levels of IgA and IgM, and no IgG antibodies against EHEC O157 LPS were detected . In one of the control colostrum samples obtained from 4 healthy mothers IgA antibody against EHEC O157 LPS was detected . To assess the potency of protection against EHEC O157:H7 by the breast milk, we monitored it by the bactericidal activity for the organism under complement-coincubation experiment, and by the neutralization test for the Stx cytotoxicity . As a result, breast milk samples (both colostrum and mature milk) from a patient were demonstrated to kill the organisms . One of 4 healthy milk samples, showed bactericidal activity though it was negative in O157-LPS antibody . This bactericidal activity seen in one healthy colostrum is possibly due to a nonspecific reaction caused by non-O157 E . coli infection . From these observations, it was suggested that the bactericidal activity was due to the IgM class antibody against EHEC O157:H7 . However, the neutralizing antibody against Stx1 and 2 could not be detected in any sample . EHEC infection at late gestation did not cause adverse effects to a fetus, and breastfeeding may have advantage for the protection of a baby against EHEC infection.

J Bacteriol, 1999 Jul, 181(13), 3928 - 34
Elements involved in catabolite repression and substrate induction of the lactose operon in Lactobacillus casei; Gosalbes MJ et al.; In Lactobacillus casei ATCC 393, the chromosomally encoded lactose operon, lacTEGF, encodes an antiterminator protein (LacT), lactose-specific phosphoenolpyruvate-dependent phosphotransferase system (PTS) elements (LacE and LacF), and a phospho-beta-galactosidase . lacT, lacE, and lacF mutant strains were constructed by double crossover . The lacT strain displayed constitutive termination at a ribonucleic antiterminator (RAT) site, whereas lacE and lacF mutants showed an inducer-independent antiterminator activity, as shown analysis of enzyme activity obtained from transcriptional fusions of lac promoter (lacp) and lacpDeltaRAT with the Escherichia coli gusA gene in the different lac mutants . These results strongly suggest that in vivo under noninducing conditions, the lactose-specific PTS elements negatively modulate LacT activity . Northern blot analysis detected a 100-nucleotide transcript starting at the transcription start site and ending a consensus RAT sequence and terminator region . In a ccpA mutant, transcription initiation was derepressed but no elongation through the terminator was observed in the presence of glucose and the inducing sugar, lactose . Full expression of lacTEGF was found only in a man ccpA double mutant, indicating that PTS elements are involved in the CcpA-independent catabolite repression mechanism probably via LacT.

Curr Opin Microbiol, 1999 Jun, 2(3), 289 - 95
Gene expression systems for lactic acid bacteria; de Vos WM; Considerable advances have been made in the genetics and molecular biology of lactic acid bacteria, including Lactococcus, Lactobacillus, Leuconostoc, Pediococcus and Streptococcus spp . These have resulted in the construction of constitutive gene expression cassettes, inducible gene expression systems, and specific protein targeting systems for these bacteria . These developments are important in the food industry where lactic acid bacteria can be exploited as food-grade cell factories.

J Med Chem, 1999 Jun 17, 42(12), 2272 - 9
Synthesis of classical and a nonclassical 2-amino-4-oxo-6-methyl-5-substituted pyrrolo{2,3-d}pyrimidine antifolate inhibitors of thymidylate synthase; Gangjee A et al.; Compounds 2-5 were designed as potential antifolate nonpolyglutamatable inhibitors of thymidylate synthase (TS) . These analogues are structurally related to 2-amino-4-oxo-5-substituted quinazolines and 2-amino-4-oxo-5-substituted pyrrolo{2, 3-d}pyrimidines which have shown excellent inhibition of TS and, for the quinazoline, significant promise as clinically useful antitumor agents . Compounds 2-4 were synthesized by appropriate amine exchange reactions on pivaloyl-protected 5-dimethylaminomethyl-substituted 6-methyl pyrrolo{2,3-d}pyrimidine 7 which in turn was obtained from the Mannich reaction of pivaloylated-6-methyl pyrrolo{2, 3-d}pyrimidine 6 . In instances where the amine exchange reaction was sluggish, the Mannich base was quaternized with methyl iodide which afforded much faster exchange reaction with improved yields . For compound 5, 4-mercaptopyridine was used as the nucleophile and reacted with 7 . The analogues 2-4 inhibited Lactobacillus casei (lc) TS and recombinant human (h) TS with IC50 in the 10(-4) to 10(-5) M range . Compound 5 inhibited lcTS and hTS 20% at 26 and 25 microM, respectively . In addition, compound 5 inhibited the growth of Pneumocystis carinii and Toxoplasma gondii cells in culture by 76% at 32 x 10(-6) M and 50% at 831 x 10(-6) M, respectively.

