Lactobacillus

Appl Environ Microbiol, 1997 May, 63(5), 1701 - 11
Sequence analysis and characterization of pOM1, a small cryptic plasmid from Butyrivibrio fibrisolvens, and its use in construction of a new family of cloning vectors for Butyrivibrios; Hefford MA et al.; As a preliminary step in the development of vector systems, we have isolated and begun to characterize small, cryptic plasmids from several strains of the rumen bacterium Butyrivibrio fibrisolvens . We present here the complete nucleotide sequence of Butyrivibrio plasmid pOM1, which was isolated from B . fibrisolvens Bu49 . While it is very similar in size to the previously characterized Butyrivibrio plasmids pRJF1 and pRJF2, pOM1 exhibits a restriction pattern which is quite distinct . Analysis of sequence data reveals that pOM1 contains only two open reading frames of significant length (ORF1 and ORF2), both of which are required for self-replication and maintenance . The protein encoded in ORF1 shows homologies with Pre (plasmid recombination enzyme) proteins encoded in plasmids from gram-positive organisms such as Staphylococcus aureus, Streptococcus agalactiae, Lactobacillus plantarum, and Bacillus thuringiensis . The putative translation product of ORF2, on the other hand, resembles Rep (replication) proteins of a different group of gram-positive plasmids, for which the Staphylococcus plasmid pSN2 is a prototype . Unlike the other characterized-Butyrivibrio plasmids, pOM1 appears to replicate via a rolling-circle mechanism . Experimental evidence showing the presence of a single-stranded replication intermediate consistent with this mechanism is presented . pOM1 has been used in the construction of a new Escherichia coli-B . fibrisolvens shuttle vector, pSMerm1, which has been successfully used to introduce a cloned gene into B . fibrisolvens harboring the pRJF1 plasmid.

J Bacteriol, 1997 May, 179(9), 3039 - 42
Cloning and characterization of cspL and cspP, two cold-inducible genes from Lactobacillus plantarum; Mayo B et al.; Two cold shock genes, cspL and cspP, have been cloned from two Lactobacillus plantarum strains . These genes, which are nonallelic, were present in all strains tested . The genes encode 66-amino-acid polypeptides related to each other and to the cold shock Csp family . Transcription of cspP rendered a single mRNA, while two cspL mRNAs were found with common 5' ends . The amounts of these transcripts increased moderately upon exposure of the cultures to cold.

Int J Food Microbiol, 1997 Apr 15, 35(3), 271 - 4
Microflora of Boza, a traditional fermented Turkish beverage; Hancioglu O et al.; Boza, a Turkish traditional beverage made by yeast and lactic acid fermentation of cooked maize, wheat and rice flours was prepared and the microbial characteristics were investigated . During the course of fermentation from 0 to 24 h, populations of lactic acid bacteria and yeast raised from 7.6 x 10(6) and 2.25 x 10(5) after inoculation to 4.6 x 10(8) and 8.1 x 10(6), respectively; pH dropped from 6.1 to 3.5; total titratable acidity by means of lactic acid increased from 0.02 to 0.27 mmol/g; alcohol content increased from 0.017% to 0.79% . Seventy seven isolates of lactic acid bacteria and 70 yeast isolates were identified . The lactic acid bacteria isolated during the fermentation included Leuconostoc paramesenteroides (25.6%), Lactobacillus sanfrancisco (21.9%), Leuconostoc mesenteroides subsp . mesenteroides (18.6%), Lactobacillus coryniformis (9.1%), L . confusus (7.8%), Leuconostoc mesenteroides subsp . dextranicum (7.3%), Lactobacillus fermentum (6.5%), Leuconostoc oenos (3.7%) . The yeasts isolated comprised Saccharomyces uvarum (83.0%) and S . cerevisiae (17.0%).

Int J Food Microbiol, 1997 Apr 15, 35(3), 259 - 65
The effect of electron beam irradiation, combined with acetic acid, on the survival and recovery of Escherichia coli and Lactobacillus curvatus; Fielding LM et al.; The preservation of food by ionising radiation may lead to undesirable sensory changes within the food . These changes can be reduced by combining irradiation with other treatments, for example the addition of organic acids . Late exponential phase cultures of Escherichia coli and Lactobacillus curvatus were irradiated, in a liquid medium, at doses of 0-1.8 kilograys (kGy), in the presence of acetic acid (0-2%) at pH 4.6 . A synergistic effect occurred when E . coli was irradiated in the presence of acetic acid (0.02-1.0%) at all doses used (0.145-1.1 kGy) . There is evidence to suggest that membrane disruption occurred in the cells as a result of the combined treatments and this may account, to some extent, for the synergism observed . The addition of acetic acid up to a concentration of 2.0% had no effect upon the radiation survival or upon the subsequent growth of L . curvatus.

Tidsskr Nor Laegeforen, 1997 Apr 10, 117(9), 1282 - 4
{Occurrence of bacterial vaginosis among abortion seekers}; Bjornerem A et al.; Bacterial vaginosis is the most common vaginal infection during the fertile period . The clinical diagnosis is based on three of Amsel's four criteria: thin, grey-white discharge, vaginal fluid pH above 4.5, a fishy odour on addition of 10% potassium hydroxide solution to the vaginal fluid, and the presence of clue cells on a saline wet mount . A probably more sensitive indicator of the diagnosis is based on Gram-stain, where the normal lactobacillus-dominated vaginal flora is changed to the lactobacillus deficient flora of bacterial vaginosis . The condition is probably associated with higher risk of complications in connection with pregnancy and gynaecological surgery . A prospective study of bacterial vaginosis based on microscopy of Gram-stained smears was conducted among 168 women applying for first trimester abortion . The prevalence of bacterial vaginosis was 24% and of Chlamydia trachomatis 8.4% . Four patients (10.3%) in the vaginosis group were treated with antibiotics for certain or suspected postabortal endometritis, as against six patients (5.4%) in the group without bacterial vaginosis.

J Mol Biol, 1997 Apr 4, 267(3), 640 - 60
Crystal structure of a ternary complex of D-2-hydroxyisocaproate dehydrogenase from Lactobacillus casei, NAD+ and 2-oxoisocaproate at 1.9 A resolution; Dengler U et al.; D-2-hydroxyisocaproate dehydrogenase (D-HicDH) from Lactobacillus casei is a homodimer with 333 amino acids and a molecular mass of 37 kDa per subunit . The enzyme belongs to the protein family of NAD+-dependent D-2-hydroxycarboxylate dehydrogenases and within this family to the subgroup of D-lactate dehydrogenases (D-LDHs) . Compared with other D-LDHs D-HicDH is characterized by a very low specificity regarding size and chemical constitution of the accepted D-2-hydroxycarboxylates . Hexagonal crystals of recombinant D-HicDH in the presence of NAD+ and 2-oxoisocaproate (4-methyl-2-oxopentanoate) were grown with ammonium sulphate as precipitating agent . The structure of these crystals was solved by molecular replacement and refined to a final R-factor of 19.6% for all measured X-ray reflections in the resolution range (infinity to 1.86 A) . Both NAD+ and 2-oxoisocaproate were identified in the electron density map; binding of the latter in the active site, however, competes with a sulphate ion, which is also defined by electron density . Additionally the final model contains 182 water molecules and a second sulphate ion . The binding of both an in vitro substrate and the natural cosubstrate in the active site provides substantial insight into the catalytic mechanism and allows us to assess previously published active site models for this enzyme family, in particular the two most controversial points, the role of the conserved Arg234 and substrate binding . Furthermore the overall topology and details of the D-HicDH structure are described, discussed against the background of homologous structures and compared with one closely and one distantly related protein.

Oral Microbiol Immunol, 1997 Apr, 12(2), 91 - 7
Inhibition of purified enolases from oral bacteria by fluoride; Guha-Chowdhury N et al.; Enolase activity in strains of oral streptococci previously has been found to be inhibited by 50% (Ki) by fluoride concentrations ranging from 50 to 300 microM or more in the presence of 0.5 to 1.0 mM inorganic phosphate ions . In this study, enolase was extracted and partly purified by a two-step process from five oral bacterial species and the effect of fluoride on the kinetics of enolase examined . The molecular weight of the putative enolase proteins was 46-48 kDa . The Vmax values ranged from 20 to 323 IU/mg and K(m) for glycerate-2-phosphate from 0.22 to 0.74 mM . Enolase activity was inhibited competitively by fluoride, with Ki values ranging from 16 to 54 microM in the presence of 5 mM inorganic phosphate ions . Ki values for phosphate ranged from 2 to 8 mM . The enolase from Streptococcus sanguis ATCC 10556 was more sensitive to fluoride (Ki = 16 +/- 2) than was enolase from Streptococcus salivarius ATCC 10575 (Ki = 19 +/- 2) or Streptococcus mutans NCTC 10449 (Ki = 40 +/- 4) and all three streptococcal strains were more sensitive to fluoride than either Actinomyces naeslundii WVU 627 (Ki = 46 +/- 6) or Lactobacillus rhamnosus ATCC 7469 (Ki = 54 +/- 6) enolases . The levels of fluoride found to inhibit the streptococcal enolases in this study are much lower than previously reported and are likely to be present in plaque, especially during acidogenesis, and could exert an anti-glycolytic effect.

J Public Health Dent, 1997 Spring, 57(2), 82 - 8
Do root lesions tend to develop in the same people who develop coronal lesions?
Beck JD, Drake CW.
OBJECTIVES: The three purposes of this study are to: (1) describe the relationship between the prevalence of coronal caries and root caries; (2) describe the relationship between the three-year incidence of coronal caries and root caries; and (3) if the two conditions are associated, develop a multiple regression model that identifies characteristics distinguishing people who had increments of both root caries and coronal caries from people who had increments of either coronal caries or root caries, or who had no new caries . METHODS: Dental examinations and interviews were conducted in the homes of a randomly selected, stratified sample of people over the age of 65 years in five North Carolina counties . The relationships between coronal and root D and DF were analyzed through contingency table analyses, and ordinal logistic regression was used to identify characteristics that differentiated people who had both coronal and root D over the three years from people who had either coronal or root D and people who had no new disease . RESULTS: Evidence of root and coronal caries in whites was much more likely to be in the form of fillings, while for blacks, it was more likely to be in the form of untreated decay . Prevalence rates of coronal and root D and DF were significantly associated for both blacks and whites . Incidence rates based on DF indicated that root and coronal caries were not associated in whites, but were associated in blacks . People more likely to experience both types of caries had more gingival recession at baseline, greater average attachment loss over the three years, and lactobacilli at baseline . In addition, the presence of Porphymonas gingivalis at three years was important for whites . CONCLUSIONS: It appears that coronal and root caries do tend to appear together in the same individuals, but fillings attenuate that relationship . The impact of dental treatment on the epidemiology of dental caries appears to be considerable and calls into question whether the F component of the caries index is related to disease as defined by epidemiologic criteria.

Community Dent Oral Epidemiol, 1997 Apr, 25(2), 165 - 9
On the pH-lowering potential of lactobacilli and mutans streptococci from dental plaque related to the prevalence of caries; Borgstrom MK et al.; The common method used today to identify persons at risk of dental caries is to estimate the numbers of cariogenic bacteria such as lactobacilli and mutans streptococci in saliva or plaque samples taken from the patient . However, the value of these bacterial counts for explaining and predicting individuals at risk of caries has not been powerful enough . Evaluating one virulence factor such as the acidogenicity of these bacteria might increase their explanatory values for caries . Sixty children aged 14-15 yrs participated in this study . Smooth surface caries and restorations were registered and total plaque samples collected . Counts of lactobacilli and mutans streptococci were estimated, and the pH-lowering potential of both bacteria was measured in an adapted glucose broth . The results showed a weak association between dental caries and lactobacilli, but in the subgroup with this bacterium the explanatory value increased to 14% and in the subgroup with a strong pH-lowering potential it was as high as 27% . For mutans streptococci the associations were weak in all groups.

Acta Odontol Scand, 1997 Apr, 55(2), 111 - 5
Oral sugar clearance and other caries-related factors in patients with myotonic dystrophy; Engvall M et al.; The aim of the investigation was to try to explain why patients with myotonic dystrophy (MD) have a high caries prevalence . Seventeen MD patients, 15 of whom had been examined 8 years earlier, and 17 matched, healthy controls participated . In connection with this follow-up examination, the oral sugar clearance was evaluated after chewing a glucose tablet . A paraffin-stimulated whole saliva sample was collected for determination of secretion rate, buffer capacity, and numbers of mutans streptococci and lactobacilli . Dietary score, plaque index, oral muscular coordination, and self-cleaning ability were also recorded . For all factors, the MD patients showed less favorable mean values than the controls; the differences between the groups were statistically significant, except for the bacterial counts and the salivary buffer capacity . Thus, the high caries prevalence in MD patients may be explained by longer oral sugar clearance time, lower salivary secretion rate, higher intake frequency of sugar-containing products, higher plaque index, and less pronounced oral muscular coordination and self-cleaning ability than in healthy individuals.

J Ind Microbiol Biotechnol, 1997 Apr, 18(4), 284 - 91
Use of virginiamycin to control the growth of lactic acid bacteria during alcohol fermentation; Hynes SH et al.; The antibiotic virginiamycin was investigated for its effects on growth and lactic acid production by seven strains of lactobacilli during the alcoholic fermentation of wheat mash by yeast . The lowest concentration of virginiamycin tested (0.5 mg Lactrol kg-1 mash), was effective against most of the lactic acid bacteria under study, but Lactobacillus plantarum was not significantly inhibited at this concentration . The use of virginiamycin prevented or reduced potential yield losses of up to 11% of the produced ethanol due to the growth and metabolism of lactobacilli . However, when the same concentration of virginiamycin was added to mash not inoculated with yeast, Lactobacillus rhamnosus and L . paracasei grew after an extensive lag of 48 h and L . plantarum grew after a similar lag even in the presence of 2 mg virginiamycin kg-1 mash . Results showed a variation in sensitivity to virginiamycin between the different strains tested and also a possible reduction in effectiveness of virginiamycin over prolonged incubation in wheat mash, especially in the absence of yeast.

J Ind Microbiol Biotechnol, 1997 Apr, 18(4), 272 - 7
Caroteno-protein and exopolysaccharide production by co-cultures of Rhodotorula glutinis and Lactobacillus helveticus; Frengova G et al.; The lactose-negative yeast Rhodotorula glutinis 22P and the homofermentative lactic acid bacterium Lactobacillus helveticus 12A were cultured together in a cheese whey ultrafiltrate containing 42 g L-1 lactose . The chemical composition of the caroteno-protein has been determined . The carotenoid and protein contents are 248 micrograms g-1 dry cells and 48.2% dry weight . Carotenoids produced by Rhodotorula glutinis 22P have been identified as beta-carotene 15%, torulene 10%, and torularhodin 69% . After separating the cell mass from the microbial association, the exopolysaccharides synthesized by Rhodotorula glutinis 22P were isolated from the supernatant medium in a yield of 9.2 g L-1 . The monosaccharide composition of the synthesized biopolymer was predominantly D-mannose (57.5%).

Eur J Oral Sci, 1997 Apr, 105(2), 162 - 9
Effects of frequent mouthrinses with palatinose and xylitol on dental plaque; Lingstrom P et al.; The aim was to evaluate the effects of frequent mouthrinses with palatinose, xylitol and a mixture of palatinose and xylitol on plaque pH, plaque formation and cariogenic microorganisms . 15 subjects refrained from toothbrushing during 3 test periods and rinsed 15 x daily for 4 d with 10 ml of: (1) 50% palatinose, (2) 37.5% palatinose + 12.5% xylitol, or (3) 50% xylitol . A contrast period with no mouthrinses was also carried out . The 4 periods were carried out in a randomized order with a cross-over design . After the 4-day periods, 3 parameters were measured: (1) plaque pH during the first 30 min after a mouthrinse with palatinose, a mixture of palatinose and xylitol or xylitol alone, directly followed by a 2nd rinse with 10% sucrose; (2) number of mutans streptococci and lactobacilli in plaque and saliva; (3) plaque index . The most pronounced pH drop for the sugar substitutes was found when rinsing with 50% palatinose after the palatinose period, and the least pH drop with 50% xylitol after the xylitol period . The sucrose rinse gave similar pH fall after all 4 periods . The microbial data showed no differences between the 4 periods, but the mutans streptococcus counts in saliva decreased after the xylitol period in contrast to the 3 other periods . Regarding the plaque index, xylitol gave lower scores compared to the other 3 periods.

J Pediatr Gastroenterol Nutr, 1997 Apr, 24(4), 399 - 404
Lactobacillus reuteri as a therapeutic agent in acute diarrhea in young children; Shornikova AV et al.; BACKGROUND: Certain strains of lactobacilli may promote recovery from acute diarrhea . Lactobacillus reuteri is of human origin and is a natural colonizer of gastrointestinal tract . In this trial, exogenously administered L . reuteri was studied as a therapeutic agent in acute diarrhea . METHODS: Forty patients between 6 and 36 months of age hospitalized with acute diarrhea (75% rotavirus) were studied . After parental consent, the patients were randomized to one of two treatment groups to receive either 10(10) to 10(11) colony-forming units of L . reuteri or a matching placebo daily for the length of hospitalization or up to 5 days . The clinical outcome of diarrhea and colonization of L . reuteri were evaluated . RESULTS: The mean (SD) duration of watery diarrhea after treatment was 1.7 (1.6) days in the L . reuteri group and 2.9 (2.3) days in the placebo group (p = 0.07) . On the second day of treatment only 26% of patients receiving L . reuteri had watery diarrhea, compared with 81% of those receiving placebo (p = 0.0005) . Cultures of lactobacilli from stool samples demonstrated that administration of L . reuteri resulted in colonization of the gastrointestinal tract . Lactobacillus reuteri accounted for > 75% of the total lactobacilli found in children fed with this product . CONCLUSIONS: Lactobacillus reuteri is effective as a therapeutic agent in acute rotavirus diarrhea in children . Further studies are warranted to confirm the present finding and to explore the full therapeutic potential of L . reuteri in acute viral diarrhea.

Clin Microbiol Rev, 1997 Apr, 10(2), 345 - 57
Management of listeriosis; Hof H et al.; Determination of the MIC in vitro is often used as the basis for predicting the clinical efficacy of antibiotics . Listeriae are uniformly susceptible in vitro to most common antibiotics except cephalosporins and fosfomycin . However, the clinical outcome is poor . This is partially because listeriae are refractory to the bactericidal mechanisms of many antibiotics, especially to ampicillin-amoxicillin, which still is regarded as the drug of choice . A true synergism can be achieved by adding gentamicin . Another point is that listeriae are able to reside and multiply within host cells, e.g., macrophages, hepatocytes, and neurons, where they are protected from antibiotics in the extracellular fluid . Only a few agents penetrate, accumulate, and reach the cytosol of host cells, where the listeriae are found . Furthermore, certain host cells may exclude antibiotics from any intracellular compartment . Thus, determination of the antibacterial efficacy of a drug against listeriae in cell cultures may be a better approximation of potential therapeutic value . Certain host cells may have acquired the property of excluding certain antibiotics, for example macrolides, from intracellular spaces, which might explain therapeutic failures of antibiotic therapy in spite of low MICs . Animal models do not completely imitate human listeriosis, which is characterized by meningitis, encephalitis, soft tissue and parenchymal infections, and bacteremia . Meningitis produced in rabbits is a hyperacute disease, whereby most listeriae lie extracellularly, fairly accessible to antibiotics that can cross the blood-cerebrospinal fluid barrier . In the murine model of systemic infection, Listeria monocytogenes is located mainly within macrophages and parenchymal cells of the spleen and liver, hardly accessible to certain drugs, such as ampicillin and gentimicin . The therapeutic efficacy of drugs clearly depends on the model used . Thus, for example, the combination of ampicillin with gentamicin acts synergistically in the rabbit meningitis model but not in the mouse model . Since conventional antimicrobial therapy with antibiotics is not satisfactory, particularly in the immunocompromised host (about 30% of patients with listeriosis die in spite of a rational choice of antibiotics), other possibilities must be considered for therapy as well as prevention . Indeed, listeriae are highly susceptible to several endogenous antibiotics, such as defensins . Bacteriocins produced by related bacterial species, e.g., lactobacilli and enterococci, are rapidly bactericidal . However, unfortunately, the use of such alternative measures along with immunization and immunmodulation is not yet feasible.

Sex Transm Dis, 1997 Apr, 24(4), 236 - 9
The use of sequential self-obtained vaginal smears for detecting changes in the vaginal flora; Schwebke JR et al.; BACKGROUND AND OBJECTIVES: The ability to study daily changes in the vaginal flora may provide insight into the pathogenesis of bacterial vaginosis . Because culture of the vaginal fluid is tedious and expensive, the utility of self-obtained vaginal smears for documenting changes in the flora was evaluated . GOALS: To validate the adequacy of self-collected vaginal fluid Gram stains and use them to monitor vaginal flora . STUDY DESIGN: Ten asymptomatic premenopausal women collected daily vaginal smears for 30 days . The smears were Gram stained and interpreted using a standardized scoring system (Nugent criteria) . In addition, results from self- and clinician-obtained vaginal smears from 18 women were compared to validate the adequacy of self-obtained smears . RESULTS: Two women had asymptomatic bacterial vaginosis . One woman, who was postpartum, had intermediate flora that toward the end of the collection period changed to Lactobacillus predominant . The remaining seven women exhibited two patterns . One was Lactobacillus morphotypes only; the second consisted of Lactobacillus-predominant days interspersed with days with moderate to high numbers of Gardnerella/Bacteroides morphotypes . There was a significant correlation of the point of change in the flora of this group with menses . CONCLUSIONS: The adequacy of self-collected vaginal fluid Gram's stains was validated . Changes in vaginal flora were demonstrated over a 30-day period by use of this methodology.

J Bacteriol, 1997 Apr, 179(8), 2697 - 706
Arginine biosynthesis and regulation in Lactobacillus plantarum: the carA gene and the argCJBDF cluster are divergently transcribed; Bringel F et al.; A cluster of citrulline biosynthetic genes has been cloned and sequenced from a fragment of Lactobacillus plantarum CCM 1904 (ATCC 8014) DNA isolated as complementing a Bacillus subtilis argF mutation . The gene order was carA-argCJBDF, with carA transcribed divergently from the arg cluster . Although other gram-positive bacteria show similar arg clusters, this arrangement for carA is thus far unprecedented . Downstream from the arg cluster, two open reading frames (ORF7 and ORF8) having unknown functions were found . Sequence analysis of the end of a 10.5-kb cloned DNA fragment showed that argF was 3.5 kb from the ldhL gene coding for L-(+)-lactate dehydrogenase . A tree representation of amino acid sequence clustering relationships of 31 ornithine carbamoyltransferases (OTCases) from various organisms revealed two prokaryotic groups: one with ArgF of L . plantarum and one with ArgF of B . subtilis, which are paralogous . This divergence was not observed in vivo because an L . plantarum argF mutant (AM 1215) harboring no OTCase activity was complemented by the argF genes of L . plantarum and B . subtilis . No OTCase activity was detectable when L . plantarum was grown in the presence of saturating amounts of arginine or citrulline . Arginine may repress the citrulline biosynthetic genes in L . plantarum by using 11 identified DNA motifs which resemble the Escherichia coli ARG box consensus and which are in most cases separated by multiples of 11 bp, corresponding to a DNA helical turn . The carA and argCJBDF genes are divergently transcribed . Their putative promoters are 6 bp apart and are partially overlapped by putative ARG boxes, suggesting concerted transcription regulation.

J Bacteriol, 1997 Apr, 179(8), 2472 - 8
Structure and regulation of expression of the Bacillus subtilis valyl-tRNA synthetase gene; Luo D et al.; We have sequenced the valyl-tRNA synthetase gene (valS) of Bacillus subtilis and found an open reading frame coding for a protein of 880 amino acids with a molar mass of 101,749 . The predicted amino acid sequence shares strong similarity with the valyl-tRNA synthetases from Bacillus stearothermophilus, Lactobacillus casei, and Escherichia coli . Extracts of B . subtilis strains overexpressing the valS gene on a plasmid have increased valyl-tRNA aminoacylation activity . Northern analysis shows that valS is cotranscribed with the folC gene (encoding folyl-polyglutamate synthetase) lying downstream . The 300-bp 5' noncoding region of the gene contains the characteristic regulatory elements, T box, "specifier codon" (GUC), and rho-independant transcription terminator of a gene family in gram-positive bacteria that encodes many aminoacyl-tRNA synthetases and some amino acid biosynthetic enzymes and that is regulated by tRNA-mediated antitermination . We have shown that valS expression is induced by valine limitation and that the specificity of induction can be switched to threonine by changing the GUC (Val) specifier triplet to ACC (Thr) . Overexpression of valS from a recombinant plasmid leads to autorepression of a valS-lacZ transcriptional fusion . Like induction by valine starvation, autoregulation of valS depends on the presence of the GUC specifier codon . Disruption of the valS gene was not lethal, suggesting the existence of a second gene, as is the case for both the thrS and the tyrS genes.

Appl Environ Microbiol, 1997 Apr, 63(4), 1284 - 7
Characterization of an intracellular oligopeptidase from Lactobacillus paracasei; Tobiassen RO et al.; An intracellular oligopeptidase from Lactobacillus paracasei Lc-01 has been purified to homogeneity by Fast Flow Q Sepharose, hydroxyapatite, and Mono Q chromatography . The molecular mass of the enzyme was determined to be 140 kDa by gel filtration and approximately 30 kDa by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and SDS-capillary electrophoresis . The pI of the enzyme was at pH 4.5 . The enzyme expressed maximum activity at pH 8.0 and 40 degrees C . Oligopeptidase activity on bradykinin was inhibited strongly by 1,10-phenantroline and EDTA and partly by p-chloromercuribenzoic acid but not by phosphoramidon or phenylmethylsulfonyl fluoride . Marked inhibition by beta-casein fragment 58 to 72 was demonstrated . The enzyme showed neither general aminopeptidase nor caseinolytic activity, and it degraded only oligopeptides between 8 and 13 amino acids . The enzyme readily hydrolyzed the Phe-Ser and Pro-Phe bonds of bradykinin; the Phe-His bond of angiotensin I; the Pro-Gln, Gln-Phe, and Phe-Gly bonds of substance P; and the Pro-Tyr bond of neurotensin . Weak activity toward the Ala-Tyr and Pro-Ser bonds of alpha(s1)-casein fragment 157 to 164, was observed . The N-terminal amino acid sequence of the oligopeptidase showed a high degree of homology to the lactacin B inducer from Lactobacillus acidophilus.

J Bacteriol, 1997 Apr, 179(7), 2459 - 63
Identification and characterization of IS1381, a new insertion sequence in Streptococcus pneumoniae; Sanchez-Beato AR et al.; A new insertion sequence (IS1381) was identified in the genome of Streptococcus pneumoniae R6 as an 846-bp segment containing 20-bp terminal inverted repeats and flanked by 7-bp direct repeats . The three sequenced copies of this element have two overlapping open reading frame (ORF) genes named orfA and orfB . However, significant variations between individual copies were found, suggesting that inactivating mutations have occurred in an original single ORF . Accordingly, the consensus IS1381 element derived from the comparison of the three available copies should contain a single ORF sufficient to encode a basic protein of 267 amino acids which exhibited high similarity to the putative transposases of ISL2 from Lactobacillus helveticus and of IS702 from the cyanobacterium Calothrix sp . strain PCC 7601 . A minimum of five to seven copies were detected by hybridization experiments in the R6 genome . In remarkable contrast with the two previously reported pneumococcal insertion sequences, several copies of IS1381 have been detected in all of the clinical isolates tested so far . Interestingly, Streptococcus oralis NCTC 11427 (type strain), a close relative of pneumococcus, does not contain this element, but its occurrence in the type strain of Streptococcus mitis (NCTC 12261) suggests that this species has exchanged DNA with S . pneumoniae directly or through an intermediate species.

Int J Food Microbiol, 1997 Mar 18, 35(1), 83 - 90
Processing and storage of lye-treated carrots fermented by a mixed starter culture; Montano A et al.; A mixed culture of Lactobacillus plantarum and Saccharomyces cerevisiae was compared with a single culture of L . plantarum as starter for the fermentation of lye-treated carrots . Using the mixed culture, more than 95% of glucose, fructose and malic acid was consumed after 7 days of fermentation in a brine containing 2.5% w/v NaCl and 0.7% acetic acid, but only 54% of sucrose was degraded . The fermentation products quantified were lactic acid, ethanol and acetic acid and carbon recovery was 88% . Using the single culture of L . plantarum, substrate consumption was lower, and carbon recovery almost 100% . In uninoculated lye-treated carrots, heterofermentative bacteria grew, with the production of considerable amounts of mannitol . In all cases, the stability, sensorial characteristics and carotenoid content of the packed product were studied during 9 months of storage at 30 degrees C, and two different preservation systems were compared: addition of preservatives, approximately 500 and 1000 mg/kg of sorbic and benzoic acid, respectively, and pasteurization at 80 degrees C for 10 min . The pasteurized samples were microbiologically stable during the storage period, while lactic acid bacteria grew in the samples with preservatives . Storage time significantly (P < 0.05) affected the texture and colour parameters (L*, a*, b*) of the carrots, but not the amounts of alpha- and beta-carotene . The type of fermentation had no significant effect on texture, colour parameters or carotenoid content . The preservation method had no significant effect on texture or carotenoid content, but did affect colour (parameter a*) . The flavour of carrots fermented by the mixed culture was significantly (P < 0.05) preferred to that of those fermented with a single culture of L . plantarum.

FEBS Lett, 1997 Mar 17, 405(1), 16 - 20
Correlated bond rotations in interactions of arginine residues with ligand carboxylate groups in protein ligand complexes; Nieto PM et al.; The 1H/15N HSQC NMR spectra of complexes of Lactobacillus casei dihydrofolate reductase containing methotrexate recorded at 1 degree C show four resolved signals for the four NH(eta) protons of the Arg57 residue . This is consistent with hindered rotation in the guanidino group resulting from interactions with the alpha-carboxylate of methotrexate . Increasing the temperature causes exchange line-broadening and coalescence of signals . Rotation rates for the N(epsilon)C(zeta) and C(zeta)N(eta) bonds have been calculated from lineshape analysis and from zz-HSQC exchange experiments . The interactions between the methotrexate alpha-carboxylate group and the Arg57 guanidino group decrease the rotation rates for the N(epsilon)C(zeta) bond by about a factor of 10 and those for the C(zeta)N(eta) bonds by more than a factor of 100 with respect to their values in free arginine . Furthermore, the relative rates of rotation about these two bonds are reversed in the protein complexes compared with their values in free arginine indicating that there are concerted rotations about the N(epsilon)C(zeta) bond of the Arg57 guanidino group and the C'C(alpha) bond of the glutamate alpha-carboxylate group of methotrexate.

FEMS Microbiol Lett, 1997 Mar 15, 148(2), 223 - 6
Identification of the replication region of the Lactobacillus acidophilus plasmid pLA106; Sano K et al.; The complete nucleotide sequence of plasmid pLA106 (2862 bp) from Lactobacillus acidophilus TK8912 was determined . Based on this sequence, the location of the genes for mobilization-plasmid recombination protein (mob), replication origin (ori), transcriptional repressor protein (repA) and replication initiation protein (repB) were predicted . Deletion analysis showed that the 1.4-kb PstI-EcoRV fragment carrying the ori, repA and repB genes is able to replicate in Lactobacillus and Escherichia coli cells . The plasmid pLA106 appears to have most features of the pLS1/pE194 plasmid family.

J Biol Chem, 1997 Mar 14, 272(11), 6890 - 7
cis-Active Ras G2-like sequence implicated in the heterotropic activation of the deoxyadenosine kinase of Lactobacillus acidophilus R-26; Guo S et al.; Deoxyadenosine kinase (dAK) forms a heterodimer with either deoxyguanosine kinase (dGK) or deoxycytidine kinase (dCK), and is heterotropically activated 3-5 times by dGuo or dCyd . Expressed alone, dAK is inactive and exhibits no response to dGuo or dCyd; activity and heterotropic response are fully restored upon reassociation with dGK or dCK . However, turnover of independently expressed dGK or dCK is nearly maximal, being further activated only 50-100% upon reassociation with dAK . In neither case is the heterotropic activation due to ligand-induced heterodimer formation . A proline/alanine substitution within a dAK segment homologous to loop G2 of Ras proteins yielded a heterodimer with dAK permanently cis-activated 2-fold, with a corresponding reduction in heterotropic activation by dGuo . A chimeric dAK, with 25% of its C terminus substituted by the homologous sequence from dGK, was inactive alone, and its characteristics were unchanged in the reconstituted heterodimer . Superimposing the Pro/Ala substitution on this chimera also reduced heterotropic activation by half . Cross-linking the dimer by 1,5-difluoro-2,4-dinitrobenzene was inhibited by ATP, dATP, dGTP, and dAdo, suggesting the proximity of the active site(s) to the interface . These data suggest that dAK depends on dGK or dCK in a manner resembling the reliance of Ras upon GTPase activating protein.

Gene, 1997 Mar 10, 187(1), 45 - 53
Genome structure of the Lactobacillus temperate phage phi g1e: the whole genome sequence and the putative promoter/repressor system; Kodaira KI et al.; The complete genome sequence of a Lactobacillus temperate phage phi g1e was established . The double-stranded DNA is composed of 42,259 bp, and encodes for sixty-two possible open reading frames (ORF) as well as several potential regulatory sequences . Based on comparative analysis with other related proteins of the Lactobacillus and Lactococcus phages as well as the Escherichia coli phages (such as lambda), functions were putatively assigned to several phi g1e ORFs: cng and cpg (encoding for repressors), hel (helicase), ntp (NTPase), and several ORFs (e.g., minor capsid proteins) . An about 1000-bp DNA region of phi g1e containing cpg and cng was inferred to function as a promoter/repressor system for the phi g1e lysogenic and lytic pathway.

J Mol Biol, 1997 Mar 7, 266(4), 776 - 96
Domain motions in dihydrofolate reductase: a molecular dynamics study; Verma CS et al.; Molecular dynamics simulations have been carried out on the enzyme dihydrofolate reductase from Lactobacillus casei complexed with methotrexate, NADPH and 264 crystallographic water molecules . Analysis of correlations in atomic fluctuations reveal the presence of highly correlated motion (correlation coefficient > 0.6) in the region between residues 30 to 35 and 85 to 90 leading to the identification of two domains, an "adenosine-binding domain" and a "large domain", which rotate by 3 to 4 degrees with respect to each other . The strongest correlation (> 0.6) within the large domain involves a coupling between the motions of the "teen-loop", and the spatially contiguous loops linking beta 6-beta 7 and beta 7-beta 8 . Moreover, there is a significant correlation (approximately 0.5) between the adenosine fragment of NADPH and the pteridine and p-aminobenzoyl fragments of methotrexate, which are separated by approximately 17 A, and is lost on removal of "rigid-body" motion from the original trajectory . This provides support for the idea that the relative motion of the two domains is a means by which the occupation of the binding site for the adenosine end of the coenzyme can affect methotrexate binding and vice versa . Quasiharmonic vibrational analysis of the trajectory reveals that the overall dynamics of the system are governed by domain motions whose contributions are dominant at low frequencies . In addition, different low-frequency modes are responsible for separately coupling the adenosine-binding site and parts of methotrexate.

Int J Food Microbiol, 1997 Mar 3, 34(3), 249 - 58
Munkoyo beverage, a traditional Zambian fermented maize gruel using Rhynchosia root as amylase source; Zulu RM et al.; A typical munkoyo beverage was made by fermenting Rhynchosia heterophylla root extract-cooked maize meal mixture with Lactobacillus confusus LZI and Saccharomyces cerevisiae YZ20 . The fermented munkoyo beverage had a pH of 3.3, lactic acid content of 60 mmol/l, ethanol 320-410 mmol/l and a characteristic 'munkoyo' aroma . L . confusus, used alone, produced a beverage with a faint munkoyo flavour note whilst beverage produced with S . cerevisiae alone seemed not to have a typical munkoyo note . R . heterophylla root extract converted 75% of the starch in sterile cooked maize meat to maltose (80% of total sugars), maltotriose (17%) and glucose (3%) in I h at 45 degrees C . During fermentation by the mixed culture or the yeast alone most of the maltose was utilised but little or none of the maltotriose . The ratio of yeast to lactic acid bacteria in the starter culture affected the rate of production of ethanol but had no effect on the growth or acid production by the bacterium . To obtain a munkoyo beverage with the desired low alcohol concentration (< 100 mmol/l), the ratio of yeast concentration (cfu/ml) to Lactobacillus concentration in the starter culture should be 1:1000 or less and the beverage should be fermented for 24 h only.

Protein Eng, 1997 Mar, 10(3), 255 - 62
Modified substrate specificity of L-hydroxyisocaproate dehydrogenase derived from structure-based protein engineering; Feil IK et al.; L-2-Hydroxyisocaproate dehydrogenase (L-HicDH) is characterized by a broad substrate specificity and utilizes a wide range of 2-oxo acids branched at the C4 atom . Modifications have been made to the sequence of the NAD(H)-dependent L-HicDH from Lactobacillus confusus in order to define and alter the region of substrate specificity towards various 2-oxocarbonic acids . All variations were based on a 3D-structure model of the enzyme using the X-ray coordinates of the functionally related L-lactate dehydrogenase (L-LDH) from dogfish as a template . This protein displays only 23% sequence identity to L-HicDH . The active site of L-HicDH was modelled by homology to the L-LDH based on the conservation of catalytically essential residues . Substitutions of the active site residues Gly234, Gly235, Phe236, Leu239 and Thr245 were made in order to identify their unique participation in substrate recognition and orientation . The kinetic properties of the L239A, L239M, L236V and T245A enzyme variants confirmed the structural model of the active site of L-HicDH . The substrates 2-oxocaproate, 2-oxoisocaproate, phenylpyruvate, phenylglyoxylate, keto-tert-leucine and pyruvate were fitted into the active site of the subsequently refined model . In order to design dehydrogenases with an improved substrate specificity towards keto acids branched at C3 or C4, amino acid substitutions at positions Leu239, Phe236 and Thr245 were introduced and resulted in mutant enzymes with completely different substrate specificities . The substitution T245A resulted in a relative shift of substrate specificity for keto-tert-leucine of more than 17000 compared with the 2-oxocaproate (kcat/KM) . For the substrates branched at C4 a relative shift of up to 500 was obtained for several enzyme variants . A total of nine mutations were introduced and the kinetic data for the set of six substrates were determined for each of the resulting mutant enzymes . These were compared with those of the wild-type enzyme and rationalized by the active site model of L-HicDH . An analysis of the enzyme variants provided new insight into the residues involved in substrate binding and residues of importance for the differences between LDHs and HicDH . After the protein design project was complete the X-ray structure of the enzyme was solved in our group . A comparison between the model and the experimental 3D structure proved the quality of the model . All the variants were designed, expressed and tested before the 3D structure became available.

J Acquir Immune Defic Syndr Hum Retrovirol, 1997 Mar 1, 14(3), 213 - 8
A placebo-controlled, double-blind prospective study in healthy female volunteers of dextrin sulphate gel: a novel potential intravaginal virucide; Stafford MK et al.; A double-blind, placebo-controlled study was designed to evaluate the safety and tolerability of intravaginal dextrin sulphate (D2S) gel to assess its preliminary suitability as a potential vaginal virucide . Tolerability was assessed by questionnaire and patient interview . Colposcopy with vaginal biopsy was performed to assess the macroscopic and microscopic evidence of inflammation . The potential impact of the gel on normal vaginal flora was examined by quantitative lactobacilli culture with assessment of the ratio of peroxide to nonperoxide-producing organisms . Colposcopy revealed mild erythema in five of 24 subjects receiving active gel and in none of the 12 placebo recipients, but histology in all subjects revealed no evidence of inflammation . No impact on vaginal lactobacilli was found . We conclude that D2S gel is safe and well tolerated intravaginally at the dosing schedule used in this study.

