Diversity Of Lactobacilli Research Articles

Molecular identification of Lactobacillus spp. associated with puba, a Brazilian fermented cassava food

Puba or carimã is a Brazilian staple food obtained by spontaneous submerged fermentation of cassava roots. A total of 116 lactobacilli and three cocci isolates from 20 commercial puba samples were recovered on de Man, Rogosa and Sharpe agar (MRS); they were characterized for their antagonistic activity against foodborne pathogens and identified taxonomically by classical and molecular methods. In all samples, lactic acid bacteria were recovered as the dominant microbiota (7.86 ± 0.41 log10 CFU/g). 16S–23S rRNA ARDRA pattern assigned 116 isolates to the Lactobacillus genus, represented by the species Lactobacillus fermentum (59 isolates), Lactobacillus delbrueckii (18 isolates), Lactobacillus casei (9 isolates), Lactobacillus reuteri (6 isolates), Lactobacillus brevis (3 isolates), Lactobacillus gasseri (2 isolates), Lactobacillus nagelii (1 isolate), and Lactobacillus plantarum group (18 isolates). recA gene-multiplex PCR analysis revealed that L. plantarum group isolates belonged to Lactobacillus plantarum (15 isolates) and Lactobacillus paraplantarum (3 isolates). Genomic diversity was investigated by molecular typing with rep (repetitive sequence)-based PCR using the primer ERIC2 (enterobacterial repetitive intergenic consensus). The Lactobacillus isolates exhibited genetic heterogeneity and species-specific fingerprint patterns. All the isolates showed antagonistic activity against the foodborne pathogenic bacteria tested. This antibacterial effect was attributed to acid production, except in the cases of three isolates that apparently produced bacteriocin-like inhibitory substances. This study provides the first insight into the genetic diversity of Lactobacillus spp. of puba.

PCR-DGGE Analysis of Lactobacillus Diversity in Pit Muds of Different Cellar-aged Luzhou Laojiao Liquor

PCR-DGGE Analysis of Lactobacillus Diversity in Pit Muds of Different Cellar-aged Luzhou Laojiao Liquor

Soybean oligosaccharides alter colon short-chain fatty acid production and microbial population in vitro1

This study was conducted to the determine fermentation characteristics of soybean oligosaccharides (SBOS) in an in vitro system. Digesta collected from the colon of Huanjiang mini-pigs was used as inoculums, and SBOS (0.2 g per 10 mL fermentation broth) was used as substrate during the in vitro fermentation. The inoculum or inoculum + glucose (0.2 g) was used as negative or positive control, respectively. The slurry was fermented in an anaerobic chamber and gas production (GP) recording was taken after 48 h of incubation by referring to the moving scale on the plunger of the glass syringes, and then GP parameters, pH value, NH(3)-N content, short chain fatty acid (SCFA) levels, and microbial community in the fermentation broth were determined. For gas production parameters, pH, and fermentation product determination after 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36, 42, and 48 h of incubation, SBOS and glucose demonstrated similar responses compared to control including increase maximal gas production, decreased lag time, decreased pH, and accumulation of NH(3) and increased SCFA. The exception was rate of GP, which was higher (P < 0.05) for SBOS compared with glucose. Incubation with SBOS increased (P < 0.05) the microbial diversity and population of Bifidobacterium and Lactobacillus but decreased (P < 0.05) Escherichia and Streptococcus when compared with incubation with glucose. These findings suggested that the SBOS can improve the gut microbiota balance in colon and modulate its metabolism.