Przegl Lek, 1999, 56(1), 26 - 9
{The role of phase contrast microscopy in the evaluation of cervix neck and vaginal biocenosis}; Basta A et al.; The aim of our study was to evaluate and compare the possibility of germ identification in cervico-vaginal infections of different origin by Ph cytology and classic fixated and stained (H-E) smears . We identified Lactobacillus vag., Gardnerella vag., short bacilli (Escherichia coli, Proteus, Klebsiella), mixed Coccus flora (diplococci, small and large cocci), Trichomonas vag., and Candidia alb . in cervico-vaginal smears . In endocervical, mature metaplastic or parabasal cells the elementary and cocoid bodies of Chlamydia trachomatis were possible to observed . The cytopathic effects caused by viral infections (HPV, HSV, CMV) were detected . The classic (koilocytosis, dyskeratosis) and discrete (binucleation, cracked cells, ghost cells, tadpole cells and large cytoplasmatic hyaline granulations) morphological changes must be confirmed by colposcopy and Digene Hybryde Capture analysis . The results of identification of vaginal biocenosis in Ph microscope and H-E smears were similar . The main benefit of Ph cytology is accuracy, speed and reliability of comprehensive information.

Biol Pharm Bull, 1999 May, 22(5), 491 - 7
Anticonvulsant activity of paeonimetabolin-I adducts obtained by incubation of paeoniflorin and thiol compounds with Lactobacillus brevis; Abdel-Hafez AA et al.; Seventeen thiopaeonimetabolin-I adducts were obtained as mixtures of diastereoisomers after incubation of paeoniflorin with Lactobacillus brevis in the presence of various thiols . The anticonvulsant activity of the adducts was investigated in mice using the maximal subcutaneous pentylenetetrazol seizure test and sodium valproate (1.5 mmol/kg) as a positive control . Thirteen adducts showed dose-dependent prolongation of latencies of clonic and tonic convulsions . Maximal protection against convulsions was effectively demonstrated by 8-(n-hexylthio)paeonimetabolin I (8) and 8-benzoylthiopaeonimetabolin I (18) at doses of 0.125 and 0.25 mmol/kg, respectively, while 100% protection was only achieved at 0.5 mmol/kg of 8-cyclopentylthiopaeonimetabolin I and 8-(p-tolylthio)paeonimetabolin I . The principal anticonvulsant activity of the diastereoisomers of 8 and 18 was attributed to their 7S-isomers {ED50 values of 0.09 and 0.12 mmol/kg, and protective indices of 5.0 and 4.0 for 8 (7S) and 18 (7S), respectively}, while the 7R counterparts {8 (7R) and 18 (7R)} showed a muscle relaxation effect.

Int J Food Microbiol, 1999 Apr 1, 48(1), 21 - 35
Effect of bacteriocin-producing lactobacilli on the survival of Escherichia coli and Listeria in a dynamic model of the stomach and the small intestine; Ganzle MG et al.; The survival of Lactobacillus curvatus LTH 1174 (bac ) and (bac ) in combination with Escherichia coli LTH 1600 or Listeria innocua DSM20649 during transit through a dynamic model of the human stomach and small intestine (GIT model) was studied . Furthermore, we determined the digestion of curvacin A during gastro-intestinal transit and the effect of this bacteriocin on microbial survival . Lb . curvatus is rapidly killed in the gastric compartment at pH < 2.0, and less than 0.01% of the cells delivered to the small intestinal compartments were recovered from the ileal compartment of the model . Meat exerted a protective effect against the lethal action of bile against Lb . curvatus . The sensitivity of E . coli to acid depended on the aeration of the preculture and decreased in the order anaerobic > strongly agitated > agitated . Lactic acid and curvacin A enhanced the lethal effect of low pH on E . coli . Accordingly, cells from strongly agitated cultures were killed faster in the gastric compartment of the GIT model than those from agitated cultures, and inactivation was accelerated in the presence of curvacin A . E . coli tolerated the bile concentrations prevailing in the small intestinal compartments of the model . The survival of Listeria innocua in the GIT model was comparable to that of Lb . curvatus . The curvacin A produced by Lb . curvatus LTH1174 (bac+) killed > 90% of the L . innocua within 10 min after mixing of the cultures . Curvacin A was not degraded in the the gastric compartment, and could be detected in the ileal compartment during the first 180 min upon addition of the meal.