J Dent Res, 1997 Mar, 76(3), 768 - 72
Incorporation of antibacterial monomer MDPB into dentin primer; Imazato S et al.; The polymerizable monomer methacryloyloxydodecylpyridinium bromide (MDPB) shows antibacterial activity when immobilized in a resin-based material . In this study, the antibacterial effect of a dentin primer incorporating MDPB was investigated . The influence of incorporation of MDPB on bond strength to dentin and on the curing performance of the adhesive system was also evaluated . Experimental primers were prepared by addition of MDPB into a proprietary primer at 1, 2, or 5% . Antibacterial effects of experimental primers were compared with those of control primer and two other proprietary primers by an agar disc-diffusion method and bactericidal activity test . Experimental primers produced greater inhibition zones against Streptococcus mutans, Actinomyces viscosus, and Lactobacillus casei than any of three proprietary primers, and inhibition increased as the concentration of MDPB was increased . Bactericidal activity of MDPB-containing primers against Streptococcus mutans was greater than those of the other three primers, with incorporation of MDPB at 5% showing complete killing of bacteria after 30 s contact . No decrease in tensile bond strength was observed for materials containing MDPB . On the contrary, the primer incorporating 1 and 2% MDPB showed higher bond strength than all the others, including the control (p < 0.05) . When the degree of conversion of the complex of primer and adhesive resin was determined with Fourier Transform Infrared Spectroscopy, there were no significant differences between any of the experimental primers and the control (p > 0.05) . These results indicate that incorporation of the antibacterial monomer MDPB enhanced the antibacterial effect of a proprietary dentin primer before curing, and had no adverse influence on bond strength to dentin and curing of the adhesive system.

Lett Appl Microbiol, 1997 Mar, 24(3), 180 - 4
A zinc-dependent proteinase from the cell wall of Lactobacillus delbrueckii subsp . bulgaricus; Stefanitsi D et al.; A zinc-dependent proteinase was extracted from the cell wall of Lactobacillus delbrueckii subsp . bulgaricus and partially purified despite a marked unstability . The caseinolytic activity was associated with a polypeptide chain of 65 kDa that belonged to the M1 family of zinc-dependent proteases . This zinc-dependent proteinase could degrade intact caseins, with a significant preference for beta-casein . The pH-profile of its activity indicated that its relative contribution to the caseinolytic activity increased at acidic pH, suggesting that this zinc proteinase could be involved in the late stages of milk fermentation.

Lett Appl Microbiol, 1997 Mar, 24(3), 153 - 8
Incorporation of nisin in micro-particles of calcium alginate; Wan J et al.; Nisin was successfully incorporated into a matrix of calcium alginate and ground into micro-particles smaller than 150 microns . Formation of micro-particles and incorporation of nisin was verified by scanning electron microscopy and by the reduction in the inactivation of nisin activity with proteolytic enzymes . Incorporation efficiency was 87-93% and the nisin in the alginate-incorporated form was 100% active against an indicator culture of Lactobacillus curvatus both in MRS broth and reconstituted skim milk.

Poult Sci, 1997 Mar, 76(3), 463 - 8
Counteracting Fusarium proliferatum toxicity in broiler chicks by supplementing drinking water with Poultry Aid Plus; Wu W; To test whether Poultry Aid Plus (PAP, a commercial product for drinking water application) could reduce the stress on broiler chicks caused by Fusarium proliferatum contamination of feed, water (with or without PAP application, according to the manufacturer's instructions), and feed (experimentally infected with F . proliferatum fermented and dried corn culture material, CM) were provided to broiler chicks for 3 wk . Eight treatments consisting of a 2 (with or without PAP in water) x 4 (0, 1, 2, and 4% CM in feed) factorial design were tested in four replicate cages of six chicks each . The diet with 2% CM reduced weight gain by 23%; this reduction was preventable by PAP water application . The diet with 4% CM caused a cumulative mortality of 87.5%, which was reduced by PAP water application to 50% . The population half-life of the chicks on the diet with 4% CM was 6.5 d; this half-life was prolonged to at least 21 d by PAP water application . The PAP application also reduced the relative weight of the small intestine and promoted Lactobacillus colonization of the large intestine regardless of the level of CM in feed . Therefore, water application of PAP can be a prophylactic measure for F . proliferatum toxicity in poultry production.

FEMS Microbiol Lett, 1997 Mar 1, 148(1), 97 - 100
Isolation and partial characterization of bacteriocins produced by Lactobacillus gasseri JCM 2124; Tahara T et al.; Four antibacterially active peptides (B1 to B4) were purified from the culture broth of L . gasseri JCM 2124 . The B2 peptide (gassericin B2) was determined to be 4400 Da by mass spectrometry and partially sequenced . Gassericin B2 did not show any sequence similarities to other known bacteriocins . The B1 and B3 peptides shared identical sequences with two peptides of a two-component bacteriocin from Lactobacillus acidophilus . However, synergistic activity upon complementation of B1 and B3 was not observed . Based on amino acid sequencing and molecular mass, it is suggested that B1 and B4 peptides were derived from B3 (gassericin B3).

FEMS Microbiol Lett, 1997 Mar 1, 148(1), 83 - 9
Establishing a model to study the regulation of the lactose operon in Lactobacillus casei; Gosalbes MJ et al.; The chromosomally encoded lactose-specific phosphoenol pyruvate-dependent phosphotransferase system (PTS) has been investigated in Lactobacillus casei ATCC 393 {pLZ15-} and it was considered an excellent system to study the regulation of the lactose operon . This chromosomal operon has been cloned and sequenced, being 99% homologous to that encoded on the plasmid pLZ64 . Expression of the lactose operon in different mutants of L . casei ATCC 393 {pLZ15-} and primer extension analysis revealed that it is subject to a dual regulation: (i) glucose repression possibly mediated by CcpA and PTS elements, and (ii) induction by lactose through transcriptional antitermination.

Curr Microbiol, 1997 Mar, 34(3), 186 - 91
Purification of glucoamylase from Lactobacillus amylovorus ATCC 33621; James JA et al.; An intracellular glucoamylase (E.C . 3.2.1.3) was purified to homogeneity from Lactobacillus amylovorus on a Fast Protein liquid chromatography System (FPLC) with a Mono Q ion-exchanger and two Superose 12 gel filtration columns arranged in series . The enzyme activity was quantified with a specific, chromogenic substrate, p-nitrophenyl-beta-maltoside.Preparative gel electrophoresis was then used to further purify active enzyme fractions . Native polyacrylamide gel electrophoresis (Native-PAGE) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the purified enzyme showed a single protein band of molecular weight 47 kDa . Glucoamylase activity of the purified protein was confirmed by its ability to degrade starch on a 0.025% starch-polyacrylamide gel stained with I2/KI . Glucoamylase exhibited optimum catalytic activity at pH 6.0 and 45 degrees C, and the enzyme had an isoelectric point near 4.39 . The glucoamylase contained high levels of hydrophilic amino acids, comparable to fungal glucoamylases.

Curr Microbiol, 1997 Mar, 34(3), 180 - 5
Lactobacillus helveticus: strain typing and genome size estimation by pulsed field gel electrophoresis; Lortal S et al.; Genomic DNAs of 22 strains of Lactobacillus helveticus of various geographical origins were analyzed by pulsed-field gel electrophoresis . Two endonucleases, SmaI and SgrAI, of the 19 tested produced DNA fragments useful for strain comparison . With the endonuclease SmaI, a characteristic restriction pattern was identified for 18 of the 22 strains . The percentage of similarity (Dice coefficient) between the profiles varied between 26% and 100%, and clustering was accomplished by using the unweighted pair group method with arithmetic averages (UPGMA) . For the strains showing identical profiles,the high genomic similarity was confirmed when the endonuclease SgrAI was used instead of SmaI . From summation of SmaI and SgrAI fragments from three L . helveticus strains(CNRZ 241, CNRZ 303, and CIP 57.15), the genomic length was estimated at ca.1 . 85-2.0 Mb.

Curr Microbiol, 1997 Mar, 34(3), 173 - 9
Purification and partial amino acid sequence of brevicin 27, a bacteriocin produced by Lactobacillus brevis SB27; Benoit V et al.; Brevicin 27, a bacteriocin produced by Lacto bacillus brevis SB27, is inhibitory mainly against closely related Lactobacillus brevis and Lactobacillus buchneri strains . It was purified from the culture supernatant by a four-step purification procedure including ammonium sulfate precipitation, cation exchange, hydrophobic interaction, and reverse-phase, high performance liquid chromatographies . The purified bacteriocin was subjected to mass spectrometry, amino acid composition analysis, and sequencing by Edman degradation . It was shown to be an about 5200-Da basic protein containing a high proportion of lysine and of hydrophobic amino acids . The partial N-terminal amino acid sequence (25 residues) was unique when compared with the Protein Data Bank (PDB), Swiss Prot, and Protein Information Resource(PIR) data banks and to the translated Gen Bank.

Gene, 1997 Feb 28, 186(2), 255 - 62
High level heterologous protein production in Lactococcus and Lactobacillus using a new secretion system based on the Lactobacillus brevis S-layer signals; Savijoki K et al.; A secretion cassette, based on the expression and secretion signals of a S-layer protein (SlpA) from Lactobacillus brevis, was constructed . E . coli beta-lactamase (Bla) was used as the reporter protein to determine the functionality of the S-layer signals for heterologous expression and secretion in Lactococcus lactis, Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus gasseri and Lactobacillus casei using a low-copy-number plasmid derived from pGK12 . In all hosts tested, the bla gene was expressed under the slpA signals and all Bla activity was secreted to the culture medium . The Lb . brevis S-layer promoters were very efficiently recognized in L . lactis, Lb . brevis and Lb . plantarum, whereas in Lb . gasseri the slpA promoter region appeared to be recognized at a lower level and in Lb . casei the level of transcripts was below the detection limit . The production of Bla was mainly restricted to the exponential phase of growth . The highest yield of Bla was obtained with L . lactis and Lb . brevis . Without pH control, substantial degradation of Bla occurred during prolonged cultivations with all lactic acid bacteria (LAB) tested . When growing L . lactis and Lb . brevis under pH control, the Bla activity could be stabilized also at the stationary phase . L . lactis produced up to 80 mg/l of Bla which to our knowledge represents the highest amount of a heterologous protein secreted by LAB so far . The short production phase implied a very high rate of secretion with a calculated value of 5 x 10(5) Bla molecules/cell per h . Such a high rate was also observed with Lb . plantarum, whereas in Lb . brevis the competition between the wild type slpA gene and the secretion construct probably lowered the rate of Bla production . The results obtained indicate wide applicability of the Lb . brevis slpA signals for efficient protein production and secretion in LAB.

Mol Gen Genet, 1997 Feb 27, 253(6), 674 - 86
Organization and expression of a gene cluster involved in the biosynthesis of the lantibiotic lactocin S; Skaugen M et al.; Some 8.8 kb of the Lactobacillus sake plasmid pCIM1 was sequenced, revealing eight tightly clustered open reading frames (ORFs) downstream from lasA, which encodes pre-lactocin S . Transcription analyses demonstrated that the genes are expressed as an operon, with transcription initiating upstream of lasA and terminating immediately 3' to the ninth ORF x lasA is also represented by two small RNAs (RNAI and RNAII) which differ in size by approximately 90 nucleotides, and primer extension experiments demonstrated a corresponding difference in the 5' termini . A palindromie sequence constitutes the 3' terminus of both RNAI and RNAII, and we propose that this sequence has a dual regulatory function in controlling the expression of las operon, acting both as a barrier to 3'-5' exonuclease degradation of the lasA-specific transcript(s), and as a "leaky" transcriptional terminator which limits the expression of down-stream genes . Three of the genes in the las operon have identifiable counterparts in other lantibiotic systems: lasM is likely to be involved in prepeptide modification, lasT, which encodes an ATP-dependent transport protein, is probably involved in the secretion of lactocin S, while lasP specifies a subtilisin-type serine protease which may be the lactocin S leader peptidase . Insertional mutation of either lasT or lasM by the resident transposable element IS1163 abolishes lactocin S production . The remaining five ORFs in the las operon are apparently unique, and their significance with respect to the lactocin S phenotype is presently not known.

Eur J Biochem, 1997 Feb 15, 244(1), 213 - 9
D-2-hydroxy-4-methylvalerate dehydrogenase from Lactobacillus delbrueckii subsp . bulgaricus . II . Mutagenic analysis of catalytically important residues; Bernard N et al.; Five residues involved in catalysis and coenzyme binding have been identified in D-2-hydroxy-4-methylvalerate dehydrogenase from Lactobacillus delbrueckii subsp . bulgaricus by using biochemical and genetical methods . Enzyme inactivation with diethylpyrocarbonate indicated that a single histidine residue was involved in catalysis . Since H296 is the only conserved histidine in the whole family of NAD-dependent D-2-hydroxyacid dehydrogenases, we constructed the H296Q and H296S mutants and showed that their catalytic efficiencies were reduced 10(5)-fold compared with the wild-type enzyme . This low residual activity was shown to be insensitive to diethylpyrocarbonate . Taken together these data demonstrate that H296 is responsible for proton exchange in the redox reaction . Two acidic residues (D259 and E264) were candidates for maintaining H296 in the protonated state and their roles were examined by mutagenesis . The D259N and E264Q mutant enzymes both showed similar and large reductions in their Kcat/K(m) ratios (200-800-fold, depending on pH), indicating that either D259 or E264 (or both) could partner H296 . The conserved R235 residue was a candidate for binding the alpha-carboxyl group of the substrate and it was changed to lysine . The R235K mutant showed a 104-fold reduced Kcat/K(m) due to both an increased K(m) and a reduced Kcat for 2-oxo-4-methylvalerate . Thus R235 plays a role in binding the substrate carboxylate similar to R171 in the L-lactate dehydrogenases . Finally, we constructed the H205Q mutant to test the role of this partially conserved histidine residue (in 10/13 enzymes of the family) . This mutant enzyme displayed a 7.7-fold increased Kcat and a doubled catalytic efficiency at pH 5, was as sensitive to diethylpyrocarbonate as the wild-type but showed a sevenfold increased K(m) for NADH and a 100-fold increase in Kd for NADH together with 10-30-fold lower substrate inhibition . The transient kinetic behaviour of the H205Q mutant is as predicted from our previous study on the enzymatic mechanism of D-2-hydroxy-4-methylvalerate dehydrogenase which showed that coenzyme binding is highly pH dependent and indicated that release of the oxidised coenzyme is a significant component of the rate-limiting processes in catalysis at pH 6.5.

Eur J Biochem, 1997 Feb 15, 244(1), 203 - 12
D-2-hydroxy-4-methylvalerate dehydrogenase from Lactobacillus delbrueckii subsp . bulgaricus . I . Kinetic mechanism and pH dependence of kinetic parameters, coenzyme binding and substrate inhibition; Alvarez JA et al.; The steady-state kinetics of D-2-hydroxy-4-methylvalerate dehydrogenase have been studied at pH 8.0 by initial velocity, product inhibition, and dead-end inhibition techniques . The mechanism is rapid-equilibrium ordered in the NAD+ plus D-2-hydroxy-4-methylvalerate direction, and steady-state ordered in the other direction . In both cases coenzyme is the first substrate added and both the E-NADH-D-2-hydroxy-4-methylvalerate and E-NAD+-2-oxo-4-methylvalerate give rise to abortive complexes which cause excess substrate inhibition . Steady-state measurements show that the rate-limiting step in both directions at pH 8.0 is between formation of the enzyme-coenzyme-substrate ternary complex and the release of the first product of the reaction . Transient kinetics combined with primary kinetic deuterium isotope effects show that in the NADH-->NAD+ direction there is a slow, rate-limiting rearrangement of the E-NADH-oxoacid complex while hydride transfer is very fast . The release of NAD+ at pH 8.0 is 200-times faster than Kcat (NADH-->NAD+) whereas the release of NADH is only 5-times faster than Kcat (NAD+-->NADH) . The pH dependence of NADH binding depends upon the presence of two ionizable residues with a pKa of about 5.9 . The pH dependence of kinetic parameters is explained by a third ionizable residue with pKa values 7.2 (in the E-NADH complex) and < or = 6.4 (in the E-NAD+ complex) which may be the proton donor and acceptor for the chemical reaction . At pH 6.5 the mechanism changes in the NADH-->NAD+ direction to be partly limited by the chemical step with a measured primary kinetic isotope effect of 5.7 and partly by an only slightly faster dissociation of NAD+ . In addition the inhibition by excess oxo-4-methylvalerate is more pronounced . The mechanism implies that removing the positive charges created by the two groups which control coenzyme affinity could both enhance the catalytic rate at pH 6.5 and diminish excess substrate inhibition to provide an enzyme better suited to the bulk synthesis of D-2-hydroxyacids.

FEBS Lett, 1997 Feb 3, 402(2-3), 157 - 61
The influence of aspartate 26 on the tautomeric forms of folate bound to Lactobacillus casei dihydrofolate reductase; Birdsall B et al.; The ternary complex of Lactobacillus casei dihydrofolate reductase (DHFR) with folate and NADP+ exists as a mixture of three interconverting forms (I, IIa and IIb) whose relative populations are pH dependent, with an effective pK of approx . 6 . To investigate the role of Asp26 in this pH dependence we have measured the 13C chemical shifts of {2,4a,7,9-(13)C4}folate in its complex with the mutant DHFR Asp26 --> Asn and NADP+ . Only a single form of the complex is detected and this has the characteristics of form I, an enol form with its N1 unprotonated . A study of the pH dependence of the 13C chemical shifts of DHFR selectively labelled with {4-(13)C}aspartic acid in its complex with folate and NADP+ indicates that no Asp residue has a pK value greater than 5.4 . Two of the Asp CO2 signals appear as non-integral signals with chemical shifts typical of non-ionised COOH groups and with a pH dependence characteristic of the slow exchange equilibria previously characterised for signals in forms I and IIb (or IIa) . It is proposed that the protonation/deprotonation controlling the equilibria involves the O4 position of the folate and that Asp26 influences this indirectly by binding in its CO2 form to the protonated N1 group of folate in forms I and IIa thus reducing the pK involving protonation at the O4 position to approx . 6 . These findings indicate that, in forms I and IIa of the ternary complex, folate binds to DHFR in a very similar way to methotrexate.

Arch Oral Biol, 1997 Feb, 42(2), 181 - 4
Interindividual differences in degradation of sodium monofluorophosphate by saliva in relation to oral health status; Klimek J et al.; The enzymatic degradation of sodium monofluorophosphate by whole saliva in patients with differing oral health status was compared Ten patients each with good or poor oral health were selected . Assessment of oral health status included indices of the amount of dental plaque, caries experience and counts of Streptococcus mutans and lactobacilli . Whole-saliva samples were collected under standardized conditions and monofluorophosphatase (MFPase) activity was measured in 2-ml saliva samples during 2 h of incubation at 37 C with 1 ml of monofluorophosphate solution (equivalent 31.5 mmol/1 F) . MFPase activity was found in all the saliva samples . The values ranged from 0.6 to 17.8 nmol F/ml saliva per min . High MFPase activities correlated well with large amounts of plaque with the D component of the DMFT index and with high counts of salivary S . mutans and lactobacilli . The results show a wide range of MFPase activity in individuals and a statistically significant correlation (p < 0.05) between high MFPase activity and poor oral health status.

Nahrung, 1997 Feb, 41(1), 18 - 21
Effect of bacterial galactosidase treatment on the nutritional status of soybean seeds and its milk derivative; Sanni AI et al.; Four field strains of Lactobacillus plantarum (LS 4, 19, 21, 133) obtained from fufu (a semi-solid product obtained by boiling fermented cassava--Manihot esculenta Crantz) and a type strain DSM 2017 were grown on different carbon sources to induce galactosidase production . LS 21 produced the highest concentration of alpha- and beta-galactosidase with 0.28 mumol/l and 0.28 mumol/l respectively on lactose and galactose . Milk obtained from soybean seeds treated with the enzyme mixture for 24 h showed a 99, 98 and 96% reduction respectively in the raffinose, stachyose and sucrose content when compared with the dry soybean seed . Glucose and galactose which were not detected in the dry seeds became readily available after soaking in both enzyme mixture and distilled water . Although there was reduction in the nutritional composition of both milk samples, reduction of phytic acid and trypsin inhibitor is beneficial to the consumers . The result of the sensory evaluation showed that the milk prepared from enzyme-treated soybean seeds was rated better in terms of flavour, texture, appearance and palatability.

J Pediatr Gastroenterol Nutr, 1997 Feb, 24(2), 153 - 61
Enteral nutrition modifies gut-associated lymphoid tissue in rat regardless of the molecular form of nitrogen supply; Guihot G et al.; BACKGROUND: It has been suggested that beneficial effect of elemental enteral diets in the treatment of inflammatory bowel diseases could be mediated by the suppression of protein dietary antigens . The objective of the present work was to study the effect of enteral diet on gut associated lymphoid tissue and on gastric Lactobacillus flora, in rat . METHODS: The effects of three molecular forms of nitrogen supply: amino acids, oligopeptides or whole casein, were compared in rats on continuous enteral diet . Frozen sections of small bowel were studied with monoclonal antibodies anti-CD5, -CD4, -CD8, -CD25, -macrophages, -MHC II . The Lactobacillus flora was also enumerated in the stomach, in order to assess the effect of ED on rat flora . RESULTS: Growth and mucosa morphology were identical in control and enteral groups . Rats on enteral diet showed, whatever was the molecular form of nitrogen supply, a decrease in CD5+, CD4+ and CD8+ intraepithelial cell numbers, but not in lamina propria cell number, and a decreased MHC II epithelial expression, when compared to control rats . The enterally fed rats also showed a decrease in Lactobacillus gastric contents . CONCLUSIONS: The current study demonstrates that continuous enteral nutrition modifies MHC II epithelial expression and gut associated lymphoid tissue cell number in rat, whatever is the molecular form of nitrogen supply . Intestinal flora could be responsible, at least for part, for these results.

Microbiol Res, 1997 Feb, 152(1), 87 - 92
Quantitation by enzyme immunoassay of spirosin from Lactobacillus reuteri and Escherichia coli; Yamato M et al.; Three EIA methods (Direct, Indirect and Sandwich EIA) were studied to quantify spirosin in Lactobacillus reuteri and Escherichia coli cultured under various conditions in an attempt to get some insight into the function of spirosome . Both Direct and Indirect EIA were suited well for the quantitation of L . reuteri spirosin while Direct EIA was appropriate for spirosin of E . coli . Sandwich EIA could not be applied successfully in either case . By use of these methods, the amounts of spirosin produced by E . coli were determined to be 1.4, 36.2 and 46.5 micrograms per mg protein of the cell lysate under aerobic, standing and anaerobic culture conditions, respectively . Since the production profile of spirosin coincided entirely with that of alcohol dehydrogenase, these findings supported the identity of spirosin to alcohol dehydrogenase in E . coli . In the same way, L . reuteri spirosin was quantified to be 73.5 and 65.4 micrograms/ mg protein of the lysate in standing and anaerobic culture, respectively . The production pattern of spirosin did not parallel that of alcohol dehydrogenase among three strains of L . reuteri, suggesting that spirosin might not be identical to alcohol dehydrogenase.

Can J Microbiol, 1997 Feb, 43(2), 157 - 63
A specific oligonucleotide primer for the rapid detection of Lactobacillus lindneri by polymerase chain reaction; Yasui T et al.; A polymerase chain reaction (PCR) method was developed for the rapid detection of the beer-spoilage heterofermentative lactic acid bacterium Lactobacillus lindneri . Three strains, the Chinese brewery isolate DA1, the Japanese commercial beer isolate BG2, and the Japanese brewery isolate SE3, which were serologically classified as belonging to L . lindneri, were used in this study . After sequencing the 16S rDNA of the isolates DA1 and BG2 and the typical beer-spoilage heterofermentative Lactobacillus brevis L63, these sequences were compared with published data . A L . lindneri specific PCR primer, DA-40, was then constructed based on the V1 variable region of 16S rDNA . The specificity of PCR using the L . lindneri specific primer DA-40 and the universal primer 907r was examined using five L . lidneri strains: the three isolates described above and two strains from culture collection, DSM 20690 and DSM 20692 . A variety of beer-spoilage lactic acid bacteria, including 71 Lactobacillus strains and 13 Pediococcus strains, were also included in this examination . No PCR product was obtained from any DNA with the exception of the five L . lindneri strains, indicating that the L . lindneri specific primer DA-40 was highly specific . The detection limit for L . lindneri in beer was 63 CFU/100 mL of beer.

Can J Microbiol, 1997 Feb, 43(2), 143 - 8
Rapid procedure for acid adaptation of oral lactic-acid bacteria and further characterization of the response; Ma Y et al.; Acid-adaptive responses could be induced readily in oral lactic-acid bacteria by growing them in batch cultures with excess sugar or more conveniently and rapidly by transferring cells to acidified growth media for the time required for biomass doubling . The response of Streptococcus mutans GS-5 was induced in a progressive rather than all-or-nothing way, and the extent of acid tolerance was inversely related to the pH of the inducing medium over a range from 8.5 to 5 . The weak acids fluoride, acetate, or lactate did not measurably enhance acid adaptation, and so the response did not appear to depend primarily on changes in delta pH or the proton motive force across the cell membrane . Transcription and translation to form new proteins did appear to be necessary, as indicated by inhibition of adaptation by rifampin or chloramphenicol and by lack of adaptation by cells suspended in phosphate buffer at pH 5 . Streptococcus salivarius and Lactobacillus casei were acid adapted by the rapid method, and the method appeared to be generally useful for oral lactic-acid bacteria . The rapid induction of the response in multiple oral lactic-acid bacteria suggests that it is of general importance for maintaining a diversity of organisms in the oral microbiota, which is regularly subjected to acid stresses.

Eur J Oral Sci, 1997 Feb, 105(1), 27 - 35
Effects of chlorhexidine on the bacterial colonization and degradation of dentin and completely demineralized dentin in situ; van Strijp AJ et al.; The effects of 0.2% chlorhexidine on selected plaque microorganisms were studied in an intraoral dentin caries model . In 8 individuals wearing partial dentures, sound and completely demineralized dentin specimens were placed consecutively in 2 periods of 4 weeks, respectively . Throughout the experimental period, the specimens were treated 2 x daily with 0.2% chlorhexidine; control specimens were treated with water . Plaque accumulation on the specimens was left undisturbed . No protection against demineralization of the dentin or degradation of the dentin collagen by the chlorhexidine treatment was observed . The chlorhexidine treatment did not result in a reduction of the total cultivable flora when compared with the control specimens . A significant reduction of mutans streptococci and total streptococci recovered from completely demineralized dentin treated with chlorhexidine was observed, but the proportions of Actinomyces and lactobacilli were not affected significantly . It is speculated that areas of exposed roots, which are difficult to reach by oral hygiene measurements, such as approximal surfaces, will not be protected by a 0.2% chlorhexidine mouthrinse against the caries process.

J Hepatol, 1997 Feb, 26(2), 417 - 24
Effect of oral supplementation of lactobacilli on bacterial translocation in acute liver injury induced by D-galactosamine; Kasravi FB et al.; BACKGROUND/AIM: Bacterial infections and sepsis are frequent complications of acute liver injury, with a high share in the mortality and morbidity of this condition . Bacterial translocation from the gut may play an important role in the high rate of infections observed . In this experiment the effect of different oral supplementation on bacterial translocation was evaluated in acute liver injury induced by D-galactosamine in the rat . METHODS: Rats were given oral supplements of lactulose, neomycin, Lactobacillus reuteri R2LC, and Lactobacillus plantarum DSM 9843 for 1 week . Liver injury was induced by intraperitoneal administration of 1.1 g/kg D-galactosamine . Twenty-four hours later, rats were sacrificed and liver enzymes and histology, intestinal bacterial count and microflora, intestinal mucosal histology, DNA and RNA content, bacterial translocation to blood, mesenteric lymph nodes, and liver, and serum endotoxin were studied or measured . RESULTS: Lactulose was highly effective in prevention of liver injury and bacterial translocation . Neomycin and Lactobacillus plantarum DSM 9843 showed a moderate effect in prevention of liver injury and bacterial translocation . Intestinal bacterial count and microflora were affected by different treatment modalities . No endotoxin concentration was found in any of the experimental groups . Both lactobacilli could significantly improve the mucosal proliferative state . CONCLUSIONS: Oral supplementation of lactulose with anti-endotoxin effect could successfully prevent the liver injury and the subsequent bacterial translocation in acute liver injury induced by administration of D-galactosamine in the rat . This effect was irrespective of the intestinal bacterial alteration or mucosal proliferative state.

J Reprod Med, 1997 Feb, 42(2), 91 - 8
Cesarean delivery . Microbial colonization in amniotic fluid; Keski-Nisula L et al.; OBJECTIVE: To determine the frequency, clinical significance and causative factors behind intraamniotic microbial colonization in uninfected parturients at the time of cesarean delivery . STUDY DESIGN: Amniotic fluid specimens for bacterial and mycoplasmal cultures were obtained by direct aspiration at cesarean section from 251 pregnant women (24-43 completed weeks) who had no clinical infection at the time of the operation . The symptoms of maternal infection were followed postoperatively for the first week of the puerperium . RESULTS: The prevalence of amniotic fluid microbial invasion was 29% (72/251) . In patients not in labor and with intact membranes, it was 13% (20/158); in patients in labor and with intact membranes, 23% (5/22); and in those with ruptured membranes, 66% (47/71) . The most common species isolated were Ureaplasma urealyticum, Lactobacillus species and coagulase-negative staphylococci . In the total 251 patients, clinically evident postoperative endometritis was observed in 6 (2%) and wound infection in 10 (4%) . In patients operated on and with intact membranes, no risk factors were found as regards amniotic fluid microbial colonization . In patients operated on after rupture of the membranes, the only significant risk factor as regards amniotic fluid microbial invasion was use of an internal monitor before the operation (P < .0003) (relative risk 10.7, 95% confidence limit 2.9-39.4) . The relative risk of postoperative endometritis was 2.3 (95% confidence limit 1.3-4.3) in patients with microbial invasion of the amniotic cavity as compared to patients without invasion . The corresponding risk value for post-operative wound infection was 1.4 (95% confidence limit 0.6-3.1) . CONCLUSION: Though the incidence of microbial invasion of the amniotic fluid before surgery was unexpectedly high, its clinical significance as regards maternal puerperal morbidity appeared to be low . The use of internal monitoring during labor was the only significant risk factor as regards amniotic fluid microbial colonization in patients operated on after membrane rupture.

Poult Sci, 1997 Feb, 76(2), 381 - 5
Effect of feeding diets containing an antibiotic, a probiotic, or yucca extract on growth and intestinal urease activity in broiler chicks; Yeo J et al.; A 6-wk study was conducted to determine the effect of feeding diets containing an antibiotic, a probiotic, or yucca extract on daily gain, feed conversion ratio, and urease activity and ammonia production in intestinal contents of broiler chicks . Four replicates of 10 broiler chicks (average body weight, 48 g) each were assigned to a control or diets containing 0.1% chloroxytetracycline (antibiotic), 0.1% Lactobacillus casei (probiotic), or 0.2% yucca extract . Feeding a diet containing the probiotic significantly (P < 0.05) increased average daily gain during the first 3-wk period compared to the control (30.7 vs 28.7 g) . This increase was partly accounted for by increased feed intake . During the first 3 wk, feeding the diet containing probiotic significantly (P < 0.05) decreased urease activity (per gram of collected contents) in small intestinal contents but not in large intestinal contents, compared with the control . Urease activity determined at 6 wk of age was not significantly affected by diet . Our studies indicate that dietary probiotic decreases urease activity in the small intestinal contents of young chicks and thus may be beneficial for improving animal health and growth, especially during early life.

Mol Microbiol, 1997 Feb, 23(3), 505 - 14
Molecular analysis of the cos region of the Lactobacillus casei bacteriophage A2 . Gene product 3, gp3, specifically binds to its downstream cos region; Garcia P et al.; The terminal nucleotide sequence of the Lactobacillus casei bacteriophage A2 DNA revealed a single-stranded extension 13 bases in length (5'-AACGGTCGGCCTC-3') at its 3' termini that defines the packaging initiation nicking site (cosN) . The cosN sequence is bisected by an axis of hyphenated twofold rotational symmetry . Directly and inverted repeated sequences located to the left (cosL) and the right (cosR) of the cosN site were observed . Analysis of the 3.4 kb EcoRI DNA sequence surrounding the cos region revealed four complete and one incomplete open reading frames (orfs) . Northern blots indicated that all were cotranscribed in a single mRNA molecule in excess of 10 kb that appeared late during infection . Minicell studies indicated that the four orfs were translated into protein . From the ORF3 amino acid sequence DNA-binding and NTP-binding domains can be predicted . The purified ORF3 (predicted molecular mass 16.8 kDa) shows specific binding to the A2 cos region, so it was renamed gp3 . Gp3 forms a specific complex with a 369 bp cos DNA segment in the presence of ATP . Gp3 interaction with the intrinsically bent cos DNA segment induces intramolecular ligation in the presence of T4 DNA ligase . The data presented here suggest that gp3 is the small subunit of the terminase enzyme.

Microbiology, 1997 Feb, 143 ( Pt 2), 527 - 37
Lactobacillus delbrueckii subsp . lactis DSM7290 pepG gene encodes a novel cysteine aminopeptidase; Klein JR et al.; A number of Escherichia coli clones were isolated from a Lactobacillus delbrueckii subsp . lactis gene library capable of hydrolysing the chromogenic substrate Gly-Ala-beta-naphthylamide (Gly-Ala-beta NA) . Some of the recombinant plasmids carried by these clones have been shown to encode the cysteine aminopeptidase gene pepC . Nucleotide sequence analyses of the plasmid inserts of the remaining clones resulted in the identification of two adjacent ORFs encoding proteins exhibiting a high degree of similarity between themselves (72.6%) and with PepC . One gene, designated pepG, was overexpressed in E . coli and the crude extracts obtained were shown to be peptidolytically active both against chromogenic substrates and peptides, and in a Salmonella typhimurium growth test . PepC and PepG activities were compared using chromogenic beta NA and p-nitroanilide substrates and leucine or proline-containing peptides were applied in growth experiments of recombinant Sal . typhimurium . The results indicate that the enzymes, although structurally related, have different substrate preferences . No enzyme activity could be ascribed to the second ORF (orfW), despite the production of a visible protein using a T7 RNA polymerase system . Primer extension analysis, using mRNA isolated from Lb . delbrueckii subsp . lactis DSM7290 did establish that orfW was transcribed.

Int J Food Microbiol, 1997 Feb, 34(2), 157 - 70
Insufficient antilisterial capacity of low inoculum Lactobacillus cultures on long-term stored meats at 4 degrees C; Buncic S et al.; Two of the 210 lactobacilli strains isolated from chilled meats produced antilisterial bacteriocins: Lactobacillus sake 265 (Lb 265) and Lactobacillus casei 52 (Lb 52) . Factors affecting antilisterial effectiveness of these and two other bacteriocin-producing (Bac+) strains (Lactobacillus sake 706, Lb 706; and Lactobacillus sake 148, Lb 148) at refrigeration temperature (4 degrees C) were studied in laboratory media and meat systems . At both 4 degrees C and 25 degrees C, these Bac+ strains grown in buffered MRS broths (pH 5.4 or 6.5) showed longer lag phases and shorter generation times than Listeria monocytogenes (mixture of strains NCTC 7973 and two food derived strains, L70 and L72) when grown in buffered BHI broths at the same pH values . These differences were more significant at 4 degrees C than at 25 degrees C . The highest concentrations of bacteriocin in MRS broth were produced at 25 degrees C and 4 degrees C by strain Lb 265 and Lb 706, respectively . Generally, production of bacteriocins was more efficient at lower pH (in buffered MRS broths of pH 5.4 and unbuffered MRS broths), than at higher pH (in buffered broths of pH 6.5) . On vacuum packaged, raw beef (pH 5.3-5.4) initial numbers of L . monocytogenes (10(3)/g) did not change significantly during 23-days storage at 4 degrees C, when inoculated either alone or in the presence of Bac+ strains inoculated at initial levels of 10(3)/g . On vacuum packaged emulsion-type of sausages (pH 6.4) inoculated with L . monocytogenes and stored at 4 degrees C for 23 days growth was not significantly affected by addition of Bac+ strains at initial levels of 10(3)/g . These results indicated that amounts of bacteriocins produced in situ by low initial numbers (10(3)/g) of the protective strains tested were not sufficient to inhibit and/or reduce L . monocytogenes on these chilled meats, where high initial numbers of lactic acid bacteria are not desirable for product quality resons . To achieve these effects, higher concentrations of active (free) bacteriocins in meats must be provided.

Int J Food Microbiol, 1997 Feb, 34(2), 145 - 56
Production, purification and characterization of reutericin 6, a bacteriocin with lytic activity produced by Lactobacillus reuteri LA6; Kabuki T et al.; A bacteriocin (Reutericin 6) produced by Lactobacillus reuteri LA6, was purified by hydrophobic chromatography from the modified MRS broth (D'-MRS) with 6180-fold increase in specific activity with 14% recovery . The molecular weight of reutericin 6 was determined to be 2.7 kDa by SDS-PAGE and ESI-MS . By amino acid analysis, reutericin 6 comprised of 67% hydrophobic and polar neutral amino acids . Lanthionine was not detected . The lytic activity against Lactobacillus delbrueckii subsp . bulgaricus JCM 1002T and N1A1 B6 was detected by the decrease of both turbidity and the number of viable cells, and by leaking of beta-galactosidase.

Int J Food Microbiol, 1997 Feb, 34(2), 131 - 43
Anti-aflatoxigenic activity of Lactobacillus casei pseudoplantarum; Gourama H et al.; Lactobacillus casei pseudoplantarum 371 isolated from a silage inoculant was found to inhibit aflatoxins B1 and G1 biosynthesis by Aspergillus flavus subsp . parasiticus NRRI . 2999, in liquid medium . The inhibitory activity in the Lactobacillus cell-free supernatant was found to be sensitive to proteolytic enzymes such as trypsin and alpha-chymotrypsin, but resistant to pepsin . Lab-Lemco tryptone broth (LTB), supplemented with 20% of dialyzed protein concentrate of the supernatant, totally inhibited the production of aflatoxins B1 and G1 . When the protein concentrate was digested with trypsin, the production of aflatoxins B1 and G1 was restored . The inhibitory activity of the supernatant was inactivated within 10 min at 100 degrees C . A . flavus grown in the Lactobacillus cell-free supernatant did not produce a mutagenic response in the Salmonella mutagenicity test . However, Lactobacillus casei pseudo plantarum 371 did not have an effect on aflatoxin production and mold growth as measured by ergosterol and plate count, when the organisms were inoculated together on sterile steamed rice.

Appl Environ Microbiol, 1997 Feb, 63(2), 513 - 8
Antagonistic activity exerted in vitro and in vivo by Lactobacillus casei (strain GG) against Salmonella typhimurium C5 infection; Hudault S et al.; The aim of this study was to compare the antagonistic properties of Lactobacillus casei GG exerted in vitro against Salmonella typhimurium C5 in a cellular model, cultured enterocyte-like Caco-2 cells, to those exerted in vivo in an animal model, C3H/He/Oujco mice . Our results show that a 1-h contact between the invading strain C5 and either the culture or the supernatant of L . casei GG impeded the invasion by the Salmonella strain in Caco-2 cells, without modifying the viability of the strain . After neutralization at pH 7, no inhibition of the invasion by C5 was observed . The antagonistic activity of L . casei GG was examined in C3H/He/Oujco mice orally infected with C5 as follows: (i) L . casei GG was given daily to conventional animals as a probiotic, and (ii) it was given once to germ-free animals in order to study the effect of the population of L . casei GG established in the different segments of the gut . In vivo experiments show that after a single challenge with C5, this strain survives and persists at a higher level in the feces of the untreated conventional mice than in those of the treated group . In L . casei GG germ-free mice, establishment of L . casei GG in the gut significantly delayed the occurrence of 100% mortality of the animals (15 days after C5 challenge versus 9 days in germ-free mice {P < 0.01}) . Cecal colonization level and translocation rate of C5 to the mesenteric lymph nodes, spleen, and liver were significantly reduced during the first 2 days post-C5 challenge, although the L . casei GG population level in the gut dramatically decreased in these animals.

Gene, 1997 Jan 31, 185(1), 119 - 25
Characterization of the genes encoding integrative and excisive functions of Lactobacillus phage øg1e: cloning, sequence analysis, and expression in Escherichia coli; Kakikawa M et al.; og1e is a temperate phage of the Lactobacillus strain G1e . The phage-host junctions attR and attL cloned from the lysogen have a 24-bp common (core) sequence implicated in recombination . DNA sequencing analysis of a 5.2-kbp SacI fragment of the og1e phage genome (42.5 kbp) revealed two possible open reading frames (ORF), xis and int, and the phage attachment (recombination) site (attP), whose 24-bp sequence is identical to the core sequence detected in attR and attL . The deduced int product (Int) is a basic protein of 391 amino acids with an estimated pI of 9.70, and significantly resembles other presumed integrases encoded by the Lactobacillus and Lactococcus phages including oadh and oLC3, as well as the Escherichia coli phages such as lambda . The predicted og1e xis protein (Xis) is small and very acidic (66 amino acids; pI 4.55), and shows a resemblance (32% overall identity) with a putative excisionase encoded by the Staphylococcus phage o11 . The og1e Int with a deduced molecular mass of 45.5 kDa was overproduced in E . coli cells, and electrophoretically analyzed.