Differences in the vaginal lactobacilli of postmenopausal women and influence of rectal lactobacilli

ABSTRACTObjective This study was undertaken to characterize the Lactobacillus spp. dominating the vaginal microbiota of healthy postmenopausal women and to determine the possible influence of rectal lactobacilli.Methods Sixty postmenopausal women aged 55–65 years without clinical signs of vaginal infection not receiving hormone replacement therapy were included in this cross-sectional observational study. Based on Gram-stained smears, 30 women with a normal vaginal flora (Nugent score 0) were included in Group 1, and 30 women with an intermediate vaginal flora characterized by an absence of vaginal lactobacilli (Nugent score 4) were included in Group 2. Vaginal and rectal smears were taken for molecular lactobacillus profiling using polymerase chain reaction and denaturing gradient gel electrophoresis. Diversity of vaginal and rectal lactobacilli in postmenopausal women was the main outcome measure.Results We noticed a minor interference of gut lactic acid bacteria on a normal vaginal microflora dominated by lactobacilli strains of the L. delbrueckii group. When the normal vaginal microflora is disturbed by depletion of lactobacilli, the gut may function as a reservoir for lactobacilli of the L. casei group, which then colonize the vagina.Conclusion Our data indicate that rectal lactobacilli may affect the vaginal flora of postmenopausal women in the case of lactobacillary absence and help to maintain a normal vaginal microbiota.

Development of a Lactobacillus specific T-RFLP method to determine lactobacilli diversity in complex samples

Terminal restriction fragment length polymorphism (T-RFLP) analysis has been widely used for studying microbial communities. However, most T-RFLP assays use 16S rDNA as the target and are unable to accurately characterize a microbial subpopulation. In this study, we developed a novel T-RFLP protocol based on Lactobacillus hsp60 to rapidly characterize and compare lactobacilli composition. The theoretical terminal restriction fragment (TRF) profiles were calculated from 769 Lactobacillus hsp60 sequences from online databases. In silico digestion with restriction endonucleases AluI and TacI on hsp60 amplicons generated 83 distinct TRF patterns, of which, 70 were species specific. To validate the assay, five previously sequenced lactobacilli were cultured independently, mixed at known concentrations and subjected to analysis by T-RFLP. All five strains generated the predicted TRFs and a qualitative consistent relationship was revealed. We performed the T-RFLP protocol on fecal samples from mice fed 6 different diets (n=4). Principal component analysis and agglomerative hierarchical clustering revealed that the lactobacilli community was strongly connected to dietary supplementation. Our study demonstrates the potential for using Lactobacillus specific T-RFLP to characterize lactobacilli communities in complex samples.

Diversity of faecal oxalate-degrading bacteria in black and white South African study groups: insights into understanding the rarity of urolithiasis in the black group

To examine whether enhanced diversity or numbers of oxalate-degrading bacteria in the gastrointestinal tracts of black South Africans play a role in determining the rarity of urolithiasis in this group. Fresh faecal samples collected from healthy black and white South African male volunteers were analysed in terms of bacterial oxalate-degrading activity, bacterial diversity and relative species abundance. Varied bacterial populations prepared from samples from the low-risk black group showed a significantly higher level of oxalate degradation. Denaturing gradient gel electrophoresis analyses of Lactobacillus and related spp. and Bifidobacterium spp. 16S rRNA PCR products revealed a significantly higher faecal Lactobacillus diversity for the low-risk black group relative to the higher-risk white group. Quantitative real-time PCR experiments did not show any significant differences between the study groups for Lactobacillus and related spp.. However, Bifidobacterium spp. were present at a significantly higher relative abundance in the black group. Oxalobacter formigenes was present only at very low levels in either group. The low abundance of O.formigenes and increased diversity and abundance of oxalate-degrading Lactobacillus and Bifidobacterium spp. in the black South African population suggest that these strains rather than O.formigenes may protect this group against calcium oxalate kidney stone disease. The South African black population harbours a pool of potential oxalate-degrading lactic acid bacteria, which is more abundant and diverse than that of white South Africans. This may be useful in developing probiotics for calcium oxalate kidney stone prophylaxis.