Infect Dis Obstet Gynecol, 1999, 7(3), 169 - 74
The role of bacterial vaginosis in infection after major gynecologic surgery; Lin L et al.; PURPOSE: Previous studies have reported an association between bacterial vaginosis (BV) and postoperative fever and infection . This prospective study investigated whether the intermediate or definite stages of BV are risk factors for postoperative infection after major gynecologic surgery . METHODS: Vaginal cultures were obtained preoperatively from 175 women undergoing gynecologic surgery . The diagnostic criteria for BV were based on Nugent's standardized method of Gram stain interpretation . Postoperative fever was defined as at least one temperature equal to 101.0 degrees F or greater, or two or more temperatures more than 6 hours apart equal to 100.4 degrees F or greater . RESULTS: Thirty-six percent of the positive-BV group developed a postoperative fever, compared with 20% of the Lactobacillus-predominant group and 12% of the intermediate-BV group (P = 0.017) . The differences between the positive-BV group and the Lactobacillus-predominant group, and between the positive-BV group and the intermediate-BV group, with respect to postoperative fever, were statistically significant (P = 0.045 and P = 0.007, respectively) . The difference between the intermediate-BV group and the Lactobacillus-predominant group was not statistically significant (P = 0.28) . CONCLUSIONS: Although the association between BV and postoperative febrile morbidity could be a spurious result of confounding with other variables, it may be prudent for the surgeon to identify patients with BV and treat them preoperatively.

J Control Release, 1999 Jun 28, 60(1), 57 - 65
Sol-gel composite films with controlled release of biocides; Bottcher H et al.; The release of biocides (benzoic, sorbic and boric acids) incorporated into modified silica films was investigated with respect to composite structure . The liberation rates of the embedded acids are proportional to the biocide-to-silica ratio and are changed by adding soluble polymers such as hydroxypropylcellulose . The rates of liberation correlate with biocidal activity, i.e., the growth of microorganisms such as Escherichia coli, Lactobacillus plantarum and Penicillium sp . is strongly suppressed by contact with such composite films . In a similar way, strong fungicide and insecticide effects were observed after impregnating wood with composites containing boric acid.

Vaccine, 1999 Apr 23, 17(17), 2117 - 28
Instruments for oral disease-intervention strategies: recombinant Lactobacillus casei expressing tetanus toxin fragment C for vaccination or myelin proteins for oral tolerance induction in multiple sclerosis; Maassen CB et al.; Lactobacillus strains possess properties that make them attractive candidates as vehicles for oral administration of therapeutics . In this report we describe the construction and analysis of recombinant Lactobacillus casei applicable in oral vaccination against an infectious disease (tetanus) and in oral tolerance induction for intervention in an autoimmune disease, multiple sclerosis . Recombinant L . casei which express surface-anchored tetanus toxin fragment C (TTFC) were generated . Quantitative analysis by flow cytometry demonstrated a high level of cell wall-bound expression of TTFC and immunogenicity was demonstrated by parenteral immunization with whole cell extracts of the recombinants . A series of expression vectors was constructed to secrete human myelin basic protein (hMBP) or hMBP as a fusion protein with beta-glucuronidase from Escherichia coli . These heterologous products produced by L . casei were detected in the growth medium and parenteral immunization with this medium evoked antibodies against hMBP, confirming that secretion indeed had occurred . Based on the different localization of the heterologous proteins, lactobacilli expressing surface-anchored TTFC are ideally suited for the induction of antibody responses, whereas lactobacilli that secrete myelin proteins can be used for the induction of peripheral T-cell tolerance . In conclusion, the specific technology described here allows the construction of a wide array of safe live recombinant lactobacilli which may prove to be useful in oral intervention strategies for the prevention of infectious diseases or treatment of autoimmune diseases.