Proc Natl Acad Sci U S A, 1997 Jan 7, 94(1), 53 - 8
The B12-dependent ribonucleotide reductase from the archaebacterium Thermoplasma acidophila: an evolutionary solution to the ribonucleotide reductase conundrum; Tauer A et al.; A coenzyme B12-dependent ribonucleotide reductase was purified from the archaebacterium Thermoplasma acidophila and partially sequenced . Using probes derived from the sequence, the corresponding gene was cloned, completely sequenced, and expressed in Escherichia coli . The deduced amino acid sequence shows that the catalytic domain of the B12-dependent enzyme from T . acidophila, some 400 amino acids, is related by common ancestry to the diferric tyrosine radical iron(III)-dependent ribonucleotide reductase from E . coli, yeast, mammalian viruses, and man . The critical cysteine residues in the catalytic domain that participate in the thiyl radical-dependent reaction have been conserved even though the cofactor that generates the radical is not . Evolutionary bridges created by the T . acidophila sequence and that of a B12-dependent reductase from Mycobacterium tuberculosis establish homology between the Fe-dependent enzymes and the catalytic domain of the Lactobacillus leichmannii B12-dependent enzyme as well . These bridges are confirmed by a predicted secondary structure for the Lactobacillus enzyme . Sequence similarities show that the N-terminal domain of the T . acidophila ribonucleotide reductase is also homologous to the anaerobic ribonucleotide reductase from E . coli, which uses neither B12 nor Fe cofactors . A predicted secondary structure of the N-terminal domain suggests that it is predominantly helical, as is the domain in the aerobic E . coli enzyme depending on Fe, extending the homologous family of proteins to include anaerobic ribonucleotide reductases, B12 ribonucleotide reductases, and Fe-dependent aerobic ribonucleotide reductases . A model for the evolution of the ribonucleotide reductase family is presented; in this model, the thiyl radical-based reaction mechanism is conserved, but the cofactor is chosen to best adapt the host organism to its environment . This analysis illustrates how secondary structure predictions can assist evolutionary analyses, each important in "post-genomic" biochemistry.

Caries Res, 1997, 31(5), 384 - 9
In vivo cariostatic effect of resin modified glass ionomer cement and amalgam on dentine; Kreulen CM et al.; Fluoride-releasing materials have been reported to be bactericidal in vitro . This may be of benefit to modern dentistry, which is directed to the preservation of tooth tissue during restorative treatment . Little is known about in vivo effects . The aim is to investigate the influence of a resin-modified glass ionomer cement (RM-GIC) on carious dentine that remains under restorations, compared to amalgam . Using a split month design, 40 molar pairs in 40 patients (mean age 14.9 years) were selected, based on clinically and radiographically diagnosed occlusal dentine caries . Under aseptic conditions, the enamel was removed and the carious dentine was sampled just beneath the dentino-enamel junction using a round bur . Without further removal of carious dentine, the molars of a pair were alternately restored with RM-GIC or amalgam . The colour and the consistency of the carious dentine were assessed . The samples were processed for microbiological determination of total viable counts (TVC), mutans streptococci (MS), and lactobacilli (LB) . After 6 months the molars were reopened, similarly sampled and evaluated, and then permanently restored after complete caries removal . For both materials a substantial decrease in the numbers of TVC, MS and LB was found after the 6-month period . Also a positive effect was observed on the colour and the consistency of the remaining carious dentine, which was comparable for the two materials . RM-GIC showed a significantly larger decrease in counts of MS and LB than amalgam, but not for TVC . Since in only few cavities the number of bacteria decreased under the level of detection, it is still considered essential to remove all carious dentine during restorative treatment.

Caries Res, 1997, 31(5), 379 - 83
Fluoride and mutans streptococci levels in plaque on aged restorations of resin-modified glass ionomer cement, compomer and resin composite; van Dijken JW et al.; The use of fluoride-releasing restoratives such as glass ionomer cements (GICs) has increased during the last decade . The antibacterial effect of released fluoride is thought to be a possible caries-preventive effect of these restorations . In this study fluoride concentrations in plaque on 1-year old resin-modified GIC, compomer and resin composite restorations were compared intraindividually and related to the occurrence of caries-associated bacteria . Plaque from class III restorations of the three restorative materials and from a proximal enamel surface in 18 individuals was analysed . Low fluoride levels were detected in all the samples, while the resin-modified GIC samples showed significantly higher amounts . The distribution of oral streptococci, mutans streptococci and lactobacilli did not differ significantly among the surfaces and did not correlate to the fluoride levels in the samples . A good correlation was found between the counts of mutans streptococci in saliva and their proportions in the plaque . The results indicate that the fluoride concentrations released in vivo from 1-year-old restoratives are not high enough to affect the plaque levels of the caries-associated bacteria mutans streptococci and lactobacilli.

Caries Res, 1997, 31(5), 349 - 55
Bacterial colonization of mineralized and completely demineralized dentine in situ; van Strijp AJ et al.; The changing environment in a developing root lesion may result in a succession of the microbial flora in the dentine . As demineralization proceeds, the collagenous matrix is exposed, which could be conducive to the growth of specific microorganisms . In this study both sound and completely demineralized dentine were placed together in the partial prothesis of 8 individuals to test whether the type of substrate influenced the composition of the bacterial flora . After 6 weeks the degradation of the collagenous matrix, the demineralization of the dentine and the microbial composition were assessed . The collagen loss varied between 0 and 69 wt% . Mineral loss from the originally sound dentine specimens ranged from virtually none to complete demineralization . Percentages of total streptococci, mutans streptococci, Actinomyces and lactobacilli isolated from both dentinal substrates did not differ significantly . The percentage of lactobacilli in the dentine specimens was positively correlated to the lesion depth . The percentage of Actinomyces species was significantly higher in both the dentine specimens that had been demineralized in vitro and those that were found to be completely demineralized in situ compared to the partially demineralized dentine specimens . In vitro, no collagenolytic activity of the predominant flora isolated from both dentinal substrates could be shown.

Gynecol Obstet Invest, 1997, 44(1), 16 - 20
Microorganisms in vaginal fluid from women in prolonged pregnancy; Goffeng AR et al.; In order to compare the vaginal microflora of women in prolonged pregnancy with that of women who delivered at term, samples for quantitative aerobic and anaerobic microbiological culture were collected from 100 women at 42 weeks of gestation and from 60 women at term . The occurrence of lactobacilli-dominated flora was similar in women at term and women with prolonged pregnancy . However, non-hydrogen-peroxide-producing lactobacilli (p < 0.01) were significantly more common and Peptostreptococci species (p < 0.05) significantly less common in postterm women as compared with term controls . In postterm women, Candida albicans was more common (p < 0.001) in microfloras dominated by non-hydrogen-peroxide-producing lactobacilli than in floras dominated by hydrogen-peroxide-producing lactobacilli . The ecosystem of the vagina in asymptomatic postterm women was disrupted concerning the composition of lactobacilli as compared with term controls.

Zh Mikrobiol Epidemiol Immunobiol, 1997 Jan-Feb, (1), 67 - 9
{The possibility of colonizing the intestines of white mice with Lactobacillus acidophilus during bacterial therapy}; Kruglikov VD et al.; The study revealed the possibility, on principle, for L . acidophilus strain VKM V-2020 D to colonize the intestine of white mice with the preservation of the viability of lactobacilli subjected to the action of antibiotics . The culture of this strain, isolated from the animals, showed the stability of its biological properties: resistance to polymyxin M, kanamycin, cyprofloxacin, nalidixic acid (including acquired resistance to rifampicin), as well as pronounced antagonism with respect to Vibrio cholerae . Good prospects for the use of L . acidophilus strain VKM V-2020 D for further studies regarding its use for prophylaxis and therapy were noted.

Gastroenterol Clin Biol, 1997, 21(4), 293 - 8
Effects of intrajejunal perfusion and chronic ingestion of Lactobacillus johnsonii strain La1 on serum concentrations and jejunal secretions of immunoglobulins and serum proteins in healthy humans; Marteau P et al.; OBJECTIVES: Link-Amster reported an increase in serum IgA when healthy subjects ingested a fermented dairy product containing Lactobacillus johnsonii La1 . We aimed to assess the effects of La1 on the jejunal secretions and serum concentrations of total and specific immunoglobulins and proteins . METHODS: Twelve healthy volunteers ingested a fermented milk containing La1 or a control from day 1 till day 28, following a randomised double blind protocol . At days 0 and 28, the jejunum was successively perfused with a control solution and with a La1 suspension . The serum concentrations and jejunal secretions of albumin, orosomucoid, transferrin, alpha 2-macroglobulin, m-IgA, p-IgA, IgG, IgM, secretory component, and specific antibodies against La1 were assessed . RESULTS: Serum concentrations of IgA slightly increased between d0 and d28 in the group receiving La1 (1.85 +/- 0.64 g/L vs 1.76 +/- 0.76; P = 0.02) . The other parameters were not altered . CONCLUSION: This study shows that the immunomodulating effects of La1 ingestion in man are not due to modification of jejunal protein permeability.

Arch Tierernahr, 1997, 50(1), 25 - 9
Effect of maduramicin and monensin on survival of Lactobacillus salivarius 51R administered in the crop and caeca of young chickens; Rada V et al.; A rifampicin-resistant Lactobacillus salivarius 51R was administered orally to newly hatched broiler chickens . The resistance to rifampicin enabled us to differentiate the organism administered from indigenous strains . One day after inoculation, Lactobacillus salivarius 51R dominated among lactobacilli in the crop and caeca of all inoculated chickens, even in those ones receiving maduramicin and monensin at 5 and 100 mg per kg of feed mixture, respectively . Coliform counts in both crop and caeca of inoculated chickens were significantly lowered on the first day after treatment . Also, counts of the crop enterococci were decreased in inoculated chickens . Rifampicin-resistant lactobacilli were still present in high numbers in the crop and caecal contents of inoculated chickens sampled 5 days after inoculation . Differences in counts of total lactobacilli, coliform bacteria, and enterococci were mostly nonsignificant in these samples . Our results demonstrate that (i) bacterial counts in the chicken gut were influenced by probiotic Lactobacillus administration, and (ii) chicken lactobacilli are resistant to ionophore coccidiostats under in vivo conditions.

Plasmid, 1997, 37(3), 199 - 203
Isolation and characterization of a plasmid from Lactobacillus fermentum conferring erythromycin resistance; Fons M et al.; Lactobacillus fermentum is a lactic acid bacterial species commonly found in the digestive tracts of pigs and rodents and also present in man . We characterized a 5.7-kb plasmid, pLEM3, conferring erythromycin resistance, which was isolated from a porcine strain of L . fermentum . Plasmid pLEM3 established efficiently in L . fermentum, conferred high-level erythromycin resistance (MIC > 1 mg/ml), and was segregationally stable . A deletion derivative of pLEM3, called pLEM5, was constructed and found to be as genetically stable as the parent . A multiple cloning site was inserted into pLEM5, generating plasmid pLEM7 . Nucleotide sequence determination of pLEM5 revealed similarities with known genes . The replicon itself is a member of the pC194 family of rolling circle plasmids . The region responsible for erythromycin resistance was 98.2% identical to the erm gene of conjugative transposon Tn1545.

Folia Microbiol (Praha), 1997, 42(1), 31 - 4
Assessment of a bacteriocin-producing Lactobacillus strain in the control of spoilage of a cereal-based African fermented food; Olasupo NA et al.; As a part of a program to develop starter cultures aiding in the spoilage control and sanitation of African fermented foods, a cereal-based food ('ogi' and its solid form 'agidi' or 'eko') was prepared using a bacteriocin-producing Lactobacillus strain as the starter culture . The survival of an enterotoxigenic Escherichia coli strain was investigated in the naturally fermented food and in food fermented with the starter bacteriocin-producing Lactobacillus strain . An inhibition of E . coli was observed within 2 h of incubation in 'ogi' fermented with the bacteriocin producing strain . After 6 h, the viable count of E . coli in locally fermented 'ogi' was log 6.41 (2.54 X 10(6) CFU/mL), whereas in 'ogi' fermented with the bacteriocin producer it was reduced to log 1.70 (0.5 x 10(2) CFU/mL) . Comparison of the shelf life of 'agidi' prepared from the naturally fermented food with that bacteriocin-producing starter culture showed that the latter had a better shelf life (kept for 11 d before spoilage occurred as compared with 7 d for the natural one) . The results are discussed in terms of the potential of bacteriocin-producing cultures in the control and retardation of spoilage and food-forne infections in some African fermented foods.

Microbiol Immunol, 1997, 41(4), 361 - 5
Experimental Helicobacter pylori infection in association with other bacteria; Isogai H et al.; We performed surgical treatment on normal ddY mice before Helicobacter pylori inoculation . The treatment was expected to obstruct bacterial flow out of the stomach and increase the chance of bacterial attachment to the gastric epithelium in mice . The bacterial challenge induced inflammation in the stomach . H . pylori was recovered from the stomach throughout the observation period . Lactobacilli and streptococci tended to relate to the increase in number of H . pylori recovered . Pretreatment with atropine was considered to confuse the gastric flora and affect the number of H . pylori recovered . These results suggested that a certain amount of time is necessary for H . pylori to contact with the gastric epithelium and that the composition of flora is important for the establishment of H . pylori infection.

J Appl Microbiol, 1997 Jan, 82(1), 115 - 20
Viability of Cryptosporidium parvum during ensilage of perennial ryegrass; Merry RJ et al.; The survival of Cryptosporidium parvum during ensilage of perennial ryegrass was examined in laboratory silos with herbage prepared in one of three different ways; either untreated, inoculated with a strain of Lactobacillus plantarum or by direct acidification with formic acid . The pH values of all silages initially fell below 4.5, but only formic acid-treated silage remained stable at less than pH 4 after 106 d, with the pH of the untreated and inoculant-treated silages rising to above 6 . The formic acid-treated silage had a high lactic acid concentration (109 g kg-1 dry matter (DM)) and low concentrations of propionic and butyric acids after 106 d . However, the untreated and inoculant-treated silages showed an inverse relationship, with low lactic acid concentrations and high concentrations of acetic, propionic and butyric acids . These silages also contained ammonia-N concentrations in excess of 9 g kg-1 DM . In terms of the viability of Cryptosporidium parvum oocysts very few differences were seen after 14 d of ensilage with ca 50% remaining viable, irrespective of treatment and total numbers had declined from the initial level of 5.9 x 10(4) to 1 x 10(4) g(-1) fresh matter . Total oocyst numbers remained approximately the same until the end of the ensiling period, with the percentage of viable oocysts declining to 46, 41 and 32% respectively for formic acid, inoculant and untreated silages . The results are discussed in terms of changes occurring during the silage fermentation, in particular the products which may influence the survival of Cryptosporidium and implications for agricultural practice and the health of silage fed livestock.

Vet Med (Praha), 1997 Jan, 42(1), 19 - 27
{Criteria for selection of lactobacilli for probiotic use}; Nemcova R; The present knowledge of research makes it possible to use a whole range of stabilized micro-organisms and their metabolites for the production of preparations known as probiotics . The mechanism of the effect of probiotics, although it is not fully elucidated, is closely connected with the properties of the production strains . When selecting them, it is necessary to respect the origin of the strain used, its ability to adhere to the epithelial cells of the gut and to produce the inhibitory substances, the ability to survive and grow in the respective ecological units . The strain should be genetically stable, it should have good growth properties in vitro and in vivo, to maintain its high viability at processing, lyophilization and storage . Lactobacilli belong to the micro-organisms most frequently used to prepare the probiotics . The statement that lactobacilli inhibit the colonization of pathogenic bacteria upon the intestinal epithelium has been confirmed by many experiments on experimental germ-free and/or gnotobiotic animals . This inhibitory process known as "competitive exclusion" can be explained by the competition for the adherence sites on the intestinal mucosa between pathogens and lactobacilli and by the production of inhibitory substances . The host specificity as well as different degree of the expression of adherent phenotype, which is conditioned, in addition to the effect of the external environment also by the presence of plasmids of adherence, present the important property of the adherence of lactobacilli . The host specificity of the lactobacilli is closely connected with the presence of the specific molecules of receptors on the host cells which can be distinguished by means of specific molecules of the bacterial cells . The competition for the nutrients to be found on the intestinal epithelium, which present the growth substrates for both the probiotic strains and the pathogens, may present an important factor influencing the colonization of lactobacilli . The inhibitory components of the lactobacilli comprise the production of bacteriocins, toxic metabolites of the oxygen and organic acids . The inhibitory spectrum of the bacteriocins is different; the overwhelming majority of them inhibits G+ bacteria within the genus or taxonomically close to the genus of Lactobacillus, others such as bulgaricin, acidolin, laktocidin, acidophilin and non-protein substance reuterin are active against a wide spectrum of G+, G- bacteria, yeasts and fungi . Of toxic oxygen metabolites, the production of hydrogen peroxide is of importance . The hydrogen peroxide along with lactoperoxidase-thiocyanate milk system exerts bacteriocid effects on most pathogens . The production of organic acids (lactic, acetic) by lactobacilli is considered to be the primary regulator of the gut microbial activity in animals . The lactic acid as a product of the intestinal fermentation is further metabolized by lactate utilizing bacteria to VFA, thus the environment of the digestive tract is acidified and the acidosensitive pathogens cannot exert their effect . When pH of the environment falls, the concentration of molecular (non-dissociated) form of weak organic acids (acetic acid, VFA) elevates . The above acids diffuse through the cell membrane into a cell, thereby exhibiting higher inhibitory capacity . In case the mechanism of the effect of probiotics is fully elucidated, the criteria of the selection could be more precisely defined and thereby also the efficiency of probiotics would be improved.

Caries Res, 1997, 31(2), 91 - 6
The effect of chlorhexidine/xylitol chewing-gum on cariogenic salivary microflora: a clinical trial in elderly patients; Simons D et al.; The effects of 14-day use of either a chlorhexidine/xylitol or a xylitol chewing gum on salivary levels of mutans streptococci, lactobacilli, and yeasts were determined for 53 subjects (mean age 79.49 +/- 7.7 years) participating in this randomised, double-blind, placebo-controlled trial . Salivary flow rates and enamel staining were measured and the attitudes of the subjects to gum chewing were evaluated by the use of structured questionnaires . The chlorhexidine/xylitol gum significantly reduced the salivary levels of mutans streptococci (p < 0.0001) lactobacilli (p < 0.05) and yeasts (p < 0.05) while the xylitol placebo gum produced significant reductions in mutans streptococci (p < 0.01) only . The study population found chewing gum twice per day for 10 min an acceptable method of receiving medication and improving oral health . Prior to gum use participants recognised persistent symptoms of dry mouth and their subjective evaluation of dry mouth was significantly (p < 0.001) related to the number of prescribed medications with xerostomic side-effects . The desire to continue gum use was significantly related to the subjects' evaluation of their oral dryness at baseline and to their perceived oral health gain from gum usage . Only those participants with stained enamel at baseline exhibited increased enamel staining following chlorhexidine/xylitol gum usage.

J Appl Microbiol, 1997 Jan, 82(1), 101 - 6
Effects of the kinetics of water potential variation on bacteria viability; Poirier I et al.; The effect of the kinetics of water potential variation (psi) on the viability of bacteria subjected to hyperosmotic stresses in water-glycerol solution was studied . The three bacteria used were Lactobacillus plantarum L-73, Leuconostoc mesenteroides LM057 and Escherichia coli TG1 . These strains were submitted to a final water potential of -107.2 MPa, -170.9 MPa and/or -244.7 MPa . In any case the kinetics of water potential variation was found to have a great effect on the cell viability . The application of slow water potential decreases could maintain an important cell viability (about 80-100%) with regard to the corresponding viability observed after a sudden step change for the same final water potential (15-57%) . For each strain tested, an optimal dehydration kinetics was determined which depended on the final water potential . The existence of this optimum could be explained thanks to the opposition of two actions affecting cell viability: a positive action relative to the slowness of the water potential variation and a negative action relative to the residence time of cells in a critical range of water potential.

Adv Biochem Eng Biotechnol, 1997, 58, 145 - 84
New alcohol dehydrogenases for the synthesis of chiral compounds; Hummel W; The enantioselective reduction of carbonyl groups is of interest for the production of various chiral compounds such as hydroxy acids, amino acids, hydroxy esters, or alcohols . Such products have high economic value and are most interesting as additives for food and feed or as building blocks for organic synthesis . Enzymatic reactions or biotransformations with whole cells (growing or resting) for this purpose are described . Although conversions with whole cells are advantageous with respect to saving expensive isolation of the desired enzymes, the products often lack high enantiomeric excess and the process results in low time-space-yield . For the synthesis of chiral alcohols, only lab-scale syntheses with commercially available alcohol dehydrogenases have been described yet . However, most of these enzymes are of limited use for technical applications because they lack substrate specificity, stability (yeast ADH) or enantioselectivity (Thermoanaerobium brockii ADH) . Furthermore, all enzymes so far described are forming (S)-alcohols . Quite recently, we found and characterized several new bacterial alcohol dehydrogenases, which are suited for the preparation of chiral alcohols as well as for hydroxy esters in technical scale . Remarkably, of all these novel ADHs the (R)-specific enzymes were found in strains of the genus Lactobacillus . Meanwhile, these new enzymes were characterized extensively . Protein data (amino acid sequence, bound cations) confirm that these catalysts are novel enzymes . (R)-specific as well as (S)-specific ADHs accept a broad variety of ketones and ketoesters as substrates . The applicability of alcohol dehydrogenases for chiral syntheses as an example for the technical use of coenzyme-dependent enzymes is demonstrated and discussed in this contribution . In particular NAD-dependent enzymes coupled with the coenzyme regeneration by formate dehydrogenase proved to be economically feasible for the production of fine chemicals.

Acta Odontol Scand, 1997 Jan, 55(1), 9 - 13
Risk factors for colonization of salivary lactobacilli and Candida in children; Ollila P et al.; We analyzed the occurrence of salivary lactobacilli and Candida in a sample of 166 children aged 1-4 years (mean, 2.5 years) in relation to possible risk factors for colonization of the microbes . The risk factors examined were sucking habits, feeding habits, symptoms of respiratory infections, and antibiotic therapy at the time of sampling . Lactobacilli occurred in 18% of the children's saliva, and Candida in 24% . In the logistic modeling the variables most strongly associated with the occurrence of lactobacilli were pacifier-sucking (relative risk (RR), 2.9; 95% confidence interval (CI), 1.1-7.0; P = 0.01) and antibiotic therapy (RR, 4.6; CI, 1.2-16.9; P = 0.01) . The association between positive Candida test and use of a pacifier was also significant (RR, 4.8; CI, 2.1-10.7; P = 0.0001) . The results of the study suggest that the use of a pacifier increases the occurrence of both salivary lactobacilli and Candida . It could therefore be a factor influencing caries susceptibility and activity in children.

J Dent, 1997 Jan, 25(1), 35 - 40
Effect of use of 0.05% cetylpyridinium chloride mouthwash on normal oral flora; Radford JR et al.; OBJECTIVES: The aims of this study were to examine the effect of the use of a mouthwash containing 0.05% cetylpyridinium chloride (CPC) on (1) the composition of the normal oral microbial flora and (2) the establishment of non-oral bacterial species in the mouth . METHOD: In a double-blind study, 129 subjects used, twice daily for 6 weeks, either a randomly assigned test or placebo mouthwash . At baseline and at the completion of the study, a sample of the oral flora was obtained by asking each subject to "swish" around the mouth for 30 s, 10 ml of distilled water . The numbers of total colony forming units (CFU), facultative bacteria, streptococci, mutans streptococci, lactobacilli, staphylococci, yeasts and enterococci were enumerated after culture on eight non-selective and selective media . RESULTS: After 6 weeks use of either the test or placebo mouthwashes, there were no significant differences (analysis of variance) between the counts (CFU/ml of sample) for any of the microbial taxa . CONCLUSIONS: These data indicate that the use of a CPC-containing mouthwash does not alter the composition of the normal oral flora or result in the establishment of non-oral and potentially pathogenic bacteria in the mouth.

Eur Urol, 1997, 31 Suppl 1, 10 - 9
Diagnosis and treatment of superficial transitional cell carcinoma of the bladder: facts and perspectives; Kurth KH; The detection of potentially highly curable low-grade bladder cancers by noninvasive techniques remains an unsolved problem . Conventional cytology detects such tumors with 50% sensitivity, the addition of DNA image analysis cytometry in patients with previous transitional cell superficial bladder carcinoma increases the chance to detect low-grade tumors . The specificity and sensitivity of detection of low-grade bladder tumors can be further improved by quantitative fluorescence image analysis using antibodies directed against tumor-associated antigens . The chance of subsequent tumor following initial complete resection is significantly lowered compared to resection alone by either intravesical adjuvant chemotherapy or immunotherapy . BCG is superior to chemotherapy in patients with high risk for recurrence, adjuvant intravesical chemotherapy does not prevent progression to > T1 when compared with resection alone, BCG may delay progression and the need for cystectomy in high-risk patients (T1, Cis or Cis associated with papillary Ta/T1, > 3 recurrences/year, grade 3 tumors) . Oral medication with bropirimine (an interferon inducer) induced complete response in patients with carcinoma in situ, oral Lactobacillus casei prolonged the recurrence-free interval to 1.8 times that in the control group . New compounds for adjuvant treatment of superficial bladder tumors are best first tested on their ablative effects (marker lesion, Cis) prior to be used for prophylaxis.

Eur J Gynaecol Oncol, 1997, 18(1), 76 - 7
Cervical intraepithelial neoplasia and bacterial vaginosis: correlation or risk factor?
Frega A, Stentella P, Spera G, Pace S, Cipriano L, Di Ruzza D, Villani C, Pachi A.
Bacterial Vaginosis (B.V.) is a syndrome defined microbiologically where lactobacilli-dominated flora is exchanged with an abundant complex flora dominated by strict and facultative anaerobic bacteria, constituted by gardenerella, micrococci, streptococci and staphylocci . It has been suggested that B.V . could be important in the development of cervical intracpithelial neoplasias, because the abnormal micro flora can produce careinogenic nitrosamines . The aim of this investigation was to evaluate the correlation between CIN and B.V . in 1,008 patients (median age: 28 years, range 17-60) who were divided into two groups: the first group consisted of 504 patients affected by CIN of different degrees, the second of 504 patients without CIN . All patients were submitted to colposcopy, pap-tests, cytology of the cervical canal and microcolpohysteroscopy in the case of lesions invading the cervical canal . The diagnosis of B.V . is based on four criteria: presence of clue cells, pH 4.5, positive amine test and increased vaginal discharge . X2 Pearson analysis was applied for statistical evaluation of the data . Among the 504 patients in the first group (women affected by CIN of different degrees), 180/504 (36%) women presented B.V . Among the second group (504 women without CIN), 248/504 (49%) women presented B.V . The results of our study demonstrate that there is no significant correlation between CIN and B.V . In the first group of patients affected by CIN and B.V., B.V . was present in 36% of the cases, while in the second group of patients not affected by CIN . B.V . was present in 49% of the cases (P < 0.00005).

Poult Sci, 1997 Jan, 76(1), 179 - 96
Principles of ex ovo competitive exclusion and in ovo administration of Lactobacillus reuteri; Edens FW et al.; The data that have been presented indicate that the in ovo use of competitive exclusion (CE) agents is feasible for both chickens and turkeys . However, there are many pitfalls that await the use of in ovo application of CE agents, including the use of nonspecies-specific intestinal microbes and the use of harmful proteolytic, gas-producing and toxin-producing intestinal microbes . Of the potential CE agents that have posthatch application, only Lactobacillus reuteri has been shown to be safe and effective in terms of not affecting hatchability and in having a prolonged effect in the hatched chick or poult . Lactobacillus reuteri administration in ovo increases its rate of intestinal colonization and decreases the colonization of Salmonella and Escherichia coli in both chicks and poults . Additionally, mortality due to in-hatcher exposure to E . coli or Salmonella is reduced with in ovo L . reuteri . Use of antibiotics in ovo may preclude the use of co-administered CE agents, but Gentamicin and L . reuteri are a compatible mixture when administered in ovo in separate compartments . Nevertheless, the intestinal morphology can be affected by both the CE agent and by antibiotics . Lactobacillus reuteri both in ovo and ex ovo will increase villus height and crypt depth, and Gentamicin in ovo causes a shortening and blunting of the villus . Both Gentamicin and L . reuteri in ovo suppress potentially pathogenic enteric microbes, but with diminished antibiotic effects shortening and blunting of the intestinal villi does not correct itself . Goblet cell numbers increase significantly on the ileum villus of chicks treated with Gentamicin in ovo, and this is presumably due to the increase in potentially pathogenic bacteria in the intestinal tract . Diminishing antibiotic effects posthatch would then negatively affect the absorption of nutrients and reduce growth at least in a transitory manner . Thus, L reuteri administration in ovo singly or in combination with Gentamicin followed by L reuteri via drinking water or feed appears to have potential to control many enteric pathogens in poultry . Additional work in the use of in ovo CE cultures is mandated because there is a world-wide movement to reduce antibiotic use in poultry due to increased microbial resistance to antibiotics . Use of naturally occurring intestinal bacterial cultures, either in mixed culture or as single well-defined cultures, has potential for immediate use in the poultry industry.

Biosci Biotechnol Biochem, 1997 Jan, 61(1), 179 - 82
Rapid detection method for bacteriocin and distribution of bacteriocin-producing strains in Lactobacillus acidophilus group lactic acid bacteria isolated from human feces; Kawai Y et al.; A new screening method, using micro plate wells, was developed for detecting the bacteriocin producer in lactic acid bacteria . The method was applied for screening the bacteriocin producer in L . acidophilus group lactic acid bacteria isolated from human feces with 19 bacteria used as indicator strains . Of the 98 strains, 62 were finally selected as the bacteriocin producers, including 39 strains positive against at least one of food-borne pathogenic bacteria.

Int J Syst Bacteriol, 1997 Jan, 47(1), 54 - 7
Comparative sequence analyses of the genes coding for 16S rRNA of Lactobacillus casei-related taxa; Mori K et al.; The primary structures of the 16S rRNA genes of the type strains of Lactobacillus casei and related taxa were determined by PCR DNA-sequencing methods . The sequences of Lactobacillus casei, Lactobacillus zeae, Lactobacillus paracasei, and Lactobacillus rhamnosus were different . The Knuc values ranged from 0.0040 to 0.0126 . On the basis of the Knuc values and the levels of DNA-DNA relatedness among the strains of these species, the L . casei-related taxa should be classified in the following three species: L . zeae, which includes the type strains of L . zeae and L . casei; a species that includes the strains of L . paracasei and L . casei ATCC 334; and L . rhamnosus.

Int J Syst Bacteriol, 1997 Jan, 47(1), 38 - 45
Phylogenetic analysis of mycoplasmas based on Hsp70 sequences: cloning of the dnaK (hsp70) gene region of Mycoplasma capricolum; Falah M et al.; A 5.0-kb region containing the hsp70 (dnaK) gene was cloned from Mycoplasma capricolum and sequenced . In addition to the hsp70 gene, this sequence region also contained the complete sequences for the grpE and orfA genes and partial sequences for the clpB and dnaJ genes . The order of the above gene sequences in the cloned fragment was found to be clpB-orfA-grpE-hsp70-dnaJ, which is similar to the order seen in various other gram-positive groups of bacteria . The Hsp70 homologs from two mycoplasma species, Mycoplasma capricolum and Mycoplasma genitalium, contain a number of sequence signatures, including the absence of a large insert in the N-terminal quadrant, that are characteristics of the homologs from gram-positive bacteria and archaebacteria . A detailed phylogenetic analysis based on Hsp70 sequences was also performed . In neighbor-joining and parsimony trees based on Hsp70 sequences, both mycoplasma species branched with the low-G + C-content gram-positive group of bacteria (e.g., Lactobacillus and Erysipelothrix species) in 87% and 96% of the bootstrap replicates, respectively, indicating their close evolutionary relationship to this group . The phylogenetic trees based on Hsp70 sequences show a polyphyletic branching of archaebacteria with the gram-postive species, which is statistically strongly favored.

J Bacteriol, 1997 Jan, 179(1), 284 - 6
In vivo expression of the Lactobacillus brevis S-layer gene; Kahala M et al.; Lactobacillus brevis possesses a surface layer protein (SlpA) with tightly regulated synthesis . The slpA gene is expressed by two adjacent promoters, P1 and P2 . The level of P2-derived transcripts was approximately 10 times higher than that of P1-derived transcripts throughout the entire growth of L . brevis . The half-lives of slpA transcripts were shown to be exceptionally long (14 min).

Appl Environ Microbiol, 1997 Jan, 63(1), 314 - 6
Purification and characterization of a prolidase from Lactobacillus casei subsp . casei IFPL 731; Fernandez-Espla MD et al.; A peptidase showing a high level of specificity towards dipeptides of the X-Pro type was purified to homogeneity from the cell extract of Lactobacillus casei subsp . casei IFPL 731 . The enzyme was a monomer having a molecular mass of 41 kDa . The pH and temperature optima were 6.5 to 7.5 and 55 degrees C, respectively . Metal chelating agents completely inhibited enzyme activity, indicating that the prolidase was a metalloenzyme . The Michaelis constant (K(m)) and Vmax for several proline-containing dipeptides were determined.

Appl Environ Microbiol, 1997 Jan, 63(1), 13 - 20
Isolation, purification, and amino acid sequence of lactobin A, one of the two bacteriocins produced by Lactobacillus amylovorus LMG P-13139; Contreras BG et al.; Lactobacillus amylovorus LMG P-13139, isolated from corn steep liquor, produces two bactericidal peptides with respective estimated molecular masses of 4.5 and 6.0 kDa upon denaturing sodium dodecyl sulfatepolyacrylamide gel electrophoresis . The antimicrobial activity detected in the fermentation supernatant fraction of L . amylovorus LMG P-13139 was heat stable (20 min, 121 degrees C), displayed a narrow inhibitory spectrum, and was sensitive to proteinase K, trypsin, and alpha-chymotrypsin but insensitive to alpha-amylase, lysozyme, catalase, and lipase . The 4.5-kDa bacteriocin was purified and characterized and designated lactobin A . Lactobin A was isolated as a floating pellicle from culture supernatant brought to 35% saturation with ammonium sulfate . Upon this ammonium sulfate treatment, crude lactobin A was incorporated, together with Tween 80 as a major contaminant, in high-molecular-mass complexes sized at approximately 670 kDa by gel filtration chromatography . Contaminating fatty acids were removed from these micelles by a simple one-step methanol-chloroform extraction without loss of activity . Both inhibitory peptides were separated in an isocratic isopropanol gradient on a PepRPC 5/5 reversed-phase column, and both peptides retained activity towards Lactobacillus helveticus ATCC 15009 upon separation . Lactobin A has a molecular mass determined by electrospray mass spectrometry of 4,879 +/- 0.69 Da . Its peptide chain contains 50 unmodified amino acids, of which 26% are glycine residues and 40% are hydrophobic residues (A, V, L, I, and P) . It displays the highest structural homology (42% identity and 28% similarity) with the lafX gene product, encoded by the second open reading frame of the lactacin F operon . These data strongly indicate that lactobin A belongs to the class IIb bacteriocins according to the classification of Klaenhammer.

Appl Environ Microbiol, 1997 Jan, 63(1), 1 - 6
Use of sulfite and hydrogen peroxide to control bacterial contamination in ethanol fermentation; Chang IS et al.; Lactic acid bacteria isolated from an industrial-scale ethanol fermentation process were used to evaluate sulfite as a bacterial-contamination control agent in a cell-recycled continuous ethanol fermentation process . The viabilities of bacteria were decreased by sulfite at concentrations of 100 to 400 mg liter-1, while sulfite at the same concentrations did not change the viability of the Saccharomyces cerevisiae strain used in this process . Sulfite was effective only in the presence of oxygen . Bacteria showed differences in their susceptibilities to sulfite . Facultatively heterofermentative Lactobacillus casei 4-3 was more susceptible than was obligatory heterofermentative Lactobacillus fermentum 7-1 . The former showed higher enzyme activities involved in the production and consumption of hydrogen peroxide than did the latter . The viability of L . fermentum 7-1 could be selectively controlled by hydrogen peroxide at concentrations of 1 to 10 mM . Based on these findings, it is hypothesized that the sulfur trioxide radical anions formed by peroxidase in the presence of hydrogen peroxide are responsible for the control of contaminating bacteria . Sulfite did not kill the yeast strain, which has catalase to degrade hydrogen peroxide . A cell-recycled continuous ethanol fermentation process was run successfully with sulfite treatments.

Caries Res, 1997, 31(1), 13 - 18
Relationship between caries and level of metabolic balance in children and adolescents with insulin-dependent diabetes mellitus; Karjalainen KM et al.; The relationship between the occurrence of caries and diabetes was explored in 80 children and adolescents with insulin-dependent diabetes mellitus . The mean age of the subjects was 14.5 years (range 11.7-18.4 years) and duration of diabetes 0.3-15.0 years (mean 6.0 years) . DFS indices in poorly controlled subjects (glycosylated haemoglobin, HbA1, values over 13%) were significantly higher than in moderately (HbA1 10.0-12.9%) or in well-controlled cases (HbA1 values < 10%) . However, the difference was not statistically significant if adjustments were made for age, age at the onset of diabetes and duration of diabetes (p = 0.1, Ancova) . Subjects with caries and/or fillings had significantly higher short- and long-term HbA1 values than subjects with intact teeth, both if all subjects or subjects with long-term disease (duration of diabetes of at least 2 years, n = 62) were included . This finding was valid after adjustments for age, duration of diabetes and age at the onset of diabetes . Association between poor control and the loss of intact dentition was also demonstrated in subjects whose diabetes was diagnosed before the age of 7 . Presence of yeasts was highly associated with poor control of diabetes, and yeasts were more frequently found in the saliva samples of subjects with decayed and/or filled teeth . Instead, salivary flow rates, salivary lactobacilli and Streptococcus mutans counts, buffering capacity and pH were not different between the subjects . As well, home care practices were similar, and all subjects had received similar regular dental treatment . In conclusion, poor control of diabetes was found to be associated with caries . The presence of yeasts may be a caries risk indicator in subjects with diabetes, since diabetes may enhance yeast growth, particularly if poorly controlled.

Caries Res, 1997, 31(1), 1 - 7
Three-year coronal caries incidence and risk factors in North Carolina elderly; Drake CW et al.; The data presented in this paper are from the Piedmont 65+ Dental Study (1988-1991), designed to assess the levels of coronal and root caries, periodontal disease, tooth loss, and a variety of dental health-related needs among a representative sample of 234 black and 218 white noninstitutionalized older adults in North Carolina . Of the 452 subjects followed for 3 years, 45% of blacks and 59% of the whites developed new coronal caries when caries was defined as decayed and filled surfaces, decayed root fragments, and crowned surface (p = 0.022) . The annualized rate of caries increment for blacks and whites was 0.8 and 1.6 surfaces per 100 at risk (p < 0.001), respectively . The mean 3-year net increment per subject, excluding newly crowned surfaces, was 1.6 and 2.1 (p = 0.025), respectively . Whites had more newly filled and crowned surfaces, whereas blacks had more newly decayed surfaces and more decayed root fragments . Logistic regression models using baseline explanatory variables showed factors related to coronal caries differed between blacks and whites . For blacks, having more teeth, higher concentration of lactobacilli in stimulated saliva, more decayed and filled root surfaces, and smoking were related to the development of new coronal DFS (mostly D) . For whites, having more coronal surfaces at risk and having more physical health problems but not seeking medical care in the past 6 months were related to the development of new coronal DFS (mostly F) . The study showed the caries attack rate to be higher for whites than blacks, mainly as a result of more crown restorations, whereas blacks appeared to be at greater risk for incident lesions . Thus, in order to obtain more realistic figures for caries risk groups, coronal caries increment can and should be presented including and excluding crowns, since the utilization of dental services is likely to differ between groups of older adults.

