J Agric Food Chem, 2000 Aug, 48(8), 3348 - 51 Rapid detection of meso-diaminopimelic acid in lactic acid bacteria by microwave cell wall hydrolysis; Marconi E et al.; Two innovative microwave hydrolysis procedures for rapidly detecting meso-diaminopimelic acid in lactic acid bacteria have been developed . Whole-cell hydrolysis was performed both in liquid phase and vapor phase with 6 N HCl in sealed vessels using a microwave oven equipped with pressure and temperature probes . The presence or absence of meso-diaminopimelic acid determined by TLC, after the application of liquid- and vapor-phase microwave hydrolysis procedures, gave the same qualitative results as those obtained by traditional hydrolysis . These standardized microwave hydrolysis procedures permit a drastic reduction in hydrolysis time, from 16-20 h to less than 10 min and, consequently, in the total time of meso-diaminopimelic acid analysis (less than 90 min) . Microwave hydrolysis in vapor phase is particularly convenient because, besides reducing hydrolysis time, it also eliminates the successive troublesome step of HCl removal. Biochemistry, 2000 Aug 22, 39(33), 10247 - 54 Binding of Nisin Z to bilayer vesicles as determined with isothermal titration calorimetry; Breukink E et al.; Nisin Z, a 34-residue lantibiotic, is secreted by some lactic acid bacteria and exerts its antibacterial activity against various Gram-positive bacteria by permeabilizing the cell membrane . It is a cationic amphiphilic peptide with several unusual dehydro residues and thioether-bridged lanthionines . Isothermal titration calorimetry was used to provide a quantitative thermodynamic description for nisin Z adsorption to and penetration into negatively charged and neutral lipid bilayers . The binding of the cationic peptide (electric charge z approximately 3.8) to anionic membranes was found to be dominated by electrostatic forces which could be described with the Gouy-Chapman theory . For biologically relevant conditions with a membrane surface potential of -40 mV, the peptide concentration near the membrane surface increases by about 2-3 orders of magnitude compared to the bulk concentration . The binding step proper, i.e., the transition from the lipid-water interface into the membrane, is almost exclusively driven by the high surface concentration . Binding can be described by a partition equilibrium of the form X(b) = KC(M) = KC(p,f) exp(-z(p)psi(0)F(0)/RT), where C(M) is the peptide surface concentration, C(p,f) the bulk concentration, and psi(0) the membrane surface potential . The intrinsic partition coefficient (K = 1.8 M(-)(1)) is remarkably small, indicating a correspondingly small hydrophobic energy contribution to the binding process . The electrostatic model was confirmed with nisin Z mutants in which valine-32 was replaced with either lysine (V32K) or glutamate (V32E), increasing or decreasing the electric charge by 1 unit . The extent of peptide binding increased for V32K and decreased for V32E as predicted by the electrostatic theory . In contrast, electrostatic effects were almost negligible for the binding of nisin Z to neutral membranes . However, the binding isotherms were characterized by a distinctly larger intrinsic binding constant K(0) of approximately 540 M(-)(1) and an enhanced hydrophobic free energy of binding . The binding of nisin Z to sonicated lipid vesicles is exothermic with a DeltaH degrees of ca . -9 and -3.4 kcal/mol for charged and neutral membranes, respectively. Int J Food Microbiol, 2000 Jul 25, 59(1-2), 47 - 57 Evaluation of the impact of short-term temperature abuse on the microbiology and shelf life of a model ready-to-use vegetable combination product; Thomas C et al.; The growth dynamics of indigenous aerobic mesophilic populations (AMP), lactic acid bacteria (LAB) and inoculated (Listeria spp.) microbial populations on cooked and fresh vegetable products, packaged as separate entities and in combination, subjected to temperature fluctuation, were assessed . Microbial proliferation was temperature and product dependent, being most pronounced at 12 degrees C in all products with maximum growth rates of 0.140, 0.175 and 0.126 log10 CFU/g per h being identified for Listeria, aerobic mesophilic and LAB populations, respectively . Listeria spp . and AMP generally demonstrated higher rates of growth within products containing cooked vegetables . Prolonged storage at 3 degrees C resulted in a reduced ability by AMP and Listeria spp . to proliferate upon exposure to growth temperatures; this was not the case with LAB populations . Comparison of Listeria population estimates made using selective (Oxford) and non-selective (nutrient agar) identified reduced recovery on the former . The magnitude of the deviation increased with the duration of exposure of Listeria populations to 3 degrees C with recoveries on selective systems being reduced by 6.3% immediately after inoculation and 82.3% after 168 h at 3 degrees C, respectively . Growth of populations associated with exposure to abuse temperatures was not accompanied by significant changes in product colour (P < 0.05). Biopolymers, 2000, 55(1), 50 - 61 Class II antimicrobial peptides from lactic acid bacteria; Nes IF et al.; Strains of lactic acid bacteria (LAB) produce a wide variety of antibacterial peptides . More than fifty of these so-called peptide bacteriocins have been isolated in the last few years . They contain 20-60 amino acids, and are cationic and hydrophobic in nature . Several of these bacteriocins consist of two complementary peptides . The peptide bacteriocins of LAB are inhibitory at concentrations in the nanomolar range, and cause membrane permeabilization and leakage of intracellular components in sensitive cells . The inhibitory spectrum is limited to gram-positive bacteria, and in many cases to bacteria closely related to the producing strain . Among the target organisms are food spoilage bacteria and pathogens such as Listeria, so that many of these antimicrobial peptides could have a potential as food preservatives as well as in medical applications . Appl Environ Microbiol, 2000 Aug, 66(8), 3528 - 34 Applicability of an Arrhenius model for the combined effect of temperature and CO(2) packaging on the spoilage microflora of fish; Koutsoumanis KP et al.; The temperature behavior of the natural microflora on the Mediterranean fish red mullet (Mullus barbatus) was examined as a case study . The growth of the spoilage bacteria Pseudomonas spp., Shewanella putrefaciens, Brochothrix thermosphacta, and lactic acid bacteria was modeled as a function of temperature and the concentration of carbon dioxide in modified atmosphere packaging . Combined models were developed and comparatively assessed based on polynomial, Belehradek, and Arrhenius equations . The activation energy parameter of the Arrhenius model, E(A), was independent of the packaging atmosphere and ranged from 75 to 85 kJ/mol for the different bacteria, whereas the preexponential constant decreased exponentially with the packaging CO(2) concentration . We evaluated the applicability of the models developed by using experimental bacterial growth rates obtained from 42 independent experiments performed with three Mediterranean fish species and growth rates predicted from the models under the same temperature and packaging conditions . The accuracy factor and bias factor were used as statistical tools for evaluation, and the developed Arrhenius model and the Belehradek model were judged satisfactory overall. J Agric Food Chem, 2000 Jun, 48(6), 2222 - 7 Evaluation of solid-phase microextraction for the isotopic analysis of volatile compounds produced during fermentation by lactic acid bacteria; Goupry S et al.; The use of solid-phase microextraction (SPME) coupled with isotope ratio mass spectrometry (IRMS) for the analysis of flavor compounds produced by lactic acid bacteria has been evaluated using both liquid and headspace sampling modes . Initially, it was necessary to optimize the conditions for the SPME extraction of flavors-diacetyl and acetoin-in standard aqueous solutions . The effects of salt, headspace versus liquid sampling, and coating phase were tested . Second, the suitability of the coupling of SPME and gas chromatography-combustion interface-IRMS (GC-C-IRMS) for the determination of delta(13)C values was assessed . It is shown that neither the analyte concentration nor the period of fiber exposure has an effect on the delta(13)C values . Finally, having verified that there are no matrix effects from the fermentation medium, it is reported for the first time that flavor compounds can be extracted directly from culture supernatant by SPME and their delta(13)C values can be obtained by GC-C-IRMS. Lett Appl Microbiol, 2000 Jul, 31(1), 63 - 7 Identification of acetic acid bacteria by restriction fragment length polymorphism analysis of a PCR-amplified fragment of the gene coding for 16S rRNA; Poblet M et al.; Acetic acid bacteria (AAB) irreversibly spoil wines and represent a serious problem . Limited studies on the ecology of AAB during winemaking have been done due to the lack of rapid and precise techniques for their identification . RFLP analysis of PCR-amplified fragment of 16S rDNA was performed on AAB reference strains . The amplified rDNAs were approximately 870-bp long for all AAB species while no amplicons were detected for lactic acid bacteria and yeasts . Out of the four restriction enzymes tested, TaqI was the most efficient one and divided the studied AAB into six groups . However, complete differentiation among collection strains of Acetobacter pasteurianus and Gluconoacetobacter hansenii was not possible. Microbes Infect, 2000 May, 2(6), 681 - 6 The role of probiotic bacteria in cancer prevention; Hirayama K et al.; Colorectal cancer is one of the most important causes of cancer morbidity and mortality in western countries {1} . A myriad of healthful effects have been attributed to the probiotic lactic acid bacteria; perhaps the most controversial remains that of anticancer activity . There is no direct experimental evidence for cancer suppression in humans as a result of consumption of lactic cultures in fermented or unfermented dairy products . However, there is a wealth of indirect evidence, based largely on laboratory studies, in the literature and this will be summarised in the present paper. Minerva Pediatr, 2000 Mar, 52(3), 161 - 5 Comparison of three probiotics in the treatment of acute diarrhea in mentally retarded children; Barone C et al.; BACKGROUND: This article aims to compare the use of VIS-01 (Yovis) with two other probiotics (lactic acid bacteria), such as Lactogermine and Codex in the treatment of acute diarrhea in children with mental retardation . A recent paper highlights the superiority of the first drug, claiming new perspectives in probiotic therapy . METHODS: The authors perform a prospective study on 33 mentally retarded children (mean age 10.3 years), divided in three groups, each treated with a different probiotic (VIS-01, Lactogermine and Codex) at the beginning of an acute diarrhea . These children were admitted at the Pediatric Unit of the Oasi Maria SS . Institute in Troina . The dosage was suited to the technical record of the drug . During the clinical course the following items have been recorded: number of evacuations; time of alvine normalization; presence, quality, and length of fever; other associated features or side effects . RESULTS: The time of alvine normalization did not show statistically significant differences between the three groups . CONCLUSIONS: In conclusion, the use of Yovis does not modify in a statistically significant way with respect to the remaining drugs the clinical course of acute diarrhea in the mentally retarded children of the present study. Curr Opin Microbiol, 2000 Jun, 3(3), 276 - 82 Lactic acid bacteria: the bugs of the new millennium; Konings WN et al.; Lactic acid bacteria (LABs) are widely used in the manufacturing of fermented food and are among the best-studied microorganisms . Detailed knowledge of a number of physiological traits has opened new potential applications for these organisms in the food industry, while other traits might be beneficial for human health . Important new developments have been made in the research of LABs in the areas of multidrug resistance, bacteriocins and quorum sensing, osmoregulation, proteolysis, autolysins and bacteriophages . Recently, progress has been made in the construction of food-grade genetically modified LABs. J Food Prot, 2000 May, 63(5), 645 - 50 Ability of dairy strains of lactic acid bacteria to bind aflatoxin M1 in a food model; Pierides M et al.; Aflatoxin M1 (AFM1) is a highly toxic compound found in milk . Its occurrence poses a threat to the health of consumers, especially young children, and leads to economic losses due to contaminated milk . The problem is global but more severe in developing countries . Consequently, there is a great demand for novel strategies to prevent the contamination and adverse effects of AFM1 . To develop a safe and practical decontamination method, a preliminary study was carried out with specific lactic acid bacteria strains that were tested for their ability to remove AFM1 from liquid media . All strains, whether viable or heat-killed, could reduce the AFM1 content of a liquid medium . Two most effective strains were also tested using contaminated skim and full cream milk . The results indicate that specific lactic acid bacteria used in dairy products can offer novel means of decontaminating aflatoxin M1 from milk. Bratisl Lek Listy, 2000, 101(1), 51 - 3 {Immunostimulatory and other beneficial health effects of lactic acid bacteria}; Ferencik M et al.; Lactic acid bacteria in functional foods can transiently colonize the intestine of man and exert beneficial probiotic effects . These were observed in a group of adult subjects administered daily by a lyophilized Enterococcus faecium M-74 in the form of waffles (Dr . Ebi) during nine weeks of a double blind placebo controlled clinical trial . The results showed significant immunostimulatory effect on both phagocytosis by neutrophils and antibody production. J Agric Food Chem, 1999 Jun, 47(6), 2379 - 85 Aroma comparisons of traditional and mild yogurts: headspace gas chromatography quantification of volatiles and origin of alpha-diketones; Ott A et al.; A quick headspace GC method for quantification of volatiles was developed, involving only minor sample preparation . Yogurt flavor compounds could be quantified in the micrograms per kilogram to milligrams per kilogram range without any difficulty, despite the complex matrix . Volatiles of traditional acidic and mild, less acidic yogurts were compared, and important differences were found for acetaldehyde, 2,3-butanedione, and 2,3-pentanedione . Concentrations of 2,3-butanedione and 2,3-pentanedione increased 2-3-fold in mild, less acidic yogurts compared to traditional acidic ones . This is due to accumulation of the precursors of the diketones, 2-acetolactate and 2-acetohydroxybutyrate, during fermentation in mild, less acidic yogurt . These precursors are subsequently converted to the corresponding diketones during storage . On the contrary, acetaldehyde formation was reduced in the mild yogurt, due to growth differences between the lactic acid bacteria used for fermentation of the milk . The quantitative results presented in this study validate previous GC sniffing conclusions (Ott et al . J . Agric . Food Chem . 