Int J Food Microbiol, 1999 Mar 15, 47(3), 203 - 9
Arginine dihydrolase pathway in Lactobacillus plantarum from orange; Arena ME et al.; Lactobacillus plantarum N8 and N4 strains isolated from orange degraded L-arginine to citrulline, ornithine and ammonia . Citrulline and ornithine were consumed . Lactobacillus plantarum N4 utilized arginine and ornithine to a higher extent than Lactobacillus plantarum N8 . Urea was not detected during arginine degradation, indicating that the amino acid degradation was carried out only by the arginine dihydrolase pathway . Citrulline increased the growth of the two strains, arginine only increased the growth of Lactobacillus plantarum N4 . Ornithine did not modify the growth of the strains studied . With different behavior, Lactobacillus plantarum N8 and N4 strains were able to derive energy and ammonia from arginine or citrulline catabolism . This is interesting for microorganisms developing in a stressful environment.

Int J Food Microbiol, 1999 Mar 15, 47(3), 189 - 201
Modeling the inhibitory effects of organic acids on bacteria; Hsiao CP et al.; The inhibitory effect of acids on microbial growth has long been used to preserve foods from spoilage . While much of the effect can be accounted for by pH, it is well known that different organic acids vary considerably in their inhibitory effects . Because organic acids are not members of a homologous series, but vary in the numbers of carboxy groups, hydroxy groups and carbon-carbon double bonds in the molecule, it has typically not been possible to predict the magnitude, or in some cases even the direction, of the change in inhibitory effect upon substituting one acid for another or to predict the net result in food systems containing more than one acid . The objective of this investigation was to attempt to construct a mathematical model that would enable such prediction as a function of the physical and chemical properties of organic acids . Principal Components Analysis (PCA) was applied to 11 properties for each of 17 acids commonly found in food systems; this resulted in four significant principal components (PCs), presumably representing fundamental properties of the acids and indicating each acid's location along each of these four scales . These properties correspond to polar groups, the number of double bonds, molecular size, and solubility in non-polar solvents . Minimum inhibitory concentrations (MICs) for each of eight acids for six test microorganisms were determined at pH 5.25 . The MICs for each organism were modeled as a function of the four PCs using partial least squares (PLS) regression . This produced models with high correlations for five of the bacteria (R2 = 0.856, 0.941, 0.968, 0.968 and 0.970) and one with a slightly lower value (R2 = 0.785) . Acid susceptible organisms (Bacillus cereus, Bacillus subtilis, and Alicyclobacillus) exhibited a similar response pattern . There appeared to be two separate response patterns for acid resistant organisms; one was exhibited by the two lactobacilli studied and the other by E . coli . Predicting the inhibitory effects of the organic acids as a function of their chemical and physical properties is clearly possible.

Int J Food Microbiol, 1999 Mar 1, 47(1-2), 79 - 87
Isolation and identification of lactobacilli from novel-type probiotic and mild yoghurts and their stability during refrigerated storage; Schillinger U; A total of 26 Lactobacillus strains were isolated from various mild yoghurts and novel-type probiotic dairy products and from a starter culture preparation and were identified by using DNA-DNA hybridization technique . The species present in those products were found to be Lactobacillus acidophilus, L . johnsonii, L . crispatus, L . casei, L . paracasei and L . rhamnosus . DNA homology analysis revealed that some strains had been misclassified by their investigators . Three strains designated as L . acidophilus (L . acidophilus LA-1, L . acidophilus ATCC 43121 and the Lactobacillus strain from Biogarde culture) were found to belong to L . johnsonii and L . acidophilus L1 to be L . crispatus . Strains designated as L . casei were found to be members of three separate species: L . casei, L . paracasei and L . rhamnosus . Viable numbers of lactobacilli in mild and probiotic yoghurts varied greatly including some products with very low Lactobacillus counts . The majority of the probiotic yoghurts, however, contained viable counts above 10(5) per g even at the end of the best before use period.