Proc Natl Acad Sci U S A, 1996 Dec 10, 93(25), 14385 - 90
Deoxycytidine kinase and deoxyguanosine kinase of Lactobacillus acidophilus R-26 are colinear products of a single gene; Ma N et al.; Three of the four deoxynucleoside kinases required for growth of Lactobacillus acidophilus R-26 exist as heterodimeric pairs specific for deoxyadenosine (dAK) and deoxycytidine (dCK) or dAK and deoxyguanosine (dGK) . However, only two tandem genes, dak/dgk, are found, and are expressed only as dAK/dGK in transformed Escherichia coli . Sequencing peptides spanning 63% of the native dCK subunit revealed a sequence identical to that deduced from dgk (beginning MTVIVL...), except that dCK lacks residues 2 and 3 (dCK is M..IVL; dGK is .TVIVL) . Also, mass spectrometry indicates that native dCK and dGK subunits are identical in mass adjusted for the first three residues . Furthermore, the native enzymes have identical isoelectric pH values, indicating an equal number of charged residues . To enable E . coli to express peptide having the native dCK sequence, codons 2 and 3 were deleted from the dgk portion of the tandem genes, resulting in expression of protein having the specificities and regulatory properties of native dAK/dCK, including heterotropic stimulation of dAK activity by deoxycytidine or dCTP (not deoxyguanosine or dGTP) and end-product inhibition of the respective activities by dATP and dCTP . Subcloning normal and mutant dgk yielded homodimeric dGK and dCK, respectively . The dCK homodimer strongly resembles human dCK, with a low K(m) for deoxycytidine, the ability to phosphorylate deoxyadenosine and deoxyguanosine at much higher K(m) values, and end-product inhibition by dCTP . Thus two distinct and specific enzymes evidently are derived from a single Lactobacillus gene . The mechanism by which this occurs in vivo has yet to be elucidated.

Gene, 1996 Dec 5, 182(1-2), 37 - 43
Structure and organisation of the pyrimidine biosynthesis pathway genes in Lactobacillus plantarum: a PCR strategy for sequencing without cloning; Elagoz A et al.; This report describes the sequence and structural organisation of the pyrimidine biosynthesis pathway genes of Lactobacillus plantarum CCM 1904 . It also describes an in vitro technique based on PCR for sequencing without cloning . This new technique was developed because it was impossible to clone certain parts of the L . plantarum genomic DNA in the Escherichia coli host . L . plantarum pyr genes are organised as a 9.8-kb operon with the following order: pyrR, pyrB, pyrC, pyrAA, pyrAB, pyrD, pyrF and pyrE . There are two major differences from the pyrimidine operons of Bacillus subtilis (Quinn et al., J . Bacteriol . 266 (1991) 9113-9127; Turner et al., J . Bacteriol, 176 (1994) 3708-3722) and Bacillus caldolyticus (Ghim et al., Microbiology 140 (1994) 479-491): the absence of pyrP encoding for uracil permease, and the absence of an open reading frame named orf2, whose function is unknown . Two mutually exclusive stem-loop structures were predicted at the 5'-end of L . plantarum pyr mRNA; this operon could be regulated by transcriptional attenuation under the control of PyrR . Complementation of E . coli pyrD, pyrF and pyrE mutants was obtained with a L . plantarum genomic DNA library . Alignment of the L . plantarum Pyr proteins with other known procaryotic Pyr proteins indicates that they display highly conserved regions in Gram-positive and Gram-negative bacteria.

Sci Total Environ, 1996 Dec 2, 192(2), 183 - 91
The association of tooth lead content with dental health factors; Gil F et al.; The purpose of this study was to determine the relationships of lead content in the human tooth with the prevalence of caries, dental plaque, pH of saliva, levels of Salivalis lactobacilli (SL) and Mutans streptococci (MS), degree of dental abrasion, tooth colour and toothbrushing frequency . A total of 220 teeth (one per person) were analysed using a microwave oven digestion procedure and lead content was measured by atomic absorption spectrometry . Tooth lead content followed a logarithmic-normal distribution and it increased with the prevalence of caries . Tooth lead concentrations were positively correlated with all the considered dental health factors except the pH of saliva, for which there was a significant negative correlation . Coloured teeth and teeth subject to abrasion showed the highest lead content . The highest number of colonies of SL and MS in saliva paralleled the highest lead tooth levels . Teeth obtained from irregular brushers presented higher tooth lead contents than subjects with a regular toothbrushing frequency . Multiple logistic regression analysis showed a significant association between tooth lead levels and dental plaque surface, Salivalis lactobacilli number, dental abrasion and dental colour . We conclude that accumulation of lead in teeth is associated with those dental health factors.

Indian J Exp Biol, 1996 Dec, 34(12), 1245 - 7
Antagonistic activity of Lactobacillus acidophilus fermented milk against different pathogenic bacteria; Gupta PK et al.; Lactobacillus acidophilus strains tested showed inhibitory activity towards Salmonella typhi, Staphylococcus aureus, Escherichia coli, Proteus vulgaris and Yersinia enterocolitica . However, wide variations in the activity of the strains were observed . Antagonistic activity of the strains exhibited high heat stability (120 min at 92 degrees C, 15 min at 121 degrees C) but it was markedly influenced by changes in pH . Effect of kind of milk on antagonistic activity was variable, whereas skimming had no significant effect.

Oral Dis, 1996 Dec, 2(4), 285 - 90
Oral candidosis in long-term hospital care: comparison of edentulous and dentate subjects; Budtz-Jlrgensen E et al.; OBJECTIVE: To obtain information on the oral health status of the elderly living in a medicalized, geriatric institution . DESIGN: A cross-sectional clinical investigation with complementary microbiological studies . SUBJECTS AND METHODS: A cohort of 233 elderly in one long-term care ward; collection of demographic data; clinical examination to determine dental and prosthetic status and health of the oral mucosae; swabs for detection of mucosal and denture colonization by Candida; paraffin stimulated saliva for detection of colonization by mutans streptococci and lactobacilli . MAIN OUTCOME MEASURES: Oral and denture hygiene; oral mucosal health; degree of colonization by Candida, mutans streptococci and lactobacilli . RESULTS: Mean age of the 233 patients was 85.6 +/- 6.9 years; 61% were totally dependent, 62.7% were wearing one or two complete dentures; 19.7% had natural teeth and no denture and 17.6% neither teeth nor denture . Of those wearing dentures 72% had denture stomatitis . Of those with natural teeth 72% were affected by active caries . Yeast counts were significantly correlated with the intensity of the erythema of the palatal mucosa, plaque score of the natural teeth, denture plaque score, and salivary counts of mutans streptococci and lactobacilli . CONCLUSIONS: High oral yeast counts and frequent prevalence of oral candidosis in elderly subjects living in institutions are associated with poor oral hygiene and neglect of denture care.

J Dent Res, 1996 Dec, 75(12), 1942 - 6
Prediction of secondary caries around tooth-colored restorations: a clinical and microbiological study; Kidd EA et al.; Caries at the margins of restorations is difficult to diagnose, and the relevance of staining and ditching around tooth-colored fillings is unclear . This clinical study questions the relevance of marginal color change and marginal ditching to the level of infection of the dentin beneath the margins of tooth-colored restorations . Clinically visible sites (197) on the tooth/restoration margin were selected in 113 teeth . The filling margin and the enamel adjacent to each site were noted as stained or stain-free, and sites were graded as intact, having a narrow ditch, or having a wide ditch . Thirty sites with frankly carious lesions were also included . Plaque was sampled at the tooth-restoration margin and the filling removed . The enamel-dentin junction (EDJ) at each sample site was noted as hard or soft when probed, and the dentin was sampled . Samples were vortexed, diluted, and cultured for total anaerobic counts, mutans streptococci, and lactobacilli . There were more bacteria in the plaque over frankly carious cavities, and the dentin was soft and heavily infected . Only 38 out of 167 sites without frankly carious cavities had soft dentin at the EDJ . Both the plaque and dentin in these sites harbored more micro-organisms . However, none of the clinical criteria chosen would reliably predict the presence of this soft dentin . In this study, only a frankly carious lesion at the margin of the filling constituted a reliable diagnosis of secondary caries.

J Dairy Sci, 1996 Dec, 79(12), 2121 - 8
Hypocholesterolemic action of Lactobacillus acidophilus ATCC 43121 and calcium in swine with hypercholesterolemia induced by diet; De Rodas BZ et al.; Thirty-three Yorkshire barrows (92 kg), fed a high cholesterol diet for 14 d had mean concentrations of serum cholesterol of 294.6 +/- 7.8 mg/dl . Starting on d 15 and for an additional 15 d, crystalline cholesterol was removed from the diet and pigs were assigned to one of four treatments: including two levels of calcium (0.7% and 1.4%) with and without added viable Lactobacillus acidophilus ATCC 43121 (2.5 x 10(11) cells per feeding) . Serum cholesterol levels decreased, as expected, for all groups . However, the declines were initiated sooner for the groups receiving L . acidophilus . and those receiving the high level of calcium than for the respective control groups . When averaged over days, pigs fed L . acidophilus had 11.8% lower total cholesterol than pigs fed a diet without L . acidophilus . Similarly, pigs fed 1.4% calcium had a significantly lower total cholesterol than pigs fed 0.7% calcium . The effects were greater on low density lipoprotein cholesterol than on high density lipoprotein cholesterol . In addition, during the overall 15-d experimental period, serum bile acids were reduced 23.9% by dietary L . acidophilus and by 21.4% by 1.4% dietary calcium compared with those of their controls . Total bile acid concentration was positively correlated with total cholesterol concentration for pigs fed L . acidophilus or 1.4% calcium . These data suggest that both L . acidophilus and calcium can enhance the reduction of serum cholesterol in pigs that had been fed a high cholesterol diet, probably through alteration in the enterohepatic circulation of bile acids.

J Dairy Sci, 1996 Dec, 79(12), 2112 - 20
Immunomodulatory activity of beta-casein permeate medium fermented by lactic acid bacteria; Laffineur E et al.; During fermentation, lactic acid bacteria may be able to release components that possess immunomodulatory activity . This activity was investigated in several culture supernatants arising from lactic acid bacteria cultured in a medium composed primarily of UF permeate of bovine milk; beta-CN was added as the sole protein source . Only a Lactobacillus helveticus supernatant allowed the modulation (both suppression and enhancement) of lymphocyte proliferation in vitro on human peripheral blood lymphocytes, but L . helveticus did not modulate the cytotoxic activity of natural killer cells or of lymphokine-activated killer cells . The addition of different quantities of culture supernatant to cultures of human mononuclear cells, stimulated by the mitogen concanavalin A, significantly increased the production of interferon-gamma and decreased the production of interleukin-2 and the expression of the alpha-chain of the interleukin-2 receptor (p55), all of which appear to be correlated with the decrease in lymphocyte proliferation . Our results suggest that the culture supernatant activity might be related to interaction with monocyte-macrophage and T helper cells, especially Th1-like cells.

Microbiology, 1996 Dec, 142 ( Pt 12), 3469 - 77
Lactobacillus curvatus has a glucose transport system homologous to the mannose family of phosphoenolpyruvate-dependent phosphotransferase systems; Veyrat A et al.; In Lactobacillus curvatus, a phosphoenolpyruvate:mannose phosphotransferase system (mannose-PTS) has been characterized and it was shown to be involved in glucose and mannose transport, but no glucose-specific PTS activity could be detected . A 2.1 kb DNA fragment amplified by PCR from the L . curvatus genome was sequenced . Sequence analysis showed four ORFs which could encode proteins similar to PTS transporters EIIA, EIIB, EIIC and EIID of the mannose class . The expression of the manB gene (encoding EIIB) from L . curvatus in a mutant of Lactobacillus sake impaired in EIIMan activity restored this activity . Furthermore, this DNA fragment complemented the regulatory function of LevE (EIIB) in a Bacillus subtilis levE-deficient mutant, suggesting that the protein encoded by manB could also play a regulatory role in L . curvatus.

Microbiology, 1996 Dec, 142 ( Pt 12), 3459 - 68
An operon from Lactobacillus helveticus composed of a proline iminopeptidase gene (pepI) and two genes coding for putative members of the ABC transporter family of proteins; Varmanen P et al.; A proline iminopeptidase gene (pepI) of an industrial Lactobacillus helveticus strain was cloned and found to be organized in an operon-like structure of three open reading frames (ORF1, ORF2 and ORF3) . ORF1 was preceded by a typical prokaryotic promoter region, and a putative transcription terminator was found downstream of ORF3, identified as the pepI gene . Using primer-extension analyses, only one transcription start site, upstream of ORF1, was identifiable in the predicted operon . Although the size of mRNA could not be judged by Northern analysis either with ORF1-, ORF2- or pepI-specific probes, reverse transcription-PCR analyses further supported the operon structure of the three genes . ORF1, ORF2 and ORF3 had coding capacities for 50.7, 24.5 and 33.8 kDa proteins, respectively . The ORF3-encoded PepI protein showed 65% identity with the PepI proteins from Lactobacillus delbrueckii subsp . bulgaricus and Lactobacillus delbrueckii subsp . lactis . The ORF1-encoded protein had significant homology with several members of the ABC transporter family but, with two distinct putative ATP-binding sites, it would represent an unusual type among the bacterial ABC transporters . ORF2 encoded a putative integral membrane protein also characteristic of the ABC transporter family . The pepI gene was overexpressed in Escherichia coli . Purified PepI hydrolysed only di and tripeptides with proline in the first position . Optimum PepI activity was observed at pH 7.5 and 40 degrees C . A gel filtration analysis indicated that PepI is a dimer of M(r) 53,000 . PepI was shown to be a metal-independent serine peptidase having thiol groups at or near the active site . Kinetic studies with proline-p-nitroanilide as substrate revealed Km and Vmax values of 0.8 mM and 350 mmol min-1 mg-1, respectively, and a very high turnover number of 135,000 s-1.

Chem Pharm Bull (Tokyo), 1996 Dec, 44(12), 2263 - 7
Chemical composition of the cell wall of lactic acid bacteria and related species; de Ambrosini VM et al.; In order to examine the relationship between biological activities and the cell wall content, the murein type and the teichoic acid of the cell wall from five strains of bacteria were studied . Two of these Lactobacillus casei CRL 431 and L . acidophilus CRL 730, are used in a commercial fermented milk (BIO MILK), which is believed to be beneficial for health . The other strains, Lactococcus lactis CRL 526, Pediococcus pentosaceus CRL 923 and Propionibacterium acidipropionici CRL 1198 were included in order to compare the cell wall structures of active and inactive strains . A method was designed to confirm the amino acids of the peptidoglycan in impure substrates . Four of the studied strains, L . casei, L . acidophilus, L . lactis and P . acidipropionici, contained glycerol teichoic acids . L . casei, L . acidophilus, P . pentosaceus and L . lactis contained A4 alpha type murein, while P . acidipropionici contained A3 gamma type . The capacity of orally administered peptidoglycans of the studied strains to stimulate phagocytosis by mouse peritoneal macrophages was analyzed . Only the PG of L . casei showed this activity . No differences were observed between active and inactive strains with respect to the chemical composition of the peptidoglycan . Therefore the biological activity is unlikely to be due to the peptidoglycan structure.

Lett Appl Microbiol, 1996 Dec, 23(6), 379 - 84
Rapid GC analysis of cellular fatty acids for characterizing Lactobacillus sake and Lact . curvatus strains of meat origin; Rementzis J et al.; A rapid procedure based on the gas chromatographic analysis of cellular fatty acids was used to differentiate between strains of Lactobacillus sake and Lact . curvatus isolated from dry salami . All strains had very similar fatty acid profiles except four of them which lacked C19 cycl acid, but neither this feature nor other differences in single fatty acid contents could be successfully correlated with the biochemical discrimination of Lact . sake from Lact . curvatus . When, however, strains were compared on the basis of the total content of fatty acids with 18 carbon atoms divided by that with 16 carbon atoms, a very good correlation with strain characterization by classical methods was achieved . It was concluded that selected cellular fatty acids ratios might be useful for characterizing phylogenetically related strains of lactic acid bacteria.

Lett Appl Microbiol, 1996 Dec, 23(6), 375 - 8
Proteolytic activity of lactobacilli in a model goats' milk curd system; Parra L et al.; Mesophyllic lactobacilli cultures propagated in MRS broth were inoculated in goats' milk curd slurries and incubated at 30 degrees C for 10 d . The micro-organisms tested were Lactobacillus casei subsp . casei IFPL 731 and IFPL 99, and Lactobacillus plantarum IFPL 3 . Whole cells, cell-free extracts and cell lysates were evaluated for acceleration of proteolysis in the curd slurries . Conversion of water-soluble nitrogen to non-protein nitrogen and amino acid nitrogen, reverse phase-HPLC peak areas and ratio of hydrophobic to hydrophilic peptides, were all affected by the type of inoculum used as well as the strain under study . The results suggest that the accelerated-ripening model system developed, containing cell lysates, may be suitable as a good and rapid indicator of the contribution of the strains to proteolysis during cheese ripening.

J Appl Bacteriol, 1996 Dec, 81(6), 669 - 77
Isolation, partial characterization and mode of action of acidocin J1229, a bacteriocin produced by Lactobacillus acidophilus JCM 1229; Tahara T et al.; Lactobacillus acidophilus JCM 1229 produces a heat-stable bacteriocin, designated as acidocin J1229, that has a narrow inhibitory spectrum . Production of acidocin J1229 in MRS broth was pH dependent, with maximum activity detected in broth culture maintained at pH 5.0 . Acidocin J1229 was purified by ammonium sulphate precipitation and sequential cation exchange and reversed-phase chromatographies . The sequence of the first 24 amino acid residues of the N terminus of acidocin J1229 was determined . The molecular mass of acidocin J1229 as determined by mass spectrometry was 6301 Da . Acidocin J1229 showed a bactericidal effect but not a bacteriolytic effect on sensitive cells . Acidocin J1229 dissipated the membrane potential and the pH gradient in sensitive cells, which affected such proton motive force-dependent processes as amino acid transport . Acidocin J1229 also caused an efflux of glutamate, previously taken up via a unidirectional ATP-driven transport system . Secondary structure prediction revealed the presence of an amphiphilic alpha-helix region that could form hydrophilic pores . These results suggest that acidocin J1229 is a pore-forming peptide that creates cell membrane channels through the "barrel-stave' mechanism.

J Bacteriol, 1996 Dec, 178(24), 7311 - 5
13C nuclear magnetic resonance analysis of glucose and citrate end products in an ldhL-ldhD double-knockout strain of Lactobacillus plantarum; Ferain T et al.; We have examined the metabolic consequences of knocking out the two ldh genes in Lactobacillus plantarum using 13C nuclear magnetic resonance . Unlike its wild-type isogenic progenitor, which produced lactate as the major metabolite under all conditions tested, ldh null strain TF103 mainly produced acetoin . A variety of secondary end products were also found, including organic acids (acetate, succinate, pyruvate, and lactate), ethanol, 2,3-butanediol, and mannitol.

Appl Environ Microbiol, 1996 Dec, 62(12), 4529 - 35
Purification of the bacteriocin bavaricin MN and characterization of its mode of action against Listeria monocytogenes Scott A cells and lipid vesicles; Kaiser AL et al.; Bavaricin MN was purified from Lactobacillus sake culture supernatant 135-fold with a final yield of 11% . Sequence analysis revealed bavaricin MN to be a 42-amino-acid peptide having a molecular weight of 4,769 and a calculated pI of 10.0 . Computer analysis indicated that the C-terminal region may form an alpha-helical structure with an amphipathic nature deemed important in the interaction of bacteriocins with biological membranes . Bavaricin MN rapidly depleted the membrane potential (delta p) of energized Listeria monocytogenes cells in a concentration-dependent fashion . At a bavaricin MN concentration of 9.0 micrograms/ml, the delta p decreased by 85% . Both the electrical potential (delta psi) and Z delta pH components of the delta p were depleted, and this depletion was not dependent on a threshold level of proton motive force . In addition to studying the effect of bavaricin MN on the delta p of vegetative cells, bavaricin MN-induced carboxyfluorescein (CF) efflux from L . monocytogenes-derived lipid vesicles was also characterized . Bavaricin MN-induced CF leakage was also concentration dependent with an optimum of pH 6.0 . The rate of CF efflux was 63% greater in lipid vesicles in which a delta psi was generated compared with that in lipid vesicles in the absence of a delta psi.

Appl Environ Microbiol, 1996 Dec, 62(12), 4450 - 60
Functional analysis of the gene encoding immunity to lactacin F, lafI, and its use as a Lactobacillus-specific, food-grade genetic marker; Allison GE et al.; Lactacin F is a two-component class II bacteriocin produced by Lactobacillus johnsonii VPI 11088 . The laf operon is composed of the bacteriocin structural genes, lafA and lafX, and a third open reading frame, ORFZ . Two strategies were employed to study the function of ORFZ . This gene was disrupted in the chromosome of NCK64, a lafA729 lafX ORFZ derivative of VPI 11088 . A disruption cassette consisting of ORFZ interrupted with a cat gene was cloned into pSA3 and introduced into NCK64 . Manipulation of growth temperatures and antibiotic selection resulted in homologous recombination which disrupted the chromosomal copy of ORFZ with the cat gene . This ORFZ mutation resulted in loss of immunity to lactacin F but had little effect on production of LafX, which is not bactericidal without LafA . Expression of ORFZ in this ORFZ- background rescued the immune phenotype . Expression of ORFZ in a bacteriocin-sensitive derivative of VPI 11088 also reestablished immunity . These data indicate that ORFZ, renamed lafI, encodes the immunity factor for the lactacin F system . The sensitivity of various Lactobacillus strains to lactacin F was further evaluated . Lactacin F inhibited 11 strains including several members of the A1, A2, A3, A4, B1, and B2 L . acidophilus homology groups . Expression of lafI in bacteriocin-sensitive strains L . acidophilus ATCC 4356, L . acidophilus NCFM/N2, L . fermentum NCDO1750, L . gasseri ATCC 33323, and L . johnsonii ATCC 33200 provided immunity to lactacin F . Furthermore, it was shown that lactacin F production by VPI 11088 could be used to select for L . fermentum NCDO1750 transformants containing the recombinant plasmid encoding LafI . The data demonstrate that lafI is functional in heterologous hosts, suggesting that it may be a suitable food-grade genetic marker for use in lactobacillus species.

Appl Environ Microbiol, 1996 Dec, 62(12), 4381 - 7
Production of pediocin AcH by Lactobacillus plantarum WHE 92 isolated from cheese; Ennahar S et al.; Among 1,962 bacterial isolates from a smear-surface soft cheese (Munster cheese) screened for activity against Listeria monocytogenes, six produced antilisterial compounds other than organic acids . The bacterial strain WHE 92, which displayed the strongest antilisterial effect, was identified at the DNA level as Lactobacillus plantarum . The proteinaceous nature, narrow inhibitory spectrum, and bactericidal mode of action of the antilisterial compound produced by this bacterium suggested that it was a bacteriocin . Purification to homogeneity and sequencing of this bacteriocin showed that it was a 4.6-kDa, 44-amino-acid peptide, the primary structure of which was identical to that of pediocin AcH produced by different Pediococcus acidilactici strains . We report the first case of the same bacteriocin appearing naturally with bacteria of different genera . Whereas the production of pediocin AcH from P . acidilactici H was considerably reduced when the final pH of the medium exceeded 5.0, no reduction in the production of pediocin AcH from L . plantarum WHE 92 was observed when the pH of the medium was up to 6.0 . This fact is important from an industrial angle . As the pH of dairy products is often higher than 5.0, L . plantarum WHE 92, which develops particularly well in cheeses, could constitute an effective means of biological combat against L . monocytogenes in this type of foodstuff.

Int J Food Microbiol, 1996 Dec, 33(2-3), 209 - 18
Isolation and characterization of bacteriocin-producing lactic acid bacteria from ready-to-eat food products; Kelly WJ et al.; Lactic acid bacteria isolated from a range of foods sold in ready-to-eat form were screened for bacteriocin production . Twenty-two bacteriocin-producing cultures were isolated from 14 of the 41 foods sampled . Bacteriocin-producing isolates from meat, fish and dairy products were Lactobacillus and Leuconostoc species typically found associated with these products . Most of these isolates gave only a narrow inhibitory spectrum although two showed activity against Listeria monocytogenes . Fruit and vegetable products gave a broader range of organisms but most of the bacteriocin-producing cultures were found to be strains of Lactococcus . Several lactococci produced a nisin-like activity, and showed a broad inhibitory spectrum against the indicator strains tested . The ease with which bacteriocin-producing strains could be isolated implies that they are already being safely consumed in food, and highlights the potential for using bacteriocin-producing cultures for biopreservation, especially in association with minimally processed products.

Curr Microbiol, 1996 Dec, 33(6), 359 - 63
Effects of some calcium-related agents on the protoplast transfection of Lactobacillus casei with phage PL-1 DNA; Kakita Y et al.; To clarify the mechanism of Ca2+ involvement in the DNA transfer through cell membrane, we studied the effects of Ca2+-chelator, Ca2+-ionophore, and Ca2+-channel blocker on the protoplast transfection of Lactobacillus casei ATCC 27092 by PL-1 phage DNA in the presence of Ca2+ . Ca2+-chelators, citrate, EDTA, and dipicolinic acid, inhibited the transfection probably by compensating the effect of Ca2+ . Ca2+-ionophores, A23187 and N,N,N', N'-tetracyclohexyl-3-oxapentanediamide, which were expected to accelerate transfection by introducing Ca2+ into cells, inhibited the transfection . This fact indicated the absence of correlation between the entry of Ca2+ and the transport of DNA into protoplasts . Verapamil, which blocks voltage-dependent Ca2+-channel besides beta-adrenergic receptor, inhibited the transfection with little effect on the survival of the protoplasts . Both flunarizine and vinpocetine, voltage-dependent Ca2+-channel blockers, did not show the selective toxicity . D-alpha-Aminoadipic acid, a glutamate receptor-operated Ca2+-channel blocker, had no effect . Propranolol, which blocks beta-adrenergic receptor as does verapamil, inhibited the transfection without severely damaging the protoplasts . These results suggested that a kind of receptor-operated Ca2+-channel was involved in the transport of PL-1 phage DNA into the cells and that the cell membrane might have a receptor structure somewhat similar to the beta-adrenergic receptor found in mammalian cells.

J Biol Chem, 1996 Nov 22, 271(47), 29521 - 4
Molecular cloning of manganese catalase from Lactobacillus plantarum; Igarashi T et al.; A genomic clone encoding manganese-containing catalase has been isolated from lactic acid bacterium Lactobacillus plantarum, sequenced, and expressed in Escherichia coli cells with an inducible expression system . The primary structure of the enzyme deduced from the nucleotide sequence, that comprises 266 amino acid residues, showed no significant homology with that of any other proteins registered on the available data bases . No peptide motifs conserved among active sites of proteins including manganese-containing enzymes were found . The E . coli cells carrying an expression construct, in which the 5'-noncoding region of the manganese catalase gene was replaced with the lac promoter, highly induced a protein reacting with the antiserum to manganese catalase . The prediction of secondary structure from the deduced primary structure suggested that the L . plantarum manganese catalase, that is classified as a novel protein on the basis of its primary structure, has a main structural motif formed by four near parallel helices between which is the catalytic site manganese.

J Med Chem, 1996 Nov 8, 39(23), 4563 - 8
2-amino-4-oxo-5-substituted-pyrrolo{2,3-d}pyrimidines as nonclassical antifolate inhibitors of thymidylate synthase; Gangjee A et al.; Six novel 2-amino-4-oxo-5-{(substituted phenyl)sulfanyl}pyrrolo{2,3-d}pyrimidines 7-12 were synthesized as potential inhibitors of thymidylate synthase (TS) and as antitumor and/or antibacterial agents . The analogues contain a 5-thio substituent with a phenyl, 4'-chlorophenyl, 3',4'-dichlorophenyl, 4'-nitrophenyl, 3',4'-dimethoxyphenyl, and 2'-naphthyl on the sulfur, and were synthesized from the key intermediate 2-(pivaloylamino)-4-oxo-6-methylpyrrolo{2,3-d}-pyrimidine, 17 . Appropriately substituted aryl thiols were appended to the 5-position of 17 via an oxidative addition reaction using iodine, ethanol, and water under conditions which also resulted in the deprotection of the 2-amino group . The compounds were evaluated against human, Lactobacillus casei, Escherichia coli, Streptococcus faecium, and Pneumocystis carinii (pc) TSs and against human, rat liver (rl), pc, and Toxoplasma gondii (tg) DHFRs . The nonclassical analogues with the 3',4'-dichloro and the 4'-nitro substituents in the side chain (9 and 10) were more potent than N-{4-{N-{(2-amino-3,4-dihydro-4-oxo-6-quinazolinyl)methyl}-N-prop- 2-ynylamino}benzoyl}-L-glutamic acid (PDDF, 1) and N-{5-{N-{(3,4-dihydro-2-methyl-4-oxo-6-quinazolinyl)methyl}-N- methylamino}-2-thenoyl}-L-glutamic acid (ZD1694,2) against human TS . Analogues with the 4'-chloro, 3',4'-dimethoxy, and naphthyl side chains (8, 11 and 12) were more potent than the unsubstituted phenyl analogue (7) but less than 2, 9, and 10 by 1 order of magnitude . They were all poor inhibitors of human, rl, and pc DHFRs (IC50 = 10(-5) M) but moderate inhibitors (IC50 = 10(-6) M) of tg DHFR . The 4-nitro analogue, 10 (EC50 1.5 microM), was comparable to PDDF in its potency as an inhibitor of the growth of the FaDu human squamous cell carcinoma cell line.

Arch Oral Biol, 1996 Nov, 41(11), 1011 - 8
Dental caries and caries-associated micro-organisms in the saliva and plaque of 3- and 4-year-old Afro-Caribbean and Caucasian children in south London; Zoitopoulos L et al.; Three and four-year-old Caucasian and Afro-Caribbean children (n = 641) attending childcare facilities in the London boroughs of Lambeth, Lewisham and Southwark were studied in order to determine the prevalence of caries and caries-associated micro-organisms and the interactions between these for each of the racial groups; dmft (decayed, missing or filled teeth) scores were recorded using British Association for the Study of Community Dentistry criteria . Saliva and plaque samples were taken from each child and the numbers of mutans streptococci, lactobacilli and yeasts per sample were determined . The mean dmft scores of the 3- and 4-year-old Afro-Caribbean children were 0.36 +/- 0.10 and 0.51 +/- 0.13, respectively, compared to 0.80 +/- 0.17 and 1.48 +/- 0.24 for the equivalent Caucasian children (p < 0.001) . Mutans streptococci and lactobacilli were recovered less frequently from the Afro-Caribbean children than from the Caucasian, but in both groups there were significant correlations between the plaque and salivary levels of mutants streptococci and caries experience . In both groups, children from whom both mutans streptococci and lactobacilli were isolated had the greatest mean dmft scores and these were not significantly different . Multiple regression analyses demonstrated that, after controlling for age and dmft, there were still significant associations between race and salivary levels of mutans streptococci and lactobacilli, p = 0.0013 and p = 0.0167, respectively . These data indicate that Afro-Caribbean children had lower levels of dental caries than Caucasian children living in the same London boroughs and attending the same preschool care facilities and, after controlling for age and caries experience, they also had lower salivary levels of mutans streptococci and lactobacilli.

Mikrobiol Z, 1996 Nov-Dec, 58(6), 12 - 8
{The lysozyme-synthetizing activity of enterococci and lactobacilli}; Kovalenko NK et al.; Lysozyme-synthesizing activity of a large collection of cultures of lactic-acid bacteria isolated from various natural substrates has been studied . It is shown that the degree of lysozyme production depends on the source of bacteria isolation . Representatives of Enterococcus genus isolated from the digestive tract of long-living people, as well as fishes, geese and ducks are most active among the coccal forms . Manifestation of lysozyme-synthesizing activity in lactobacilli depends on the group and species belonging of strains . It is established that the capacity to produce lysozyme can serve a diagnostic characteristic under identification of lactobacillus of subgenus Betabacterium . Lysozyme produced by lactic acid bacteria is one of the components in the total complex of the mechanism of biological activity of this important group of microorganisms.

Minerva Med, 1996 Nov, 87(11), 545 - 50
{Clinical assessment of a new oral bacterial treatment for children with acute diarrhea}; Michielutti F et al.; This study was carried out to evaluate the efficacy of a new oral bacteriotherapeutic drug in 63 children under 4 years old affected by infective diarrhoea or by extraintestinal infective pathology caused by oral antibiotic therapy . The patients were divided into three groups: the first and the second included subjects affected by acute diarrhoea enrolled in a comparative and controlled study; the third included subjects in chemotherapeutic treatment because suffering from infective extraintestinal pathologies, these patients were enrolled in a not controlled study . The first group underwent the rehydratant treatment for the acute enteritis together with the therapy with inactivated Lactobacillus acidophilus LB to value its antidiarrheic activity . To the second group (control group) was administered a no bacteriotherapeutic drug, while to the third group was administered the antibiotic therapy for extra-intestinal pathologies together with inactivated Lactobacillus acidophilus to avoid possible phenomena due to intestinal dysmicrobism . For all the patients included in the study, were reported; the number, the characteristics, the consistency of the motions and the description of the symptomatology during the treatment and daily . The greater part of the patients affected by the intestinal infective pathology subdued bacteriologic tests by coproculture . The obtained results showed a statistically significant clinical improvement of the first group patients compared with those of the second group, while those of the third group showed that the drug activity prevents the intestinal dysmicrobism affections due to the antibiotic therapy.

Med Microbiol Immunol (Berl), 1996 Nov, 185(3), 157 - 61
Effects on antitumor activity and cytokine production in the thoracic cavity by intrapleural administration of Lactobacillus casei in tumor-bearing mice; Matsuzaki T et al.; The effects Lactobacillus casei YIT9108 (LC 9018) on antitumor activity and cytokine production in Meth A fibrosarcoma (Meth A)-bearing BALB/c mice were examined . Intrapleural (i.pl.) administration of LC 9018 was effective in prolonging the survival of Meth A-bearing mice, and frequently cured mice of the tumor . However, the results also indicated that the effect of LC 9018 was in part inhibited in mice treated with anti-CD3 or anti-CD8 antibody, but not affected in anti-CD4 antibody-treated mice . In contrast, LC 9018 had little effect on Meth A-bearing SCID or nude mice . These results demonstrated that CD8+ T cells participated in prolonging the survival of Meth A-bearing mice . Moreover, the examination of the production of several cytokines revealed that the production of interferon-gamma and interleukin-6 was, in particular, augmented in the exudated fluid of the thoracic cavity in BALB/c mice injected with LC 9018 i.pl . These results suggested that i.pl . administration of LC 9018 induced those cytokines which had the potential to activate the thoracic macrophages or proliferate the thoracic lymphocytes to the cytotoxic T cells . Taken together, these findings demonstrated that the prolonging effects on survival by i.pl . administration of LC 9018 depended on CD8+ T cells, and the i.pl . administration of LC 9018 into i.pl . Meth A-bearing mice induced several cytokines which participated in the subsequent immunoresponses.

Appl Microbiol Biotechnol, 1996 Nov, 46(4), 334 - 9
Mathematical description of the growth of Lactobacillus sake and Lactobacillus pentosus under conditions prevailing in fermented sausages; Dossmann MU et al.; The growth behaviour of Lactobacillus sake and Lactobacillus pentosus was determined in a model system stimulating the conditions of fermenting sausages . Minor effects on the growth were observed by varying the concentrations of glucose, peptone, manganese and sodium nitrite . Temperature and sodium chloride concentration were found to have most effect on the growth . The measured data were used for a mathematical model describing the growth response of L . sake and L . pentosus sufficiently well to estimate the behaviour of the investigated strains . In all combinations relevant to sausage fermentation L . sake proved to be more competitive . It exhibited a shorter lag phase, higher maximal growth rate and higher final cell yield than L . pentosus.

Berl Munch Tierarztl Wochenschr, 1996 Nov-Dec, 109(11-12), 428 - 30
The effect of lactobacilli inoculation on organic acid levels in the mucosal film and the small intestine contents in gnotobiotic pigs; Bomba A et al.; The effect of the inoculation of three Lactobacillus plantarum strains upon lactic, acetic, acetoacetic and propionic acid levels in the mucosal film (F) and the jejunal and ileal contents (O) has been investigated in gnotobiotic pigs . In the jejunum of the inoculated animals, the mucosal film revealed significantly increased levels of lactic, propionic and acetoacetic acids when compared to the contents (25.3 vs . 10.8 mmol.l-1, 18.5 vs . 5 mmol.l-1 and 29.7 vs . 11.2 mmol.l-1, respectively) as well as insignificantly increased acetic acid levels (11.0 vs . 5.8 mmol.l-1) . In the ileum of gnotobiotic pigs, propionic acid levels of the mucosal film were significantly higher than those of the contents (21.2 vs . 9.5 mmol.l-1, p < 0.05) . In comparison to the contents, the increased lactic, acetic and acetoacetic acid levels in the film proved to be insignificant . The above results suggest that the significantly increased levels of the Lactobacilli-produced organic acids may present an efficient barrier inhibiting the adherence of digestive tract pathogens to the intestinal mucosa.

Sex Transm Dis, 1996 Nov-Dec, 23(6), 489 - 93
The vaginal microflora of pig-tailed macaques and the effects of chlorhexidine and benzalkonium on this ecosystem; Patton DL et al.; BACKGROUND AND OBJECTIVES: To characterize normal vaginal microflora of pig-tailed macaques and to evaluate two commonly used intravaginal compounds, chlorhexidine (CHG), a vaginal antiseptic (Surgilube, E . Fougera, Melville, NY), and benzalkonium chloride (BZK) (spermicidal contraceptive) in this monkey model to assess effects on the vaginal microflora . STUDY DESIGN: Vaginal swabs were collected for microbiologic analysis to characterize normal flora . Subsequently, the vagina was exposed to either CHG or BZK twice at 24-hour intervals . RESULTS: The vaginal microflora of 26 pig-tailed macaques was found to be remarkably similar to the vaginal flora of the human with respect to frequency of vaginal colonization by H2O2-producing lactobacilli, Prevotella species, and several other microorganisms . After two vaginal applications at 24-hour intervals, CHG had only small effects on the vaginal microflora of five animals . By contrast, BZK applied by the same protocol had profound adverse effects on the lactobacilli and Peptostreptococcus and more transient effects on vaginal Prevotella and viridans streptococci of six animals . CONCLUSIONS: These observations demonstrate that the vaginal microflora of the pig-tailed macaque is a useful model in which to further evaluate newly developed intravaginal contraceptives that may be microbicidal and/or virucidal before widespread intravaginal use in women.

Sex Transm Dis, 1996 Nov-Dec, 23(6), 461 - 4
Effects of nonoxynol-9 on vaginal microflora and chlamydial infection in a monkey model; Patton DL et al.; BACKGROUND AND OBJECTIVES: Nonoxynol-9, an intravaginal microbicide, is chlamydiacidal in vitro but also cytotoxic . This study examines the effects of nonoxynol-9 in vivo, using a pigtail macaque model of chlamydial cervicitis . GOALS: To establish a minimum infectious dose of Chlamydia trachomatis in the macaque, and to observe the effects of a single dose of nonoxynol-9 on efficiency of chlamydial infection, vaginal microflora, and cervicovaginal irritation . STUDY DESIGN: The effects of 4% nonoxynol-9, C . trachomatis (5,000 or 10,000 IFU) or both nonoxynol-9 application and chlamydial infection were studied in 17 macaques . RESULTS: Following a single application of nonoxynol-9, chlamydial infection was prevented in 4 of 6 monkeys infected with 10,000 IFU; there was a transient decrease in anaerobic gram-negative rods (P < 0.05) and Peptostreptococci (P > 0.05), but no change in Lactobacillus . Mild cervicovaginal irritation was observed in the monkeys . CONCLUSIONS: A single dose of nonoxynol-9 causes minimal vaginal flora and epithelial irritation, and may be useful for prevention of chlamydial infection.

J Appl Bacteriol, 1996 Nov, 81(5), 474 - 80
Colonization by lactobacilli of piglet small intestinal mucus; Rojas M et al.; The colonization potential of lactobacilli was investigated using small intestinal mucus extracts from 35-d-old pigs . Mucus-secreting tissue from the small intestine of piglets was gently rinsed to remove contents and then shaken in buffer to release mucus from the surface . Numbers of lactobacilli in different portions of the small intestine of 35-d-old pigs were enumerated . Also, mucus isolated from the small intestine of pigs was investigated for its capacity to support the growth of lactobacilli . Results indicated that Lactobacillus spp . inhabit the mucus layer of the small intestine and can grow and adhere to ileal mucus . From adhesion studies of Lactobacillus fermentum 104R to mucus analysed by Scatchard plot, it is suggested that an associating system showing positive cooperativity is involved . Proteinaceous compounds(s) involved in the adhesion to mucus were detected in the spent culture fluid from the growth of strain 104R . Studies are continuing in order to identify and characterize the adhesion-promoting protein(s) . From the data, it is proposed that lactobacilli colonize the mucus layer of the small intestine of pigs.