1997, 45, 850-858), showing that yogurt aroma is the superposition of impact flavor compounds generated by fermentation on milk compounds. Appl Environ Microbiol, 2000 May, 66(5), 2216 - 9 Simultaneous immunofluorescent detection of coentrapped cells in gel beads; Prioult G et al.; An immunofluorescent method involving double color labeling and confocal microscopy was reported to specifically detect lactic acid bacteria and probiotic cells coimmobilized in gels beads . The method described is rapid (4 h) and sensitive and may be useful for studying cell dynamics during mixed-culture starter production using immobilized cells in gel beads . Microscopic observations were perfectly correlated to cell counts obtained using a sandwich enzyme-linked immunosorbent assay. J Gastroenterol, 2000, 35(4), 299 - 303 Rifampicin-associated pseudomembranous colitis; Nakajima A et al.; We report a case of pseudomembranous colitis that developed in a patient with liver cirrhosis during anti-tuberculosis therapy with rifampicin and isoniazid . The association between rifampicin and pseudomembranous colitis has been controversial; this report, however, supports the association . Colonoscopy performed 3 days after the onset of the pseudomembranous colitis revealed only reddish patches and a few aphthoid lesions, but 4 days later pseudomembranes were apparent . The pseudomembranous colitis was successfully controlled by discontinuation of the anti-tuberculosis agents, along with the administration of lactic acid bacteria, without vancomycin or metronidazole . Possible predisposing factors for the development of pseudomembranous colitis in this patient are also discussed. J Bacteriol, 2000 May, 182(9), 2643 - 8 A C-terminal disulfide bridge in pediocin-like bacteriocins renders bacteriocin activity less temperature dependent and is a major determinant of the antimicrobial spectrum; Fimland G et al.; Several lactic acid bacteria produce so-called pediocin-like bacteriocins that share sequence characteristics, but differ in activity and target cell specificity . The significance of a C-terminal disulfide bridge present in only a few of these bacteriocins was studied by site-directed mutagenesis of pediocin PA-1 (which naturally contains the bridge) and sakacin P (which lacks the bridge) . Introduction of the C-terminal bridge into sakacin P broadened the target cell specificity of this bacteriocin, as illustrated by the fact that the mutants were 10 to 20 times more potent than the wild-type toward certain indicator strains, whereas the potency toward other indicator strains remained essentially unchanged . Like pediocin PA-1, disulfide-containing sakacin P mutants had the same potency at 20 and 37 degrees C, whereas wild-type sakacin P was approximately 10 times less potent at 37 degrees C than at 20 degrees C . Reciprocal effects on target cell specificity and the temperature dependence of potency were observed upon studying the effect of removing the C-terminal disulfide bridge from pediocin PA-1 by Cys-->Ser mutations . These results clearly show that a C-terminal disulfide bridge in pediocin-like bacteriocins contributes to widening of the antimicrobial spectrum as well as to higher potency at elevated temperatures . Interestingly, the differences between sakacin P and pediocin PA-1 in terms of the temperature dependency of their activities correlated well with the optimal temperatures for bacteriocin production and growth of the bacteriocin-producing strain. J Am Coll Nutr, 2000 Apr, 19(2 Suppl), 137S - 146S Effect of lactic acid bacteria on diarrheal diseases; Heyman M; Microbial balance is an important factor in the maintenance of intestinal homeostasis, and yogurt or fermented milk supplementation has been proposed to control diarrheal diseases . A number of studies using animal models and clinical studies in humans have confirmed the beneficial effect of such fermented products in case of lactose intolerance, viral diarrhea or antibiotics-associated diarrhea . The mechanisms by which lactic acid bacteria exert their effects are multiple . Bacterial lactase improves the absorption of lactose, but fermented products slow down the intestinal transit facilitating the action of residual intestinal lactase . The transient passage of lactic acid bacteria in the digestive tract may represent a microbial barrier against the development of pathogenic bacteria, probably due to the release of compounds contributing to the maintenance of colonization resistance to pathogens . The beneficial effects are mainly described in the presence of live bacteria, but inactivated bacteria may also present preventive or curative capacities in diarrheal diseases . Moreover, lactic acid bacteria has been described as reinforcing the non-specific immune defence but also specific immunity, particularly the secretory immune system mediated by secretory IgA or IgM in response to particulate infectious antigens and perhaps to soluble food antigens . Other possible mechanisms include the trophic effect on the intestinal layer, and a down-regulatory activity in cow's milk allergy as well as anti-inflammatory effects have also been suggested. J Appl Microbiol, 2000 Mar, 88(3), 449 - 57 Anti-Listeria effect of enterocin A, produced by cheese-isolated Enterococcus faecium EFM01, relative to other bacteriocins from lactic acid bacteria; Ennahar S et al.; Enterocin A produced by Enterococcus faecium EFM01 displayed a narrow antimicrobial spectrum, mainly directed against Listeria spp . In particular, the bacteriocin was extremely active against 13 Listeria monocytogenes strains . This high specificity of action of enterocin A for Listeria spp . relative to lactic acid bacteria, together with its broad range of activity from pH 4.0 to pH 9.0, are factors which may be of great interest with respect to the potential antilisterial use of this bacteriocin in fermented foods . Assessment of the effect of enterocin A concentration on the extent and kinetics of bactericidal activity on L . monocytogenes Lm 6 (107 cfu ml-1 in culture broth), suggested that viability losses of higher than 5 log10, and time intervals necessary for maximum loss of viability of less than 2 h, could not be obtained . Moreover, it was shown that both parameters are closely dependent on the Listeria strain used . On the other hand, at concentrations inducing destruction of approximately 2 log10 cycles, maximum loss of viability was achieved within time intervals which varied widely from one lactic acid bacteria bacteriocin to another. J UOEH, 2000 Mar 1, 22(1), 13 - 8 Enzymatic determination of sn-glycerol-1-phosphate; Nishihara M et al.; A sensitive and positive colorimetric method for quantification of sn-glycerol-1-phosphate (G-1-P) is described . The use of G-1-P-specific dehydrogenase from Methanobacterium thermoautotrophicum and a tetrazolium salt (an NAD-recycling system) allowed a positive measurement of G-1-P, and caused an increase in sensitivity . Because G-1-P is not only the backbone of the ether glycerolipids in Archaea (formerly archaebacteria) but also the component of lipoteichoic acid polymers from some Gram-positive bacteria, membrane-derived oligosaccharide from Escherichia coli, unacylated moiety of phosphatidylglycerol from bacteria and mitochondria, and some phosphoglycolipids of lactic acid bacteria, this method may be useful in the structural and metabolic studies of these materials. Lett Appl Microbiol, 2000 Feb, 30(2), 136 - 41 The viable but non-culturable state of wine micro-organisms during storage; Millet V et al.; Colony counting and DEFT did not give the same results when wine micro-organisms were enumerated . Both methods were used to monitor the population of acetic acid bacteria (AAB) and lactic acid bacteria (LAB) during wine storage . Results suggest that part of the populations had reached a viable but non-culturable (VBNC) state . These cells were unable to produce colonies but could hydrolyse fluorescent esters and could be counted by DEFT . For AAB, O2 deprivation quickly induced this state . Recovery from this state was very rapid as soon as O2 was available . The response was not so clear for LAB during wine storage . However, a similar state was induced by sulfiting . Moreover, filtration of wine stored in barrels and contaminated by Brettanomyces, AAB and LAB demonstrated that cell size was not homogeneous . Cells which remained in wine after several weeks could pass through a 0.45-microm membrane . However, when they re-entered a growing phase, they were again retained by membrane filtration . During and after the decline phase, wine micro-organisms might survive as smaller cells in a VBNC state. Am J Clin Nutr, 2000 Apr, 71(4), 861 - 72 Immunologic effects of yogurt; Meydani SN et al.; Many investigators have studied the therapeutic and preventive effects of yogurt and lactic acid bacteria, which are commonly used in yogurt production, on diseases such as cancer, infection, gastrointestinal disorders, and asthma . Because the immune system is an important contributor to all of these diseases, an immunostimulatory effect of yogurt has been proposed and investigated by using mainly animal models and, occasionally, human subjects . Although the results of these studies, in general, support the notion that yogurt has immunostimulatory effects, problems with study design, lack of appropriate controls, inappropriate route of administration, sole use of in vitro indicators of the immune response, and short duration of most of the studies limit the interpretation of the results and the conclusions drawn from them . Nevertheless, these studies in toto provide a strong rationale for the hypothesis that increased yogurt consumption, particularly in immunocompromised populations such as the elderly, may enhance the immune response, which would in turn increase resistance to immune-related diseases . This hypothesis, however, needs to be substantiated by well-designed randomized, double-blind, placebo-controlled human studies of an adequate duration in which several in vivo and in vitro indexes of peripheral and gut-associated immune response are tested. Berl Munch Tierarztl Wochenschr, 2000 Feb, 113(2), 46 - 52 {Food as a potential vector for antibiotic resistances . 