J Clin Periodontol, 1999 May, 26(5), 322 - 7
The effect of periodontal therapy on the number of cariogenic bacteria in different intra-oral niches; Quirynen M et al.; Several publications have reported an increased susceptibility for root caries after periodontal therapy . It has been suggested that newly exposed roots were less resistant to cariogenic species . This study examined the hypothesis that the increased susceptibility could also be related to an intra-oral microbial shift during the initial phase of the periodontal therapy from a perio-pathogenic to a more cariogenic flora . 10 patients with severe periodontitis were followed for 8 months after thorough scaling and root planing in combination with optimal plaque control . At baseline and after 4 and 8 months, samples were taken from the saliva, the tongue dorsum and the supragingival interdental spaces . These samples were cultured both aerobically and anaerobically in order to determine the total number of colony forming units (CFU) per sample as well as the number of CFU of Streptococcus mutans and Lactobacillus species . Oral hygiene parameters were recorded at the same visits . Finally, at baseline and at the 8 months follow-up, changes in caries activity and periodontal health were registered . Although the total number of aerobic and anaerobic CFU in samples from the tongue and the saliva remained nearly constant over the entire observation period (variations within 0.5 log), significant (p< or =0.05) increases in the number of S . mutans could be detected, especially at month 8 . The significant decrease in the total number of anaerobic CFU in samples from the teeth was not associated with a reduction in the number of S . mutans, so that also for this niche the relative proportion of the latter increased . The number of lactobacilli species for the different niches showed only negligible changes (within 0.5 log values), except for samples from the teeth for which a small (1 log), but statistically significant (p<0.01), reduction could be detected . The periodontal conditions improved for all patients, but the caries activity could not be arrested . These findings seem to indicate that the increased caries susceptibility after periodontal therapy might partially be explained by a significant increase in the number of S . mutans due to ecological changes within the oral cavity . The clinical consequence of this observation would be to advocate a more strict caries preventive program during initial periodontal therapy.

Curr Microbiol, 1999 May, 38(5), 279 - 84
Selection of vaginal H2O2-generating Lactobacillus species for probiotic use; Ocana VS et al.; Lactobacilli are believed to contribute to the control of the vaginal microflora by different mechanisms such as production of antagonistic substances like lactic acid, bacteriocins, and H2O2 . This paper describes the selection of H2O2-generating lactobacilli among 35 hydrophobic isolates from the human vagina . Lactobacillus crispatus F117, which generated the highest H2O2 level, was chosen to study: (a) the kinetics of H2O2 production considering different culture conditions, and (b) the effect of this metabolite on the growth of urogenital tract pathogens . The levels of H2O2 in L . crispatus supernatant increased during its growth and were maximum at the early stationary phase (3.29 mmol H2O2 L-1) under aerated conditions (agitated cultures) . In nonagitated cultures there were no detectable levels of H2O2 . L . crispatus F117 spent supernatant inhibited Staphylococcus aureus growth in plaque assay . Inhibition was due to H2O2 since catalase treatment of the supernatant suppressed inhibition . In mixed cultures performed with L . crispatus and S . aureus a significant decrease in pathogen growth was observed . The inhibitory effect depended on the initial inoculum of S . aureus . Further evaluation of the properties of L . crispatus F117 will be performed to consider its inclusion in a probiotic for local use in the vaginal tract.

Pediatr Dent, 1999 May-Jun, 21(3), 176 - 80
Effects of four anticaries agents on lesion depth progression in an in vitro caries model; Klein U et al.; PURPOSE: This study compares four chemotherapeutic regimens used for inhibiting carious lesion progression: silver nitrate (AgNO3); silver fluoride/stannous fluoride (AgF/SnF2); silver diammine fluoride (SDF); and chlorhexidine (CHX) . METHODS: For this study, a bacterial model system containing Mutans streptococci (MS) and Lactobacilli casei (L) was used to generate carious lesions on 85 extracted sound permanent third molars which were randomly assigned to four test groups and one control group . At week two, the four treatment regimens were applied to the lesions (one treatment per test group) . RESULTS: Six weeks later, lesions treated with a single AgF/SnF2 or AgNO3 application demonstrated 29% and 19% less lesion progression, respectively, than did the control group (P < 0.05) . SDF and CHX did not differ significantly from the control . CONCLUSION: AgF/SnF2 and AgNO3 may be useful in slowing down carious lesion depth progression.