J Prosthet Dent, 1996 Nov, 76(5), 483 - 6
In vitro evaluation of antibacterial effects of photo-cured glass ionomer liners and dentin bonding agents during setting; Fraga RC et al.; Two dentin bonding agents (Optibond and Syntac), an enamel bonding agent (Heliobond), and two photo-cured glass ionomer cements (Vitremer and Variglass VLC) and their inhibitory effects on bacterial growth during setting were examined . Cultures of eight bacterial species were used to test these materials, except for Vitremer glass ionomer cement, which was tested against only five species . The photo-cured glass ionomer cements and the Syntac dentin bonding system with glutaraldehyde demonstrated a significant inhibitory effect on the growth of several bacteria . Meanwhile, Variglass VLC glass ionomer cement did not exhibit this effect on Lactobacillus casei and Streptococcus sobrinus . Optibond light-cured dentin bonding agent, with fluoride and fillers in its composition, and Heliobond (negative control group) did not demonstrate any inhibitory effect.

J Bacteriol, 1996 Nov, 178(22), 6487 - 95
A bifunctional urease enhances survival of pathogenic Yersinia enterocolitica and Morganella morganii at low pH; Young GM et al.; To infect a susceptible host, the gastrointestinal pathogen Yersinia enterocolitica must survive passage through the acid environment of the stomach . In this study, we showed that Y . enterocolitica serotype O8 survives buffered acidic conditions as low as pH 1.5 for long periods of time provided urea is available . Acid tolerance required an unusual cytoplasmically located urease that was activated 780-fold by low-pH conditions . Acid tolerance of Helicobacter species has also been attributed to urease activity, but in that case urease was not specifically activated by low-pH conditions . A ure mutant strain of Y . enterocolitica was constructed which was hypersensitive to acidic conditions when urea was available and, unlike the parental strain, was unable to grow when urea was the sole nitrogen source . Examination of other urease-producing gram-negative bacteria indicated that Morganella morganii survives in acidic conditions but Escherichia coli 1021, Klebsiella pneumoniae, Proteus mirabilis, Providencia stuartii, and Pseudomonas aeruginosa do not . Consistent with these results, biochemical evidence demonstrated that Y . enterocolitica and M . morganii ureases were activated in vitro by low pH with an unusually low activity optimum of pH 5.5 . In whole cells activation occurred as medium values decreased below pH 3.0 for Y . enterocolitica and pH 5.5 for M . morganii, suggesting that in vivo activation occurs as a result of cytoplasmic acidification . DNA sequence analysis of portions of the M . morganii ure locus showed that the predicted primary structure of the enzyme structural subunits is most similar to those of Y . enterocolitica urease . One region of similarity between these two ureases located near the active site is distinct from most other ureases but is present in the urease of Lactobacillus fermentum . This region of similarity may be responsible for the unique properties of the Y . enterocolitica and M . morganii ureases since the L . fermentum urease also has been shown to have a low pH optimum for activity.

Arch Fam Med, 1996 Nov-Dec, 5(10), 593 - 6
Ingestion of yogurt containing Lactobacillus acidophilus compared with pasteurized yogurt as prophylaxis for recurrent candidal vaginitis and bacterial vaginosis; Shalev E et al.; To compare and assess ingestion of yogurt that contained live Lactobacillus acidophilus with pasteurized yogurt as prophylaxis for recurrent bacterial vaginosis (BV) and candidal vaginitis, we designed a crossover trial during which patients were examined monthly for candidal infection and BV while they were receiving either a pasteurized yogurt or a yogurt that contained live L acidophilus . Forty-six patients in 2 groups of 23 were randomly assigned to each of the study groups . At least 28 (61%) participated during the first 4 months of the study . Seven patients completed the entire study protocol . We concluded that daily ingestion of 150 mL of yogurt, enriched with live L acidophilus, was associated with an increased prevalence of colonization of the rectum and vagina by the bacteria, and this ingestion of yogurt may have reduced episodes of BV.

Am J Orthod Dentofacial Orthop, 1996 Nov, 110(5), 469 - 75
Clinical and microbiologic evaluation of a resin modified glass ionomer cement for orthodontic bonding; Wright AB et al.; This study evaluated the clinical performance of a new resin modified glass ionomer cement, Geristore (Den-Mat Corp., Santa Maria, Calif.), for the bonding of orthodontic brackets and its effect on certain caries-associated microorganisms . This cement has been shown to possess increased mechanical properties and long-term fluoride release . There were 716 brackets bonded in 40 patients (17 males and 23 females), with a split-mouth technique and a composite resin, Phase II (Reliance, Itasca, III.), as a control . Bond failures were recorded up to 1 year . Plaque scores and plaque samples were taken from the area of the bonding adhesive in 20 patients, before, at 1 week, and 5 months after the placement of brackets . The plaque samples were investigated for the presence of Streptococcus mutans and lactobacilli . The overall bond failure rate was found to be 8.9% for Geristore and 3.1% for Phase II (p < 0.05) . Labially, there was no significant difference (p > 0.05) in bond failure rate: 3.8% for Geristore and 1.7% for Phase II . The proportions of S . mutans and lactobacilli in plaque taken from around Geristore cement were reduced at 1 week and 5 months, when compared with Phase II resin, and this reduction was statistically significant (p < 0.05) at 1 week . Results of this study suggest that Geristore may be of use in the labial segments, especially in caries prone patients, in whom demineralization at debond may present an esthetic and restorative problem several years after treatment.

Biochem Biophys Res Commun, 1996 Nov 1, 228(1), 148 - 52
Binding specificity of Lactobacillus to glycolipids; Yamamoto K et al.; Lactobacillus, a representative useful bacterium, in the intestinal tract was found to bind to some specific glycosphingolipids, like the pathogenic intestinal bacteria . Thin layer chromatography overlay assays using rabbit antiserum against Lactobacillus casei revealed that the bacteria bound to GA1 and trihexosylceramide strongly, but not to any gangliosides . The bacteria generally bound to glycosphingolipids having short sugar chains and galactosyl moiety in the non-reducing terminal . L.casei did not bind to GM1, but bound to the product after sialidase treatment, GA1 . This indicated that sialic acid inhibited the adhesion of L.casei to tissues . L.casei actually bound nonacid glycosphingolipids but not acid glycosphingolipids extracted from the small intestinal mucosa of rats.

Clin Chem, 1996 Nov, 42(11), 1847 - 54
Enzymatic deconjugation of erythrocyte polyglutamyl folates during preparation for folate assay: investigation with reversed-phase liquid chromatography; Pfeiffer CM et al.; Erythrocyte (RBC) folates occur mainly as 5-methyltetrahydrofolate polyglutamates . Determination of RBC folate concentration requires an initial deconjugation of these polyglutamates . In this study, existing HPLC methods were adapted to investigate the rate and extent of this deconjugation process . The action of endogenous plasma pteroyl-polyglutamate hydrolase activity was strongly affected by the conditions of sample preparation, with pH of the incubation mixture more critical to effective deconjugation than incubation time . Dilution of whole blood with 10 g/L ascorbic acid yielded fast hydrolysis of long-chain polyglutamates, and total conversion to 5-methyltetrahydrofolate monoglutamate occurred after 90 min of incubation at 37 degrees C . In contrast, dilution of whole blood with 10 g/L sodium ascorbate, with up to 90 min of incubation at 37 degrees C, yielded a mixture of polyglutamates of 5-methyltetrahydrofolate (glun = 1-8) . As documented by direct HPLC analysis and in concurrent assays with Lactobacillus casei, acidification provided by ascorbic acid can have dramatic effects on the measurement of RBC folates.

Am J Clin Nutr, 1996 Nov, 64(5), 767 - 71
A placebo-controlled study of the effect of sour milk on blood pressure in hypertensive subjects; Hata Y et al.; A placebo-controlled study was conducted to test the effect of Calpis (Calpis Food Industry Co, Ltd, Tokyo, Japan) sour milk, i.e., a milk fermented with a starter containing Lactobacillus helveticus and Saccharomyces cerevisiae, on the blood pressure of 30 elderly hypertensive patients, most of whom were taking antihypertensive medication . Subjects were randomly assigned to two groups . One group ingested daily 95 mL of the sour milk for 8 wk, and the other group ingested the same amount of artificially acidified milk as a placebo for 8 wk . In the sour-milk group, systolic blood pressure decreased significantly 4 and 8 wk after ingestion, by 9.4 +/- 3.6 mm Hg (mean+/- SE, P < 0.05) and 14.1 +/- 3.1 mm Hg (P < 0.01), respectively . The diastolic blood pressure also decreased significantly, by 6.9 +/- 2.2 mm Hg (P < 0.01), by 8 wk after ingestion of the sour milk began . No significant changes in blood pressure were observed in the placebo group . The decrease in systolic and diastolic blood pressure in the sour-milk group tended to be greater than in the placebo group . No marked changes were observed in other indexes, including pulse rate, body weight, and blood serum variables in both groups.

Appl Environ Microbiol, 1996 Nov, 62(11), 4238 - 42
Inhibition of microbial growth by ajoene, a sulfur-containing compound derived from garlic; Naganawa R et al.; Ajoene, a garlic-derived sulfur-containing compound that prevents platelet aggregation, exhibited broad-spectrum antimicrobial activity . Growth of gram-positive bacteria, such as Bacillus cereus, Bacillus subtilis, Mycobacterium smegmatis, and Streptomyces griseus, was inhibited at 5 micrograms of ajoene per ml . Staphylococcus aureus and Lactobacillus plantarum also were inhibited below 20 micrograms of ajoene per ml . For gram-negative bacteria, such as Escherichia coli, Klebsiella pneumoniae, and Xanthomonas maltophilia, MICs were between 100 and 160 micrograms/ml . Ajoene also inhibited yeast growth at concentrations below 20 micrograms/ml . The microbicidal effect of ajoene on growing cells was observed at slightly higher concentrations than the corresponding MICs . B . cereus and Saccharomyces cerevisiae were killed at 30 micrograms of ajoene per ml after 24 h of cultivation when cultivation was started at 10(5) cells per ml . However, the minimal microbicidal concentrations for resting cells were at 10 to 100 times higher concentrations than the corresponding MICs . The disulfide bond in ajoene appears to be necessary for the antimicrobial activity of ajoene, since reduction by cysteine, which reacts with disulfide bonds, abolished its antimicrobial activity.

J Infect Dis, 1996 Nov, 174(5), 1058 - 63
Hydrogen peroxide-producing lactobacilli and acquisition of vaginal infections; Hawes SE et al.; This cohort study of 182 women attending a sexually transmitted disease clinic evaluated the hypothesis that women colonized by lactobacilli have decreased acquisition of vaginal infections . During a 2-year follow-up, 50 women acquired bacterial vaginosis (BV), 25 acquired symptomatic vulvovaginal candidiasis (VVC), and 7 acquired vaginal trichomoniasis . By multivariate analysis, utilizing Cox proportional hazards modeling with time-dependent covariates, acquisition of BV was independently associated with lack of vaginal H2O2-producing lactobacilli (hazard ratio {HR} = 4.0, P < .001) or presence of only non-H2O2-producing lactobacilli (HR = 2.2, P = .02) . Acquisition of BV was associated with having a new sex partner (HR = 2.5, P = .004) and with douching for hygiene (HR = 2.1, P = .05) . Absence of lactobacilli did not increase acquisition of VVC . Trichomoniasis was associated only with having a new sex partner (HR = 4.7, P = .05) . These results support the hypothesis that H2O2-producing vaginal lactobacilli protect against acquisition of BV but do not protect against VVC or vaginal trichomoniasis.

Curr Microbiol, 1996 Nov, 33(5), 302 - 5
Influence of Carbohydrates on the alpha-Galactosidase Activity of Lactobacillus fermentum
Garro MS, de Valdez GF, Oliver G, de Giori GS.
The influence of soybean galactosaccharides (stachyose, raffinose, melibiose) as well as galactose and glucose on the synthesis and activity of alpha-galactosidase (alpha-gal) from Lactobacillus fermentum CRL 251 was studied . Stachyose was the most effective inducer, followed by melibiose, raffinose, and galactose; scarce activity was detected with glucose . Exogenously supplied glucose inhibited the synthesis of the enzyme in cultures of L . fermentum growing on galactose . This effect was reversed by the addition of cyclic adenosine-3',5' monophosphate (cAMP), which suggests that this compound could be involved in the regulation of alpha-gal synthesis.

Gene, 1996 Oct 17, 176(1-2), 215 - 23
Cloning, sequence analysis, and expression of the genes encoding lytic functions of Bacteriophage phi g1e; Oki M et al.; The lysis genes of a Lactobacillus phage phi g1e were cloned, sequenced, and expressed in Escherichia coli . Nucleotide sequencing of a 3813-bp phi g1e DNA revealed five successive open reading frames (ORF), Rorf50, Rorf118, hol, and lys and Rorf175, in the same DNA strand . By comparative analysis of the DNA sequence, the putative hol product (holin) has an estimated molecular weight is 14.2 kDa, and contains two potential transmembrane helices and highly charged N- and C-termini, resembling predicted holins (which are thought to be a cytoplasmic membrane-disrupting protein) encoded by other phages such as mv1 from Lactobacillus bulgaricus, phi adh from Lactobacillus gasseri, as well as monocins from Listeria . On the other hand, the putative phi g1e lys product (lysin) of 48.4 kDa shows significant similarity with presumed muramidase, known as a cell wall peptidoglycandegrading enzyme, encoded by the Lactobacillus phage mv1 and phi adh, the Lactococcus lactis phage phi LC3, and the Streptococcus pneumoniae phages Cp-1, Cp-7 and Cp-9 . When expressed in E . coli, the phi g1e lysin and/or holin decreased the cell turbidity significantly, suggesting that the phi g1e hol-lys system is involved in cytolytic process.

FEMS Microbiol Lett, 1996 Oct 15, 144(1), 33 - 8
A collagen binding protein from Lactobacillus reuteri is part of an ABC transporter system?
Roos S, Aleljung P, Robert N, Lee B, Wadstrom T, Lindberg M, Jonsson H.
The gene coding for a collagen binding protein from Lactobacillus reuteri NCIB 11951 was cloned and sequenced . A genomic lambda library was constructed and recombinant plaques were screened using antisera raised against purified collagen binding proteins from the same L . reuteri strain . The positive plaques were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis, which revealed the expression of a 29 kDa protein, which reacted with the antisera and bound 125I-labelled type I collagen . The sequence of the corresponding gene, cnb showed that the collagen binding protein has sequence similarities to the solute binding component of bacterial ABC transporters.

Gene, 1996 Oct 10, 175(1-2), 157 - 65
Cloning and nucleotide sequence of the major capsid proteins of Lactobacillus bacteriophage phi gle; Kakikawa M et al.; Bacteriophage phi gle was induced from a lysogenic Lactobacillus strain Gle . phi gle genome is double-stranded DNA of approximately 42.5 kilo-base (kb) pairs . SDS poly-acrylamide gel electrophoresis demonstrated that the phage particles contain 4 major structural (capsid) proteins, gpB, gpG, gpO, and gpP, whose molecular weights (MW) are estimated to be 64, 43, 29 and 26 kilodaltons (kDa), respectively . More than 16 minor proteins ranging from 113 to 9.6 kDa were also detected . The genes for the major capsid proteins were cloned and each DNA sequence was determined . N-terminal amino acid alignments determined by protein sequencing completely coincided with those deduced from the nucleotide sequences.

Gene, 1996 Oct 10, 175(1-2), 49 - 57
The early gene region completes the nucleotide sequence of Lactobacillus delbrueckii subsp . lactis phage LL-H; Mikkonen M et al.; Transcription of genes from phage LL-H can be divided into an early phase and a late phase . The early gene region was located in a 5.9-kb segment of the phage LL-H genome and it was part of the sequence that completed the phage LL-H genome sequence, 34 659 bp in size . Phage LL-H is the first completely sequenced Lactobacillus phage . In the main coding strand of phage LL-H genome 48 putative ORFs could be detected, but only four small putative ORFs could be found in the opposite strand . The ORFs covered 85.6% of the main coding strand . Function could be assigned to eleven of the phage LL-H ORFs either by biochemical analyses or by database homologies . A single-strand-binding protein, SSB, was detected in addition to the previously determined functions (small and large subunits of terminase, intron-encoded endonuclease, six structural proteins, phage lysin) . For 15 additional ORFs of phage LL-H homology was detected in databases, but no function could be inferred for them.

Res Microbiol, 1996 Oct, 147(8), 619 - 24
Genetic analysis of the replication region of the Lactobacillus plasmid vector pPSC22; Cocconcelli PS et al.; The sequence and genetic organization of the 1,600-bp replication region of the Lactobacillus vector pPSC22, a plasmid derived from a 7-kb cryptic plasmid of L . plantarum used for the cloning of heterologous genes in several lactobacilli, were determined . Sequence analysis revealed the presence of a plus origin of replication containing the two functional elements nic and bind, required for initiation of the leading strands typical of the rolling circle (RC)-replicating plasmids belonging to the pLS1 family . Two open reading frames (copA and repA) were located within the Lactobacillus portion of pPSC22 . The repA gene product, a 234-amino acid protein, showed homologies with the Rep protein of the streptococcal plasmid pLS1 and contained the three conserved domains detected in most Rep proteins of RC-replicating plasmids and ss-coliphages . The genetic organization of the replication region of pPSC22 shared relevant homologies with the lactococcal plasmids pWVO1 and pFX2.

Eur J Oral Sci, 1996 Oct-Dec, 104(5-6), 619 - 22
Controlled study of the association of smoking with lactobacilli, mutans streptococci and yeasts in saliva; Sakki T et al.; The effect of smoking on salivary microbe levels was studied in 780 subjects by multivariate analysis, taking into account some confounding factors . Lactobacilli, mutans streptococci and yeasts were detected with Dentocult-LB, Dentocult-SM and Oricult-N tests . The explanatory variables considered were gender, presence of natural teeth, presence of removable denture, presence of decayed teeth, toothbrushing frequency, use of sugar in coffee or tea, consumption frequency of sugary products, secretion rate of stimulated and unstimulated saliva, buffering capacity of saliva, pH of saliva, oral hygiene and tobacco smoking habits . Smoking was strongly associated with higher lactobacilli counts and presence of yeasts, independently of oral status, hygiene or salivary factors . The relation between smoking and mutans streptococci was weaker . The overall associations of lactobacilli and yeasts with the study variables followed a very similar pattern.

Clin Infect Dis, 1996 Oct, 23(4), 773 - 8
Lactobacillus bacteremia: description of the clinical course in adult patients without endocarditis; Antony SJ et al.; Lactobacillus bacteremia in the absence of endocarditis is a rare entity, and the clinical relevance of such bacteremia remains unclear . The clinical courses of lactobacillus bacteremia without endocarditis in 43 previously described patients and 12 new patients were reviewed . Bacteremia with Lactobacillus alone occurred in 34 (62%) of the patients, and 12 (22%) of the patients had bacteremia with other organisms, including Lactobacillus . Lactobacillus was isolated from another site in 18 (33%) of these patients . Intravenous catheter infections were not noted in these patients . Underlying conditions included cancer (6 patients), organ transplantation (9), diabetes mellitus (4), and recent surgery (12) . Fever occurred in all patients, and eight (15%) of the patients experienced a sepsis syndrome . The mortality rate was 14%; however, only three deaths were attributed soley to lactobacillus sepsis . Lactobacillus bacteremia is an uncommon condition that usually occurs in patients with severe underlying illnesses and is frequently seen as a part of a polymicrobial infection . Blood cultures positive for Lactobacillus represent true infection and not contamination . Although resistance to commonly used antibiotics is common, the mortality rate associated with this bacteremia appears to be low.

Clin Infect Dis, 1996 Oct, 23(4), 748 - 52
Vaginal microflora associated with bacterial vaginosis in Japanese and Thai pregnant women; Puapermpoonsiri S et al.; The vaginal flora of 118 Japanese and 208 Thai pregnant women were investigated for the presence of bacterial vaginosis (BV), BV-associated organisms, and BV-associated enzyme . A similar prevalence of BV was found among the Japanese (13.6%) and Thai women (15.9%) . The microbial flora of women with BV were complex; the mean number of isolates recovered in the BV group was approximately 2 times more than that in a group of healthy women . Prevotella species, Porphyromonas species, Peptostreptococcus species, Mobiluncus species, Gardnerella vaginalis, and H2O2-nonproducing lactobacilli were significantly associated with BV . These organisms were less associated with H2O2-producing lactobacilli, which were predominant in women with normal flora, suggesting that H2O2-producing lactobacilli have antibacterial activity against BV-associated organisms . The vaginal sialidase assay by means of a filter-paper spot test was not proved to be a useful screening aid for diagnosis of BV because of the low sensitivity (69.4%) of this test.

Chem Res Toxicol, 1996 Oct-Nov, 9(7), 1140 - 4
Addition of deoxyribose to guanine and modified DNA based by Lactobacillus helveticus trans-N-deoxyribosylase; Muller M et al.; The use of bacterial trans-N-deoxyribosylase was evaluated as an alternative method for deoxyribosylation in the synthesis of deoxyribonucleosides containing potentially mutagenic adducts . A crude enzyme preparation was isolated from Lactobacillus helveticus and compared to Escherichia coli purine nucleoside phosphorylase . trans-N-deoxyribosylase was more regioselective than purine nucleoside phosphorylase in the deoxyribosylation of Gua at the N9 atom, as compared to N7, as demonstrated by NMR analysis of the product . 5,6,7,9-Tetrahydro-7-acetoxy-9-oxoimidazo{1,2-a}purine was efficiently deoxyribosylated by trans-N-deoxyribosylase but not at all by purine nucleoside phosphorylase . Other substrates for trans-N-deoxyribosylase were N2-(2-oxoethyl)Gua, pyrimido{1,2-a}purin-10(3H)-one, 1,N2-epsilon-Gua, N2,3-epsilon-Gua, 3,N4-epsilon-Cyt, 1,N6-epsilon-Ade, C8-methylGua, and C8-aminoGua, most of which gave the desired isomer (bond at the nitrogen corresponding to N9 in Gua) in good yield . Neither N7-alkylpurines nor C8-(arylamino)-substituted guanines were substrates . The approach offers a relatively convenient method of enzymatic preparation of many carcinogen-DNA adducts at the nucleoside level, for either use as standards or incorporation into oligonucleotides . trans-N-deoxyribosylase can also be used to remove deoxyribose from modified deoxyribonucleosides in the presence of excess Cyt.

J Appl Bacteriol, 1996 Oct, 81(4), 348 - 54
Inducible transport of citrate in Lactobacillus rhamnosus ATCC 7469; de Figueroa RM et al.; Lactobacillus rhamnosus ATCC 7469 exhibited diauxie when grown in a medium containing both glucose and citrate as energy source . Glucose was used as the primary energy source during the glucose-citrate diauxie . Uptake of citrate was carried out by an inducible citrate transport system . The induction of citrate uptake system was repressed in the presence of glucose . This repression was reversible and mediated by cAMP.

J Clin Microbiol, 1996 Oct, 34(10), 2497 - 9
Vaginal microbiology of women with acute recurrent vulvovaginal candidiasis; Sobel JD et al.; Alterations in the autochthonous vaginal microflora can predispose women to recurring attacks of Candida vaginitis . Quantitative aerobic and anaerobic cultures were obtained from 24 premenopausal women with acute recurrent vulvovaginal candidiasis and from 21 healthy asymptomatic premenopausal women . Lactobacillus species constituted the predominant flora in both groups, with a mean log10 CFU/ml of 8.7, a total isolation rate of 96%, and a mean of 1.6 Lactobacillus species isolated per patient compared with a mean log10 CFU/ml of 8.9, a total isolation rate of 90%, and a mean of 1.2 Lactobacillus species isolated per patient in the vaginitis and control groups, respectively . The results of this small study failed to provide evidence of an altered or abnormal vaginal bacterial flora in women with non-antibiotic-induced recurrent vulvovaginal candidiasis suffering from acute Candida vaginitis.

Antonie Van Leeuwenhoek, 1996 Oct, 70(2-4), 187 - 221
The proteolytic systems of lactic acid bacteria; Kunji ER et al.; Proteolysis in dairy lactic acid bacteria has been studied in great detail by genetic, biochemical and ultrastructural methods . From these studies the picture emerges that the proteolytic systems of lactococci and lactobacilli are remarkably similar in their components and mode of action . The proteolytic system consists of an extracellularly located serine-proteinase, transport systems specific for di-tripeptides and oligopeptides (> 3 residues), and a multitude of intracellular peptidases . This review describes the properties and regulation of individual components as well as studies that have led to identification of their cellular localization . Targeted mutational techniques developed in recent years have made it possible to investigate the role of individual and combinations of enzymes in vivo . Based on these results as well as in vitro studies of the enzymes and transporters, a model for the proteolytic pathway is proposed . The main features are: (i) proteinases have a broad specificity and are capable of releasing a large number of different oligopeptides, of which a large fraction falls in the range of 4 to 8 amino acid residues; (ii) oligopeptide transport is the main route for nitrogen entry into the cell; (iii) all peptidases are located intracellularly and concerted action of peptidases is required for complete degradation of accumulated peptides.

Antonie Van Leeuwenhoek, 1996 Oct, 70(2-4), 147 - 59
Lytic systems in lactic acid bacteria and their bacteriophages; Gasson MJ; Lytic systems of lactic acid bacteria and their bacteriophages are reviewed with an emphasis on molecular characterization . Details of enzyme biochemistry and the cloning and analysis of lytic genes are presented, with coverage of lactococcal prolate headed bacteriophages, lactococcal isometric bacteriophages, Lactobacillus bacteriophages and lactococcal autolysins . Some comments on the importance of autolysis in cheese ripening are included and the biotechnological exploitation of cloned and characterized lytic genes is presented.

Antonie Van Leeuwenhoek, 1996 Oct, 70(2-4), 129 - 45
Inducible gene expression and environmentally regulated genes in lactic acid bacteria; Kok J; Relatively recently, a number of genes and operons have been identified in lactic acid bacteria that are inducible and respond to environmental factors . Some of these genes/operons had been isolated and analysed because of their importance in the fermentation industry and, consequently, their transcription was studied and found to be regulatable . Examples are the lactose operon, the operon for nisin production, and genes in the proteolytic pathway of Lactococcus lactis, as well as xylose metabolism in Lactobacillus pentosus . Some other operons were specifically targetted with the aim to compare their mode of regulation with known regulatory mechanisms in other well-studied bacteria . These studies, dealing with the biosynthesis of histidine, tryptophan, and of the branched chain amino acids in L . lactis, have given new insights in gene regulation and in the occurrence of auxotrophy in these bacteria . Also, nucleotide sequence analyses of a number of lactococcal bacteriophages was recently initiated to, among other things, specifically learn more about regulation of the phage life cycle . Yet another approach in the analysis of regulated genes is the 'random' selection of genetic elements that respond to environmental stimuli and the first of such sequences from lactic acid bacteria have been identified and characterized . The potential of these regulatory elements in fundamental research and practical (industrial) applications will be discussed.

Antonie Van Leeuwenhoek, 1996 Oct, 70(2-4), 113 - 28
Biosynthesis of bacteriocins in lactic acid bacteria; Nes IF et al.; A large number of new bacteriocins in lactic acid bacteria (LAB) has been characterized in recent years . Most of the new bacteriocins belong to the class II bacteriocins which are small (30-100 amino acids) heat- stable and commonly not post-translationally modified . While most bacteriocin producers synthesize only one bacteriocin, it has been shown that several LAB produce multiple bacteriocins (2-3 bacteriocins) . Based on common features, some of the class II bacteriocins can be divided into separate groups such as the pediocin-like and strong anti-listeria bacteriocins, the two-peptide bacteriocins, and bacteriocins with a sec-dependent signal sequence . With the exception of the very few bacteriocins containing a sec-dependent signal sequence, class II bacteriocins are synthesized in a preform containing an N-terminal double-glycine leader . The double-glycine leader-containing bacteriocins are processed concomitant with externalization by a dedicated ABC-transporter which has been shown to possess an N-terminal proteolytic domain . The production of some class II bacteriocins (plantaricins of Lactobacillus plantarum C11 and sakacin P of Lactobacillus sake) have been shown to be transcriptionally regulated through a signal transduction system which consists of three components: an induction factor (IF), histidine protein kinase (HK) and a response regulator (RR) . An identical regulatory system is probably regulating the transcription of the sakacin A and carnobacteriocin B2 operons . The regulation of bacteriocin production is unique, since the IF is a bacteriocin-like peptide with a double-glycine leader processed and externalized most probably by the dedicated ABC-transporter associated with the bacteriocin . However, IF is not constituting the bacteriocin activity of the bacterium, IF is only activating the transcription of the regulated class II bacteriocin gene(s) . The present review discusses recent findings concerning biosynthesis, genetics, and regulation of class II bacteriocins.

Int J Syst Bacteriol, 1996 Oct, 46(4), 1158 - 63
Lactobacillus curvatus subsp . curvatus subsp . nov . and Lactobacillus curvatus subsp . melibiosus subsp . nov . and Lactobacillus sake subsp . sake subsp . nov . and Lactobacillus sake subsp . carnosus subsp . nov., new subspecies of Lactobacillus curvatus Abo-Elnaga and Kandler 1965 and Lactobacillus sake Katagiri, Kitahara, and Fukami 1934 (Klein et al . 1996, emended descriptions), respectively; Torriani S et al.; Lactobacillus curvatus and Lactobacillus sake are each genetically homogeneous species, as indicated by the high levels of DNA homology (> or = 76%) exhibited by strains of these taxa . However, the results of a numerical analysis of total soluble cell protein patterns and biochemical test data revealed that there are two phenotypic subgroups within L, curvatus and two phenotypic subgroups within L . sake . The overall randomly amplified polymorphic DNA (RAPD)-PCR band patterns obtained for the majority of L . curvatus strains corresponded well to the pattern obtained for the type strain of L . curvatus (strain DSM 20019) . However, six strains of L . curvatus had different, but similar, RAPD-PCR profiles and grouped in a separate genetic cluster, which was linked to one of the clusters of L . sake strains . On the basis of these results, differences in biochemical and physiological characteristics, and total soluble cell protein profiles, we describe the subspecies L . curvatus subsp . curvatus subsp . nov . and L . curvatus subsp . melibiosus subsp . nov . for L . curvatus Abo-Elnaga and Kandler 1965 (Klein et al . 1996, emended description) . Strains of L . sake grouped in two RAPD-PCR clusters, which was consistent with previous reports of phenotypic heterogeneity . Strains of Lactobacillus bavaricus, including type strain LMG 9844, clustered with the type strain of L . sake (strain NCFB 2714), indicating that these organisms belong to the same genetic group . We propose that strains of L . sake Katagiri, Kitahara, and Fukami 1934 (Klein et al . 1996, emended description) should be reclassified as members of L . sake subsp . sake subsp . nov . and L . sake subsp . carnosus subsp . nov . Strains of L . bavaricus are reclassified as members of L . sake subsp . sake, and the name L . bavaricus Stetter and Stetter 1980 is rejected.

Curr Microbiol, 1996 Oct, 33(4), 256 - 60
Cloning and expression of the Zymomonas mobilis "production of ethanol" genes in Lactobacillus casei; Gold RS et al.; This study describes the expression of the Zymomonas mobilis genes coding for pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adh) in Lactobacillus casei 686 . To promote transcription, the promoter and ribosome binding site (RBS) from the Lactococcus lactis subsp . lactis-derived vector, pMGE36e, were inserted upstream of the pdc gene . The former sequences were positioned such that translation of pdc was coupled to translation of an 81-base pair open reading frame terminating within the pdc initiation site . The recombinant plasmid (pRSG02) was electroporated into L . casei, and transformants were obtained . Northern analysis confirmed the production of a 3 . 1-kb transcript corresponding to the predicted size of the PET operon . Western blot analyses revealed that the recombinant strain expressed both enzymes . The recombinant produced more than twice the ethanol produced by the parental L . casei strain.

Carbohydr Res, 1996 Sep 23, 291, 155 - 64
Structural elucidation of an extracellular polysaccharide produced by Lactobacillus helveticus; Staaf M et al.; An extracellular polysaccharide produced by a strain of Lactobacillus helveticus isolated from cheese milk has been investigated . Sugar and methylation analysis together with 1H and 13C NMR spectroscopy revealed that the polysaccharide is composed of hexasaccharide repeating units . The sequence of sugar residues was determined by use of two-dimensional nuclear Overhauser effect spectroscopy and heteronuclear multiple-bond correlation experiments . The structure of the repeating unit of the exopolysaccharide from L . helveticus is as follows: {sequence: see text}

Biochem Biophys Res Commun, 1996 Sep 13, 226(2), 391 - 5
Production of hydroxy fatty acid (10-hydroxy-12(Z)-octadecenoic acid) by Lactobacillus plantarum from linoleic acid and its cardiac effects to guinea pig papillary muscles; Yamada Y et al.; Lactobacillus plantarum produced 10-hydroxy-12(Z)-octadecenoic acid (10-OHODA) from linoleic acid . It was suspected that 10-OHODA might be closely related to leukotoxin (9,10-epoxy-12-octa-decenoic acid (LTx)) which was regarded as a toxic and/or defensive substance in living beings . The cardiac effect of 10-OHODA, which was biosynthesized by Lactobacillus plantarum, on an isolated guinea-pig papillary muscle was determined . Its effect on the contractile force of the tissue preparations was examined both in terms of its concentration and the time of exposure . A decrease in muscular tension was observed immediately after administration of 10-OHODA at concentrations of 30, 100, and 300 microM . We also compared the effect of 10-OHODA on muscle tension with that of LTx and its isomer 12,13-epoxy-9-octadecenoic acid (LTx') . Each inhibitory effect on the contractile force of the papillary muscle was statistically significant in the concentration of 300 microM 5 min after administration compared to the control in the absence of each fatty acid, suggesting that 10-OHODA is likely to exert some influence on the circulatory system together with LTx and LTx'.

Biosci Biotechnol Biochem, 1996 Sep, 60(9), 1434 - 8
A new screening method for the selection of Lactobacillus acidophilus group lactic acid bacteria with high adhesion to human colonic mucosa; Takahashi N et al.; A hemagglutination (HA) assay was done for the screening of lectin-like components in surface layer protein (SLP) from Lactobacillus (L.) acidophilus A group strains . The new screening method, using polystyrene beads coated with rat-colonic mucin (RCM), which combines sugar chains similar to those of human colonic mucin, was also done . The results showed that the HA assay was not a good indicator for selecting strains having high adhesion to the human intestinal tract . The SLPs from 3 strains that strongly bound to RCM also bound well to carbohydrate portions of Carnoy's-fixed human colonic mucous layer . These results suggest that this method is a new promising screening technique for the L . acidophilus strains having high adhesion to the human intestinal tract.

Br J Clin Pract, 1996 Sep, 50(6), 331 - 4
Bacterial vaginosis; Priestley CJ et al.; Bacterial vaginosis (BV) is an alteration of the vaginal flora, where the normally predominant lactobacilli are replaced by a cocktail of organisms including Gardnerella vaginalis and anaerobes . It presents with a grey, homogenous, offensive vaginal discharge that has a raised pH . However, around half the women with this condition are asymptomatic . Diagnosis is best made by microscopic examination of a Gram-stained smear of vaginal secretions . Treatment is with metronidazole or clindamycin . The indications for treatment of asymptomatic BV are not clear, but women should probably be treated before any invasive gynaecological procedure, including intrauterine contraceptive device (IUCD) insertion . BV during pregnancy is associated with preterm labour, although a causal effect is not proven; studies are in progress to determine whether treatment of BV will improve the outcome of these pregnancies.

Plasmid, 1996 Sep, 36(2), 116 - 24
Molecular characterization of a plasmid-borne (pTC82) chloramphenicol resistance determinant (cat-TC) from Lactobacillus reuteri G4; Lin CF et al.; Lactobacillus reuteri G4 contains a 7.0-kb plasmid (pTC82) encoding resistance to chloramphenicol (Cm) . Determination of the nucleotide sequence of the genetic determinant (cat-TC) encoding resistance to Cm on pTC82 revealed an open reading frame for a 238-amino-acid Cm acetyltransferase (CAT) monomer . This structural cat gene, 714 bp in length, was highly related (ca . 95% nucleotide and ca . 81% amino acid identity) to the 648-bp cat gene from Staphylococcus aureus plasmid pC194 . A total of 6 bp transversions and 4 bp deletions was observed along the whole DNA sequence of cat-TC compared to that of cat-pC194 . To determine the activity of the putative cat-TC gene, recombinant plasmid pUC8217 containing the cat determinant from pTC82 was subjected to a maxicell analysis . The observed molecular mass of the synthesized protein, based on electrophoretic mobility, was in reasonable agreement with the 27.3 kDa predicted from the DNA sequence . This is the first reported nucleotide sequence of a Cm-resistance determinant from L . reuteri and also the first evidence of adding Lactobacillus to the list of versatile bacterial genera which naturally acquire the cat-pC194 gene in the microbial ecological system.

J Can Dent Assoc, 1996 Sep, 62(9), 700, 703 - 7
Mutans streptococci caries and chlorhexidine; Bowden GH; Mutans streptococci, particularly Streptococcus mutans and Streptococcus sobrinus, can be shown to be highly associated with caries in humans . Together with Lactobacillus spp., they are regarded as significant odontopathogens . Because of their association with dental disease, an evaluation of the numbers of Mutans streptococci organisms in plaque and saliva may aid in the diagnosis of caries activity . In conjunction with this concept, control and prevention of caries has been sought by reducing the numbers of bacteria colonizing an individual . Despite the associations between dental disease and Mutans streptococci, which can be demonstrated in groups of people, these methods have not been entirely successful . Because of the wide range of factors involved, counts are not very effective in diagnosing caries activity or risk in an individual . Nevertheless, counts may be used to establish a normal pattern of colonization for a patient, and deviation from this pattern will indicate a change in their oral status, which can be included as a parameter in diagnosis . Accurate and relatively simple commercial tests for counting mutans streptococci and lactobacilli are available . In patients with high caries activity and high counts of mutans streptococci, chlorhexidine may be employed as an adjunct to other preventive measures . Chlorhexidine delivered in a gel form has been shown to be effective in the control and prevention of caries . Combinations of chlorhexidine with fluoride may be even more effective . Sustained release devices, like varnishes, reduce the numbers of mutans streptococci in a patient's mouth to levels below detection for long periods, but their effectiveness in preventing and controlling caries has not yet been assessed . The decision to use microbiological methods to aid diagnosis, and chlorhexidine to reduce or eliminate mutans streptococci, rests with the practitioner . Although the microbiological tests for caries activity or prediction are not 100 per cent accurate, they can be useful in certain situations . In addition, chlorhexidine as an adjunct in control and prevention of caries has been shown to have value . This short review introduces readers to the literature, so that they will not dismiss microbiology, but make decisions on the use of microbiological methods based on their own experience and the experience of others.

Cleft Palate Craniofac J, 1996 Sep, 33(5), 424 - 8
Prevalence of Streptococcus mutans and lactobacilli in 18-month-old children with cleft lip and/or palate; Bokhout B et al.; The prevalence of Streptococcus mutans and lactobacilli was determined in 62 18-month-old Dutch children with a cleft lip and/or palate . Plaque and saliva samples were collected, a dental examination was performed, and the parents were interviewed with a structured questionnaire regarding general health, dietary habits, fluoride exposure, and socioeconomic class . Appropriate dilutions of the plaque and saliva samples were cultured on selective media to count all viable bacteria, S . mutans and lactobacilli . S . mutans was detected in the saliva of 45% of the children, and lactobacilli was detected in 16% . Also, S . mutans was detected in 48% of the plaque samples and lactobacilli in 8% . Of all of the variables examined, consumption of more than three snacks and beverages between main meals was significantly associated with presence of S . mutans in saliva . Preoperative infant orthopedic treatment (i.e., wearing an acrylic plate from shortly after birth) was significantly associated with presence of lactobacilli in saliva . The presence of S . mutans in the plaque samples was also significantly associated with presence of lactobacilli in saliva . These results indicate that children with oral cleft are at an increased risk of being infected by S . mutans and lactobacilli at a very early age . Such early colonization indicates a high risk for caries in the primary dentition.

Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 1996 Sep, 82(3), 268 - 75
Effects of compliance with fluoride gel application on caries and caries risk in patients after radiation therapy for head and neck cancer; Epstein JB et al.; The use of fluoride gel applied in a custom tray once daily has become standard for patients who have xerostomia after undergoing radiation therapy . Compliance may be poor as a result of the inconvenient method of application and because many patients with head and neck cancer have poor health behaviors . Our aim was to investigate the effect of compliance with fluoride gel application on caries and caries risk . Patients were prescribed neutral sodium fluoride gel (5000 ppm) before undergoing radiotherapy Fifty-two patients were willing to visit the dental clinic for dental examination, measurement of saliva, and quantitative culture of Streptococcus mutans and lactobacillus species . Before radiotherapy was performed, decayed, missing, and filled surfaces data were recorded for all patients in the study . Of these patients, 27 used fluoride gel once daily, as directed . Radiation dose, number of fractions, and duration of radiation had a significant inverse effect on postradiotherapy whole resting saliva (p = 0.04, p = 0.01, and p = 0.01) and on whole stimulated saliva (p = 0.02, p < 0.01, and p < 0.01) . Patients with a subjective feeling of dry mouth had significantly less saliva production at rest (p = 0.01) and on stimulation (p = 0.01) . A trend toward reduction of S . mutans counts was seen in those patients who used their fluoride gel regularly (p = 0.057) . High lactobacilli counts were found in the patients with high and low compliance with fluoride gel use . Differences in the mean caries incidence between those who reported compliance with daily fluoride application and those who did not comply were not found significant because of the large SD in the patient groups, although differences in the mean for these groups were seen . The lack of a statistically significant difference may be due to the multiple factors associated with caries . Therefore patient care must be individualized, and patients must be assessed at regular intervals to determine the caries risk and caries activity to provide guidance for maintenance of the dentition.

Int J Food Microbiol, 1996 Sep, 32(1-2), 199 - 207
Histamine and tyramine production by bacteria from meat products; Masson F et al.; A series of 94 strains of lactic acid bacteria and Micrococcaceae were tested for their ability to decarboxylate histidine and tyrosine in a laboratory medium . Histamine and tyramine were quantified by using a fluorimetric and a HPLC method . There was no significant difference between the results obtained with either method . Among the strains tested, only three released histamine . On the other hand, all the strains of Carnobacterium produced high concentrations of tyramine (2193 micrograms/ml) . Some strains of Lactobacillus curvatus and also Lactobacillus plantarum showed tyramine production . Micrococcaceae and Lactobacillus sake did not produce tyramine.

Microbiology, 1996 Sep, 142 ( Pt 9), 2375 - 84
The presence of two S-layer-protein-encoding genes is conserved among species related to Lactobacillus acidophilus; Boot HJ et al.; Previously we have shown that the type strain of Lactobacillus acidophilus possesses two S-protein-encoding genes, one of which is silent, on a chromosomal segment of 6 kb . The S-protein-encoding gene in the expression site can be exchanged for the silent S-protein-encoding gene by inversion of this slp segment . In this study the presence of S-protein and corresponding S-protein-encoding genes of strains belonging to species that are closely related to L . acidophilus was determined . All strains investigated were identified by numerical comparison of highly standardized one-dimensional SDS-PAGE whole-cellular-protein patterns . Western blot and Southern blot methods were used to identify the presence of, and homology between, S-proteins and S-protein-encoding genes . From these analyses we conclude that strains of L . acidophilus, L . crispatus, L . amylovorus and L . gallinarum possess an S-layer and contain two slp genes . Strains of L . helveticus possess an S-layer but have only one intact slp gene . Strains of L . gasseri, L . johnsonii and L . delbrueckii subsp . bulgaricus have neither an S-layer nor S-protein-encoding genes hybridizing with probes derived from the L . acidophilus slpA or slpB region . The presence of a highly conserved 5' region in the slp genes of strains of L . acidophilus, L . crispatus, L . amylovorus and L . gallinarum suggests that S-layer variation is a common feature for strains of these species.

J Bacteriol, 1996 Sep, 178(18), 5431 - 7
Knockout of the two ldh genes has a major impact on peptidoglycan precursor synthesis in Lactobacillus plantarum; Ferain T et al.; Most bacteria synthesize muramyl-pentapeptide peptidoglycan precursors ending with a D-alanyl residue (e.g., UDP-N-acetylmuramyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala) . However, it was recently demonstrated that other types of precursors, notably D-lactate-ending molecules, could be synthesized by several lactic acid bacteria . This particular feature leads to vancomycin resistance . Vancomycin is a glycopeptide antibiotic that blocks cell wall synthesis by the formation of a complex with the extremity of peptidoglycan precursors . Substitution of the terminal D-alanine by D-lactate reduces the affinity of the antibiotic for its target . Lactobacillus plantarum is a lactic acid bacterium naturally resistant to vancomycin . It converts most of the glycolytic pyruvate to L- and D-lactate by using stereospecific enzymes designated L- and D-lactate dehydrogenases, respectively . In the present study, we show that L . plantarum actually synthesizes D-lactate-ending peptidoglycan precursors . We also report the construction of a strain which is deficient for both D- and L-lactate dehydrogenase activities and which produces only trace amounts of D- and L-lactate . As a consequence, the peptidoglycan synthesis pathway is drastically affected . The wild-type precursor is still present, but a new type of D-alanine-ending precursor is also synthesized in large quantities, which results in a highly enhanced sensitivity to vancomycin.

J Bacteriol, 1996 Sep, 178(18), 5388 - 94
The Lactobacillus acidophilus S-layer protein gene expression site comprises two consensus promoter sequences, one of which directs transcription of stable mRNA; Boot HJ et al.; S-proteins are proteins which form a regular structure (S-layer) on the outside of the cell walls of many bacteria . Two S-protein-encoding genes are located in opposite directions on a 6.0-kb segment of the chromosome of Lactobacillus acidophilus ATCC 4356 bacteria . Inversion of this chromosomal segment occurs through recombination between two regions with identical sequences, thereby interchanging the expressed and the silent genes . In this study, we show that the region involved in recombination also has a function in efficient S-protein production . Two promoter sequences are present in the S-protein gene expression site, although only the most downstream promoter (P-1) is used to direct mRNA synthesis . S-protein mRNA directed by this promoter has a half-life of 15 min . Its untranslated leader can form a stable secondary structure in which the 5' end is base paired, whereas the ribosome-binding site is exposed . Truncation of this leader sequence results in a reduction in protein production, as shown by reporter gene analysis of Lactobacillus casei . The results obtained indicate that the untranslated leader sequence of S-protein mRNA is involved in efficient S-protein production.

Appl Environ Microbiol, 1996 Sep, 62(9), 3220 - 6
The proteolytic system of Lactobacillus sanfrancisco CB1: purification and characterization of a proteinase, a dipeptidase, and an aminopeptidase; Gobbetti M et al.; A cell envelope 57-kDa proteinase, a cytoplasmic 65-kDa dipeptidase, and a 75-kDa aminopeptidase were purified from Lactobacillus sanfrancisco CB1 sourdough lactic acid bacterium by sequential fast protein liquid chromatography steps . All of the enzymes are monomers . The proteinase was most active at pH 7.0 and 40 degrees C, while aminopeptidase and dipeptidase had optima at pH 7.5 and 30 to 35 degrees C . Relatively high activities were observed at the pH and temperature of the sourdough fermentation . The proteinase is a serine enzyme . Urea-polyacrylamide gel electrophoresis of digest of alpha s1- and beta-caseins showed differences in the pattern of peptides released by the purified proteinase and those produced by crude preparations of the cell envelope proteinases of Lactobacillus delbrueckii subsp . bulgaricus B397 and Lactococcus lactis subsp . lactis SK11 . Reversed-phase fast protein liquid chromatography of gliadin digests showed a more-complex peptide pattern produced by the proteinase of Lactobacillus sanfrancisco CB1 . The dipeptidase is a metalloenzyme with high affinity for dipeptides containing hydrophobic amino acids but had no activity on tripeptides or larger peptides . The aminopeptidase was also inhibited by metal-chelating agents, and showed a broad N-terminal hydrolytic activity including di- and tripeptides . Km values of 0.70 and 0.44 mM were determined for the dipeptidase on Leu-Leu and the aminopeptidase on Leu-p-nitroanilide, respectively.

Cent Afr J Med, 1996 Aug, 42(8), 249 - 52
Bacteriological studies of dental caries in Ile-Ife, Nigeria; Adetunji OF et al.; To determine the relationship between bacterial colonization of tooth surfaces and dental caries, selective agar media-MM10 Sucrose, Rogosa SL and Blood agar were used to isolate bacteria from the scrappings of 60 tooth surfaces of 30 children and young adults . Mean age +/- SD was 13.3 +/- 4.1 (range seven to 19 years) . Streptococcus mutans was isolated from 36 surfaces representing 60pc Lactobacillus species from 38 surfaces (68pc), and Actinomyces species from 12 surfaces (20pc) . The individual prevalences of these organisms decreased with age . The distribution of bacteria according to surfaces examined showed that the pits and fissures were the main habitat of Streptococcus mutans and Lactobacilli were sensitive to erythromycin . Actinomyces species were 100pc sensitive to Penicillin . All the bacteria species isolated were also found to be 100pc sensitive to Olfoxacin (Tarivid) . It is suggested that the use of antibiotics may stop the growth of cariogenic bacteria in individuals and thereby contribute to a decline in the incidence and prevalence of dental caries in the community.

Lett Appl Microbiol, 1996 Aug, 23(2), 67 - 71
Antagonistic effects of intestinal Lactobacillus isolates on pathogens of chicken; Jin LZ et al.; Twelve Lactobacillus strains isolated from chicken intestine, which demonstrated a strong and moderate capacity to adhere to the ileal epithelial cells in vitro, were used to investigate their inhibitory ability against five strains of salmonella, i.e . Salmonella enteritidis 935/79, Salm . pullorum, Salm . typhimurium, Salm . blockley and Salm . enteritidis 94/448, and three serotypes of Escherichia coli, viz . E . coli O1:K1, O2:K1 and O78:K80 . The results showed that all the 12 Lactobacillus isolates were able to inhibit the growth of the five strains of salmonella, and the three strains of E . coli in varying degrees . Generally, they were more effective in inhibiting the growth of salmonella than E . coli . Inhibition of the pathogenic bacteria was probably due to the production of organic acids by the Lactobacillus isolates.

Eur J Epidemiol, 1996 Aug, 12(4), 383 - 90
Bacterial vaginosis: prevalence in an Italian population of asymptomatic pregnant women and diagnostic aspects; Cristiano L et al.; The present study has been carried out with the main objective of determining the prevalence rate of bacterial vaginosis (BV) in a population of asymptomatic pregnant women (8th to 9th month of pregnancy) . Out of a total 1,441 patients examined BV was found to be present in 70 (4.9%) . The diagnosis was made when an analysis of the vaginal discharge revealed the simultaneous presence of at least three out of four of the following laboratory indices: (1) direct Gram stain positive (bacterial flora mixed with Gram-negative coccobacilli and variable-gram predominant over the lactobacillus flora); (2) pH > 4.5; (3) positive odour test with KOH 10%; (4) presence of clue cells . After a discussion of the principal laboratory and clinical signs presently used for the diagnosis of BV, the authors suggest the exclusion of the evaluation of the appearance of the vaginal discharge from the standard diagnostic criteria . Further, three diagnostic methods are hypothesized for use in different settings.

J Dairy Sci, 1996 Aug, 79(8), 1316 - 21
Identification of an antihypertensive peptide from casein hydrolysate produced by a proteinase from Lactobacillus helveticus CP790; Maeno M et al.; Casein hydrolysate, produced by an extracellular proteinase from Lactobacillus helveticus CP790, was fractionated by two-step reverse-phase HPLC . Only one fraction showed antihypertensive activity as measured by systolic blood pressure in spontaneously hypertensive rats after oral administration . Ten peptides in the fraction were further purified and identified by analysis of amino acid sequences . Each identified peptide was chemically synthesized, and the antihypertensive activity of each peptide was evaluated in spontaneously hypertensive rats . The synthetic peptide with a sequence of Lys-Val-Leu-Pro-Val-Pro-Gln, found in beta-casein, indicated strong antihypertensive activity from 2 to 10 h after oral administration of 2 mg of peptide/kg of BW, and the effect was maximal at 6 h after oral administration (-31.5 +/- 5.6 mm Hg) . Moreover, the antihypertensive effect of the peptide was dependent on the dosage of peptide from 0.5 to 2 mg of peptide/kg of BW . Interestingly, the antihypertensive peptide showed lower inhibitory activity of angiotensin I-converting enzyme, but the activity was increased after pancreatin digestion.

Int J Food Microbiol, 1996 Aug, 31(1-3), 87 - 98
Lactic acid fermentation of cassava dough into agbelima; Amoa-Awua WK et al.; The souring of cassava dough during fermentation into the fermented cassava meal, agbelima, was investigated . Four different types of traditional inocula were used to ferment the dough and increases in titrable acidity expressed as lactic acid from 0.31-0.38 to 0.78-0.91% (w/w) confirmed the fermentation to be a process of acidification . The microflora of all inocula and fermenting dough contained high counts of lactic acid bacteria, 10(8)-10(9) cfu/g in all inocula and 10(7)-10(8), 10(8)-10(9) and 10(9) cfu/g at 0, 24 and 48 h in all fermentations . Lactobacillus plantarum was the dominant species of lactic acid bacteria during all types of fermentation accounting for 51% of 171 representative isolates taken from various stages of fermentation . Other major lactic acid bacteria found were Lactobacillus brevis, 16%, Leuconostoc mesenteroides, 15% and some cocci including Streptococcus spp . whose numbers decreased with fermentation time . The lactic acid bacteria were responsible for the souring of agbelima through the production of lactic acid . All L . plantarum, L . brevis and L . mesenteroides isolates examined demonstrated linamarase as well as other enzymatic activities but did not possess tissue degrading enzymes like cellulase, pectin esterase and polygalacturonase . The aroma profile of agbelima did not vary with the type of inoculum used and in all samples the build-up of aroma compounds were dominated by a non-identified low molecular weight alcohol, 1-propanol, isoamyl alcohol, ethyl acetate, 3-methyl-1-butanol and acetoin . Substantial reductions occurred in the levels of cyanogenic compounds present in cassava during fermentation into agbelima and detoxification was enhanced by the use of inoculum.

Int J Food Microbiol, 1996 Aug, 31(1-3), 59 - 68
Characterization of Lactobacillus sake strains associating with production of ropy slime by randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) patterns; Bjorkroth J et al.; Randomly amplified polymorphic DNA (RAPD) patterns and pulsed-field gel electrophoresis (PFGE) patterns were used for the characterization of ropy slime-producing Lactobacillus sake strains . The two most revealing commercially available primers (OPJ 12 and OPJ 16, Operon Inc . Alameda, USA) and two rare-cutting enzymes (AvrII and SmaI) were chosen from a pretested lot for the typing of 69 ropy slime-producing strains, 7 non-ropy isolates and 4 non-ropy reference strains . Both RAPD and PFGE patterns confirmed the group division established in previous studies and provided new information concerning ropy slime-producing strains . PFGE patterns were found to have the greatest discriminatory power, revealing the genetic variation of the main group of ropy slime-producing L . sake strains and distinguishing all non-ropy strains from slime-producers.

Mol Microbiol, 1996 Aug, 21(4), 799 - 809
Interchange of the active and silent S-layer protein genes of Lactobacillus acidophilus by inversion of the chromosomal slp segment; Boot HJ et al.; The most-dominant surface-exposed protein in many bacterial species is the S-protein . This protein crystallises into a regular monolayer on the outside surface of the bacteria: the S-layer . Lactobacillus acidophilus harbours two S-protein-encoding genes, slpA and slpB, only one of which (slpA) is expressed . In this study, we show by polymerase chain reaction (PCR) analysis that slpA and slpB are located on a 6 kb chromosomal segment, in opposite or orientations . In a small fraction of the bacterial population, this segment is inverted . The inversion leads to interchanging of the expressed and silent S-protein-encoding genes, and places the formerly silent gene behind the S-promoter which is located outside the inverted segment . A 26 bp sequence showing a high degree of similarity with the consensus sequence recognized by the Din family of invertases is present in the region where recombination occurs . Expression of the slpA gene seems to be favoured under laboratory growth conditions because 99.7% of the chromosomes of an L . acidophilus ATCC 4356 broth culture had the slpA gene present at the slp expression site.

FEMS Immunol Med Microbiol, 1996 Aug, 15(1), 23 - 6
Identification and plasmid profiles of Lactobacillus species from the vagina of 100 healthy women; Reid G et al.; It was hypothesized that Lactobacillus acidophilus might not be the dominant aerobic or microaerophilic Lactobacillus species in the human vagina, and that the dominant isolates are likely to express a variety of properties associated with colonization . To examine the question, vaginal swabs were collected from 100 healthy premenopausal women and cultured to detect the dominant aerobic or microaerophilic isolates of Lactobacillus . Only eight species were detected, with Lactobacillus jensenii being the dominant colonizers in the highest number (35) of women . Twelve different plasmid profiles were found amongst the isolates, but there was no association between plasmids and vaginal colonization or hydrogen peroxide production . Of the strains tested, few were resistant to the spermicidal agent nonoxynol-9 . The data identify species within which strains may possess properties associated with maintenance of a healthy vaginal ecology.

J Am Coll Nutr, 1996 Aug, 15(4), 408 - 12
Effect of the oral administration of Lactobacillus brevis subsp . coagulans on interferon-alpha producing capacity in humans; Kishi A et al.; OBJECTIVE: This study was designed to determine whether the oral administration of Lactobacillus brevis subsp . coagulans modulates immunological responses in human subjects, and whether there are differences in response between live and heat-treated preparations . METHODS: The effect of the oral administration of Lactobacillus brevis subsp . coagulans (Labre) for 4 weeks on the interferon-alpha (IFN-alpha) producing capacity of apparently healthy subjects was evaluated . Sixty volunteers were divided into five groups for the determination of virus-induced IFN-alpha production in response to various doses of live and to heat-killed Labre . 2-5A synthetase activity was measured to detect trace amounts of IFN production . Routine blood tests were also performed to determine the state of health of the subjects involved in this study and to test any side effects of Labre treatment . RESULTS: The oral administration of live Labre showed a statistically significant increase in IFN-alpha production at 2 weeks (p < 0.05) and at 4 weeks (p < 0.05) in the group receiving 600 million bacteria/day and at 4 weeks (p < 0.05) in the group receiving 300 million bacteria/day . In particular, IFN-alpha production in those with initially low levels rose significantly when either 300 million or 600 million bacteria/day were ingested . Consumption of heat-killed Labre 300 million bacteria/day did not result in a statistically significant change in IFN-alpha production . The level of 2-5A synthetase activity remained the same in the control and experimental groups . CONCLUSIONS: Oral administration of live Labre significantly increased IFN-alpha production in a dose-dependent manner . Labre intake tended to be most beneficial in subjects with initially low levels of IFN-alpha production . Heat-treated Labre did not elicit a response similar to that of the live bacteria.

J Appl Bacteriol, 1996 Aug, 81(2), 201 - 6
Effect of adherent Lactobacillus spp . on in vitro adherence of salmonellae to the intestinal epithelial cells of chicken; Jin LZ et al.; Single strains of Lactobacillus acidophilus and Lact . fermentum, isolated from chicken intestine, were used to study in vitro interactions with Salmonella enteritidis, Salm . pullorum or Salm . typhimurium in an ileal epithelial cell (IEC) radioactive assay . Exclusion, competition and displacement phenomena were investigated by respectively incubating (a) lactobacilli and IEC together, prior to addition of salmonellae, (b) lactobacilli, IEC and salmonellae together, and (c) salmonellae and IEC, followed by the lactobacilli . Lactobacilli were selected for study because of their strong ability to adhere to IEC and poor aggregation with salmonellae . The results demonstrated that Lact . acidophilus significantly reduced (P < 0.05) the attachment of Salm . pullorum to IEC in the tests for exclusion and competition, but not in the displacement tests . Lactobacillus fermentum was found to have some ability to reduce the attachment of Salm . typhimurium to IEC under the conditions of exclusion (P < 0.08), competition (P < 0.09), but not displacement . However, both Lact . acidophilus and Lact . fermentum were unable to reduce the adherence of Salm . enteritidis to IEC under any of the conditions.

J Appl Bacteriol, 1996 Aug, 81(2), 113 - 9
Application of antimicrobial-producing lactic acid bacteria to control pathogens in ready-to-use vegetables; Vescovo M et al.; Five psychrotrophic strains of lactic acid bacteria (Lactobacillus casei, Lact . plantarum and Pediococcus spp.) were isolated from 22 samples of commercial salads . These strains were shown to inhibit Aeromonas hydrophila, Listeria monocytogenes, Salmonella typhimurium and Staphylococcus aureus on MRS agar, in salads and in juice prepared from vegetable salads . Lactobacillus casei IMPCLC34 was most effective in reducing total mesophilic bacteria and the coliform group; Aer . hydrophila, Salm . typhimurium and Staph . aureus disappeared after 6 d of storage, while the counts for L . monocytogenes remained constant . The potential application of antimicrobial-producing lactic acid bacteria as biopreservatives of ready-to-use vegetables is suggested.

J Bacteriol, 1996 Aug, 178(15), 4727 - 30
The genes for phosphofructokinase and pyruvate kinase of Lactobacillus delbrueckii subsp . bulgaricus constitute an operon; Branny P et al.; In Lactobacillus delbrueckii subsp . bulgaricus, the pyk gene coding for pyruvate kinase and the pfk gene coding for phosphofructokinase formed a bicistronic operon transcribed into a 2.9-kb RNA . The nucleotide sequence of the pyk gene indicated that the encoded protein possessed an extra C-terminal domain with a potential phosphoenolpyruvate-dependent autophosphorylation site.

J Bacteriol, 1996 Aug, 178(15), 4472 - 83
Characterization of the locus responsible for the bacteriocin production in Lactobacillus plantarum C11; Diep DB et al.; Lactobacillus plantarum C11 secretes a small cationic peptide, plantaricin A, that serves as induction signal for bacteriocin production as well as transcription of plnABCD . The plnABCD operon encodes the plantaricin A precursor (PlnA) itself and determinants (PlnBCD) for a signal transducing pathway . By Northern (RNA) and sequencing analyses, four new plantaricin A-induced operons were identified . All were highly activated in concert with plnABCD upon bacteriocin induction . Two of these operons (termed plnEFI and plnJKLR) each encompass a gene pair (plnEF and plnJK, respectively) encoding two small cationic bacteriocin-like peptides with double-glycine-type leaders . The open reading frames (ORFs) encoding the bacteriocin-like peptides are followed by ORFs (plnI and -L, respectively) encoding cationic hydrophobic proteins resembling bacteriocin immunity proteins . On the third operon (termed plnMNOP), a similar bacteriocin-like ORF (plnN) and a putative immunity ORF (either plnM or -P) were identified as well . These findings suggest that two bacteriocins of two-peptide type (mature PlnEF and PlnJK) and a bacteriocin of one-peptide type (mature PlnN) could be responsible for the observed bacteriocin activity . The last operon (termed plnGHSTUV) contains two ORFs (plnGH) apparently encoding an ABC transporter and its accessory protein, respectively, known to be involved in processing and export of peptides with precursor double-glycine-type leaders . Promoter structure was established . A conserved regulatory-like box encompassing two direct repeats was identified in the promoter regions of all five plantaricin A-induced operons . These repeats may serve as regulatory elements for gene expression.

Gastroenterology, 1996 Aug, 111(2), 334 - 44
The effects of Lactobacillus strains and oat fiber on methotrexate-induced enterocolitis in rats; Mao Y et al.; BACKGROUND & AIMS: Administration of methotrexate to rats on an elemental diet results in severe enterocolitis and death . Lactobacilli, an integral part of the healthy gastrointestinal microecology, may provide therapeutic benefits to help the recovery from enterocolitis . The purpose of this study was to evaluate the effects of lactobacilli and oatbase on methotrexate-induced enterocolitis in rats . METHODS: Rats received continuous intragastric infusion of elemental diet or with supplementation of oatbase, Lactobacillus reuteri R2LC, and Lactobacillus plantarum DSM 9843, with and without fermentation, from the beginning of the study . Methotrexate (20 mg/kg) was injected intraperitoneally on day 3, and the sampling was performed on day 6 . RESULTS: Lactobacilli and oatbase decreased body weight loss and intestinal permeability and increased bowel mucosal mass in enterocolitic rats . Administration of lactobacilli, but not oatbase, decreased the intestinal myeloperoxidase level, reestablished intestinal microecology, and reduced bacterial translocation to extraintestinal sites . Both lactobacilli and oatbase reduced plasma endotoxin levels . The effects of lactobacilli were greater with fermentation than without fermentation or oatbase alone, and L . plantarum was more effective in reducing intestinal pathogens than L . reuteri . CONCLUSIONS: Exogenous administration of lactobacilli, especially L . plantarum with fermentation, is helpful in reducing the severity of enterocolitis in rats.

Biochim Biophys Acta, 1996 Jul 26, 1302(2), 129 - 37
Lipid composition of the phosphatidylcholine-producing bacterium Hyphomicrobium vulgare NP-160; Batrakov SG et al.; The extractable lipids of the PC-producing, methylotrophic, budding bacterium Hyphomicrobium vulgare NP-160 grown in a mineral-salts medium containing methanol as the carbon source, were studied by chromatographic and spectrometric methods . They were found to be comprised of PC (35% of the total lipids), PDME (33%), PMME (1%), PE (9%), PG (10%), DPG (6%), and a non-phosphorus, ornithine-containing lipoamino acid, OL (6%) . No low-polarity lipids, such as fatty acid esters of glycerol or of other alcohols, were detected . The sole fatty-acyl constituents of PDME and PMME were cis-octadec-11-enoic (cis-vaccenic) acid residues, whereas the other phospholipids contained, in addition, 1 to 5 mol % of MOA (lactobacillic acid) residues located predominantly at the sn-1 position of their glycerol residues . OL consisted of two molecular species, 2-N-{3'-(cis-octadec-11"-enoyloxy)octadecanoyl}-L- ornithine and 2-N-{3'-(cis-11", 12"-methyleneoctadecanoyloxy)octadecanoyl}-L-ornithine in the molar ratio 94:6 . When the culture medium was devoid of phosphate, a threefold increase in OL together with a three-fold decrease in PE were observed, no significant changes in proportions of the remaining lipids occurring . The most striking feature of the lipid composition in this case was the presence of considerable amounts of fatty acid methyl esters, mainly methyl cis-vaccenate, along with minute amounts of wax esters.

Carbohydr Res, 1996 Jul 19, 288, 203 - 18
Structural characterization of the exopolysaccharide produced by Lactobacillus acidophilus LMG9433; Robijn GW et al.; The exopolysaccharide produced by Lactobacillus acidophilus LMG9433 in a semi-defined medium was found to be a charged heteropolymer, with a composition of D-glucose, D-galactose, D-glucuronic acid, and 2-acetamido-2-deoxy-D-glucose in molar ratios of 2:1:1:1 . By means of methylation analysis, uronic acid degradation, de-N-acetylation/deamination, partial acid hydrolysis, and 1D/2D NMR studies the polysaccharide was demonstrated to consist of repeating units with the following structure: {Table: see text}

Carbohydr Res, 1996 Jul 19, 288, 57 - 74
Predicting helical structures of the exopolysaccharide produced by Lactobacillus sake 0- 1; Robijn GW et al.; The viscous exopolysaccharide (EPS) produced by Lactobacillus sake 0- 1 is a high molecular mass polymer (Mm 6 x 10(6) Da) consisting of pentasaccharide repeating units with a composition of D-glucose, L-rhamnose, and sn-glycerol 3-phosphate in molar ratios of 3:2:1 . One of the rhamnose residues in the repeating unit is partially 2-O-acetylated . The O-deacetylated, deglycerophosphorylated EPS has been investigated by molecular mechanics calculations . A complete conformational analysis of each of the constituent disaccharide fragments has been performed using the flexible residue approach with the MM3(92) force field . Furthermore, using the same force field, CICADA analyses were accomplished on hexa- and octasaccharide substructure of the polysaccharide . Based on these analyses, insight was obtained into nine conformational minima for the polysaccharide . The low energy conformations found by CICADA were extrapolated to regular polysaccharide structures using a polysaccharide builder program . The generated helices exhibit either 2-fold or 3- or 4-fold right-handed chiralities, and in each case the helices are highly extended.

Plasmid, 1996 Jul, 36(1), 49 - 54
Nucleotide sequence analysis of pOg32, a cryptic plasmid from Leuconostoc oenos; Brito L et al.; Analysis of the nucleotide sequence of Leuconostoc oenos plasmid pOg32 (2544 bp) revealed three open reading frames (ORFs) in one of the DNA strands preceded by putative promoters and ribosome binding sites . ORF1 corresponded to a polypeptide similar to the replication proteins (Rep) of pT181 plasmid family . A nucleotide sequence like the double strand origin (DSO) of the same plasmid family was found inside the presumptive rep gene . ORF2 is capable of encoding a protein resembling the recombination enzyme (Pre) of two lactobacilli plasmids . Immediately upstream of the presumed pre gene, a sequence similar to the consensus RSA regions of those plasmids was encountered . Between ORF3 and ORF1, a sequence comparable to the RSB consensus region of the single strand origin ssoA was detected . The putative RSB region was located at the 3'-end of an imperfect palindrome which may be a single stranded origin . The described features, common to other small plasmids of Gram-positive bacteria, suggest that pOg32 replicates by the rolling circle mechanism . The amino acid sequence encoded by ORF3 was not similar to any known protein.

J Endod, 1996 Jul, 22(7), 356 - 7
Antibacterial activity of 10% carbamide peroxide bleaching agents; Gurgan S et al.; The antibacterial activity of three commercial 10% carbamide peroxide bleaching agents (Nite White, Karisma, and Opalescence) on Streptococcus mutans, Streptococcus mitis, Streptococcus sanguis, Lactobacillus casei, and Lactobacillus acidophilus was examined . Chlorhexidine (0.2%) was used as a positive control . Test materials and control solution were inserted in wells punched on the surface of disk sensitivity agars seeded with bacteria . After incubation of 24 to 48 h, zones of inhibition were measured . All three of the test materials displayed greater inhibition than the control . The pH of the solutions did not effect the bacterial inhibition.

Mol Membr Biol, 1996 Jul-Sep, 13(3), 173 - 81
The application of pH-sensitive fluorescent dyes in lactic acid bacteria reveals distinct extrusion systems for unmodified and conjugated dyes; Glaasker E et al.; Intracellular pH in bacteria can be measured efficiently between internal pH values of 6.5 and 8.5 with the fluorescent pH indicator 2',7'-bis-(2-carboxyethyl)-5{and-6}-carboxyfluorescein (BCECF) . A new fluorescent pH probe with a lower pKa(app) than BCECF was synthesized from fluorescein isothiocyanate and glutamate . The new probe, N-(fluorescein thio-ureanyl)-glutamate (FTUG), was much less sensitive to changes in concentrations of KCl than was BCECF . Similar to BCECF, an efflux of FTUG independent of the proton motive force, but dependent on ATP, was observed both in Lactobacillus plantarum and Lactococcus lactis . Corrections for probe efflux allowed accurate measurements of the pHin . Similar intracellular pH values were determined with FTUG and BCECF, in the range where both probes can be applied, and the pH values correlated well with those estimated from the distribution of radio-labelled benzoic acid . Since FITC can easily be coupled to substrates containing an amino group, it is possible to develop other FITC derivatives as well . The mechanisms of probe excretion and the nature of the excreted product(s) were studied in further detail for BCECF and FTUG . BCECF was excreted from wild-type L . lactis in an unmodified form as was determined by chromatographic and mass spectrometry analysis . In the case of FTUG, the excreted product was a conjugated derivative . Unmodified FTUG was not excreted, although it was present in cellular extracts from L . lactis . Exit of BCECF was completely inhibited in a BCECF efflux mutant (Bef-) of L . lactis, whereas FTUG-conjugate efflux in this mutant was similar to the wild-type . Addition of indomethacin, a known inhibitor of BCECF efflux in human epithelial cells, resulted in complete inhibition of BCECF efflux in wild-type L . lactis, whereas FTUG-conjugate exit was only slightly affected . The results of the mutant and inhibitor studies suggest that FTUG-conjugate and BCECF efflux in L . lactis are mediated by different ATP-driven extrusion systems for organic anions.

Diagn Microbiol Infect Dis, 1996 Jul, 25(3), 147 - 9
In vitro activity of quinupristin/dalfopristin (RP 59500) against a large collection of infrequently isolated or tested species; Barrett MS et al.; Quinupristin/dalfopristin (RP 59500, Synercid) is a parenteral streptogramin combination antimicrobial that possesses a synergistic and often bactericidal action against many Grampositive species . In this study, a collection of 1270 uncommonly isolated or tested strains were evaluated for susceptibility to quinupristin/dalfopristin using agar dilution minimum inhibitory concentration (MIC) methods described in the National Committe for Clinical Laboratory Standards . The greatest antimicrobial activity observed for quinupristin/dalfopristin was against staphylococci, streptococci, the pathogenic neisseria, Legionella spp., Lactobacillus spp., and Peptostreptococcus spp . (MIC90 range, 0.5-2 micrograms/ml) . Marginal activity (MIC90s, 4 to 8 micrograms/ml) was identified for the rarer enterococci, Leuconostoc spp., Pediococcus spp., and Streptococcus bovis . Against Haemophilus parainfluenzae, Bacteroides thetaiotaomicron, Fusobacterium spp., and Prevotella spp., the streptogramin was inactive . Although no susceptible breakpoint has been approved for quinupristin/dalfopristin, three possible breakpoints (< or = 1, < or = 2, or < or = 4 micrograms/mL) were evaluated . Acceptance of the lower breakpoints (< or = 1 or < or = 2 micrograms/mL) would limit quinupristin/dalfopristin use to staphylococci, streptococci, gonococci, meningococci, and Legionella spp . These results markedly expand the understanding of the usable spectrum of quinupristin/dalfopristin.

Eur J Surg, 1996 Jul, 162(7), 537 - 44
The effect of pretreatment with endotoxin and lactobacillus on bacterial translocation in acute liver injury; Kasravi FB et al.; OBJECTIVE: To evaluate the effect of pretreatment with endotoxin or Lactobacillus reuteri pretreatment on bacterial translocation after acute liver injury . DESIGN: Experimental study . SETTING: University department, Sweden . SUBJECTS: 96 Sprague-Dawley rats were divided into four groups of 24 each . Three of them received intraperitoneal D-galactosamine, the fourth received pyrogen free water and was used as the normal control . Twenty-four hours later the study was terminated and samples collected . INTERVENTIONS: Endotoxin and L reuteri R2LC were injected intraperitoneally three days, one week, and two weeks before induction of liver injury . MAIN OUTCOME MEASURES: Extent of liver injury and bacterial translocation to mesenteric lymph nodes, liver, and systemic blood . RESULTS: The extent of liver injury and rate of bacterial translocation were lower three days after pretreatment with endotoxin, than after pretreatment with L reuteri . There was no other difference among the other groups . High concentrations of serum endotoxin were detected three days after pretreatment with endotoxin . There were no significant changes in small intestinal and caecal bacterial counts . CONCLUSION: Pretreatment with endotoxin effectively prevented liver injury by D-galactosamine and subsequent bacterial translocation . Pretreatment with L reuteri had no beneficial effect.

Pediatr Dent, 1996 Jul-Aug, 18(4), 306 - 11
Salivary factors in children and adolescents with insulin-dependent diabetes mellitus; Karjalainen KM et al.; To determine whether hyperglycemia in IDDM (insulin-dependent diabetes mellitus) could interfere with salivary secretion rates, salivary glucose levels, and salivary microbial counts, we studied salivary factors in two groups of children and adolescents with IDDM . One study group included 14 children with newly diagnosed IDDM )mean age 11 years, SD +/- 2.4 years) . Samples of saliva were collected on admission to hospital and after 2 weeks on insulin treatment . The other study group were 50 IDDM children (mean age 14.4 years, SD +/- 1.7 years, mean duration of diabetes 6.2 years, SD +/- 1.4 years) visiting the outpatient diabetic clinic . Samples of saliva were collected during two visits, approximately 3 months apart . In the newly diagnosed IDDM cases, mean salivary glucose level decreased from 54.1 +/- 31.7 mg/l to 35.2 +/- 29.5 mg/l (P = 0.096) after beginning insulin treatment . During hyperglycemia, salivary glucose levels correlated with mean blood glucose levels for the day concerned (r = 0.65, P < 0.05) . The results suggest that high blood glucose levels can increase salivary glucose levels . Stimulated saliva secretion increased significantly from 5.4 +/- 3.3 ml/5 min to 7.3 +/- 2.6 ml/5 min (P < 0.01) while glucose balance improved . In the long-term IDDM cases, salivary flow rates and salivary glucose levels were not significantly related to the glycosylated hemoglobin (HbA1) values . Salivary glucose levels and salivary secretion rates were inversely correlated (P < 0.05) . In conclusion, hyperglycemia was observed to be associated with decreased salivary secretion and high salivary glucose levels . As a consequence, salivary lactobacilli and yeast counts tended to increase.

Int J Food Microbiol, 1996 Jul, 30(3), 293 - 302
rRNA gene restriction patterns as a characterization tool for Lactobacillus sake strains producing ropy slime; Bjorkroth J et al.; The rRNA gene restriction patterns (ribotypes) of 69 ropy slime producing Lactobacillus sake strains isolated mainly from vacuum-packaged meat products of ten meat plants were determined . Ribotypes were compared to the corresponding patterns of non-ropy L . sake strains, and also to other species of the genus Lactobacillus, Carnobacterium and Weissella associated with meat products . Ropy slime-producing L . sake strains were divided into four characteristic groups corresponding to the phenotypic carbohydrate grouping . No association between certain ribotypes and individual plants was detected . Ribotyping was unable to distinguish slime producing and non-ropy strains of L . sake group sharing the same carbohydrate pattern . Otherwise, ribotyping distinguished the ropy slime producing strains from the non-ropy L . sake reference strains and all L . sake strains from other species of the genus Lactobacillus, Carnobacterium and Weissella . These results suggest that ribotyping is a suitable method for detection and surveillance of the contamination of ropy slime-producing L . sake strains but the patterns alone cannot be used as markers of slime production capability.

Appl Environ Microbiol, 1996 Jul, 62(7), 2610 - 4
Control of beef spoilage by a sulfide-producing Lactobacillus sake strain with bacteriocinogenic Leuconostoc gelidum UAL187 during anaerobic storage at 2 degrees C; Leisner JJ et al.; Chill-stored, vacuum-packaged beef inoculated with sulfide-producing Lactobacillus sake 1218 developed a distinct sulfide odor within 3 weeks of storage at 2 degrees C, at which time the bacteria had reached maximum numbers of 10(6) CFU cm(-2) . Coinoculation of the meat with the wild-type, bacteriocinogenic (Bac+) strain of Leuconostoc gelidum UAL187 delayed the spoilage by L . sake 1218 for up to 8 weeks of storage . Coinoculation of meat samples with an isogenic, slowly growing Bac+ variant, UAL187-22, or with the Bac- variant UAL187-13 did not delay the onset of spoilage by L . sake 1218 . The study showed that spoilage of chill-stored, vacuum-packaged beef by a susceptible target organism could be dramatically delayed by the Bac+ wild-type strain of L . gelidum UAL187 . Inoculation with L . sake 1218 can be used as a model system to determine the efficacy of biopreservation of vacuum-packaged meats.

Appl Environ Microbiol, 1996 Jul, 62(7), 2244 - 51
A mannose-specific adherence mechanism in Lactobacillus plantarum conferring binding to the human colonic cell line HT-29; Adlerberth I et al.; Two Lactobacillus plantarum strains of human intestinal origin, strains 299 (= DSM 6595) and 299v (= DSM 9843), have proved to be efficient colonizers of the human intestine under experimental conditions . These strains and 17 other L . plantarum strains were tested for the ability to adhere to cells of the human colonic cell line HT-29.L.plantarum 299 and 299v and nine other L . plantarum strains, including all six strains that belong to the same genetic subgroup as L . plantarum 299 and 299v, adhered to HT-29 cells in a manner that could be inhibited by methyl-alpha-D-mannoside . The ability to adhere to HT-29 cells correlated with an ability to agglutinate cells of Saccharomyces cerevisiae and erythrocytes in a mannose-sensitive manner and with adherence to D-mannose-coated agarose beads . L . plantarum 299 and 299v adhered to freshly isolated human colonic and ileal enterocytes, but the binding was not significantly inhibited by methyl-alpha-D-mannoside . Periodate treatment of HT-29 cells abolished mannose-sensitive adherence, confirming that the cell-bound receptor was of carbohydrate nature . Proteinase K treatment of the bacteria also abolished adherence, indicating that the binding involved protein structures on the bacterial cell surface . Thus, a mannose-specific adhesin has been identified in L . plantarum; this adhesin could be involved in the ability to colonize the intestine.