2: Relevance of lactic acid bacteria}; Klein G; Transfer of antibiotic resistances via the food chain is possible through the ingestion of resistant parts of the original food microflora . Lactic acid bacteria (especially glycopeptide resistant enterococci) are considered as important vectors because of their ability to transfer resistances by genetic mechanisms . Therefore a literature review and own investigations concerning the incidence and the resistance profile of enterococci from fresh meat were performed . The isolates harboured in part resistances relevant for human medicine . However, they could be isolated only sporadically and could not be demonstrated quantitatively in most cases . The resistance profile differed from those of human clinical origin . These results were confirmed by other authors . Additionally other investigators could prove molecular differences compared to clinical strains . Therefore food can only be considered as a vector if resistance transfer from food isolates to pathogenic microorganisms is possible . Such a transfer could be shown only in very low frequencies . In conclusion so far lactic acid bacteria cannot be considered as the main source for the incidence of antibiotic resistances in man. J Dairy Res, 2000 Feb, 67(1), 83 - 90 Method of quantifying the loss of acidification activity of lactic acid starters during freezing and frozen storage; Fonseca F et al.; We have developed a method to quantify the resistance to freezing and frozen storage of lactic acid starters, based on measuring the time necessary to reach the maximum acidification rate in milk (tm) using the Cinac system . Depending on the operating conditions, tm increased during the freezing step and storage . The loss of acidification activity during freezing was quantified by the difference (delta tm) between the tm values of the concentrated cell suspension before and after freezing . During storage at -20 degrees C, linear relationships between tm and the storage time were established . Their slope, k, allowed the quantitation of the decrease in acidification activity during 9-14 weeks of frozen storage . The method was applied to determine the resistance to freezing and frozen storage of four strains of lactic acid bacteria and to quantify the cryoprotective effect of glycerol. J Dairy Res, 2000 Feb, 67(1), 65 - 71 Inability of dairy propionibacteria to grow in milk from low inocula; Piveteau P et al.; Growth of propionibacteria in complex media was independent of the initial number of cells; in contrast, growth of propionibacteria in milk and whey did not occur if the initial level of cells was < 10(6) cfu/ml . Addition of vitamins, minerals or complex nitrogen sources to the milk or whey, or incubation under anaerobic conditions had no effect on the lack of growth . Addition of freeze-dried whey, prepared from skim milk reconstituted from powder, to a complex medium prevented growth from low inocula in the complex medium, demonstrating the presence of an inhibitor or inhibitors in the whey . The inhibitor(s) was heat stable, had a low molecular mass and retained its activity for at least 4 weeks at 20 degrees C . Pregrowth of some lactic acid bacteria, used as starter cultures in Swiss-type cheese manufacture, in milk for 2 weeks at 20 degrees C removed the inhibition, which explains how propionibacteria develop in Swiss-type cheese from low numbers even though they are inhibited in milk. FEMS Microbiol Lett, 2000 Feb 1, 183(1), 31 - 5 Ethyl carbamate precursor citrulline formation from arginine degradation by malolactic wine lactic acid bacteria; Mira de Orduna R et al.; Major commercially available strains for induction of malolactic fermentation in wine were examined for arginine metabolism in a resting cell system at wine pH with the aim of evaluating their ability to excrete and utilize citrulline, a precursor of carcinogenic ethyl carbamate (urethane) . All strains tested excreted citrulline from arginine degradation . Citrulline was stored intracellularly during growth in arginine rich medium and was released upon lysis of the cells . All strains were found to degrade citrulline as a sole amino acid and some of them were able to reutilize previously excreted citrulline. FEMS Microbiol Rev, 2000 Jan, 24(1), 85 - 106 Class IIa bacteriocins: biosynthesis, structure and activity; Ennahar S et al.; In the last decade, a variety of ribosomally synthesized antimicrobial peptides or bacteriocins produced by lactic acid bacteria have been identified and characterized . As a result of these studies, insight has been gained into fundamental aspects of biology and biochemistry such as producer self protection, membrane-protein interactions, and protein modification and secretion . Moreover, it has become evident that these peptides may be developed into useful antimicrobial additives . Class IIa bacteriocins can be considered as the major subgroup of bacteriocins from lactic acid bacteria, not only because of their large number, but also because of their activities and potential applications . They have first attracted particular attention as listericidal compounds and are now believed to be the next in line if more bacteriocins are to be approved in the future . The present review attempts to provide an insight into general knowledge available for class IIa bacteriocins and discusses common features and recent findings concerning these substances. J Food Prot, 2000 Dec, 63(12), 1702 - 6 Reduction of normal flora by irradiation and its effect on the ability of Listeria monocytogenes to multiply on ground turkey stored at 7 degrees C when packaged under a modified atmosphere; Thayer DW et al.; Listeria monocytogenes did not multiply faster during storage at 7 degrees C on irradiated than on nonirradiated raw ground turkey, and there was a concentration-dependent inhibition of its multiplication by CO2 . Ground turkey was gamma irradiated at 5 degrees C to 0, 1.5, and 2.5 kGy and inoculated (approximately 100 CFU/g) after irradiation with a cocktail of L . monocytogenes ATCC 7644, 15313, 49594, and 43256 . The meat was then packaged in air-permeable pouches or under atmospheres containing 30 or 53% CO2, 19% O2, and 51 or 24% N2 and stored at 7 degrees C for up to 28 days . A dose of 2.5 kGy extended the time for the total plate count (TPC) to reach 10(7) CFU/g from 4 to 19 days compared to that for nonirradiated turkey in air-permeable pouches . Following a dose of 2.5 kGy at the end of the 28-day study, the TPCs were 10(6.42) and 10(4.98) under 25% and 50% CO2 atmospheres, respectively . Under air, 30% CO2, and 53% CO2 atmospheres, the populations of L . monocytogenes after 19 days incubation were 10(4.89), 10(3.60), and 10(2.67) CFU/g . The populations of lactic acid bacteria and anaerobic or facultative bacteria were also reduced by irradiation . Irradiating ground turkey did not decrease its safety when it was contaminated following processing with L . monocytogenes. Neurosci Lett, 1999 Dec 24, 277(2), 127 - 30 Lipid peroxidative stress and antioxidative enzymes in brains of milk-supplemented rats; Bay BH et al.; Skim milk cultured with lactic acid bacteria has been previously reported to reduce lipid peroxidation in rat livers . In this study, the effects of skim milk and cultured milk supplementation on peroxidative stress in brains of weanling rats were investigated . We observed a reduction of brain thiobarbituric acid reacting substances (TBARS) concentration in milk-supplemented animals as compared with controls . In brains of control rats, the superoxide dismutase (SOD) enzyme levels were significantly higher than those from the milk-supplemented animals . In addition, SOD activity in control animal brains had a positive correlation with the TBARS concentration . There was no significant differences in the brain glutathione-S-transferase (GST) levels of all the three groups of animals . The results suggest that milk supplementation may be beneficial in reducing peroxidative stress in the developing rat brain. J Agric Food Chem, 1999 Jul, 47(7), 2959 - 62 Enhancement of polyphenol recovery from rosemary (Rosmarinus officinalis) and sage (Salvia officinalis) by enzyme-assisted ensiling (ENLAC); Weinberg ZG et al.; The efficacy of enzyme-assisted ensiling (ENLAC) in the recovery of polyphenols from rosemary and sage was tested . Fresh rosemary and sage were chopped and ensiled in 0.5-L anaerobic jars . Treatments comprised control (no additives), 0.5% glucose and lactic acid bacteria, and 1% cellulase plus 1% hemicellulase plus pectinase . Following storage at room temperature for 45 days (experiment 1) and 26 days (experiment 2), polyphenols were extracted from the silages in ethanol either by direct blending or by cold extraction . The enzyme treatment resulted in silages with the lowest pH values, lowest fiber content, highest water-soluble sugar content, and highest polyphenol recovery; this treatment resulted in increased polyphenol recovery from rosemary and sage, by 100 and 20%, respectively . Comparison between direct blending and cold extraction revealed similar efficiency of polyphenol recovery. Microbiol Immunol, 1999, 43(10), 925 - 35 Cytokine secretion by stimulated monocytes depends on the growth phase and heat treatment of bacteria: a comparative study between lactic acid bacteria and invasive pathogens; Haller D et al.; The consumption of food containing lactic acid bacteria (LAB) has been shown to exert immunomodulatory effects in humans . The specific cellular interaction of these bacteria with immuno-competent cells has not yet been fully understood . Since the TNF-alpha secretion of stimulated monocytes is an important initial response to a bacterial challenge, we investigated the potential of LAB originating from the human intestine or fermented food in comparison to the effect of invasive pathogens . The challenge of monocytes with three LAB strains, Listeria monocytogenes or enterohaemorrhagic Escherichia coli (EHEC) elicited a strain specific, dose-dependent biphasic TNF-alpha secretion . The concentration (EDmax) of bacteria or bacterial cell wall components necessary to induce maximal TNF-alpha secretion (TNFmax) by monocytes was mathematically approximated . It was shown for exponentially growing LAB strains that the maximal TNF-alpha secretion (TNFmax) was stronger (57 to 78%) upon stimulation with living bacteria than with heat killed cells . In contrast to log-phase bacteria, the maximal TNF-alpha secretion of monocytes (TNFmax) was higher (15 to 55%) after the stimulation with heat killed, stationary-phase bacteria when compared to that of live LAB . Thus, monocyte stimulation was clearly affected by the growth phase of bacteria . Purified cell walls of LAB strains revealed only a limited potential for monocyte stimulation . LPS exhibited a higher capacity to stimulate monocytes than purified gram positive cell walls or muramyldipeptide . In comparison to pathogenic bacteria, the maximal secretory TNF-alpha response (TNFmax) was up to 2 fold higher with LAB strains . In general, the amount of bacteria (EDmax) necessary to induce maximal TNF-alpha secretion (TNFmax) was approximately 1 to 3 log higher for heat killed bacteria when compared to live bacterial cells illustrating the significant lower potential of heat killed bacteria to activate monocytes. J Agric Food Chem, 1999 Oct, 47(10), 4003 - 8 Contribution to the knowledge of malolactic fermentation influence on wine aroma; de Revel G et al.; In this work, we study two aspects of malolactic fermentation: the use of industrial lactic acid bacteria starter-cultures in a white Sauvignon wine and the effects of the bacterial activity on the composition of wines in terms of volatile substances from oakwood during partial malolactic fermentation in barrels . A sensory evaluation was made by the use of discriminative and descriptive methods . The consequences of bacterial development are thus limited, but it is nevertheless possible to make characteristic observations . The carbonyl substances were formed in connection with a more or less fast bacterial growth and a degradation of the citric acid . However, the influence of the bacterial starter-culture is difficult to establish . The concentration of the compounds resulting from wood was higher in the wines after malolactic fermentation compared to a wine not having undergone bacterial development . Greater complexity was perceived during the sensory analysis, with buttered, spiced, roasted, vanilla, and smoked notes . On the other hand, the intensity of the descriptors characteristic of grape variety decreased. Lipids, 1999 Oct, 34(10), 1107 - 15 Stability of cyclopropane and conjugated linoleic acids during fatty acid quantification in lactic acid bacteria; Dionisi F et al.; Seven methods commonly used for fatty acid analysis of microorganisms and foods were compared to establish the best for the analysis of lyophilized lactic acid bacteria . One of these methods involves fat extraction followed by methylation of fatty acids, while the other methods use a direct methylation of the samples, under different operating conditions (e.g., reaction temperature and time, reagents, and pH) . Fatty acid methyl esters were identified by gas chromatography-mass spectrometry and quantified by on-column capillary gas chromatography . Two reliable methods for the analysis of fatty acids in bacteria were selected and further improved . They guarantee high recovery of classes of fragile fatty acids, such as cyclopropane and conjugated acids, and a high degree of methylation for all types of fatty acid esters . These two direct methylation methods have already been successfully applied to the analysis of fatty acids in foods . They represent a rapid and highly reliable alternative to classical time- and solvent-consuming methods and they give the fatty acid profile and the amount of each fatty acid . Using these methods, conjugated linoleic acids were identified and quantified in lactic acid bacteria. J Food Prot, 1999 Nov, 62(11), 1297 - 302 Growth rates of mesophilic bacteria, aerobic psychrotrophic bacteria, and lactic acid bacteria in low-dose-irradiated pork; Venugopal RJ et al.; Frozen pork patties, thawed overnight at 0 degrees C or temperature abused through storage at 15 degrees C for 24 h, were packaged using both vacuum and air packaging methods . Immediately after packaging, both sets of patties were irradiated at 0, 0.5, 1, and 2 kGy . All the samples were stored at 2 degrees C and were analyzed for populations of mesophilic, psychrotrophic, and lactic acid bacteria every 3 days for 30 days . By using a mesophilic population of 10(7) cells/g as a criteria for spoilage, fresh pork patties receiving a dose of 0 kGy had shelf lives of 11 and 16 days with air and vacuum packaging methods, respectively, whereas temperature-abused patties had a shelf life of 7 days with both air and vacuum packaging methods . Both fresh and abused patties that received a dose of 2 kGy had shelf lives that were greater than 30 days at 2 degrees C with both air and vacuum packaging methods . Descriptive models based on the Gompertz equation for mesophilic, psychrotrophic, and lactic acid bacteria were developed, and the generation time and lag-phase duration for each bacterial population were calculated. Appl Microbiol Biotechnol, 1999 Nov, 52(5), 628 - 38 Production, recovery and purification of bacteriocins from lactic acid bacteria; Parente E et al.; Bacteriocins produced by lactic acid bacteria are a heterogeneous group of peptide inhibitors which include lantibiotics (class I, e.g . nisin), small heat-stable peptides (class II, e.g . pediocin AcH/PA1) and large heat-labile proteins (class III, e.g . helveticin J) . Many bacteriocins belonging to the first two groups can be successfully used to inhibit undesirable microorganisms in foods, but only nisin is produced industrially and is licensed for use as a food preservative in a partially purified form . This review focuses on the production and purification of class I and class II bacteriocins from lactic acid bacteria . Bacteriocin production is growth associated but the yield of bacteriocin per unit biomass is affected by several factors, including the producing strain, media (carbohydrate and nitrogen sources, cations, etc.) and fermentation conditions (pH, temperature, agitation, aeration and dilution rate in continuous fermentations) . Continuous fermentation processes with cell recycle or immobilized cells can result in a dramatic improvement in productivity over batch fermentations . Several simple recovery processes, based on adsorbing bacteriocin on resins or silica compounds, have been developed and can be used to build integrated production processes. Biochemistry, 1999 Nov 23, 38(47), 15438 - 47 Solution structure of carnobacteriocin B2 and implications for structure-activity relationships among type IIa bacteriocins from lactic acid bacteria; Wang Y et al.; Carnobacteriocin B2 (CbnB2), a type IIa bacteriocin, is a 48 residue antimicrobial peptide from the lactic acid bacterium Carnobacterium pisicola LV17B . Type IIa bacteriocins have a conserved YGNGVXC sequence near the N-terminus and usually contain a disulfide bridge . CbnB2 seemed to be unique in that its two cysteines (Cys9 and Cys14) could be isolated as free thiols {Quadri et al . (1994) J . Biol . Chem . 