Can J Microbiol, 1999 Jan, 45(1), 77 - 87
The influence of bacterial inoculants on the microbial ecology of aerobic spoilage of barley silage; Inglis GD et al.; The aerobic decomposition of barley silage treated with two inoculants (LacA and LacB) containing mixtures of Lactobacillus plantarum and Enterococcus faecium was investigated over a 28-day period . Initially, yeast and bacterial populations were larger in silage inoculated with LacA than in silage treated with LacB or water alone (control) . Differences in the succession of yeasts in silage treated with LacA were observed relative to the other two treatments . From silage treatment with LacA, Issatchenkia orientalis was the most prevalent yeast taxon over all of the sample times, and the filamentous fungus Microascus brevicaulis was also frequently isolated at later sample dates (> or = 14 days) . In contrast, Saccharomyces exiguus was the most prominent yeast recovered from silage treated with LacB and water alone on days 2 and 4, although it was supplanted by I . orientalis at later sample times . Successional trends of bacteria were similar for all three treatments . Lactobacillus spp . were initially the most prevalent bacteria isolated, followed by Bacillus spp . (primarily Bacillus pumilus) . However, the onset of Bacillus spp . prominence was faster in LacA silage, and Klebsiella planticola was frequently recovered at later sample times (> or = 14 days) . More filamentous fungi were recovered from LacA silage on media containing carboxylmethylcellulose, pectin, or xylan . The most commonly isolated taxa were Absidia sp., Aspergillus flavus, Aspergillus fumigatus, Byssochlamys nivea, Monascus ruber, Penicillium brevicompactum, Pseudoallescheria boydii, and M . brevicaulis . The results of this study indicated that the two bacterial inoculants incorporated into barley at the time of ensilage affected the microbial ecology of silage decomposition following exposure to air . However, neither of the microbial inoculants effectively delayed aerobic spoilage of barley silage, and the rate of decomposition of silage treated with one of the inoculants (LacA) was actually enhanced.

Can J Microbiol, 1999 Jan, 45(1), 51 - 8
Brewing spoilage Lactobacilli detected using monoclonal antibodies to bacterial surface antigens; Whiting MS et al.; A panel of thirteen monoclonal antibodies (Mabs) was assembled that reacts with surface antigens on eight of eleven Lactobacillus brewing spoilage organisms, including one or more of L . brevis, L . buchneri, L . casei-alactosus, L . plantarum, or unspeciated isolate(s) . Immunoblotting was done to identify the antigens involved in Mab binding . Antigen stability in situ was tested by protease treatment and by surface antigen extraction of washed bacteria . Protease susceptibility of extracted surface antigens was also examined . In most cases, Lactobacillus surface antigens detected by the Mabs appear to be noncovalently bound proteins readily altered or removed from the bacterium by various environmental conditions . This research identifies brewing conditions that need to be tested to ascertain whether bacterial surface antigen-reactive Mabs can be used for the rapid, sensitive, and specific detection of Lactobacillus brewing spoilage organisms.

J Appl Microbiol, 1999 May, 86(5), 812 - 6
Stable expression of the Lactobacillus casei bacteriophage A2 repressor blocks phage propagation during milk fermentation; Alvarez MA et al.; A general strategy was applied to implement resistance against temperate bacteriophages that infect food fermentation starters through cloning and expression of the phage repressor . Lactobacillus casei ATCC 393 and phage A2 were used to demonstrate its feasibility as milk fermentation is drastically inhibited when the strain is infected by this phage . The engineered strain Lact . casei EM40::cI, which has the A2 repressor gene (cI) integrated into the genome, was completely resistant and able to ferment milk whether phage was present or not . In addition, viable phages were eliminated from the milk, probably through adsorption to the cell wall . Finally, the integration of cI in the genome resulted in a stable resistance phenotype, being unnecessary selective pressure during milk fermentation.

Digestion, 1999, 60(3), 203 - 9
Effect of whey-based culture supernatant of Lactobacillus acidophilus (johnsonii) La1 on Helicobacter pylori infection in humans; Michetti P et al.; BACKGROUND: Specific strains of Lactobacillus acidophilus are known to inhibit intestinal cell adhesion and invasion by enterovirulent bacteria . As L . acidophilus can survive transiently in the human stomach, it may downregulate Helicobacter pylori infection . METHODS: The ability of L . acidophilus (johnsonii) La1 supernatant to interfere with H . pylori bacterial growth, urease activity, and adhesion to epithelial cells was tested in vitro . Its effect on H . pylori infection in volunteers was monitored in a randomized, double-blind, controlled clinical trial, using a drinkable, whey-based, La1 culture supernatant . H . pylori infected volunteers were treated 14 days with 50 ml of La1 supernatant four times a day combined with either omeprazole 20 mg four times a day or with placebo . Infection was assessed by breath test, endoscopy, and biopsy sampling, performed at inclusion, immediately at the end of the treatment (breath test only), and 4 weeks after the end of the treatment . RESULTS: La1 supernatant inhibited H . pylori growth in vitro, regardless of previous binding of H . pylori to epithelial cells . In 20 subjects (8 females, 12 males, mean age 33.1 years) a marked decrease in breath test values was observed immediately after treatment with La1 supernatant, both in the omeprazole and in the placebo group (median 12.3 vs . 28.8 and 9.4 vs . 20.4, respectively; p < 0.03) . In both treatment groups, breath test values remained low 6 weeks after treatment (omeprazole treated 19.2, placebo treated 8 . 3; p < 0.03 vs . pretreatment), but the persistence of H . pylori infection was confirmed in gastric biopsies . CONCLUSION: La1 culture supernatant shown to be effective in vitro has a partial, acid-independent long-term suppressive effect on H . pylori in humans.