J Allergy Clin Immunol, 1996 Jul, 98(1), 216 - 24
Suppression of lymphocyte proliferation in vitro by bovine caseins hydrolyzed with Lactobacillus casei GG-derived enzymes; Sutas Y et al.; BACKGROUND: Processing of proteins in the gut and activation of T-cell suppression leads to systemic hyporesponsiveness to ingested protein antigens . OBJECTIVE: The study was designed to determine whether lactobacilli, a major part of human intestinal microflora, can contribute to degradation of food antigens in the gut and modify their immunoactivities . METHODS: Lymphocyte transformation tests were carried out in healthy adults to determine the mitogen-induced lymphocyte proliferative responses to bovine caseins hydrolyzed with pepsin and trypsin and to bovine caseins additionally hydrolyzed with enzymes derived from Lactobacillus casei strain GG (ATCC 53103) . RESULTS: In experiments done with caseins hydrolyzed with pepsin and trypsin, beta- and alpha(s1)-caseins significantly suppressed the proliferation of lymphocytes at 0.1 and 10 micrograms/ml, respectively, when compared with corresponding control cultures without these hydrolysates . In contrast, kappa-casein significantly stimulated the proliferation of lymphocytes at 10 micrograms/ml . In experiments done with caseins additionally hydrolyzed with L . casei GG-derived enzymes, there was one consistent effect on lymphocyte proliferation: suppression by alpha(sl)-, beta-, and kappa-caseins at 0.1, 10, and 1000 micrograms/ml, respectively . CONCLUSIONS: Hydrolysis of caseins with L . casei GG-derived enzymes generates molecules with suppressive effects on lymphocyte proliferation . In addition, intestinal bacteria can be beneficial in the downregulation of hypersensitivity reactions to ingested proteins in patients with food allergy.

Acta Obstet Gynecol Scand, 1996 Jul, 75(6), 520 - 5
Fetal fibronectin and microorganisms in vaginal fluid of healthy pregnant women; Rossel Goffeng A et al.; OBJECTIVE . To determine fetal fibronectin in vaginal fluid from healthy women during uncomplicated pregnancy and to investigate possible relationships to gestational age and the vaginal microflora . MATERIALS AND METHODS . Samples of vaginal fluid were collected for fetal fibronectin determination and for quantitative aerobic and anaerobic microbiological culture from 22 women followed longitudinally at 12, 28 and 37 weeks gestation cross-sectionally in women at 12 weeks (n = 10), 28 weeks (n = 10), 37 weeks (n = 10), and 39 weeks (n = 30) gestation, respectively . Fetal fibronectin was determined by a quantitative enzyme immunoassay (Adeza Biomedical) . RESULTS . There were no significant differences between the concentrations of fetal fibronectin in vaginal secretions at any of the four measurement points (12, 28, 37 and 39 weeks gestation) . Women with elevated fetal fibronectin concentration (> or = 0.05 mg/L) had less often hydrogen peroxide-producing facultative lactobacilli (p < 0.0001), and more often bacterial vaginosis (p < 0.02) and Peptostreptococcus species (p < 0.002) . Bacterial vaginosis (p < 0.01) and Candida albicans (p < 0.01) were more frequently found in women lacking hydrogen peroxide-producing lactobacilli . CONCLUSION . Fetal fibronectin in vaginal fluid was more associated with the vaginal microflora than with the gestational age of the pregnancy . Presence of hydrogen peroxide-producing lactobacilli seems to be the most important factor for a stable vaginal microflora.

J Bacteriol, 1996 Jul, 178(13), 3869 - 76
The D-Alanyl carrier protein in Lactobacillus casei: cloning, sequencing, and expression of dltC; Debabov DV et al.; The incorporation of D-alanine into membrane-associated D-alanyl-lipoteichoic acid in Lactobacillus casei requires the 56-kDa D-alanine-D-alanyl carrier protein ligase (Dcl) and the 8.9-kDa D-alanyl carrier protein (Dcp) . To identify and isolate the gene encoding Dcp, we have cloned and sequenced a 4.3-kb chromosomal fragment that contains dcl (dltA) . In addition to this gene, the fragment contains three other genes, dltB, d1tC, and a partial dltD gene . dltC (246 nucleotides) was subcloned from this region and expressed in Escherichia coli . The product was identified as apo-Dcp lacking the N-terminal methionine (8,787.9 Da) . The in vitro conversion of the recombinant apo-Dcp to holo-Dcp by recombinant E . coli holo-ACP synthase provided Dcp which accepts activated D-alanine in the reaction catalyzed by Bcl . The recombinant D-alanyl-Dcp was functionally identical to native D-alanyl-Dcp in the incorporation of D-alanine into lipoteichoic acid . L . casei Dcp is 46% identical to the putative product of dltC in the Bacillus subtilis dlt operon (M . Perego, P . Glaser, A . Minutello, M . A . Strauch, K . Leopold, and W . Fischer, J . Biol . Chem . 270:15598-15606, 1995), and therefore, this gene also encodes Dcp . Comparisons of the primary sequences and predicted secondary structures of the L . casei and B . subtilis Dcps with that of the E . coli acyl carrier protein (ACP) were undertaken together with homology modeling to identify the functional determinants of the donor and acceptor specificities of Dcp . In the region of the phospho-pantetheine attachment site, significant similarity between Dcps and ACPs was observed . This similarity may account for the relaxed acceptor specificity of the Dcps and ACPs in the ligation Of D-alanine catalyzed by Dcl . In contrast, two Dcp consensus sequences, KXXVLDXLA and DXVKXNXD, share little identity with the rest of the ACP family and, thus, may determine the donor specificity of D-alanyl-Dcp in the D-alanylation of membrane-associated D-alanyl-lipoteichoic acid.

Curr Microbiol, 1996 Jul, 33(1), 31 - 4
Adhesion of Lactobacillus fermentum 104-S to porcine stomach mucus; Henriksson A et al.; The adhesion to whole and fractionated porcine gastric mucus of both Lactobacillus fermentum 104-S cells and a saccharide extracted from this strain was investigated . It has been shown previously that this saccharide had affinity for nonsecreting gastric epithelium . The mucus component(s) with affinity the bacterial cells was partly characterized by gel filtration and treatment with protease or metaperiodate . L . fermentum 104-S extracts containing the saccharide were radioactively labeled, fractionated by gel filtration, and tested for affinity for the gastric mucus component showing receptor activity for the whole cells of strain 104-S . The mucus material with affinity for the bacterial cells had a relative molecular weight of 30-70 K . From the results of treatment with protease or metaperiodate, it is proposed that the mucus components(s) that adhered to the whole bacterial cells contained glycoprotein groups . The radioactively labeled saccharide extracted from L . fermentum 104-S cells did not bind to the mucus fraction that had affinity for the whole cells . Conclusively, we suggest that the mechanism by which cells of L . fermentum 104-S adhere to the gastric mucus is different from the mechanism mediating the adhesion of this strain to the nonsecreting gastric epithelium . Cells of L . fermentum 104-S adhere to a glycoproteinaceous mucus component with a relative molecular weight of 30-70 K.

Anal Biochem, 1996 Jul 1, 238(2), 179 - 83
A combined high-performance liquid chromatographic-microbiological assay for serum folic acid; Kelly P et al.; An assay of folic acid in human serum is described involving HPLC fractionation of deproteinized serum prior to Lactobacillus casei assay . High specific activity {3H}folic acid is added as internal standard to 1 ml serum prior to deproteinization with perchlorate and an aliquot is applied to a C18 reverse-phase HPLC column . The folic acid fraction was assayed by L . casei microtiter plate assay . Intra- and interassay variations (CV) were 5.5 and 7.5% respectively for sera (n = 10) spiked with folic acid . The percentage recovery for folic acid additions of 10 and 20 ng/liter were 105.2 and 103.7%, respectively . The lower limit of detection was 1 ng folic acid/ml serum . Folates other than folic acid and 5-methyltetrahydrofolate were not detected . The assay permitted serial measurements to be made of folates in serum following an oral dose.

J Biol Chem, 1996 Jun 14, 271(24), 14421 - 9
Covalent structure, synthesis, and structure-function studies of mesentericin Y 105(37), a defensive peptide from gram-positive bacteria Leuconostoc mesenteroides; Fleury Y et al.; A 37-residue cationic antimicrobial peptide named mesentericin Y 105(37) was purified to homogeneity from cell-free culture supernatant of the Gram-positive bacterium Leuconostoc mesenteroides . The complete amino acid sequence of the peptide, KYYGNGVHCTKSGCSVNWGEAASAGIHRLANGGNGFW, has been established by automated Edman degradation, mass spectrometry, and solid phase synthesis . Mesentericin Y 105(37) contains a single intramolecular disulfide bond that forms a 6-membered ring within the molecule . Mesentericin Y 105(37) was synthesized by the solid phase method . The synthetic replicate was shown to be indistinguishable from the natural peptide with respect to electrophoretic and chromatographic properties, mass spectrometry analysis, automated amino acid sequence determination, and antimicrobial properties . At nanomolar concentrations, synthetic mesentericin Y 105(37) is active against Gram+ bacteria in the genera Lactobacillus and Carnobacterium . Most interestingly, the peptide is inhibitory to the growth of the food-borne pathogen Listeria . CD spectra of mesentericin Y 105(37) in low polarity medium, which mimic the lipophilicity of the membrane of target organisms, indicated 30-40% alpha-helical conformation, and predictions of secondary structure suggested that the peptide can be configured as an amphipathic helix spanning over residues 17-31 . To reveal the molecular basis of the specificity of mesentericin Y 105(37) targetting and mode of action, NH2- or COOH-terminally truncated analogs together with point-substituted analogs were synthesized and evaluated for their ability to inhibit the growth of Listeria ivanovii . In sharp contrast with broad spectrum alpha-helical antimicrobial peptides from vertebrate animals, which can be shortened to 14-18 residues without deleterious effect on potency, molecular elements responsible for anti-Listeria activity of mesentericin Y 105(37) are to be traced at once to the NH2-terminal tripeptide KYY, the disulfide bridge, the putative alpha-helical domain 17-31, and the COOH-terminal tryptophan residue of the molecule . It is proposed that the amphipathic helical domain of the peptide interacts with lipid bilayers, leading subsequently to alteration of the membrane functions, whereas residues 1-14 form part of a recognition structure for a membrane-bound receptor, which may be critical for peptide targetting . Because mesentericin Y 105(37) is easy to synthesize at low cost, it may represent a useful and tractable tool as a starting point for the design of more potent analogs that may be of potential applicability in foods preservation.

Community Dent Oral Epidemiol, 1996 Jun, 24(3), 169 - 74
Dental caries in relation to diet, saliva and cariogenic microorganisms in Tanzanians of selected age groups; Mazengo MC et al.; The relationship between diet and dental caries in a Tanzanian population was studied . Mutans streptococci, lactobacilli, yeasts, salivary flow rate as well as buffer effect were also analyzed . A random sample of 12-, 35-44- and 65- to 74- year olds was drawn from Msongola (rural) and Ukombozi (urban), Dar-es-Salaam . The mean of two 24-h recalls was used for the assessment of food intake . The percentage of those with at least one carious tooth ranged from 30% in the 12-year-olds to 80% in the oldest age group . The mean number of decayed teeth (DT) increased significantly with age (P = 0.000) but was not significantly associated with the area of residence . DT increased significantly (P = 0.048) with the number of snacks per day and was also associated with dietary sucrose (P = 0.025), total carbohydrates (P = 0.002) and fiber (P = 0.002) . Among salivary variables lactobacilli (P = 0.000) correlated positively with DT . Our study did not reveal any strong association between total energy intake and dental caries in rural or urban populations in Tanzania but snacking and sucrose intake were significantly associated with caries, in particular in the urban area.

Community Dent Oral Epidemiol, 1996 Jun, 24(3), 159 - 63
Number of mutans streptococci or lactobacilli in a total dental plaque sample does not explain the variation in caries better than the numbers in stimulated whole saliva; Sullivan A et al.; For practical reasons the numbers of mutans streptococci (MS) and lactobacilli (LB) in plaque are commonly estimated from saliva samples . The saliva counts are considered to be a reasonable indicator of the entire dentition's total microbial load . However, the value of salivary counts for explaining and predicting caries have been found to be low . There was therefore reason to compare the relationships between caries on the one hand and, on the other, the number of MS or LB in plaque and in saliva, respectively, in order to assess their relative merits for explaining the variation in caries, both in a total material and in subgroups with less favourable oral hygiene . Sixty children aged 14-15 years participated in the study . Caries and plaque were registered and the number of MS and LB was estimated in total plaque and in stimulated saliva samples . The results showed that the number of MS or LB in plaque did not explain the variation in caries to a greater degree than did the salivary counts . For both bacteria the explanatory values increased, as expected, in subgroups with less favourable oral hygiene, but not even at this higher level of explanation was there any difference between plaque and saliva . The LB count was a stronger explanatory variable than the MS count . It was concluded that the number of MS and LB, estimated in total plaque as well as in saliva samples, is not a useful tool in prediction.

Biol Chem Hoppe Seyler, 1996 Jun, 377(6), 357 - 62
Rapid purification and characterization of two distinct N-deoxyribosyltransferases of Lactobacillus leichmannii; Becker J et al.; Two distinct N-deoxyribosyltransferases of Lactobacillus leichmannii, designated as DRTase I and DRTase II, were separated and purified almost to homogeneity by one-step affinity chromatography . DRTase I is distinguished by specifically catalyzing the direct transfer of 2-deoxyribosyl residues from purine deoxyribonucleosides to free purine bases, whereas DRTase II has a rather broad substrate specificity and is able to transfer the deoxyribosyl moiety between pyrimidines and between purines and pyrimidines . Furthermore, in addition to the different substrate spectrum, we clearly differentiated the two enzymes by comparing their varying temperature/activity and pH/activity profiles, their kinetic constants, their behaviour in Western blot analysis, and their N-terminal amino acid sequences . Denaturing and non-denaturing DISK-PAGE revealed strong evidence that both intact enzymes consist of hexamers with subunit molecular weights of approximately 20,000 for DRTase I and 18,000 for DRTase II.

J Dairy Sci, 1996 Jun, 79(6), 971 - 9
The effect of milk fermentation by Lactobacillus helveticus on the release of peptides during in vitro digestion; Matar C et al.; This study evaluated the effect of protein hydrolysis by lactic acid bacteria during milk fermentation on the release of amino acids and peptides duing subsequently simulated peptic and pancreatic digestion . After digestion with trypsin, we compared the elution patterns of proteins and peptides obtained from unfermented milk and from milk fermented by Lactobacillus helveticus under pH control, using HPLC gel filtration and reverse-phase HPLC . The results indicate that milk fermentation affects the release of some amino acids during simulated gastrointestinal digestion and has a major impact on the modification of protein elution profiles obtained after digestion with trypsin . We conclude that proteolysis during fermentation may lead to the formation of novel peptides during gastrointestinal digestion.

J Vet Med Sci, 1996 Jun, 58(6), 591 - 3
Homofermentative Lactobacillus species predominantly isolated from canine feces; Fujisawa T et al.; Lactobacillus salivarius group biovars VIa and VIb, which are homofermentative Lactobacillus, were predominantly isolated from canine feces . Identification and biotyping of L . salivarius group biovars VIa and VIb were originally done by Mitsuoka et al . (1976) . These strains were tentatively identified as L . salivarius by their phenotypic characteristics . They are, however, more similar to those of some new Lactobacillus species, particularly L . animalis and L . murinus, than those of L . salivarius and have now been identified as L . animalis by DNA-DNA homology.

Acta Odontol Scand, 1996 Jun, 54(3), 193 - 9
Caries prevalence and salivary and microbial conditions in 88-year-old Swedish dentate people; Lundgren M et al.; As part of a comprehensive investigation of 88-year-old people, caries prevalence, stimulated salivary secretion rate, buffer capacity, and the prevalence of lactobacilli and mutans streptococci were studied in a subsample of 92 dentate subjects . The mean number of remaining teeth was 14.1 +/- 7.3 . The DMFT was 25.2 +/- 3.0, and DF surfaces 38.3 +/- 22.7 . Root caries experience was found in 85% of the subjects, with a mean root caries index of 36.6 +/- 28.5% . The men had significantly higher mean values of salivary secretion rate (2.0 +/- 1.3 ml/min) than the women (1.1 +/- 0.6 ml/min) (p < 0.001) . The mean final pH of buffer capacity was 6.3 +/- 1.3 . High counts of lactobacilli (> 10(5)) and mutans streptococci (> 10(6)) were found in 49% and 55% of the subjects, respectively, of whom most were denture wearers . The mean number of total mutans streptococci was higher in persons harboring both Streptococcus mutans and S . sobrinus than in subjects with only S . mutans.

Hiroshima J Med Sci, 1996 Jun, 45(2), 63 - 8
Enhancement of host resistance to microbial infections in mice fed a high fat diet by Lactobacillus casei cells; Watanabe T et al.; The carbon clearance ability of female ddY mice was markedly reduced by feeding with a high fat-low carbohydrate (HFLC) diet for 8 weeks . The reduced clearance ability was restored by a single intraperiotoneal (i.p.) injection with heat-killed Lactobacillus casei (YIT 9018) cells (LC 9018) . The i.p . injection of LC 9018 into the HFLC diet-fed mice led to a remarkable enhancement of nonspecific resistance when they were exposed to 50% lethal doses of Pseudomonas aeruginosa or herpes simplex virus, type 1 . The resistance-enhancing capacity of LC 9018 against P . aeruginosa infection was significantly maintained for 7 days after the ip inoculation with LC 9018 in mice fed the HFLC diet . The reduced in vivo killing activity of peritoneal exudate cells (macrophage-rich) from mice fed the HFLC diet to P . aeruginosa infection was markedly augmented by the i.p . administration of LC 9018 . The results indicate that LC 9018, one of the bacterial immunostimulants, may restore the reduced host defense functions in mice induced by feeding with a high fat diet for a long period.

Microbiol Rev, 1996 Jun, 60(2), 280 - 300
Molecular and industrial aspects of glucose isomerase; Bhosale SH et al.; Glucose isomerase (GI) (D-xylose ketol-isomerase; EC . 5.3.1.5) catalyzes the reversible isomerization of D-glucose and D-xylose to D-fructose and D-xylulose, respectively . The enzyme has the largest market in the food industry because of its application in the production of high-fructose corn syrup (HFCS) . HFCS, an equilibrium mixture of glucose and fructose, is 1.3 times sweeter than sucrose and serves as a sweetener for use by diabetics . Interconversion of xylose to xylulose by GI serves a nutritional requirement in saprophytic bacteria and has a potential application in the bioconversion of hemicellulose to ethanol . The enzyme is widely distributed in prokaryotes . Intensive research efforts are directed toward improving its suitability for industrial application . Development of microbial strains capable of utilizing xylan-containing raw materials for growth or screening for constitutive mutants of GI is expected to lead to discontinuation of the use of xylose as an inducer for the production of the enzyme . Elimination of Co2+ from the fermentation medium is desirable for avoiding health problems arising from human consumption of HFCS . Immobilization of GI provides an efficient means for its easy recovery and reuse and lowers the cost of its use . X-ray crystallographic and genetic engineering studies support a hydride shift mechanism for the action of GI . Cloning of GI in homologous as well as heterologous hosts has been carried out, with the prime aim of overproducing the enzyme and deciphering the genetic organization of individual genes (xylA, xylB, and xylR) in the xyl operon of different microorganisms . The organization of xylA and xylB seems to be highly conserved in all bacteria . The two genes are transcribed from the same strand in Escherichia coli and Bacillus and Lactobacillus species, whereas they are transcribed divergently on different strands in Streptomyces species . A comparison of the xylA sequences from several bacterial sources revealed the presence of two signature sequences, VXW(GP)GREG(YSTAE)E and (LIVM)EPKPX(EQ)P . The use of an inexpensive inducer in the fermentation medium devoid of Co2+ and redesigning of a tailor-made GI with increased thermostability, higher affinity for glucose, and lower pH optimum will contribute significantly to the development of an economically feasible commercial process for enzymatic isomerization of glucose to fructose . Manipulation of the GI gene by site-directed mutagenesis holds promise that a GI suitable for biotechnological applications will be produced in the foreseeable future.

Appl Environ Microbiol, 1996 Jun, 62(6), 2111 - 6
Analysis of Lactobacillus phages and bacteriocins in American dairy products and characterization of a phage isolated from yogurt; Kilic AO et al.; Yogurt and acidophilus milk that contain Lactobacillus acidophilus could promote human health because L . acidophilus can inhibit enteric and food-borne microbial pathogens . To evaluate the stability of diary L . acidophilus cultures, we studied whether some diary lactobacilli could be inhibited by phages or bacteriocins released by other dairy lactobacilli . From 20 yogurts and two acidophilus milks purchased at local food markets, 38 Lactobacillus strains were isolated . Eight Lactobacillus type strains were used as controls . With mitomycin induction and agar spot assay, phages and bacteriocins were isolated from these strains and their activities were analyzed . Lactobacillus strains from 11 yogurts released phages, while the strains from most of the remaining products released bacteriocins . One phage, designated phi y8, was characterized . It was spontaneously released from its host strain L . acidophilus Y8, at a rate of about 10(4)/ml . This phage lysed nine other dairy Lactobacillus strains tested . It had a burst size of 100, an elongated prolate head of 39 by 130 nm, a long, flexible but noncontractile tail of 300 nm, and a 54.3-kb linear double-stranded DNA . DNA fingerprinting analysis indicated that L . acidophilus phages of nine yogurts in this study belonged to the same type as phi y8 . Although they may be sensitive to bacteriocins, all lysogens resisted further phage attacks, whereas most nonlysogens were sensitive to both phages and bacteriocins . Therefore, Lacotbacillus cultures of some American yogurts and acidophilus milks may be unstable or unsafe because they can either be inhibited by phages or bacteriocins or release them to inhibit lactobacilli or other diary products.

Appl Microbiol Biotechnol, 1996 Jun, 45(5), 638 - 45
Molecular characterization, over-expression and purification of a novel dipeptidase from Lactobacillus helveticus; Vesanto E et al.; A dipeptidase gene (pepD) from an industrial Lactobacillus helveticus strain was isolated by colony hybridization . An open reading frame (ORF) of 1422 base pairs (bp) with a coding capacity for a 53.5-kDa protein (PepD) was identified . The ORF was preceded by a typical prokaryotic promoter region, and an inverted repeat structure with delta G of -51.0 kJ mol-1 was found downstream of the coding region . The deduced amino acid sequence of the 53.5-kDa protein revealed no marked homologies when compared to the data bases of EMBL and SWISS-PROT . The 5'end of the 1.6-kb pepD transcript was determined both by a conventional primer extension method and using an automated sequencer . pepD was found to be maximally expressed at late exponential growth . The pepD gene was cloned into an expression vector to over-produce PepD in Escherichia coli JM105 . Purification of PepD to homogeneity was achieved using three chromatographic steps . PepD was able to hydrolyze a number of dipeptides with the exception of those containing a proline residue . Optimal PepD activity was observed at pH 6.0 and 55 degrees C . The enzyme was inhibited by p-hydroxymercuribenzoate and reactivated by dithiothreitol whereas ethylenediaminetetraacetate had no inhibitory effect on PepD . The enzymatic properties of PepD suggest that it represents a novel dipeptidase type among lactic acid bacteria.

Cancer Immunol Immunother, 1996 Jun, 42(5), 285 - 90
Suppressive effects of Lactobacillus casei cells, a bacterial immunostimulant, on the incidence of spontaneous thymic lymphoma in AKR mice; Watanabe T; The mean survival age of female AKR/J mice was significantly prolonged, the enlargement of thymus was markedly suppressed, and the proliferation of ecotropic and recombinant murine leukemia viruses (MuLV) was markedly inhibited when 8-week-old female AKR/J mice were injected intraperitoneally (i.p.) with heat-killed Lactobacillus casei cells twice weekly for 8 weeks . In contrast, such actions of heat-killed L . casei cells were not seen in 20-week-old female AKR/J mice . The leukemogenic activity of the cell-free extract of thymus from adult female AKR/J mice in newborn female AKR/J mice was drastically reduced by i.p . treatment with heat-killed L . casei cells . The difference in adjuvant effectiveness of heat-killed L . casei cells on 8- and 20-week-old animals may be dependent on the difference in the enhancing activity of the cell-mediated immune systems between the groups induced by heat-killed L . casei cells, and, as a result, on the difference in the degree of proliferation of ecotropic and recombinant MuLV in thymus, which consequently causes thymic lymphoma.

Microbiology, 1996 Jun, 142 ( Pt 6), 1437 - 48
Analysis of the sakacin P gene cluster from Lactobacillus sake Lb674 and its expression in sakacin-negative Lb . sake strains; Huhne K et al.; Sakacin P is a small, heat-stable, ribosomally synthesized peptide produced by certain strains of Lactobacillus sake . It inhibits the growth of several Gram-positive bacteria, including Listeria monocytogenes . A 7.6 kb chromosomal DNA fragment from Lb . sake Lb674 encompassing all genes responsible for sakacin P production and immunity was sequenced and introduced into Lb . sake strains Lb790 and Lb706X which are bacteriocin-negative and sensitive to sakacin P . The transformants produced sakacin P in comparable amounts to the parental strain, Lb674 . The sakacin P gene cluster comprised six consecutive genes: sppK, sppR, sppA, spiA, sppT and sppE, all transcribed in the same direction . The deduced proteins SppK and SppR resembled the histidine kinase and response regulator proteins of bacterial two-component signal transducing systems of the AgrB/AgrA-type . The genes sppA and spiA encoded the sakacin P preprotein and the putative immunity protein, respectively . The predicted proteins SppT and SppE showed strong similarities to the proposed transport proteins of several other bacteriocins and to proteins implicated in the signal-sequence-independent export of Escherichia coli haemolysin A . Deletion and frameshift mutation analyses showed that sppK, sppT and sppE were essential for sakacin P production in Lb706X . The putative SpiA peptide was shown to be involved in immunity to sakacin P . Analogues of sppR and spiA were found on the chromosomes of Lb . sake Lb706X and Lb790, indicating the presence of an incomplete spp gene cluster in these strains.

J Trop Pediatr, 1996 Jun, 42(3), 162 - 5
Lactobacillus GG and acute diarrhoea in young children in the tropics; Pant AR et al.; A prospective, placebo controlled, triple blind clinical trial was undertaken in Thailand to determine the effect of Lactobacillus GG on recovery from acute diarrhoea in children . Thirty-nine children (mean age = 8 months) were enrolled and following rehydration received either oral Lactobacillus GG (n = 20) as a freeze-dried preparation or placebo (n = 19) twice daily for 2 days . The clinical characteristics of the study groups were similar . There was no significant difference overall in clinical response detected between the study groups . When only those with acute non-bloody diarrhoea (n = 26) were considered, the mean duration of diarrhoea was significantly shorter in the lactobacillus group (1.9 days) than in the placebo group (3.3 days) (P < 0.055) . Stool frequency was less on the second day in the lactobacillus group (P < 0.05) . The results suggest that Lactobacillus GG accelerates recovery from acute watery diarrhoea in young children in a tropical setting.

Lett Appl Microbiol, 1996 Jun, 22(6), 439 - 42
Comparison of the adherence of three Lactobacillus strains to Caco-2 and Int-407 human intestinal cell lines; Sarem F et al.; Adhesion of three Lactobacillus strains onto human epithelial intestinal Caco-2 and Int-407 cell lines was compared . More adhesion occurred onto Int-407 . The trypsin and sodium periodate pretreatment of bacteria revealed different mechanisms of adhesion depending on the Caco-2 and Int-407, involving carbohydrates and proteins . The absence of adherence for one Lactobacillus strain onto both cell lines indicated the specificity of the adhesion . Electron microscopic observations showed that bacteria adhered by underlying the brush border microvilli of the Caco-2 surface contrasting onto the Int-407 which entrapped and surrounded them by fimbrial extracellular cell matrix material.

Lett Appl Microbiol, 1996 Jun, 22(6), 420 - 4
Salivacin 140, a novel bacteriocin from Lactobacillus salivarius subsp . salicinius T140 active against pathogenic bacteria; Arihara K et al.; Fifteen of 353 environmental isolates of lactic acid bacteria consistently showed activity against Listeria monocytogenes, Streptococcus mutans, Actinomyces viscosus, and/or Propionibacterium acnes . Strain T140, isolated from the surface of Japanese pampas grass leaves and identified as Lactobacillus salivarius subsp . salicinius, also had activity against several Lactobacillus species, Staphylococcus aureus and Yersinia enterocolitica . Since the antagonistic factor(s) produced by T140 was sensitive to a proteolytic enzyme, it was concluded that a bacteriocin (named salivacin 140) was involved in the inhibition activity . Strain T140 required a high initial pH (7.5-8.5) in agar plates for bacteriocin production.

Eur J Biochem, 1996 Jun 1, 238(2), 435 - 9
NMR detection of arginine-ligand interactions in complexes of Lactobacillus casei dihydrofolate reductase; Gargaro AR et al.; 1H-NMR and 15N-NMR signal assignments have been made for the eight arginine residues in Lactobacillus casei dihydrofolate reductase in its binary complex with methotrexate and in its ternary complex with methotrexate and NADPH . 1H-NMR chemical shifts for the guanidino groups of two of the arginines (Arg57 and Arg43) were sensitive to different modes of binding of the guanidino groups with charged oxygen atoms of the ligands . In the complexes formed with methotrexate, Arg57 showed four non-equivalent NH eta proton signals indicating hindered rotation about the N epsilon-C zeta and C zeta-N eta bonds . The NH eta 12 and NH eta 22 protons showed large downfield shifts, which would be expected for a symmetric end-on interaction of these protons with the charged oxygen atoms of a carboxylate group in methotrexate . These effects were not observed for the complex formed with trimethoprim, which does not contain any carboxylate groups . In the complex formed with NADPH present, Arg43 showed a large downfield chemical shift for its NH epsilon proton and a retardation of its rate of exchange with water . This pattern of deshielding contrasts with that detected for Arg57 and is that expected for a side-on interaction of the guanidino group protons with charged oxygen atoms of the ribose 2'-phosphate group of NADPH.

Scand J Immunol, 1996 Jun, 43(6), 687 - 9
Down-regulation of anti-CD3 antibody-induced IL-4 production by bovine caseins hydrolysed with Lactobacillus GG-derived enzymes; Sutas Y et al.; A prerequisite for systemic hyporesponsiveness to dietary antigens is their processing in the gut . This study investigated whether bovine caseins degraded by enzymes of an intestinal bacterial strain, Lactobacillus GG (ATCC 53103), could regulate the cytokine production by anti-CD3 antibody-induced peripheral blood mononuclear cells of 14 atopic patients, aged 5-29 (mean, 16) months . Purified casein up-regulated the interleukin-4 and interferon-gamma production, P = 0.008 and P = 0.008, respectively . Conversely, Lactobacillus GG-degraded casein down-regulated the interleukin-4 production, P = 0.003, with no effect on interferon-gamma . These results indicate that intestinal bacteria may modify immunomodulatory properties of native food proteins and introduce a promising tool to provide protection from potentially harmful dietary antigens at a young age.

J Bacteriol, 1996 Jun, 178(11), 3059 - 65
A new cell surface proteinase: sequencing and analysis of the prtB gene from Lactobacillus delbruekii subsp . bulgaricus; Gilbert C et al.; Investigation of the chromosomal region downstream of the lacZ gene from Lactobacillus delbrueckii subsp . bulgaricus revealed the presence of a gene (prtB) encoding a proteinase of 1,946 residues with a predicted molecular mass of 212 kDa . The deduced amino acid sequence showed that PrtB proteinase displays significant homology with the N termini and catalytic domains of lactococcal PrtP cell surface proteinases and is probably synthesized as a preproprotein . However, the presence of a cysteine near the histidine of the PrtB active site suggests that PrtB belongs to the subfamily of cysteine subtilisins . The C-terminal region strongly differs from those of PrtP proteinases by having a high lysine content, an imperfect duplication of 41 residues, and a degenerated sequence compared with the consensus sequence for proteins anchoring in the cell walls of gram-positive bacteria . Finally, the product of the truncated prtM-like gene located immediately upstream of the prtB gene seems too short to be involved in the maturation of PrtB.

Carbohydr Res, 1996 May 14, 285, 129 - 39
Structural studies of the exopolysaccharide produced by Lactobacillus paracasei 34-1; Robijn GW et al.; The exopolysaccharide produced by Lactobacillus paracasei 34-1 in a semi-defined medium was found to be a heteropolymer, composed of D-galactose, 2-acetamido-2-deoxy-D-galactose, and sn-glycerol 3-phosphate in molar ratios of 3:1:1 . By means of deglycerophosphorylation, methylation analysis, and 1D/2D NMR studies (1H, 13C, and 31P) the polysaccharide was shown to consist of repeating units with the following structure: {formula: see text}.

Spec Care Dentist, 1996 May-Jun, 16(3), 123 - 7
Effect of chlorhexidine gel treatment on the prevalence of mutans streptococci and lactobacilli in patients with impaired salivary secretion rate; Bondestam O et al.; The potential pathogenic role of mutans streptococci in the etiology of dental caries is well-documented . Mutans streptococci are sensitive to chlorhexidine (CHX), and several methods for the clinical use of CHX have been described . An important target group for caries-preventive measures is patients with impaired salivary secretion due to the use of therapeutic drugs such as psychotropics . The aim of the present study was to compare two methods for antimicrobial treatment in such patients . Twenty-four volunteering patients at a hospital clinic were randomly divided into three groups: Group A, in which each participant was treated with 10% CHX gel in gel trays on two consecutive days, followed by application of a fluoride varnish; Group B, in which the patients were treated with the same CHX gel as above; and Group C, which was used as a control . After treatment, there was a reduction of mutans streptococci in the two groups treated with CHX . In group A, the sames collected one, three, and five weeks after the treatment were significantly lower than baseline values . No clearcut reduction of the number of mutans streptococci was observed in the subjects not treated with CHX . These data indicate that treatment with CHX gel in gel trays is superior to polishing the teeth with CHX gel . From a clinical point of view, our observations suggest that it is important to monitor the effect of antimicrobial treatment individually in order to optimize preventive programs in patients with impaired salivary secretion.

FEMS Microbiol Lett, 1996 May 1, 138(2-3), 233 - 7
Electrotransformation of lactobacillus acidophilus group A1; Walker DC et al.; Two strains of Lactobacillus acidophilus Group A1, the neotype ATCC 4356 and a human isolate NCFM-N2, widely used as a dietary adjunct in milk and cultured dairy products, were transformed with plasmid DNA by electroporation . The transformation characteristics exhibited by the two L acidophilus strains were found to differ markedly even though they appeared similar at the genomic level based on the DNA patterns of SmaI restriction fragments . To our knowledge, this is the first report of a consistent, reproducible transformation system of Lactobacillus acidophilus strains comprising the A1 DNA homology group.

Pediatr Dent, 1996 May-Jun, 18(3), 228 - 35
Dental disease, caries related microflora and salivary IgA of children with severe congenital cardiac disease: an epidemiological and oral microbial survey; Franco E et al.; The objectives were to determine levels of dental caries, plaque accumulation, gingival inflammation, knowledge of dental health practices, and oral bacterial loading of S . mutans, Lactobacillus sp., Candida sp., and salivary IgA in the mouths of children afflicted with severe congenital heart disease . A total of 60 children from the cardiac units of the Hospital for Sick Children and Guys Hospital Paediatric Department were compared with 60 case-matched control children from the Department of Orthodontics and Paediatric Dentistry, UMDS (Guys Dental School), London . Using the methodology of the World Health Organization, the decayed, missing and filled surfaces and teeth of primary (dmft) and permanent (DMFT) were compared . There were similar levels of caries in the cardiac (dmft 3.9 and DMFT 2.7) and the control (dmft 3.7 and DMFT 2.0) . A significant difference was the proportion of untreated carious lesions in the cardiac group (52%) compared to the control group (32%; P < 0.001) . Standard oral microbiological techniques were used to isolate S . mutans, Lactobacillus sp., Candida sp., and conventional methods for estimating salivary IgA . There was no difference between the cardiac and the control group . Children with severe congenital cardiac disease have moderately high levels of dental caries with a significantly greater amount of untreated disease . The high bacterial loading associated with high levels of bacterial dental plaque and gingivitis may put cardiac patients at unnecessary risk of developing bacterial endocarditis.

Br Poult Sci, 1996 May, 37(2), 341 - 6
The influence of Lactobacillus acidophilus and bacitracin on layer performance of chickens and cholesterol content of plasma and egg yolk; Abdulrahim SM et al.; 1 . The influence of Lactobacillus acidophilus alone or in combination with zinc bacitracin on the performance of laying hens was monitored over a period of 4 months . 2 . Lactobacillus acidophilus improved egg production, food conversion and reduced the cholesterol concentration in the eggs, but zinc bacitracin had no effect when administered alone . 3 . In combination, bacitracin had an adverse effect on the otherwise beneficial activity of the culture.

Nahrung, 1996 May, 40(3), 142 - 5
Effect of various types of fermentation on in vitro protein and starch digestibility of differently processed pearl millet; Sharma A et al.; Pearl millet (Pennisetum typhoideum) grains were fermented with Lactobacilli and yeast alone, in combination and with natural flora at 30 degrees C for 48 h after giving various processing treatments viz, fine and coarse grinding, soaking, debranning, dry heat treatment, germination and autoclaving after adding of water . Fermentation was carried out with Lactobacillus acidophilus and Rhodotorula isolated from naturally fermented pearl millet and Lactobacillus acidophilus, Candida utilis and natural fermentation using freshly ground pearl millet flour as inoculum . All the processing treatments except coarse grinding improved the protein and starch digestibility . Autoclaving enhanced the digestibilities of processed samples which was further improved by different types of fermentation, the maximum being in case of germinated and naturally fermented pearl millet . A combination of Lactobacilli and yeast was more effective in increasing the protein as well as starch digestibility as compared to pure culture fermentation.

Crit Rev Food Sci Nutr, 1996 May, 36(5), 397 - 411
Bitterness in cheese: a review; Habibi-Najafi MB et al.; Bitterness, the necessary consequence of proteolysis, has been under investigation from different perspectives . This review attempts to give more up-to-date information on the definition of some principal aspects, the relationship between the proteolytic activity and bitter peptide accumulation in cheese, and methods of isolation and detection of bitter peptides . Further knowledge on the physicochemical properties of bitter peptides in cheese as well as in synthetic peptides and the possible control methods for bitterness are discussed . Particular interest in using some strains of lactobacilli or their enzymes as an adjunct in accelerated ripened cheese (ARC) and enzyme-modified cheese (EMC) without bitterness is also described in detail.