26, 12204-12211} . To establish the structural consequences of the presence or absence of a disulfide bridge and to investigate if the YGNGVXC sequence is a receptor-binding motif {Fleury et al . (1996) J . Biol . Chem . 271, 14421-14429}, the three-dimensional solution structure of CbnB2 was determined by two-dimensional (1)H nuclear magnetic resonance (NMR) techniques . Mass spectroscopic and thiol modification experiments on CbnB2 and on model peptides, in conjunction with activity measurements, were used to verify the redox status of CbnB2 . The results show that CbnB2 readily forms a disulfide bond and that this peptide has full antimicrobial activity . NMR results indicate that CbnB2 in trifluoroethanol (TFE) has a well-defined central helical structure (residues 18-39) but a disordered N terminus . Comparison of the CbnB2 structure with the refined solution structure of leucocin A (LeuA), another type IIa bacteriocin, indicates that the central helical structure is conserved between the two peptides despite differences in sequence but that the N-terminal structure (a proposed receptor binding site) is not . This is unexpected because LeuA and CbnB2 exhibit >66% sequence identity in the first 24 residues . This suggests that the N-terminus, which had been proposed {Fleury et al . (1996) J . Biol . Chem . 271, 14421-14429} to be a receptor binding site of type IIa bacteriocins, may not be directly involved and that recognition of the amphiphilic helical portion is the critical feature. Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 391 - 4 The role of lactic acid bacteria in colon cancer prevention: mechanistic considerations; Hirayama K et al.; Colorectal cancer is one of the most important causes of cancer morbidity and mortality in Western countries . While a myriad of healthful effects have been attributed to the probiotic lactic acid bacteria, perhaps the most controversial remains that of anticancer activity . It should be pointed out already at this point that there is no direct experimental evidence for cancer suppression in humans as a result of consumption of lactic cultures in fermented or unfermented dairy products . However, there is a wealth of indirect evidence, based largely on laboratory studies, in the literature . The precise mechanisms by which lactic acid bacteria may inhibit colon cancer are presently unknown . However, such mechanisms might include: enhancing the host's immune response; binding and degrading potential carcinogens; quantitative and/or qualitative alterations in the intestinal microflora incriminated in producing putative carcinogen(s) and promoters (e.g . bile acid-degrading bacteria); producing antitumorigenic or antimutagenic compounds in the colon; alteration of the metabolic activities of intestinal microflora; alteration of physicochemical conditions in the colon; effects on physiology of the host . These potential mechanisms are discussed in the present paper. Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 367 - 76 Anchoring of proteins to lactic acid bacteria; Leenhouts K et al.; The anchoring of proteins to the cell surface of lactic acid bacteria (LAB) using genetic techniques is an exciting and emerging research area that holds great promise for a wide variety of biotechnological applications . This paper reviews five different types of anchoring domains that have been explored for their efficiency in attaching hybrid proteins to the cell membrane or cell wall of LAB . The most exploited anchoring regions are those with the LPXTG box that bind the proteins in a covalent way to the cell wall . In recent years, two new modes of cell wall protein anchoring have been studied and these may provide new approaches in surface display . The important progress that is being made with cell surface display of chimaeric proteins in the areas of vaccine development and enzyme- or whole-cell immobilisation is highlighted. Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 185 - 98 Bacteriocins: mechanism of membrane insertion and pore formation; Moll GN et al.; Lactic acid bacteria produce several types of pore forming peptides . Class I bacteriocins are lantibiotics that contain (methyl)lanthionine residues that may form intramolecular thioether rings . These peptides generally have a broad spectrum of activity and form unstable pores . Class II bacteriocins are small, heat stable peptides mostly with a narrow spectrum of activity . Most bacteriocins interact with anionic lipids that are abundantly present in the membranes of gram-positive bacteria . 'Docking molecules' may enhance the conductivity and stability of lantibiotic pores, while 'receptors' in the target membrane may determine specificity of class II bacteriocins . Insertion into the membrane of many bacteriocins is proton motive force driven . Lantibiotics may form pores according to a 'wedge-like' model, while class II bacteriocins may enhance membrane permeability either by the formation of a 'barrel stave' pore or by a 'carpet' mechanism. Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 89 - 113 Bacteriophage defence systems in lactic acid bacteria; Forde A et al.; The study of the interactions between lactic acid bacteria and their bacteriophages has been a vibrant and rewarding research activity for a considerable number of years . In the more recent past, the application of molecular genetics for the analysis of phage-host relationships has contributed enormously to the unravelling of specific events which dictate insensitivity to bacteriophage infection and has revealed that while they are complex and intricate in nature, they are also extremely effective . In addition, the strategy has laid solid foundations for the construction of phage resistant strains for use in commercial applications and has provided a sound basis for continued investigations into existing, naturally-derived and novel, genetically-engineered defence systems . Of course, it has also become clear that phage particles are highly dynamic in their response to those defence systems which they do encounter and that they can readily adapt to them as a consequence of their genetic flexibility and plasticity . This paper reviews the exciting developments that have been described in the literature regarding the study of phage-host interactions in lactic acid bacteria and the innovative approaches that can be taken to exploit this basic information for curtailing phage infection. Antonie Van Leeuwenhoek, 1999 Jul-Nov, 76(1-4), 3 - 23 From DNA sequence to application: possibilities and complications; Venema G et al.; The development of sophisticated genetic tools during the past 15 years have facilitated a tremendous increase of fundamental and application-oriented knowledge of lactic acid bacteria (LAB) and their bacteriophages . This knowledge relates both to the assignments of open reading frames (ORF's) and the function of non-coding DNA sequences . Comparison of the complete nucleotide sequences of several LAB bacteriophages has revealed that their chromosomes have a fixed, modular structure, each module having a set of genes involved in a specific phase of the bacteriophage life cycle . LAB bacteriophage genes and DNA sequences have been used for the construction of temperature-inducible gene expression systems, gene-integration systems, and bacteriophage defence systems . The function of several LAB open reading frames and transcriptional units have been identified and characterized in detail . Many of these could find practical applications, such as induced lysis of LAB to enhance cheese ripening and re-routing of carbon fluxes for the production of a specific amino acid enantiomer . More knowledge has also become available concerning the function and structure of non-coding DNA positioned at or in the vicinity of promoters . In several cases the mRNA produced from this DNA contains a transcriptional terminator-antiterminator pair, in which the antiterminator can be stabilized either by uncharged tRNA or by interaction with a regulatory protein, thus preventing formation of the terminator so that mRNA elongation can proceed . Evidence has accumulated showing that also in LAB carbon catabolite repression in LAB is mediated by specific DNA elements in the vicinity of promoters governing the transcription of catabolic operons . Although some biological barriers have yet to be solved, the vast body of scientific information presently available allows the construction of tailor-made genetically modified LAB . Today, it appears that societal constraints rather than biological hurdles impede the use of genetically modified LAB. Bratisl Lek Listy, 1999 May, 100(5), 238 - 45 {Successful modification of human intestinal microflora with oral administration of lactic acid bacteria}; Ferencik M et al.; Lactic acid bacteria in food can transiently colonize the intestine and exert health beneficial (probiotic) effects . These include: 1 . Lactose digestion, improvement of diarrheal disorders (including traveller's diarrhea), prophylaxis of intestinal and urogenital infections--as a result of formation or reconstruction of a balanced indigenous microflora . 2 . Inhibition of the mutagenicity of the intestinal contents and reduction of the incidence of intestinal tumours . 3 . Immunomodulatory effects resulting in the improved host resistance . 4 . Depression of the serum cholesterol level . The most of these effects were observed in a group of adult subjects administered daily by a lyophilized Enterococcus faecium M-74 in the form of waffles (Dr . Ebi) during nine weeks of a double blind placebo controlled clinical trial . The bacterium temporarily colonized the host intestine and its secretion in stool persisted for six weeks after the last dose . The mean activities of beta-D-glucuronidase in stools of subjects given waffles containing enterococci were reduced comparing to stools of placebo subjects . After six weeks of daily eating the waffles with enterococci, an increased production of superoxide and other reactive oxygen intermediates by peripheral neutrophils was observed . The increase corresponded in time with an elevated formation of IgG by peripheral blood mononuclear cells after polyclonal activation with mitogenes . Higher activities of myeloperoxidase and elastase in peripheral neutrophils were also ascertained during eating of waffles containing of E . faecium M-74 . Hence, intake of E . faecium M-74 in the form of waffles may have an significant immunostimulatory effect on both phagocytosis performed by neutrophils and antibody production . (Tab . 6, Ref . 