Clin Exp Immunol, 1999 May, 116(2), 283 - 90
Immunomodulatory effects of Lactobacillus plantarum colonizing the intestine of gnotobiotic rats; Herias MV et al.; We have studied the effect of the probiotic strain Lactobacillus plantarum 299v on the immune functions of gnotobiotic rats . One group of germ-free rats was colonized with the type 1-fimbriated Escherichia coli O6:K13:H1 and another group with the same E . coli strain together with L . plantarum 299v . One and 5 weeks after colonization, bacterial numbers were determined in the contents of the small intestine, caecum and mesenteric lymph nodes . Small intestinal sections were examined for CD8+, CD4+, CD25+ (IL-2R alpha-chain), IgA+ and MHC class II+ cells and mitogen-induced spleen cell proliferation was determined . Immunoglobulin levels and E . coli-specific antibodies were measured in serum . Rats given L . plantarum in addition to E . coli showed lower counts of E . coli in the small intestine and caecum 1 week after colonization compared with the group colonized with E . coli alone, but similar levels after 5 weeks . Rats colonized with L . plantarum + E . coli had significantly higher total serum IgA levels and marginally higher IgM and IgA antibody levels against E . coli than those colonized with E . coli alone . They also showed a significantly increased density of CD25+ cells in the lamina propria and displayed a decreased proliferative spleen cell response after stimulation with concanavalin A or E . coli 1 week after colonization . The results indicate that L . plantarum colonization competes with E . coli for intestinal colonization and can influence intestinal and systemic immunity.

Clin Exp Immunol, 1999 May, 116(2), 276 - 82
Lactobacilli from human gastrointestinal mucosa are strong stimulators of IL-12 production; Hessle C et al.; Interaction of macrophages with bacteria is a stimulus for production of cytokines such as IL-10 and IL-12 . IL-12 stimulates T cell and natural killer (NK) cell cytotoxicity and interferon-gamma (IFN-gamma) production . IL-10 opposes the T cell-stimulating action of IL-12, decreases the release of proinflammatory cytokines from macrophages, and stimulates B cells . We have studied the capacity of human intestinal isolates from the three Lactobacillus species dominating on the human gastrointestinal mucosa, L . plantarum, L . rhamnosus and L . paracasei ssp . paracasei, to induce production of IL-10 and IL-12 from human blood mononuclear cells, or monocytes . Whole killed lactobacilli were potent stimulators of IL-12 over a wide range of bacterial concentrations . Lactobacillus paracasei gave the highest levels of IL-12 (1.5 ng/ml in response to 5 x 106 bacteria/ml), roughly 10 times more than obtained by stimulation with L . rhamnosus or L . plantarum . Escherichia coli induced on average < 50 pg/ml of IL-12 regardless of the bacterial concentration used . The secretion of free p40 subunit IL-12 followed the same pattern as the secretion of p70 (bioactive IL-12) with regard to the efficiency of different bacteria as stimulators . Escherichia coli was the most efficient trigger of IL-10 production, inducing 0.5 ng/ml IL-10 after stimulation with 5 x 106 bacteria/ml . Lactobacillus rhamnosus induced the highest levels of IL-10 among the lactobacilli (0.5 ng/ml) compared with 0.1 ng/ml evoked by L . plantarum or L . paracasei, but 10 times more bacteria were required for optimal stimulation than with E . coli . When neutralizing anti-IL-10 antibodies were added to the cultures, the IL-12-inducing capacity of L . rhamnosus was increased markedly, while that of E . coli remained low . The results show that mucosa-associated lactobacilli can be potent stimulators of IL-12, and thus potentially of cell-mediated immunity, if they pass over the gut epithelial barrier and interact with cells of the gut immune system.

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