Vet Med (Praha), 1996 May, 41(5), 155 - 8
Interactions of Lactobacillus spp . and enteropathogenic Escherichia coli under in vitro and in vivo conditions; Bomba A et al.; In the present study, the effect of Lactobacillus spp . against enteropathogenic Escherichia coli 08:K88+Ent+ under in vitro and in vivo conditions has been compared and the effect of inoculation of Lactobacillus spp . upon the colonization of both the jejunum and ileum by enteropathogenic E . coli 08:K88+Ent+ in 9 gnotobiotic pigs has been observed . Under in vitro conditions, the strain Lactobacillus spp . showed the inhibition of 2.1 +/- 0.1 mm against enteropathogenic E . coli 08:K88+Ent+ . Two days after the inoculation, the enteropathogenic E . coli 08:K88+Ent+, inoculated to the control group of gnotobiotic pigs (E), colonized the mucosa of both jejunum and ileum of gnotobiotic pigs at counts of 6.41 and 6.08 log 10/cm2, respectively . In experimental group (L-E), the counts of adhered enteropathogenic E . coli in the identical sections of the small intestine, following the inoculation by Lactobacillus spp., amounted to 6.35 and 6.43 log/cm2, respectively . In both groups, numbers of E . coli in the intestinal content of both jejunum and ileum were nearly the same (group E 9.03 and 9.31 log 10/ml; group L-E 8.97 and 9.11 log 10/ml) . Two to five days after E . coli inoculation, Lactobacillus spp . counts adhered to the jejunal wall ranged from 5.4 to 6.49 log 10 cm2; in the ileum they ranged from 6.05 to 6.77 log 10 cm2 . In the jejunal content, the lactobacilli counts ranged from 6.81 to 8.86 log 10/ml and in the ileum from 8.5 to 898 log 10/ml . Two days after the E . coli inoculation, the concentration of lactic acid in the content of jejunum in gnotobiotic pigs of the groups E and L-E was 16.3 mmol/l and 23.6 mmol/l, respectively . The concentration of acetic acid in the jejunum of the pigs of E and L-E groups was 15.9 mmol/l and 19.6 mmol/l, respectively . Similarly, the higher concentrations of both acids were found also in the ileum of the L-E pigs . The results obtained indicate that the used strain of Lactobacillus spp . which has been preventively inoculated to gnotobiotic pigs, did not prevent the adhesion of enteropathogenic E . coli 08:K88+Ent+ to the mucosa of both jejunum and ileum also despite of the demonstrated inhibitory effect against enteropathogenic E . coli under in vitro conditions and despite good adherent ability in vivo . In both groups of animals, the diseases with pronounced clinical signs as well as losses have occurred.

World J Surg, 1996 May, 20(4), 474 - 81
Nutritional support to prevent and treat multiple organ failure; Bengmark S et al.; Enteral nutrition (EN) has several advantages over parenteral nutrition (PN) for postoperative/posttrauma patients . Modern technologies for tube-feeding have made early EN possible . Jejunal tube-feeding has advantages over gastric tube-feeding: faster metabolic recovery, less vomiting, and less risk of regurgitation and aspiration . Immediate or early EN stimulates the splanchnic and hepatic circulations, improves mucosal blood flow, prevents intramucosal acidosis and permeability disturbances, and eliminates the need for stress ulcer prophylaxis . Saliva containing important antimicrobial substances and gastric acidity are important in sepsis prevention . Chewing, saliva, and gastric acidity support gastric nitric oxide (NO) release, important for mucosal blood flow, gastrointestinal (GI) motility, mucus formation, and bacteriostasis . An oral supply of NO-donating substances and chewing of nitrate-rich food, such as lettuce or spinach, can be useful . Oral and mucosa-protective lipids are recommended . H2 blockers and saliva-inhibiting drugs are avoided . Immediate EN should be given, starting with 25 ml/hr and increasing to 100 ml/hr over 24 to 48 hours . For the immunocompromised patient special attention should be given to the purity of water . Bottled water can contain bacteria such as Pseudomonas . Food antioxidants such as glutathione, vitamin E, and beta-carotenes are important . Ingredients for the colonic mucosa are important . Approximately 10% of caloric need is satisfied by so-called colonic food (prebiotics), fermented at the level of the colonic mucosa to produce colonic mucosa nutrients and to prevent gut origin sepsis . More than 10 g of fiber per day is recommended . The fermenting flora (probiotic flora) is deranged owing to disease or antibiotic treatment, and resupply of flora is important . A new concept of ecoimmune nutrition is presented for enteral supply of mucosa-reconditioning ingredients: new surfactants, pseudomucus, fiber, amino acids such as arginine, and mucosa-adhering Lactobacillus plantarum 299.

Appl Environ Microbiol, 1996 May, 62(5), 1847 - 51
Defective site-specific integration elements are present in the genome of virulent bacteriophage LL-H of Lactobacillus delbrueckii; Mikkonen M et al.; The phage attachment site, attP, and the integrase-encoding gene, int, are sufficient to promote site-specific integration of the temperate phage mv4 genome into the chromosome of the Lactobacillus delbrueckii host (L . Dupont, B . Boizet-Bonhoure, M . Coddeville, F . Auvray, and P . Ritzenthaler, J . Bacteriol . 177:586--595, 1995) . The mv4 genome region containing these elements was compared at the nucleotide and amino acid levels with that of the closely related virulent phage LL-H . Complex DNA rearrangements were identified; a truncated integrase gene and two sites homologous to the mv4 attP site were detected in the genome of the virulent phage LL-H . These observations suggest that the two phages derive from a common temperate ancestor.

Appl Environ Microbiol, 1996 May, 62(5), 1676 - 82
Biochemical and genetic characterization of enterocin A from Enterococcus faecium, a new antilisterial bacteriocin in the pediocin family of bacteriocins; Aymerich T et al.; A new bacteriocin has been isolated from an Enterococcus faecium strain . The bacteriocin, termed enterocin A, was purified to homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, N-terminal amino acid sequencing, and mass spectrometry analysis . By combining the data obtained from amino acid and DNA sequencing, the primary structure of enterocin A was determined . It consists of 47 amino acid residues, and the molecular weight was calculated to be 4,829, assuming that the four cysteine residues form intramolecular disulfide bridges . This molecular weight was confirmed by mass spectrometry analysis . The amino acid sequence of enterocin A shared significant homology with a group of bacteriocins (now termed pediocin-like bacteriocins) isolated from a variety of lactic acid-producing bacteria, which include members of the genera Lactobacillus, Pediococcus, Leuconostoc, and Carnobacterium . Sequencing of the structural gene of enterocin A, which is located on the bacterial chromosome, revealed an N-terminal leader sequence of 18 amino acid residues, which was removed during the maturation process . The enterocin A leader belongs to the double-glycine leaders which are found among most other small nonlantibiotic bacteriocins, some lantibiotics, and colicin V . Downstream of the enterocin A gene was located a second open reading frame, encoding a putative protein of 103 amino acid residues . This gene may encode the immunity factor of enterocin A, and it shares 40% identity with a similar open reading frame in the operon of leucocin AUL 187, another pediocin-like bacteriocin.

J Bacteriol, 1996 May, 178(10), 2749 - 56
Identification of a Bacillus thuringiensis gene that positively regulates transcription of the phosphatidylinositol-specific phospholipase C gene at the onset of the stationary phase; Lereclus D et al.; A transcriptional analysis of the phosphatidylinositol-specific phospholipase C (plcA) gene of Bacillus thuringiensis indicated that its transcription was activated at the onset of the stationary phase in B . thuringiensis but was not activated in B . subtilis . The B . thuringiensis gene encoding a transcriptional activator required for plcA expression was cloned by using a B . subtilis strain carrying a chromosomal plcA'-'lacZ fusion as a heterologous host for selection . This trans activator (designated PlcR) is a protein of a calculated molecular weight of 33,762 which appears to be distantly related to PreL and NprA, regulator proteins enhancing transcription of neutral protease genes during the stationary phase of a Lactobacillus sp . and B . stearothermophilus, respectively . plcR gene transcription was analyzed in B . thuringiensis and in B . subtilis . PlcR positively regulated its own transcription at the onset of the stationary phase . There is a highly conserved DNA sequence (17 bp) 34 nucleotides upstream from the plcR transcriptional start site and 49 nucleotides upstream from the plcA transcriptional start site . As PlcR positively regulates its own transcription and plcA transcription, this conserved DNA sequence may be the specific recognition target for PlcR activation.

J Biol Chem, 1996 Apr 26, 271(17), 10060 - 5
Glycine betaine fluxes in Lactobacillus plantarum during osmostasis and hyper- and hypo-osmotic shock; Glaasker E et al.; Bacteria respond to changes in medium osmolarity by varying the concentrations of specific solutes in order to maintain constant turgor . The primary response of Lactobacillus plantarum to an osmotic upshock involves the accumulation of compatible solutes such as glycine betaine, proline, and glutamate . We have studied the osmotic regulation of glycine betaine transport in L . plantarum by measuring the overall and unidirectional rates of glycine betaine uptake and exit at osmostasis, and under conditions of osmotic upshock and downshock . At steady state conditions, a basal flux of glycine betaine (but no net uptake or efflux) is observed that amounts to about 20% of the rate of "activated"' uptake (uptake at high osmolarity) . No direct exchange of 14C-labeled glycine betaine in the medium for unlabeled glycine betaine in the cytoplasm was observed in glucose metabolizing and resting cells, indicating that a separate glycine betaine efflux system is responsible for the exit of glycine betaine . Upon osmotic upshock, the uptake system for glycine betaine is rapidly activated (within seconds), whereas the basal efflux is inhibited . These two responses account for a rapid accumulation of glycine betaine until osmostasis is reached . Upon osmotic downshock, glycine betaine is rapidly released by the cells in a process that has two kinetic components, i.e . one with a half-life of less than 2 s which is unaffected by the metabolic status of the cells, the other with a half-life of 4-5 min in glucose-metabolizing cells which is dependent on internal pH or a related parameter . We speculate that the former activity corresponds to a stretch-activated channel, whereas the latter may be facilitated by a carrier protein . Glycine betaine uptake is strongly inhibited immediately after an osmotic downshock, but slowly recovers in time . These studies demonstrate that in L . plantarum osmostasis is maintained through positive and negative regulation of both glycine betaine uptake and efflux, of which activation of uptake upon osmotic upshock and activation of a "channel-like" activity upon osmotic downshock are quantitatively most important.

Br Dent J, 1996 Apr 20, 180(8), 287 - 91
Criteria for caries removal at the enamel-dentine junction: a clinical and microbiological study; Kidd EA et al.; In the UK cavity preparation at the enamel-dentine junction (EDJ) is considered complete when all soft and/or stained tissue is removed . The aim of the present work was to link the clinical criteria of dentine consistency and dentine colour with the microbiological status of the tissue . Cavities were prepared in 564 teeth . Under rubber dam, access to the EDJ was gained and the sample sites selected (n = 847) . Their consistency was noted as hard or soft and wet or dry when probed . The colour of the site was noted as stain-free or stained . Dentine was sampled using a round bur . After microbiological processing the total anaerobic count and counts of mutans streptococci and lactobacilli were expressed as log10 {CFU per sample} . Soft sites harboured significantly more bacteria than hard sites (P < 0.001) . Soft and wet sites harboured significantly more bacteria than soft and dry sites (P < 0.001) . Stained and hard sites harboured more bacteria than stain-free and hard sites (P < 0.05) but this difference was not considered to be clinically relevant . The relatively simple clinical criteria used here correlated significantly with the microbial findings . All soft dentine must be removed at the EDJ to ensure minimal infection of the underlying hard dentine . However, it may not be necessary to continue preparation until the EDJ is also stain-free.

Structure, 1996 Apr 15, 4(4), 437 - 47
Insights into substrate binding by D-2-ketoacid dehydrogenases from the structure of Lactobacillus pentosus D-lactate dehydrogenase; Stoll VS et al.; BACKGROUND: D-Lactate dehydrogenases (D-LDHs) and L-lactate dehydrogenases (L-LDHs) catalyze a reaction differing only in the chirality of the product . Both enzymes utilize the same kind of amino acid side chains in substrate binding and catalysis . Models based on D-LDH-related enzymes propose that these side chains assume identical roles in both enzymes with their active sites related by a simple geometrical relationship such as a mirror plane . RESULTS: The crystal structure of the homodimeric D-LDH from Lactobacillus pentosus has been determined to 2.6 A resolution by multiple isomorphous replacement methods and the resulting molecular model refined to an R-factor of 19.1% . Topologically, the enzyme is closely related to other D-2-ketoacid dehydrogenase enzymes . Each subunit comprises two domains enclosing a deep cleft containing the active site . Substrate binding and domain closure have been modelled . CONCLUSIONS: Comparison of the D-LDH structure with other members of the protein family and with the L-specific enzyme has confirmed that no overall structural relationship exists between the L-LDH and D-LDH enzymes - they belong to distinct protein classes . The small size of the ketoacid substrate and the very restricted number of functionally appropriate side chains will constrain the choice of amino acids and their placement in the active site . Our models imply that although the same kinds of amino acids are involved in substrate binding their exact chemical role might differ in the two dehydrogenases.

Microb Drug Resist, 1996 Spring, 2(1), 77 - 84
The dlt operon in the biosynthesis of D-alanyl-lipoteichoic acid in Lactobacillus casei; Neuhaus FC et al.; The D-alanine incorporation system allows Lactobacillus casei to modulate the chemical properties of lipoteichoic acid (LTA) and hence control its proposed functions, i.e., regulation of autolysin action, metal ion binding, and the electromechanical properties of the cell wall . The system requires the D-alanine-D-alanyl carrier protein ligase (Dcl) and the D-alanyl carrier protein (Dcp) . Our results indicate that the genes for these proteins are encoded in the dlt operon and that this operon contains at least 2 other genes, dltB and dltD . The aim of this paper is to describe the genetic organization of the operon, the role of the D-alanyl carrier protein, and the function of the putative protein encoded by dltB in the intramembranal translocation of the activated D-alanine.

Microbiology, 1996 Apr, 142 ( Pt 4), 809 - 16
Characterization of a prolinase gene and its product and an adjacent ABC transporter gene from Lactobacillus helveticus; Varmanen P et al.; A prolinase (pepR) gene was cloned from an industrial Lactobacillus helveticus strain (53/7) . Three clones, hybridizing with a gene probe specific for a peptidase shown to have activity against di- and tripeptides, were detected from a L . helveticus genomic library constructed in Escherichia coli . None of the three clones, however, showed enzyme activity against the di- or tripeptide substrates tested . One of the clones, carrying a vector with a 5.5 kb insert, was further characterized by DNA sequencing . The sequence analysis revealed the presence of two ORFs, ORF1 and ORF2 of 912 and 1602 bp, respectively . ORF2, located upstream of and in the opposite orientation to ORF1, had a promoter region overlapping that of ORF1 . ORF1 had the capacity to encode a 35083 Da protein . When amplified by PCR, ORF1 with its control regions specified a 35 kDa protein in E . coli that was able to hydrolyse dipeptides, with highest activity against Pro-Leu, whereas from the tripeptides tested, only Leu-Leu-Leu was slowly degraded . By the substrate-specificity profile and protein homologies, the 35 kDa protein was identified as a prolinase . The activity of the cloned prolinase was inhibited by p-hydroxymercuribenzoate . Northern and primer-extension analyses of ORF1 revealed a 1.25 kb transcript and two adjacent transcription start sites, respectively, thus confirming the DNA sequence data . ORF2 had encoding capacity for a 59.5 kDa protein that showed significant homology to several members of the family of ABC transporters . Determination of the mRNA levels at different growth phases revealed that the pepR gene and ORF2 are transcribed in L . helveticus at the exponential and stationary phases of growth, respectively . Furthermore, two ORF2 deletion constructs, carrying the intact pepR gene, showed that this upstream operon adversely affected PepR activity in E . coli, which explains the enzymic inactivity of the original clones.

Microbiology, 1996 Apr, 142 ( Pt 4), 799 - 808
A new, broad-substrate-specificity aminopeptidase from the dairy organism Lactobacillus helveticus SBT 2171; Sasaki M et al.; An aminopeptidase with a very broad substrate specificity was purified to homogeneity from Lactobacillus helveticus SBT 2171 by FPLC . The enzyme was purified 144-fold from a cell-free extract with a yield of 16% . The purified enzyme appeared as a single band on an SDS-PAGE gel . It had a molecular mass of 95 kDa and an isoelectric point of 4.9 . The enzyme hydrolysed a large range of naphthylamide- and nitroanilide-substituted amino acids, as well as several di-, tri- and oligopeptides . It also exhibited significant proline-iminopeptidase-like activity, since it hydrolysed several proline-containing peptides . Prolyl-p-nitroanilide was hydrolysed with a low affinity (Michaelis-Menten constant 0.6 mM) and a Vmax of 2.5 mumol min-1 (mg protein)-1 while lysyl-p-nitroanilide was hydrolysed with a high affinity {Km 0.003 mM; Vmax 37.5 mumol min-1 (mg protein)-1} . The aminopeptidase activity, which was optimal between pH 6.0 and 8.0 and at 50 degrees C, was very stable at 30 degrees C for more than 7 d . The activity lost by treatment with the thiol-blocking reagents could be restored with beta-mercaptoethanol, while Co2+ and Mn2+ restored the activity of the EDTA-treated enzyme . Immunological experiments with antibodies raised against the aminopeptidases from Lactococcus lactis and Lb . helveticus clearly showed that both aminopeptidases are at least immunologically different from each other.

Int J Syst Bacteriol, 1996 Apr, 46(2), 588 - 94
Characterization of lactobacilli by Southern-type hybridization with a Lactobacillus plantarum pyrDFE probe; Bringel F et al.; Lactobacillus plantarum, Lactobacillus pentosus, and Lactobacillus paraplantarum (M.-C . Curk, J.-C . Hubert, and F . Bringel, Int . J . Syst . Bacteriol . 46:595-598, 1996) can hardly be distinguished on the basis of their phenotypes . Unlike L . plantarum and L . paraplantarum, L . pentosus ferments glycerol and xylose but not melezitose . We identified two L . pentosus strains (CNRZ 1538 and CNRZ 1544) which ferment glycerol and melezitose but not xylose . alpha-Methyl-D-mannoside was fermented by 66% of the L . plantarum strains tested but not by L . paraplantarum strains . In this paper we describe a simple method to identify L . plantarum, L . pentosus, and L . paraplantarum . This method is based on nonradioactive Southern-type hybridization between BglI DNA digests of the lactobacilli tested and a DNA probe (L . plantarum pyrDFE genes from strain CCM 1904) . A total of 68 lactobacilli were classified into five groups on the basis of the bands detected . Two groups contained L . plantarum strains; one of these groups contained 31 strains, including the type strain, and was characterized by bands at 7, 4, and 1 kb, and the other group contained strain LP 85-2 and was characterized by bands at 5 and 1.1 kb . Only one band (a band at around 7 kb) was detected in the strains belonging to the L . pentosus group, and two bands (at 4 and 1 kb) were found in the strains belonging to the L . paraplantarum group . No hybridization was detected in the last group, which contained Lactobacillus casei, Lactobacillus coryniformis, Lactobacillus paracasei, Lactobacillus brevis, Lactobacillus delbrueckii, and Lactobacillus leichmannii strains.

Int J Syst Bacteriol, 1996 Apr, 46(2), 449 - 53
Lactobacillus panis sp . nov., from sourdough with a long fermentation period; Wiese BG et al.; Two Lactobacillus strains isolated from rye sourdough most closely resemble Lactobacillus oris on the basis of their physiological, morphological, and chemotaxonomic characteristics . A 16S ribosomal DNA sequence analysis showed that these two strains clustered with, but were separate from, L . oris, Lactobacillus vaginalis, and Lactobacillus pontis . The results of DNA-DNA hybridization experiments indicated that the new two isolates represent a new Lactobacillus species, for which we propose the name Lactobacillus panis; strain DSM 6035T is the type strain of this species.

Curr Microbiol, 1996 Apr, 32(4), 232 - 6
Molecular characterization of the xerC gene of Lactobacillus leichmannii encoding a site-specific recombinase and two adjacent heat shock genes; Becker J et al.; Sequencing of four overlapping DNA fragments comprising 3.527 kb isolated from a L . leichmannii genomic library revealed three complete open reading frames (ORFs) and one that was truncated . The deduced amino acid sequences of the complete ORFs showed considerable similarities with the already known sequences of the xerC, hslV, and hslU gene products of Escherichia coli: the site-specific XerC recombinase, a member of the lambda integrase family, and the HtpI resp . HtpO heat shock proteins . The deduced amino acid sequence of the fourth, incomplete ORF upstream the xerC gene showed strong homology with the gid A gene product of B . subtilis.

Curr Microbiol, 1996 Apr, 32(4), 183 - 7
Evaluation of numerical analysis of random amplified polymorphic DNA (RAPD)-PCR as a method to differentiate Lactobacillus plantarum and Lactobacillus pentosus; Van Reenen CA et al.; Lactobacillus plantarum and Lactobacillus pentosus grouped into one protein profile cluster at r > or = 0.70, separate from Lactobacillus casei, Lactobacillus sake, and Lactobacillus curvatus . Similar sugar fermentation reactions were recorded for representative strains of L . plantarum and L . pentosus . Representative strains, including the type of each species, were selected from the different protein profile clusters and their genetic relatedness determined by using numerical analysis of random amplified polymorphic DNA (RAPD)-PCR . The type strains of L . plantarum (ATCC 14917T) and L . pentosus (NCFB 363T) displayed different RAPD profiles and grouped into two independent clusters, well separated from L . casei, L . curvatus, and L . sake . Numerical analysis of RAPD-PCR proved a reliable and accurate method to distinguish between strains of L . plantarum and L . pentosus.

Plant Foods Hum Nutr, 1996 Apr, 49(3), 241 - 52
Levels of antinutritional factors in pearl millet as affected by processing treatments and various types of fermentation; Sharma A et al.; Pearl millet (Pennisetum typhoideum) was fermented with Lactobacilli or yeasts alone and in combination, and with natural microflora after various processing treatments, as grinding, soaking, debranning, dry heat treatment, autoclaving and germination . Fermentation was carried out at 30 degrees C for 48 hours with Lactobacillus plantarum (LP) and Rhodotorula (R) isolated from naturally fermented pearl millet and Lactobacillus acidophilus (LA), Candida utilis (CU) and natural microflora (NF) . Germination and autoclaving, and debranning and autoclaving were the most effective processing treatments to reduce the phytic acid, amylase inhibitors and polyphenols . There was a further reduction in these antinutrients due to fermentation . Phytic acid and amylase inhibitors were completely eliminated after fermentation in some of the samples especially in soaked, debranned and germinated ones . Polyphenols were altered non-significantly in general but fermentation with Lp + R and NF caused a significant increase in polyphenols.

Biosci Biotechnol Biochem, 1996 Apr, 60(4), 708 - 10
Coexistence of two kinds of 6-phospho-beta-galactosidase in the cytosol of Lactobacillus gasseri JCM1031--purification and characterization of 6-phospho-beta-galactosidase II; Suzuki M et al.; Lactobacillus (L.) gasseri JCM1031 has 2 kinds of 6-phospho-beta-galactosidase (P-beta-gal) in the cytosol . P-beta-gal I was already isolated and characterized for our previous paper {Biosci . Biotech . Biochem., 60, 139-141 (1996)} . Another, P-beta-gal II, was purified to homogeneity through several liquid chromatographic steps for this paper . The molecular mass of the purified enzyme was estimated to be 58 kDa by SDS-PAGE . The Km and V(max) for ONPGal-6P were 0.76 mM and 86.0 mumol/min/mg, respectively . Reducing reagents and Fe2+ ion activated the enzyme, but PCMB, Zn2+, and Hg2+ ions, and alkylation reagents strongly inhibited it . Twenty-five residues of the N-terminal amino acid sequence of the enzyme were identified . P-beta-gal II was different from P-beta-gal I in several characteristics.

Int J Food Microbiol, 1996 Apr, 29(2-3), 397 - 402
Control of Listeria monocytogenes in ground beef by 'Lactocin 705', a bacteriocin produced by Lactobacillus casei CRL 705); Vignolo G et al.; The effectiveness of Lactobacillus casei CRL 705 as well as that of Lactocin 705, the associated bacteriocin produced, in reducing population levels and growth of Listeria monocytogenes in sterile and non-sterile ground beef was studied . Predetermined numbers of L . monocytogenes and concentrations of Lactocin 705 were added to the meat slurries . Listeria in the bacteriocin-treated and control samples during incubation at 20 degrees C were enumerated as CFU on Bacto blood agar base . Results indicated that reduction in numbers of Listeria was largest with high levels of Lactocin 705 and few initial cell numbers of the pathogen present in the meat slurry . However, when the producer strain was added to the slurry, no significant inhibition was detected . Furthermore, inhibition by listeria was shown to be greater when meat slurries were heat-treated.

Poult Sci, 1996 Apr, 75(4), 491 - 4
The effect of Lactobacillus acidophilus on the production and chemical composition of hen's eggs; Haddadin MS et al.; Laying hens were fed for a 48-wk period with a basal diet supplemented with a selected strain of Lactobacillus acidophilus at levels up to four million viable cells per gram of feed . Levels of egg production and feed conversion were significantly higher (8 and 14.8%, respectively) than in the control flock, and cholesterol values in yolks were decreased by 18.8% . It is suggested that the latter effect was a reflection of lower serum cholesterol concentrations in treated birds; a maximum reduction of over 55% followed incorporation of the culture into the feed . The level of viable cells in the feed was confirmed as being critical to register the above effects.

Zhonghua Yi Xue Za Zhi, 1996 Apr, 76(4), 284 - 6
{Detection of bacterial vaginosis in gram stained vaginal smears and papanicolaou stained cervical smears}; Fan S et al.; OBJECTIVE: To determine the sensitivity and specificity of diagnosis of bacterial vaginosis (BV) by papanicolaou (PAP)-stained cervical smears and gram-stained vaginal smears according to clinical criteria . METHODS: In the prospective study of 196 non-pregnant women of child-bearing age, 94 were clinically diagnosed to have BV . Gram-stained vaginal smears and PAP-stained cervical smears were collected from all enrolled patients . RESULTS: In comparison with clinical diagnosis of BV, the sensitivity and specificity of gram-stained vaginal smears and PAP-stained cervical smears were 94.7% (89/94), 98.0% (100/102) 85.1% (80/94), and 95.1% (97/102) . The characteristics of BV in gram-stained vaginal smears and PAP-stained cervical smears included small bacteria of Gardnerella and bacteroides morphotypes and curved gram variable rods and absence of bacteria of Lactobacillus morphotypes . CONCLUSION: It is possible to screen and manage BV according to Gram-stained vaginal smears or PAP-stained cervical smears.

Acta Odontol Scand, 1996 Apr, 54(2), 118 - 21
Multifactorial modeling for prediction of caries increment in adolescents; Raitio M et al.; The purpose of the study was to develop a multifactorial model for the prediction of 11-month caries increment in adolescents . The mean age of the subjects (n = 181) at the base-line examination was 13 years and 3 months . The risk indicators consisted of past caries experience, white spot lesions, visible plaque, gingivitis, salivary secretion rate, buffer effect, sucrase, mutans streptococci, lactobacilli, and Candida . The multifactorial modeling included all the above risk indicators, age, and gender and resulted in different models in boys and girls, indicating the difficulty of caries prediction in adolescents . When boys and girls were combined, the final model included past caries experience, Candida, and salivary sucrase . Although the accuracy of the model was slightly below the 80% level recommended for screening purposes, the results provide clinically valuable information . The risk of caries increases with an increasing number of positive tests within the model.

Acta Odontol Scand, 1996 Apr, 54(2), 113 - 7
Assessment of single risk indicators in relation to caries increment in adolescents; Raitio M et al.; Base-line data on a series of risk indicators were related to 11-month caries increment in 181 subjects with a mean age of 13 years and 3 months . A caries increment equalling or exceeding one tooth surface was recorded in 21% of the subjects . The risk indicators consisted of past caries experience, white spot lesions, visible plaque and gingivitis, and six salivary tests: secretion rate, buffer effect, sucrase, mutans streptococci, lactobacilli, and Candida . Significant associations between caries increment and past caries experience (p = 0.002), white spot lesions (p = 0.01), lactobacilli (p = 0.02), Candida (p = 0.006), and sucrase (p = 0.02) were observed . The ensuing odds ratios were thus recorded: past caries experience, 3.6; white spot lesions, 2.9; salivary sucrase activity, 2.9; lactobacilli, 2.5; and Candida, 2.8.

New Microbiol, 1996 Apr, 19(2), 123 - 32
Composition of the Lactobacillus acidophilus complex isolated from vaginal flora; Lachlak N et al.; One hundred and fifty human vaginal samples containing a diversity of pathogens or nonpathogens (Gardnerella vaginalis, Streptococcus sp., Staphylococcus sp., Candida albicans . Mycoplasma sp.) were examined for their content in lactobacilli of the Lactobacillus acidophilus complex . Although all samples contained lactobacilli, strains of the L . acidophilus complex were present in only twenty-nine cases . Isolates were further characterized and compared with type strains or reference strains in an attempt to differentiate by phenotypic means the genospecies of the L . acidophilus complex . Data regarding specific activities of beta-galactosidase (beta-gal) and of phospho-beta-galactosidase (P-beta-gal) provided no specific information at the species level within the L . acidophilus complex . DNA-relatedness differentiates this genospecies . Most lactobacilli isolated from the vaginal flora of symptomatic women were genotypically close to L . gasseri CIP 102991T by the technique of DNA/DNA hybridization.

Scand J Immunol, 1996 Apr, 43(4), 398 - 405
Humoral immune responses against particulate bacterial antigens are dependent on marginal metallophilic macrophages in the spleen; Buiting AM et al.; Lymphoid organs are populated by different macrophage subpopulations . In the spleen, four subpopulations can be characterized using differences in, for example, morphology, localization, cell markers and repopulation kinetics after liposome-mediated depletion . The involvement of the different macrophage subpopulations in the immune response to particulate antigens was studied in vivo by intravenous injection of clodronate containing liposomes to eliminate the splenic macrophages, followed by immunization with trinitrophenylated Brucella abortus (TNP-BA; thymus-independent (TI)) or TNP-Lactobacillus acidophilus (TNP-LB; thymus-dependent (TD)) at different time intervals . A strong decrease in the number of antibody-secreting cells (ASC) against TNP-LB was measured after elimination of all splenic macrophages . When TNP-LB was injected after repopulation of the red pulp macrophages (completed after 2 weeks), the ASC response was still strongly reduced . Restoration of the capacity to mount an immune response correlated well with the reappearance of the marginal metallophilic macrophages . It is concluded that this particular subset of macrophages is involved in the immune response to these particulate bacterial TD antigens . In contrast, the response against the particulate bacterial TI antigen TNP-BA was not impaired after depletion of splenic macrophages, although apparent changes in IgG isotypes were observed.

Z Lebensm Unters Forsch, 1996 Apr, 202(4), 324 - 8
Behaviour of Yersinia enterocolitica and Aeromonas hydrophila in skim milk during fermentation by various lactobacilli; Ozbas ZY et al.; In this study, behaviour of Yersinia enterocolitica and Aeromonas hydrophila in skim milk during fermentation by various Lactobacillus sp . were determined . pH values of the skim milk samples were also examined during fermentation . The amount of produced lactic acid and diacetyl/acetoin productions of the Lactobacillus sp . were estimated . Antimicrobial effects of the lactobacilli on Y . enterocolitica and A . hydrophila were also determined by an agar diffusion method . While Y . enterocolitica was not inhibited and grew during fermentation, A . hydrophila was inhibited, in part, and the growth was retarded . Results were supported by the agar diffusion method for Y . enterocolitica, whereas inhibition activity was not found for A . hydrophila . The highest lactic acid productions were estimated in L . bulgaricus (7.50 mg/ml) and L . acidophilus (5.63 mg/ml) and four out of six Lactobacillus sp . were found to be diacetyl/acetoin producers.

J Bacteriol, 1996 Apr, 178(8), 2459 - 61
Lactobacillus bulgaricus asparagine synthetase and asparaginyl-tRNA synthetase: coregulation by transcription antitermination?
Kim SI, Germond JE, Pridmore D, Soll D.
Genes encoding the ammonia-dependent asparagine synthetase (asnA) and asparaginyl-tRNA synthetase (asnS) have been cloned from Lactobacillus bulgaricus ATCC 11842 . The nucleotide sequence suggests that asnA and asnS are organized as one operon and regulated by the tRNA-directed transcription antitermination mechanism (T . M . Henkin, Mol . Microbiol . 13:381-387, 1994).

J Bacteriol, 1996 Apr, 178(8), 2232 - 7
Induction of bacteriocin production in Lactobacillus sake by a secreted peptide; Eijsink VG et al.; Lactobacillus sake LTH673 is known to produce a bacteriocin called sakacin P . Production of and immunity to sakacin P were found to depend on the presence of a protease-sensitive component that is produced by L . sake LTH673 itself . This component (called inducing factor {IF}) was purified from culture supernatants and shown to be a basic, nonbacteriocin peptide consisting of 19 amino acids, which in principle is capable of forming a highly amphiphilic helical structure . Circular dichroism studies showed that IF indeed could adopt a helical structure, but only in membrane-mimicking environments . Both purified IF and chemically synthesized IF induced expression of the structural gene for sakacin P and concomitant secretion of the gene product . In addition, IF induced its own production and immunity to sakacin P and related bacteriocins . These results indicate that bacteriocin production by L . sake LTH673 is controlled by an autoinduction pathway in which IF may function as a cell density signal.

J Surg Res, 1996 Apr, 62(1), 63 - 8
The effect of endotoxin and Lactobacillus pretreatment on peritoneal macrophage behavior in acute liver injury in rat; Kasravi FB et al.; The effect of endotoxin and Lactobacillus R2LC pretreatment in acute liver injury, induced by D-galactosamine was studied . Administration of D-galactosamine resulted in much higher luminescent activity than the control (49.24 mV vs 19.75 mV), while there was no change detected on the metabolic response to phorbol-12-myristate-13-acetate (PMA) stimulation in the calorimeter . Pretreatment of animals with intraperitoneal administration of heat-killed Lactobacillus resulted in higher oxygen free radical production (105.46 mV) and a much higher metabolic response to PMA in microcalorimeter (24.63 pW per cell vs 13.03 in the control) . On the other hand pretreatment with endotoxin resulted in higher luminometric response to PMA compared to liver injury group (65.87 mV), and no response in the microcalorimeter at all . Phagocytic activity was decreased from 86 to 59% after administration of D-galactosamine, and was not significantly influenced by any of the pretreatment modalities . This experiment showed that pretreatment with Lactobacillus resulted in increased macrophage metabolic activity, while endotoxin pretreatment rendered the macrophages unresponsive to subsequent stimulation . These findings may explain why pretreatment with endotoxin is beneficial in acute liver injury induced by D-galactosamine, but not with gram-positive bacteria including Lactobacillus.

J Med Chem, 1996 Mar 29, 39(7), 1438 - 46
2,4-diamino-5-deaza-6-substituted pyrido{2,3-d}pyrimidine antifolates as potent and selective nonclassical inhibitors of dihydrofolate reductases; Gangjee A et al.; Fifteen novel nonclassical and two classical 2,4-diamino-6-(benzylamino)pyrido{2,3-d}pyrimidine antifolates were synthesized as potential inhibitors of Pneumocystis carinii, (pc) Toxoplasma gondii, (tg) rat liver (rl), and human (h) recombinant dihydrofolate reductases (DHFR) . These analogues lack a 5-methyl substitution which has been shown to be important for increased hDHFR inhibitory activity . In addition, they contain a reversal of the C9-N10 bridge present in folates and most antifolates . The synthesis of the compounds involved the reaction of 2,4,6-triaminopyrimidine with the sodium salt of nitromalonaldehyde to afford the key intermediate 2,4-diamino-6-nitropyrido{2,3-d}pyrimidine (7), in a single step . Reduction of 7 to the 2,4,6-triaminopyrido{2,3-d}pyrimidine (8), followed by reductive amination with the appropriate benzaldehydes or phenylacetaldehydes afforded the target compounds . N9 methylation of these analogues was carried out using formaldehyde and sodium cyanoborohydride . The analogues demonstrated significant inhibition of pcDHFR and tgDHFR . N9 methylation significantly increased DHFR inhibitory potency . Compound 11, the 3'4'5'-trimethoxy-substituted analogue with a selectivity ratio of 9.4 for tgDHFR (compared to rlDHFR) was the most selective analogue of the nonclassical series . Compound 22, the N9 methyl 2'5'-dimethoxy-substituted analogue was the most potent analogue against tgDHFR (IC 50 = 6.3 nM) and was the second most selective analogue for tgDHFR (compared to rlDHFR) in the nonclassical series . The naphthyl-substituted analogues 23-25 were generally more potent against rlDHFR than against pcDHFR and tgDHFR . Selected analogues were also evaluated against Streptococcus faecium (sf) DHFR, Escherichia coli (ec) DHFR, Lactobacillus casei (lc) DHFR and tgDHFR with hDHFR as the mammalian reference, under slightly different assay conditions than those employed for rlDHFR . Analogues 11 and 22 had selectivity ratios of greater than 100 for tgDHFR (compared to hDHFR) . Analogue 22 in particular, was the most selective analogue of the nonclassical series against tgDHFR (selectivity ratio = 303.5) with excellent potency (28 nM) . Analogue 11, also displayed significant selectivity for sfDHFR (selectivity ratio = 4902) . Compound 22 was evaluated in vivo for the inhibition of the growth of T.gondii trophozoites in mice, where at 50 mg/kg orally, it demonstrated distinct prolongation of survival without toxicity . Compounds 11, 12 and 21-23 were evaluated as antitumor agents in the National Cancer Institutes preclinical in vitro screening program . Compounds 12, 22, and 23 showed GI50s for tumor growth inhibition in the 10 -6 - 10 -7 M range.

Appl Environ Microbiol, 1996 Mar, 62(3), 892 - 7
Isolation, partial characterization, and mode of action of Acidocin J1132, a two-component bacteriocin produced by Lactobacillus acidophilus JCM 1132; Tahara T et al.; Lactobacillus acidophilus JCM 1132 produces a heat-stable, two-component bacteriocin designated acidocin J1132 that has a narrow inhibitory spectrum . Maximum production of acidocin J1132 in MRS broth was detected at pH 5.0 . Acidocin J1132 was purified by ammonium sulfate precipitation and sequential cation exchange and reversed-phase chromatographies . Acidocin J1132 activity was associated with two components, termed alpha and beta . On the basis of N-terminal amino acid sequencing and the molecular masses of the alpha and beta components, it is interpreted that the compounds differ by an additional glycine residue in the beta component . Both alpha and beta had inhibitory activity, and an increase in activity by the complementary action of the two components was observed . Acidocin J1132 is bactericidal and dissipates the membrane potential and the pH gradient in sensitive cells, which affect such proton motive force-dependent processes as amino acid transport . Acidocin J1132 also caused efflux of preaccumulated amino acid taken up via a unidirectional ATP-driven transport system . Secondary structure prediction revealed the presence of an amphiphilic alpha-helix region that could form hydrophilic pores . These results suggest that acidocin J1132 is a pore-forming bacteriocin that creates cell membrane channels through the "barrel-stave" mechanism.

Appl Environ Microbiol, 1996 Mar, 62(3), 1089 - 92
Growth inhibition of metronidazole-susceptible and metronidazole-resistant strains of Gardnerella vaginalis by Lactobacilli in vitro; McLean NW et al.; Metronidazole resistance was produced in susceptible Gardnerella vaginalis after subculture in the presence of metronidazole . Metronidazole-resistant gardnerellae were less susceptible to growth inhibition by Lactobacillus culture filtrates . A low pH (+/- 4) and lactic acid accounted for 60 to 95% of inhibitory activity, and H2O2 accounted for only 0 to 30% . However, in the presence of myeloperoxidase, H2O2-producing lactobacilli decreased the viability of metronidazole-susceptible gardnerellae 2,000-fold.

Biosci Biotechnol Biochem, 1996 Mar, 60(3), 488 - 9
Decrease of tissue angiotensin I-converting enzyme activity upon feeding sour milk in spontaneously hypertensive rats; Nakamura Y et al.; Blood pressure increases were inhibited by feeding a diet containing sour milk fermented by a starter containing Lactobacillus helveticus and Saccharomyces cerevisiae to spontaneously hypertensive rats . In rats fed with the sour milk, the angiotensin I-converting enzyme activity of the aorta was significantly lower than that of rats fed with the control commercial diet.

Clin Infect Dis, 1996 Mar, 22(3), 564 - 6
Lactobacilli and bacteremia in southern Finland, 1989-1992; Saxelin M et al.; In order to assess the potential of lactobacilli to cause serious infections, we studied the prevalence of bacteremia due to Lactobacillus species during a 4-year period (1989-1992) in southern Finland, which has a population of about 2.5 million . Among 3,317 blood culture isolates, lactobacilli were identified in eight patients, five of whom had a severe disease predisposing to bacteremic complications . The eight strains isolated were identified to the species level and typed by carbohydrate fermentation tests and by direct sequencing of enzymatically amplified 16S rRNA . The results did not provide evidence that any particular species or subspecies of Lactobacillus was the cause of the infections; no infections caused by isolates similar to the recently introduced dairy probiotic strain, Lactobacillus GG (ATCC 53103), were observed . The data show an infrequent association of lactobacilli with bacteremic infections in spite of the ubiquitous presence of these organisms in the gastrointestinal tract and their widespread consumption in fermented milks; thus, there is strong evidence that their pathogenic potential is very low.

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