29.) Med Hypotheses, 1999 Jul, 53(1), 87 - 8 Protection against an infectious disease by enterohaemorrhagic E . coli 0-157; Ota A; Preventive measures against infection by enterohaemorrhagic E . coli 0-157 are described . Eating yoghurt and Kefir supposedly induces more bifid bacteria and lactic acid bacteria to colonize in the intestines, thereby protecting humans from infection by E . coli 0-157 . Some foods, such as plum extract, act as a mild antibiotic and produce an acidic environment within the intestine, thus interfering with growth of the E . coli 0-157 . The natural colonization of harmless E . coli or other bacteria that are more powerful than E . coli 0-157 can possibly protect against infection . A vaccination against E . coli 0-157 H7 may also be effective . In addition, it has been suggested that the correct levels of nitric oxide and calcium in the blood may activate immunity and protect against infection by E . coli 0-157. Appl Microbiol Biotechnol, 1999 Aug, 52(2), 179 - 85 Mechanism of L-methionine overproduction by Escherichia coli: the replacement of Ser-54 by Asn in the MetJ protein causes the derepression of L-methionine biosynthetic enzymes; Nakamori S et al.; We derived L-methionine-analogue-resistant mutants from Escherichia coli JM109 strain by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine and selected the potent L-methionine-overproducing strains by microbioassay using lactic acid bacteria . One of the mutants, strain TN1, produced approximately 910 mg L-methionine/l following the addition of 0.1% yeast extract to fundamental medium containing glucose and ammonium sulfate . The L-methionine biosynthetic enzymes, cystathionine gamma-synthase and cystathionine beta-lyase, of the L-methionine-overproducing mutants were little repressed by L-methionine . To analyse the mechanism of L-methionine overproduction in the mutant strains, the metJ gene coding for the E . coli met repressor, MetJ protein, was cloned and sequenced by the polymerase chain reaction . The same single-amino-acid subsitution (wild-type Ser-->Asn) at position 54 was observed in four independent L-methionine-producing mutants . When the wild-type metJ gene was then introduced into strain TN1 having the mutant metJ gene, the level of enzyme synthesis and the L-methionine productivity in the transformants were found to revert to those of the wild-type . It was therefore considered that only one point mutation in the metJ gene occurred in the L-methionine-producing mutants . These results demonstrate the important role of residue 54 of the MetJ protein in L-methionine overproduction, probably because of the derepression of L-methionine biosynthetic enzymes. Int J Food Microbiol, 1999 Sep 15, 50(1-2), 131 - 49 Food fermentations: role of microorganisms in food production and preservation; Caplice E et al.; Preservation of foods by fermentation is a widely practiced and ancient technology . Fermentation ensures not only increased shelf life and microbiological safety of a food but also may also make some foods more digestible and in the case of cassava fermentation reduces toxicity of the substrate . Lactic acid bacteria because of their unique metabolic characteristics are involved in many fermentation processes of milk, meats, cereals and vegetables . Although many fermentations are traditionally dependent on inoculation from a previous batch starter cultures are available for many commercial processes such as cheese manufacture thus ensuring consistency of process and product quality . This review outlines the role of lactic acid bacteria in many such fermentations and the mechanisms of antibiosis with particular reference to bacteriocins and gives a brief description of some important fermented foods from various countries . It is anticipated that the contribution of the advances in lactic acid bacteria research towards improvement of strains for use in food fermentation will benefit both the consumer and the producer. Protein Eng, 1999 Aug, 12(8), 681 - 6 Deletion of the four C-terminal residues of PepC converts an aminopeptidase into an oligopeptidase; Mata L et al.; The aminopeptidase PepC is a cysteine peptidase isolated from lactic acid bacteria . Its structural and enzymatic properties closely resembles those of the bleomycin hydrolases, a group of cytoplasmic enzymes isolated from eukaryotes . Previous biochemical and structural data have shown that the C-terminal end of PepC partially occupies the active site cleft . In this work the substrate specificity of PepC was engineered by deletion of the four C-terminal residues . The mutant PepCDelta432-435 cleaved peptide substrates as an oligopeptidase while the aminopeptidase specificity was totally abolished . The substrate size dependency indicated that PepCDelta432-435 possesses an extended binding site able to accommodate four residues of the substrate on both sides of the cleaved bond . The activity of PepCDelta432-435 towards tryptic fragments of casein revealed a preference for peptides with hydrophobic amino acids at positions P2 and P3 and for Gly, Asn and Gln at position P1 . PepCDelta432-435 was shown to be highly sensitive to the thiol peptidase inhibitors leupeptin or E64 which are inefficient towards the wild-type PepC . In conclusion, deletion of the four C-terminal residues in PepC produces a new enzyme with properties resembling those of an endopeptidase from the papain family. Crit Rev Food Sci Nutr, 1999 Jul, 39(4), 329 - 67 Changes in the components of dry-fermented sausages during ripening; Ordonez JA et al.; Several chemical changes occur during the ripening of dry-fermented sausages that determine the flavor and odor of the end product . The phenomena that take place during fermentation, that is, both acidification of the sugars by lactic acid bacteria and reduction of nitrates and nitrites to nitric oxide by micrococci have been known for several years . However, the chemical changes involved in this process, and, particularly, the agents responsible have not yet been established, although they have been attributed to changes in the majority components (proteins and lipids) and to the ingredients added (spices and condiments) in the preparation of the original mixture . The typical flavor and odor of dry-fermented sausages cannot be attributed to volatile substances alone, but to a large number of volatile and nonvolatile compounds present in the product in suitable proportions . Microbial growth in the sausage together with activity of the meat endogenous enzymes are undoubtedly partially responsible for the development of a number of aromatic and sapid compounds . However, lipid autooxidation reactions are also an important source of these substances, and it is not yet known which of these processes is more important in sausage ripening . Much research has focused on the break up of triglycerides into free fatty acids, diglycerides, and monoglycerides during ripening and the progressive increase in the amounts of different carbonyl oxidation products . Carbonyl compounds probably play a significant role in determining the flavor because, in general, these have very low perception thresholds, in the ppm and ppb range . Similarly, the protein breakdown to yield peptides and amino acids has been studied extensively, the latter being substrates of several microbial and chemical reactions that generate many flavor compounds. Acta Med Croatica, 1999, 53(1), 23 - 8 Probiotics or microbes against microbes; Zivkovic R; The brief historical survey of the discovery of Lactic Acid Bacteria (LAB) is followed by an account of the studies of LAB, since 1965 by many researchers named probiotics or biotherapeutic agents . However, as their action also involves certain antibiotic characteristics, the term "biotherapeutic bacteria" appears to suit them best . The favorable clinical effect of many LAB on various pathologic states in humans, especially in children, has now been positively demonstrated . Clinical success achieved by particular LAB in different pathologic conditions is described, with special reference to the scientifically verified effects of LGG, which has also been used in Croatia for the manufacture of fermented dairy products since 1998. J Food Prot, 1999 Apr, 62(4), 418 - 25 Centralized packaging of retail meat cuts: a review; Tewari G et al.; Centralized packaging of retail meat cuts is growing more popular because of its economies and potential to maintain quality, enhance safety, and extend the shelf life of fresh meat . Requirements for optimizing shelf life of centrally prepared retail cuts for periods up to 15 weeks are slightly different from those needed to extend the shelf life of fresh, chilled meat . Chilled meat primarily deteriorate at the cut or uncut muscle surface . In long-term storage, primal cuts are placed in an atmosphere saturated with carbon dioxide and containing very low residual oxygen . These cuts are held at -1.5+/-0.5 degrees C . When the meat is removed, it is fabricated into retail or food service cuts . New fresh surfaces are created in the process, revitalizing the meat's appearance . After being prepared for retail display, the meat normally has four more days of shelf life . Depending on the meat species, shelf life is usually limited by development of undesirable organoleptic changes, usually defects in color, which are independent of microbial presence . The microbes consist of a lactic acid bacterial population that maximizes under storage conditions at about 10(8) CFU/cm2 well before shelf life ends . Circumstances are different with centralized distribution of retail-ready fresh meat . The wholesale storage period following initial packaging of the retail cuts is about 20 to 30 days . Prepared products must withstand retail display for up to 2 days without further manipulation of package contents . Retail packages are simply moved from their storage container (usually a unit or overwrap containing a modified atmosphere) to retail display, where desirable meat color develops upon exposure to air . Three gas atmospheres have some potential to satisfy storage needs for centralized distribution of retail-ready packages: 100% CO2, 100% N2, or 70% N2 + 30% CO2 . Shelf life is limited by undesirable changes in surfaces exposed at initial packaging, caused by growth of psychrotrophic bacteria . If 100% CO2 is used, these are all lactic acid bacteria (LAB) . Therefore, initial bacterial numbers on the meat and storage temperature become critical to success . The most attractive storage option is 100% CO2 used at - 1.5 +/-0.5 degrees C . This review presents the reason for that recommendation, along with basic concepts of meat chemistry, a discussion of modified atmosphere packaging, meat microbiology, and current results with simulated centralized packaging of retail-ready meats. Nahrung, 1999 Jun, 43(3), 159 - 64 Antihypertensive peptides derived from milk proteins; Yamamoto N et al.; This paper reviews the angiotensin I-converting enzyme inhibitory peptides originated from milk proteins . Focus was put on the peptides derived from milk casein by the action of some proteolytic enzymes and fermented products by lactic acid bacteria . Some of the angiotensin I-converting enzyme inhibitory peptides exhibit significant antihypertensive effects in spontaneously hypertensive rats . However, there were some antihypertensive peptides with low inhibitory activity of this enzyme . Key factors needed for the peptide to demonstrate the antihypertensive effects are discussed . Fermented milk, which has inhibitory activity of the enzyme, showed the reduction of blood pressure of hypertensive subjects . The possibility of the bioactive peptides for functional foods are also discussed. J Food Prot, 1999 Jun, 62(6), 619 - 24 Effects of antioxidants and gamma irradiation on the shelf life of beef patties; Lee JW et al.; To improve the storage safety of two types of ground beef patty popular in Korea (general beef patties and bulgogi patties), we added various antioxidants (200 ppm; including butylated hydroxyanisole, ascorbyl palmitate, alpha-tocopherol, and beta-carotene) to typical formulations of patties, cooked the patties to 70 degrees C, and irradiated them at a dose of 1.5 or 3 kGy . During 30 d of storage at 5 degrees C, the number of aerobic bacteria and lactic acid bacteria were determined using total aerobic plate count and phenyl ethyl alcohol-sucrose agar, respectively . The concentration of thiobarbituric acid was also determined in each type of patty . No colonies were observed in patties irradiated at 3 kGy regardless of which antioxidant was added . In control patties and patties with butylated hydroxyanisole that were irradiated at a dose of 1.5 kGy, growth of microorganisms appeared to be more rapid than in patties with natural antioxidants . The microbiological safety of nonirradiated patties could not be ensured for a period of 20 d . Lipid oxidation was retarded in both types of patty when an antioxidant was added . Ascorbyl palmitate had the strongest antioxidant effect among the natural antioxidants . However, butylated hydroxyanisole was more effective than ascorbyl palmitate when used in an equal amount. Int J Food Microbiol, 1999 Apr 1, 48(1), 11 - 20 Fermentation of low-salt miso as affected by supplementation with ethanol; Chiou RY et al.; Steam-cooked soybeans and rice koji were combined (1:1, w/w), mixed with 5% (w/w) NaCl and ground into a fine paste . Samples (30 g) were deposited in nylon/polyethylene plastic bags and supplemented with 10 ml of aqueous ethanol solutions to give concentrations of 0, 2.5, 5, 7.5, 10, 15, 20, and 25% ethanol . Mixtures were homogenized, sealed, and incubated at 28 degrees C for eight weeks . Mold populations were less than 3 log10 CFU/g in all miso products after four weeks of fermentation . Yeast populations increased to 6.1 log10 CFU/g in the control (0% added ethanol) during the first week of fermentation and remained stable throughout the eight-week fermentation period . Yeasts were not detected in products containing 5-25% ethanol . Populations of lactic acid bacteria (LAB) increased to 6 log10 CFU/g after one week of fermentation in products containing 0 and 2.5% ethanol . However, after eight weeks of fermentation, LAB populations in all products were less than 4 log10 CFU/g . Rapid decreases in pH occurred only in products supplemented with 0 or 2.5% ethanol . Percentages of soluble protein in miso products containing various ethanol concentrations during the eight-week fermentation period revealed that protease activity was still active or not greatly inhibited in products supplemented with less than 10% ethanol . In comparison, koji enzymes were comparatively less affected by ethanol than were populations of molds, yeasts, and LAB . Total soluble carbohydrate and glucose contents were higher in products supplemented with 5, 7.5 and 10% ethanol than in other products . Discoloration (browning) during fermentation occurred most rapidly in products supplemented with 5 or 7.5% ethanol . Sensory evaluation of the low-salt (5%) product supplemented with 7.5% ethanol and fermented for eight weeks revealed normal or enhanced flavor ratings compared to ratings for a commercial product. Eur J Clin Nutr, 1999 May, 53(5), 339 - 50 Lactic acid bacteria and the human gastrointestinal tract; Hove H et al.; OBJECTIVE: This review summarises the effects of lactic acid bacteria on lactose malabsorption, bacterial/viral or antibiotic associated diarrhoea, and describes the impact of lactic acid bacteria on cancer and the fermentative products in the colon . RESULTS: Eight studies (including 78 patients) demonstrated that lactase deficient subjects absorbed lactose in yogurt better than lactose in milk, while two studies (25 patients) did not support this . Two studies (22 patients) showed that unfermented acidophilus milk was absorbed better than milk, while six studies (68 patients) found no significant differences . Addition of lactose hydrolysing enzyme, lactase, to milk improved lactose malabsorption in seven studies (131 lactose malabsorbers), while one study (10 malabsorbers) demonstrated no improvement . Lactic acid bacteria alleviated travellers' diarrhoea in one study (94 individuals) while a study including 756 individuals was borderline statistically significant . One study (50 individuals) did not find an effect of lactic acid bacteria on travellers' diarrhoea . Six studies (404 infants) demonstrated a significant effect of lactic acid bacteria on infant diarrhoea, while one study (40 infants) did not . Lactic acid bacteria moderated antibiotic associated diarrhoea in three studies (66 individuals), while two studies (117 individuals) were insignificant . CONCLUSIONS: Lactase deficient subjects benefit from a better lactose absorption after ingestion of yoghurt compared with milk and from milk added lactase, whereas ingestion of unfermented acidophilus milk does not seem to improve lactose absorption . The majority of studies support that lactic acid bacteria alleviate bacterial/viral induced diarrhoea, especially in infants, while the effect on antibiotic associated diarrhoea is less clear . Experimental studies indicate an effect of lactic bacteria on human cell cancer lines, but clinical evidence is lacking . A 'stabilising' effect of lactic acid bacteria on the colonic flora has not been documented. Int J Food Microbiol, 1999 Mar 1, 47(1-2), 33 - 42 Inhibition of Listeria monocytogenes by Carnobacterium spp . strains in a simulated cold smoked fish system stored at 4 degrees C; Duffes F et al.; Preservation of smoked salmon from bacterial spoilage, and especially from Listeria monocytogenes by bacteriocin producers is a promising challenge . Over a hundred lactic acid bacteria, isolated from commercial vacuum packaged cold smoked salmon, were screened for their antagonistic activity against L . innocua . Twenty-two strains were able to produce bacteriocin-like proteinaceous substances . These strains were characterized physiologically and biochemically as Carnobacterium strains . Three different groups were determined by pulsed-field gel electrophoresis after Sma I and Apa I DNA digestion . Peptidoglycan hydrolases patterns completed the characterization of these strains . All were confirmed as being Carnobacterium piscicola . Growth and bacteriocin production of three strains of each group and two well known bacteriocin producers (C . divergens V41 and C . piscicola V1) were tested in a simulated cold smoked fish system at 4 degrees C . These strains were able to reach 10(8) cfu ml(-1) in 21 days and to produce as much bacteriocin activities in the cold smoked fish system as in the rich media . Carnobacterium divergens V41 and C . piscicola V1 were the most effective strains in co-culture experiments, inhibiting L . monocytogenes as early as day 4, whereas C . piscicola SF668 inhibiting effect was observed at day 13 . The potential for using such biopreservation treatments on whole smoked salmon is discussed. Lett Appl Microbiol, 1999 May, 28(5), 368 - 72 Presence of peptidase activities in different varieties of cheese; Gatti M et al.; Lactic acid bacteria (LAB) counts, PepX activity towards H-Phe-Pro-beta NA, and aminopeptidase activity towards H-Arg-beta NA . HCl, H-Lys-beta NA, H-Leu-beta NA, H-Pro-beta NA, H-Glu-beta NA derivatives have been evaluated in 32 commercial samples of cheese, one processed cheese, and one yoghurt . The presence of intracellular exo-peptidase activities in cheese extracts free from bacterial cells was detected, even after 1 year of ripening . An inverse ratio between the presence of viable lactic microflora and peptidase activity in the cheese extracts was observed . The importance of LAB starter exo-peptidases in the degradation of casein oligopeptides, and the key role of autolysis in the release of peptidases in the cheese, are discussed. J Dairy Sci, 1999 May, 82(5), 851 - 62 Effect of high pressure homogenization on microbial and chemico-physical characteristics of goat cheeses; Guerzoni ME et al.; The objective of this work was to compare goat cheeses obtained from milk previously subjected to high pressure homogenization (1000 bar) with those produced from untreated milk and milk subjected to sanitization (61 degrees C; 20 min) or to pasteurization (72 degrees C; 15 s) . The pressure homogenization treatment had both direct and indirect effects on cheese characteristics and their evolution during ripening . The direct effects were principally linked to the change in water-binding capacity of proteins as shown also by the lower whey separation . The indirect effects involved the microbial growth or activity and, particularly, modifications of the population of the lactic acid bacteria that occurred naturally and their evolution as well as a more precocious yeast and mold growth with a consequent rapid rise in pH . Although the treatment proved to enhance both proteolytic and lipolytic activities according to Fourier transform infrared analysis, which was used to obtain a rapid description of the biochemical modification, the cheeses homogenized under high pressure showed relevant qualitative differences only in the zone corresponding to amide I and amide II signals of proteins . The activation of these enzymatic activities observed in the homogenized cheeses could be either an indirect effect of the shift of the microbial population or a consequence of a different exposure of the macromolecules to the enzymatic activity . Scanning electron microscopy analyses of goat cheeses revealed that cheeses homogenized under high pressure had a more homogeneous microstructure than did the others. Hum Antibodies, 1999, 9(1), 37 - 45 Human monoclonal IgM DJ binds to ssDNA and human commensal bacteria; Dimitrijevic LA et al.; In this study we tried to elucidate further the crossreactivity pattern and binding characteristics of human monoclonal IgM DJ which is an anti-DNA antibody and possesses Y7 natural idiotope . Isolated IgM DJ and its enzymatically obtained fragments Fab' and (Fab')2 were tested for binding to more than 26 antigens and nine bacteria in indirect ELISA . Inhibition of binding studies and examination of the stability of antigen-antibody complexes were also done in ELISA assay . IgM DJ bound to single stranded DNA and human lactic acid bacteria, such as L . acidophyllus, B . bifidum and L . plantarum . This binding was shown to be mediated through IgM DJ Fab' fragment . High avidity and low affinity of interactions was estimated from the binding curves of Fab', (Fab')2 fragments and whole IgM . The common epitopic motif on both antigens were negatively charged phosphodiester moieties . Complexes formed with ssDNA and B . bifidum were resistant to washing with high salt . This suggested that electrostatic attraction was not a strong component of the binding . A novel pattern of natural autoantibody reactivity in a human system related to cross-reactivity with DNA and LAB is described . Possible involvement of LAB in induction of natural anti-DNA antibodies is discussed. J Biotechnol, 1999 Feb 19, 68(2-3), 171 - 8 Safety of industrial lactic acid bacteria; Adams MR; Lactic acid bacteria (LAB) are ubiquitous in fermented and non-fermented foods and are common components of the human commensal microflora . This long history of human exposure and consumption has led to the reasonable conclusion that they are generally safe . Recent attention has also focused on their possible role as probiotic bacteria, promoting beneficial health effects . There have, however, been a number of reports of human infections caused by LAB and these are reviewed . In most cases, the source of the infection was the commensal LAB flora rather than ingested bacteria and the patient had some underlying disease or predisposing condition . Even as opportunistic pathogens, the LAB, with the notable exception of the enterococci, are much less successful than a number of other members of the commensal microflora . The use of new strains for probiotic use is likely to require more detailed evidence for their safety, particularly if the strains have been genetically modified or have been derived from animals . Procedures that have been proposed for assessing the safety of new strains are described. Syst Appl Microbiol, 1999 Feb, 22(1), 87 - 96 A polyphasic study on the taxonomic position of industrial sour dough yeasts; Mantynen VH et al.; The sour dough bread making process is extensively used to produce wholesome palatable rye bread . The process is traditionally done using a back-slopping procedure . Traditional sour doughs in Finland comprise of lactic acid bacteria and yeasts . The yeasts present in these doughs have been enriched in the doughs due to their metabolic activities, e.g . acid tolerance . We characterized the yeasts in five major sour bread bakeries in Finland . We found that most of the commercial sour doughs contained yeasts which were similar to Candida milleri on the basis of 18S rDNA and EF-3 PCR-RFLP patterns and metabolic activities . Some of the bakery yeasts exhibited extensive karyotype polymorphism . The minimum growth temperature was 8 degrees C for C . milleri and also for most of sour dough yeasts. Crit Rev Food Sci Nutr, 1999 Jan, 39(1), 13 - 126 Probiotic spectra of lactic acid bacteria (LAB); Naidu AS et al.; Lactic acid bacteria (LAB) and their probio-active cellular substances exert many beneficial effects in the gastrointestinal tract . LAB prevent adherence, establishment, and replication of several enteric mucosal pathogens through several antimicrobial mechanisms . LAB also release various enzymes into the intestinal lumen and exert potential synergistic effects on digestion and alleviate symptoms of intestinal malabsoption . Consumption of LAB fermented dairy products with LAB may elicit antitumor effects . These effects are attributed to the inhibition of mutagenic activity; decrease in several enzymes implicated in the generation of carcinogens, mutagens, or tumor-promoting agents; suppression of tumors; and the epidemiology correlating dietary regimes and cancer . Specific cellular components in LAB strains seem to induce strong adjuvant effects including modulation of cell-mediated immune responses, activation of reticuloendothelial system, augmentation of cytokine pathways and regulation of interleukins, and tumor necrosis factors . Oral administration of LAB is well tolerated and proven to be safe in 143 human clinical trials and no adverse effects were reported in any of the total 7,526 subjects studied during 1961-1998 . In an effort to decrease the reliance on synthetic antimicrobials and control the emerging immunocompromised host population, the time has come to carefully explore the prophylactic and therapeutic applications of probiotic LAB. Appl Microbiol Biotechnol, 1998 Nov, 50(5), 511 - 9 Mechanistic action of pediocin and nisin: recent progress and unresolved questions; Montville TJ et al.; Nisin and pediocin PA-1 are examples of bacteriocins from lactic acid bacteria (LAB) that have found practical applications as food preservatives . Like other natural antimicrobial peptides, LAB bacteriocins act primarily at the cytoplasmic membranes of susceptible microorganisms . Studies with in vivo as well as in vitro membrane systems are directed toward understanding how bacteriocins interact with membranes so as to provide a mechanistic basis for their rational applications . The dissipation of proton motive force was identified early on as the common mechanism for the lethal activity of LAB bacteriocin . Models for nisin/membrane interactions propose that the peptide forms poration complexes in the membrane through a multistep process of binding, insertion, and pore formation . This review focuses on the current knowledge of: (1) the mechanistic action of nisin and pediocin-like bacteriocins, (2) the requirement for a cell factor such as a membrane protein, (3) the influence of membrane potential, pH, and lipid composition on the specificity and efficacy of bacteriocins, and (4) the roles of specific amino acids and structural domains of the bacteriocins in their action. Pediatr Nurs, 1998 Jul-Aug, 24(4), 317 - 23 Rotavirus: an overview--from discovery to vaccine; Harrison MS; Rotavirus is the single most important cause of both nosocomially-acquired and severe, dehydrating diarrhea . It occurs with equal frequency throughout the world, regardless of the level of sanitation . After primary infection, mild or asymptomatic reinfection is common . Current management involves the use of oral rehydration therapy and early feeding of an age-appropriate diet . Cereal-based oral rehydration solutions, lactic acid bacteria, and oral immunoglobulins may play a role in future treatment . A rhesus rotavirus, quadravalent oral vaccine, currently being considered for licensure, may be given concurrently with other routine infant immunizations and has an efficacy rate of 80% against severe disease . Pediatric nurses should be aware of these recent advances in treatment and prevention, which should significantly reduce the impact of rotavirus in the near future. Minerva Pediatr, 1998 May, 50(5), 163 - 73 {Probiotics in childhood}; D'Angelo G et al.; The Probiotics (Lactic acid bacteria) represent a nutritional live microbial supplement that positively affects host by enhancing the microbial balance . A survey is made of the most relevant studies concerning the use of probiotics in the prevention and treatment of infantile acute diarrhoea (by rotavirus or other agents), pseudomembranous colitis, hospital-acquired and antibiotic-associated diarrhoeas . Although the probiotics mechanism of action is not yet completely understood, it has been hypothesized that they exert an inhibitory effect on the intestinal inflammation by immune response modulation . Due to this property, the use of probiotics has therefore been suggested in other severe diseases such as chronic inflammatory bowel diseases, rheumatoid arthritis, food allergy, atopic dermatitis and as immunoadjuvant for oral vaccines. Lett Appl Microbiol, 1998 Nov, 27(5), 270 - 4 Recovery of total microbial RNA from lactic acid fermented foods with a high starch content; Ampe F et al.; An optimized procedure for the recovery of RNA from micro-organisms involved in the fermentation of starchy foods (mainly hard-to-lyse lactic acid bacteria) is reported . Critical steps for the extraction were: cell recovery by differential centrifugation; cell wall digestion with both mutanolysin and lysozyme; and CTAB treatment for the elimination of starch . Digestion of starch with alpha-amylase did not improve extraction yields . The method yielded high amounts of RNA from pozol, a Mexican maize-based fermented food, and was found to extract total RNA efficiently from all the micro-organisms potentially present in these ecosystems . Both rRNA and mRNA recovered were of high quality and suitable for hybridization studies. J Food Prot, 1998 Sep, 61(9), 1210 - 2 Interactions between pairs of bacteriocins from lactic bacteria; Mulet-Powell N et al.; Activity of pairs of crude extracts of lactic acid bacteria (LAB) containing different bacteriocins (nisin, pediocin AcH, lacticin 481, lactacin F, and lactacin B) was measured against 10 different indicator strains . Experiments were carried out both in liquid and on solid media . Both synergisms and antagonisms were observed . Lacticin 481 produced mainly antagonistic effects whereas pediocin AcH produced mainly synergistic effects . The use of more than one LAB bacteriocin as a combination biopreservative might be envisaged. Acta Paediatr, 1998 Sep, 87(9), 986 - 90 Community-based survey of paediatric diarrhoeal morbidity and home treatment practices in Finland; Rautanen T et al.; To determine total diarrhoeal morbidity and current home case management practices, a recall study was conducted among 345 mothers whose 406 children under 5 y of age had had diarrhoea in the past 4 months . The seasonally adjusted annual diarrhoea incidence rate was 0.48 episodes/child/y . For home treatment, increased amounts of fluid were given in 93% and oral rehydration solution (ORS) in 37% of cases . However, when given, ORS was diluted with other fluids in 41% of cases . More than half (55%) of the children received increased or normal amounts of food during the diarrhoeal episode, but 7% of the children were kept fasting for at least 1 d . Use of antidiarrhoeal drugs was minimal (0.7%), but products containing lactic acid bacteria were given in 44% of cases . Case management practice in cases of diarrhoea at home have much improved during the last 20 y, but are still not optimal. Int J Food Microbiol, 1998 Jul 21, 42(3), 213 - 7 Effect of nitrate and nitrite curing salts on microbial changes and sensory quality of non-fermented sausages; Sanz Y et al.; The effects of nitrate and nitrite curing salts on microbial changes and sensory quality of non-fermented sausages of small diameter were investigated . During pre-ripening (day 5), levels of lactic acid bacteria and yeasts were slightly higher in nitrite-made sausages than in those made with nitrate . In contrast, nitrite discouraged the growth of psychrotrophs as occurs in fermented sausages . By the end of ripening (day 26), levels of microorganisms were similar in both batches of sausages except for psychrotrophs being higher in those made with nitrite . Nitrate-made sausages showed higher aroma and taste intensity. Appl Environ Microbiol, 1998 Sep, 64(9), 3275 - 81 Comparative studies of class IIa bacteriocins of lactic acid bacteria; Eijsink VG et al.; Four class IIa bacteriocins (pediocin PA-1, enterocin A, sakacin P, and curvacin A) were purified to homogeneity and tested for activity toward a variety of indicator strains . Pediocin PA-1 and enterocin A inhibited more strains and had generally lower MICs than sakacin P and curvacin A . The antagonistic activity of pediocin-PA1 and enterocin A was much more sensitive to reduction of disulfide bonds than the antagonistic activity of sakacin P and curvacin A, suggesting that an extra disulfide bond that is present in the former two may contribute to their high levels of activity . The food pathogen Listeria monocytogenes was among the most sensitive indicator strains for all four bacteriocins . Enterocin A was most effective in inhibiting Listeria, having MICs in the range of 0.1 to 1 ng/ml . Sakacin P had the interesting property of being very active toward Listeria but not having concomitant high levels of activity toward lactic acid bacteria . Strains producing class IIa bacteriocins displayed various degrees of resistance toward noncognate class IIa bacteriocins; for the sakacin P producer, it was shown that this resistance is correlated with the expression of immunity genes . It is hypothesized that variation in the presence and/or expression of such immunity genes accounts in part for the remarkably large variation in bacteriocin sensitivity displayed by lactic acid bacteria. Biosci Biotechnol Biochem, 1998 Jul, 62(7), 1445 - 7 Application of two-dimensional mapping for an analysis of galactosyllactoses in yogurt; Saito T et al.; A two-dimensional mapping analysis was performed by HPLC for 4 kinds of standard galactosyllactoses (GLs, trisaccharide) which were assumed to be produced from lactose (galactopyranosyl beta 1-->4 glucopyranose) in yogurt during the fermentation of lactic acid bacteria . After the pyridylamination of GLs, they were analyzed by HPLC in the reverse-phase (RP) and anion-exchange (AE) modes . The retention times of each peak obtained were converted to glucose units (GU) in RP mode for the pyridylaminated isomaltooligosaccharides (G1-3) and to relative retention time (RRT) in AE mode against pyridylaminated-isomaltotriose, and then the address data {GU, RRT} were plotted on a graph . This two-dimensional mapping method was found useful for a rapid qualitative evaluation of the chemical structure of trisaccharides formed in yogurt. J Food Prot, 1998 May, 61(5), 591 - 600 Shelf-life of prepeeled potato cultivated, stored, and processed by various methods; Ahvenainen RT et al.; The effects of cultivation conditions, winter storage, peeling method, browning prevention chemicals replacing sodium bisulfite, and packing methods on the sensory, nutritional and microbiological quality of pre-peeled potato were examined . Two different cultivation lots of the potato variety Van Gogh were used . Cultivation and harvesting conditions and peeling method were the most important facts reducing the sensory quality, especially the appearance, of prepeeled and sliced potatoes . Cooking and baking of potatoes decreased the appearance defects detected in raw potatoes . The levels of vitamin C in packaged samples decreased during winter storage . Cooking for 10 min and keeping potatoes at 60 degrees C for 1 h after cooking also decreased the content of vitamin C . In potato samples immediately after treatments aerobic bacteria were present at levels of 400 to 2,950 CFU/g and lactic acid bacteria at levels of 8 to 16 CFU/g . The number of aerobic bacteria did not increase during storage, and the number of lactic acid bacteria increased at the most to 90 CFU/g . Peeling, washing and packaging methods, cultivation conditions, and winter storage did not have important effects on the number of microbes present. Nippon Geka Gakkai Zasshi, 1998 Jun, 99(6), 362 - 7 {An overview on chemoprevention of colorectal cancer}; Narisawa T; Chemoprevention of colorectal cancer has been extensively investigated in animal models and in high-risk human populations with inherited or acquired genetic changes, using anticarcinogenic agents from natural and synthetic sources . To understand active agents using a short-term assay, reliable intermediate biomarkers other than cancer are required as end-points . Endoscopically detectable aberrant crypt foci and adenomas are useful biomarkers in human intervention trials . Indomethacin and other nonsteroidal antiinflammatory drugs (NSAIDs) inhibit carcinogen-induced colon cancer development in rats . It was reported that a number of colorectal polyps in familial adenomatous polyposis patients regress after several months of sulindac treatment . Epidemiological studies have shown that regular use of aspirin and other NSAIDs reduces the risk of colorectal cancers and adenomas . In addition, ursodeoxycholic acid and alpha-difluoromethylornithine, a selective inhibitor of ornithine decarboxylase, have been employed in human intervention trials . Vegetable antioxidants such as carotenoids and flavonoids, omega-3 fatty acids, lactic acid bacteria, and indigestible oligosaccharides may also be promising chemopreventive agents. J Food Prot, 1998 Jul, 61(7), 885 - 90 Use and removal of sulfite by conversion to sulfate in the preservation of salt-free cucumbers; Mcfeeters RF; Cucumbers (Cucumis sativus) were microbiologically stable in cover liquid containing 300 ppm of added sodium metabisulfite (calculated as SO2), 20 mM calcium chloride, and HCl to give an equilibrated pH of 3.5 . The sulfur(IV) oxoanions could be easily removed to nondetectable levels (< 3 ppm) by addition of an equimolar amount of hydrogen peroxide, which rapidly converted S(IV) primarily to sulfate ions . When sulfur(IV) oxoanions were removed from stored fresh cucumbers, 85% of the added metabisulfite could be accounted for by formation of sulfate ions . If cucumbers were heated before addition and removal of sulfur(IV) oxoanions, 96% of that added was converted to sulfate by hydrogen peroxide . Preservation of cucumbers in this way does not require fermentation, so addition of salt is not needed to select for lactic acid bacteria. J Dairy Sci, 1998 May, 81(5), 1214 - 21 Influence of salt on the quality of reduced fat cheddar cheese; Mistry VV et al.; Cream was homogenized in a two-stage homogenizer (17.25 MPa in the first stage and 3.43 MPa in the second stage); blended with skim milk to produce milk containing 1.25% fat, which was pasteurized (63 degrees C for 30 min); and then manufactured into reduced fat Cheddar cheese . After milling, the curd was divided into three equal portions of 13 kg each . Three salting rates, 2.3, 3.8, and 5%, yielded cheeses with 1.3, 1.7, and 2.0% salt and 2.7, 3.7, and 4.5% salt in the moisture phase . Cheese moisture contents ranged from 45% (2.0% salt) to 47.7% (1.3% salt), and fat contents ranged from 14.6 to 15.1% . In the texture profile analysis, the hardness and fracturability of the cheeses increased as the salt content increased . Both parameters decreased during ripening, but cheeses with 4.5% salt in the moisture phase remained the hardest . Cheeses with the most salt had the least desirable body characteristics, but there were no differences in flavor . Intensity of bitterness was lowered as the amount of salt in cheese increased . During ripening, the number of lactic acid bacteria decreased more slowly in cheese with 2.7% salt in the moisture phase than in those with 3.7 or 4.5% salt in the moisture phase . As the salt content increased, proteolysis and the general rate of ripening decreased . Degradation of alpha s-casein was reduced by higher percentages of salt, but no differences were found in the degradation of beta-casein. J Cell Biochem Suppl, 1997, 27, 52 - 8 Influence of tea catechins on the digestive tract; Hara Y; Tea catechins undergo various metabolic changes after they are taken orally, though a large percentage are excreted intact with the feces . Epidemiological studies suggest a protective effect of tea against various human cancers, including colon and rectum . The bactericidal property of tea catechins plays several roles in the digestive tract . In the small intestine, catechins inhibit alpha-amylase activity, and a certain amount is absorbed into the portal vein . Although catechins are bactericidal, they do not affect lactic acid bacteria . Including tea catechins in the diet for several weeks decreases putrefactive products and increases organic acids by lowering pH . These changes were achieved in tube-fed patients by administering 100 mg of tea catechins (equivalent to a cup of green tea) three times daily with meals for 3 weeks . When catechin administration ceased, the effects reversed after 1 week . Catechins should be considered further in colon carcinogenesis studies. J Dairy Sci, 1998 Feb, 81(2), 444 - 53 Proteolysis during ensilage of forages varying in soluble sugar content; Davies DR et al.; The effect of contrasting concentrations of water-soluble carbohydrates of herbage on silage fermentation and composition was examined using grass with high {250 g/kg of dry matter (DM)} concentrations of water-soluble carbohydrates and grass and clover with low (66 g/kg of DM) concentrations of water-soluble carbohydrates . Herbages were ensiled untreated, after inoculation with lactic acid bacteria, or after treatment with formic acid . Good quality silages were produced from herbage with high concentrations of water-soluble carbohydrates, regardless of treatment, and all pH values were below 3.7 after 90 d of ensilage . However, the silage formed from inoculated herbage had a significantly lower concentration of ammonia N and a significantly higher proportion of residual ribulose-1,5-bisphosphate carboxylase compared with the other two silages . Fast protein liquid chromatography (Pharmacia, Uppsala, Sweden) was used to measure ribulose-1,5-bisphosphate carboxylase, and measurement of true plant protein fractions in herbage and silage showed benefits over traditional measurements such as the measurement of N and ammonia N . Herbages with low concentrations of water-soluble carbohydrates produced inferior quality silages that had lower ribulose-1,5-bisphosphate carboxylase contents and higher ammonia N contents, regardless of treatment; few significant differences were observed among treatments . Under good ensiling conditions, when available water-soluble carbohydrate is adequate, the use of inoculants can improve fermentation characteristics and increase the ribulose-1,5-bisphosphate carboxylase content of silages . However, when the herbage has low concentrations of water-soluble carbohydrates, even in inoculated herbages, lactic acid bacteria may follow a heterofermentative pathway instead of a homofermentative pathway, which can result in a decrease in silage quality and a reduction in intact ribulose-1,5-bisphosphate carboxylase. Plant Foods Hum Nutr, 1997, 51(1), 43 - 51 Microbial and biochemical changes occurring during production of masvusvu and mangisi, traditional Zimbabwean beverages; Zvauya R et al.; Biochemical and microbiological changes that occur during production of masvusvu and mangisi, both traditional Zimbabwean beverages made from malted finger millet flour were investigated in this study . During cooking to produce masvusvu, amylase was active within the first 20 minutes but its activity decreased drastically at temperatures of above 60 C . Free reducing sugars increased from 3.8 to 308.1 mg/ml . During fermentation to produce mangisi, total aerobic mesophilic bacteria, lactic acid bacteria and yeast and molds increased with fermentation time . Total titratable acidity increased from 0.13 to 0.67 percent, lactic acid from 0.51 to 4.10g/l and pH decreased from 6.10 to 3.98. Int J Food Microbiol, 1997 Aug 19, 38(1), 65 - 70 A computerised system for the identification of lactic acid bacteria; Wijtzes T et al.; A generic computerised system for the identification of bacteria was developed . The system is equipped with a key to the identification of lactic acid bacteria . The identification is carried out in two steps . The first step distinguishes groups of bacteria by following a decision tree with general identification tests . The second step in the identification is the distinction of species within a group on the basis of biochemical fermentation patterns . During grouping, probabilities for test failure are used . These probabilities can be used for assessing the quality of a given test answer . The probabilities are also used to select the most probable test answer in cases where the test result is inconclusive . The probabilities of test failure were determined by a group of experts and a group of potential users of the identification system . During species identification, similarity indices are calculated for all bacteria in a group . The described identification system has the ability to "learn" from different sessions in the species identification step, improving both identification speed and accuracy . Because of the versatile way in which the system is set up, it can very easily be expanded with identification keys to other organisms. Postepy Hig Med Dosw, 1997, 51(6), 605 - 19 {The significance of lactic acid bacteria in treatment and prophylaxis of digestive tract disorders}; Strus M; Probiotic bacteria are used to treat disturbed intestinal microflora and increased gut permeability which are characteristic to many intestinal disorders . Examples include children with acute rotavirus diarrhoea, subjects with food allergy, subjects with colonic disorders and patients undergoing pelvic radiotherapy and sometimes changes associated with colon cancer development . In all such disease states altered intestinal microflora, impaired gut barrier and different types of intestinal inflammation are present . Successful probiotic bacteria are able to survive gastric conditions and colonise the intestine, at least temporarily, by adhering to the intestinal epithelium . Already existing preparations containing viable lactic bacteria of human origin appear to have value in restoring normal microbial functions and alleviating symptoms in some patients with gastrointestinal infection and other conditions . Current scientifically based research efforts world-wide are now focusing on the development of high quality products containing microorganisms preselected for specific probiotic characteristics. Z Ernahrungswiss, 1997 Dec, 36(4), 375 - 93 {Lactose intolerance and consumption of milk and milk products}; Sieber R et al.; The disaccharide lactose is present as a natural component of foods only in milk and dairy products . In the gastrointestinal tract, lactose is hydrolysed by the enzyme beta-galactosidase (lactase) into glucose and galactose . These components are absorbed . With the exception of the caucasian race, the lactase activity decreases in most people at an age of 4 to 6 years . Lactose intake can cause symptoms of bloating, flatulence, abdominal pain, and diarrhea due to the lactose reaching the large intestine . This phenomenon is called lactose intolerance . It is generally recommended to those persons that they refrain from the consumption of milk and dairy products . However, most lactose intolerant people are able to digest small amounts of milk . They can also consume cheese that contains no (hard and semi-hard) or only small amounts of lactose (present in only 10% of soft cheeses) . These products are very important sources of calcium . Compared to milk, the lactose content of yogurt is usually lower by about one third . Studies during the last 10 years have shown that in spite of its lactose content yogurt is very well tolerated by lactose intolerant persons . This advantage is ascribed to the presence of living lactic acid bacteria in fermented dairy products which survive passage through the stomach and also to the lactase present in these products. Arch Tierernahr, 1997, 50(2), 187 - 200 {Fermentation process during the ensiling of green forage low in nitrate . 2 . Fermentation process after supplementation of nitrate, nitrite, lactic acid bacteria and formic acid}; Kaiser E et al.; The effect of adding nitrate and nitrite (0.05% and 0.01% N in DM) of two inoculants or formic acid on the ensiling of orchardgrass and a grass-legumes-mixture, both low in nitrate, was proved in two experiments during ensiling starting in an early stage of fermentation silages without additives contained butyric acid, with increasing amounts up to 180 day of storage period . Silages with added nitrate or nitrite (0.1% N in DM) contained no butyric acid despite of a delay in the formation of lactic acid Nitrite was more effective as nitrate (both 0.05% N in DM) to suppress butyric acid fermentation . However, both additives, nitrite and nitrate, increased the lactic acid fermentation . Interpreting this facts it was hypothesized that the clostridia was inhibited by nitrate and nitrite . Addition of inoculants improved the formation of lactic acid, and decreased pH-value in comparison to control silages . The formation of butyric acid was limited, but not suppressed . The effect of inoculants differed in the intensity of fermentation and the formation of by-products of lactic acid fermentation . The effect of formic acid was not sure. Crit Rev Biotechnol, 1997, 17(3), 209 - 25 Antifungal attributes of lactic acid bacteria--a review; Batish VK et al.; Molds constitute a very important contaminating flora of dairy products . Contamination with undesirable molds has been a serious and frequently disturbing problem in the dairy industry that results in huge losses due to spoilage of cheese and other fermented foods incriminated by a variety of mycoflora such as Aspergillus, Penicillium, Fusarium, Rhizopus, and Mucor . The considerable drop in pH caused by the growth of lactic acid bacteria (LAB) in fermented milk makes such foods a breeding ground for the highly opportunistic fungi to proliferate and thrive, spoiling the products and effecting cost and its commensurate accessories . The major antimicrobial substances isolated from the LAB are found effective against bacteria only and their inhibition toward the growth of contaminating bacteria has been explored in detail . However, studies on the fungistatic properties of LAB are relatively rare . This article reviews the investigative studies on the antifungal aspects of different lactic acid bacteria and the prospects of this exceptional trait as a potential food biopreservative. Arch Tierernahr, 1997, 50(1), 87 - 102 {Fermentation process during the ensiling of green forage low in nitrate . 1 . Fermentation process in untreated green forage}; Kaiser E et al.; The fermentation process of ensiling green forage, low in nitrate, was proved in 8 experiments with ryegrass, ochardgrass and grass-legumes mixture . It was demonstrated that also in easily fermentable green forage the absence of nitrate promote the occurrence of butyric acid simultaneously with the lactic acid fermentation even at an early stage of fermentation . It is supposed that the lack of nitrate as a natural inhibitor of clostridia leads to early formation of butyric acid . The evolution of clostridia in the beginning of the fermentation process was more rapid than expected . It seems that easily soluble carbohydrates are the substrates of butyric acid formation . That is why in green forage, low on nitrate, clostridia act as food competitors for lactic acid bacteria . Amino acids were not degraded in the early stage of fermentation . In spite of the high content of butyric acid the amount of ammonia was low . Apart from n-butyric acid volatile fatty acids > or = C4 did not occur . The lactic acid formation reached only a restricted extent, also in green forage with a high content of sucrose . It was assumed that there are differences in ensilability of carbohydrate fractions between forage plants. Lett Appl Microbiol, 1997 Jul, 25(1), 73 - 4 Research note: unsuitability of the MRS medium for the screening of hydrogen peroxide-producing lactic acid bacteria; Rodriguez JM et al.; The effect of MRS broth on the stability of hydrogen peroxide (H2O2) has been studied . Known concentrations (1-100 micrograms ml-1) of H2O2 were prepared in distilled water, phosphate buffer (pH 7.0) and MRS broth (pH 6.2 and 3.9) . H2O2 was very stable in aqueous and buffer solutions but it was rapidly degraded in MRS broth (pH 3.9) . The presence of H2O2 in MRS broth (pH 6.2) could not be detected. Trends Biotechnol, 1997 Jul, 15(7), 270 - 4 Probiotic properties of lactic-acid bacteria: plenty of scope for fundamental R & D; Tannock GW; Probiotic products are marketed widely throughout the world . This is especially true of yogurts that contain strains of lactic-acid bacteria of intestinal origin . Consumption of these products is aimed at promoting the wellbeing of the consumer by impacting on the collection of microorganisms that normally inhabit the intestinal tract . The development of scientifically valid probiotics requires more detailed knowledge of this intestinal microflora than is currently available. Int J Food Microbiol, 1997 Apr 29, 36(1), 31 - 8 Determination of ready-to-eat vegetable salad shelf-life; Garcia-Gimeno RM et al.; The shelf-life of ready-to-eat vegetable salads established by manufacturers is usually 7-14 days depending on the type of vegetable, and is determined by loss in organoleptic qualities . A more objective method to predict shelf-life and spoilage would be desirable . The present study monitored the evolution of spoilage organisms in a mixed salad of red cabbage, lettuce and carrot stored at 4 degrees C, 10 degrees C and 15 degrees C . Changes in carbon dioxide and oxygen concentrations and pH were also monitored . Predictive modelling was used to established a theoretical shelf-life time as a function of temperature . Lactic acid bacteria at levels of 10(6) cfu/g appeared to be related to both spoilage and theoretically-predicted shelf-life values. Lett Appl Microbiol, 1997 Apr, 24(4), 265 - 8 Comparison of aerobic and anaerobic methods for the microbiological monitoring of chilled packaged meat during storage; Bell RG et al.; Aerobic and anaerobic plate counts were compared for routine monitoring of the microflora, dominated by lactic acid bacteria, developing on vacuum- and carbon dioxide-packaged raw meat during chilled storage . No statistical differences were observed between aerobic and anaerobic enumerations, made on plate count and blood agar plates, of the microflora developing on beef striploins packaged under vacuum or carbon dioxide during 14 weeks' storage at 0 degree C . With both techniques the spoilage microflora development differed between the two packaging regimes . The results indicate that there is no necessity for aerobic plate counts to be replaced by anaerobic plate counts in the routine microbiological examination of the spoilage microflora developing on chilled meats packaged under anoxic modified atmospheres. Trends Biotechnol, 1997 Apr, 15(4), 135 - 40 Controlled overproduction of proteins by lactic acid bacteria; Kuipers OP et al.; Lactic acid bacteria are widely used in industrial food fermentations, contributing to flavour, texture and preservation of the fermented products . Here we describe recent advances in the development of controlled gene expression systems, which allow the regulated overproduction of any desirable protein by lactic acid bacteria . Some systems benefit from the fact that the expression vectors, marker genes and inducing factors can be used directly in food applications since they are all derived from food-grade lactic acid bacteria . These systems have also been employed for the development of autolytic bacteria, suitable for various industrial applications. Biopolymers, 1997, 43(2), 129 - 34 Antihypertensive peptides derived from food proteins; Yamamoto N; This paper reviews the angiotensin I converting enzyme inhibitory peptides originated from food material