Differences in faecal bacteria populations and faecal bacteria metabolism in healthy adults and celiac disease patients

Differences in the intestinal microbiota between children and adults with celiac disease (CD) have been reported; however, differences between healthy adults and adults with CD have not been clearly demonstrated. The aim of this study was to evaluate the differences in the intestinal microbiota between adults with CD and healthy individuals. Microbial communities in faecal samples were evaluated by PCR-denaturing gradient gel electrophoresis (DGGE) and gas-liquid chromatography of short chain fatty acids (SCFAs). The study group included 10 untreated CD patients, 11 treated CD patients and 11 healthy adults (in normal gluten diet and in GFD). UPGMA clustered the dominant microbial communities of healthy individuals together and separated them from the dominant microbial communities of the untreated CD patients. Most of the dominant microbial communities of the treated CD patients clustered together with those of healthy adults. The treated CD patients showed a reduction in the diversity of Lactobacillus and Bifidobacterium species. The presence of Bifidobacterium bifidum was significantly higher in untreated CD patients than healthy adults. There was a significant difference between untreated CD patients and healthy adults, as well as between treated CD patients and healthy adults, regarding acetic acid, propionic acid, butyric acid, and total SCFAs. healthy adults have a different faecal microbiota from that of untreated CD patients. A portion of the treated CD patients displayed a restored "normal" microbiota. The treated CD patients significantly reduce the Lactobacillus and Bifidobacterium diversity. Healthy adults have a different faecal SCFAs content from that of CD patients.

The effect of including Lactobacillus reuteri KUB-AC5 during post-hatch feeding on the growth and ileum microbiota of broiler chickens

The probiotic strain Lactobacillus reuteri KUB-AC5, which was originally isolated from chicken intestine, was fed to newborn broiler chicks for the first week post-hatch. The growth and ileum microbiota of the chickens were carefully monitored for 6 wk. The inclusion of 5 log cfu/g of feed statistically increased the BW gain in the first week compared with that of the control group, but this effect did not continue thereafter. Significant effects on host feed consumption and the feed-to-growth conversion ratio were not detected. The total amount and composition of ileum bacteria were investigated by quantitative PCR and pyrosequencing of the 16S rRNA gene (rDNA), respectively, and were compared between the control and the probiotic-treated groups. The amount of total bacterial 16S rDNA in ileum samples at d 42 was 5 times higher in the probiotic group than in the control, whereas no significant difference was observed at d 21. A composition analysis revealed the establishment of lactobacilli-enriched microbiota in the probiotic-treated chickens at d 42. At this point, the population level and species diversity of lactobacilli were significantly enhanced compared with those of the control group. In addition, Actinobacteria, mainly genera Corynebacterium and Dietzia, were also statistically higher in the probiotic group. However, Proteobacteria, including those of the family Campylobacterales and some other nonbeneficial bacterial groups, were decreased in the probiotic group at the growing stage. Therefore, with probiotic supplementation, it was demonstrated that Lactobacillus reuteri KUB-AC5 in the early post-hatching period had a delayed effect on ileum microbiota, which resulted in the enrichment of potentially beneficial lactobacilli and the suppression of Proteobacteria, including nonbeneficial bacterial groups.

Assessment of the Fecal Lactobacilli Population in Patients with Hepatitis B Virus-Related Decompensated Cirrhosis and Hepatitis B Cirrhosis Treated with Liver Transplant

This study aims to provide an overview of the diversity of intestinal Lactobacillus among Chinese patients with hepatitis B virus (HBV)-related decompensated cirrhosis and who received liver transplant for hepatitis B cirrhosis. Fecal samples were collected from 38 healthy volunteers, 61 patients with HBV-related decompensated cirrhosis (group LC) and 74 patients who had liver transplant for hepatitis B cirrhosis (group LT). Quantitative polymerase chain reaction technology with species-specific primers was applied to investigate lactobacilli 16S rDNA in crude DNA, extracted from fecal samples. Software package Statistical Package for the Social Sciences and Palaeontological Statistics for Windows was used to analyze the data. Lactobacilli population of the two patient groups was different from the healthy control subjects, principal differences being marked decrease in the population of Lactobacillus rhamnosus (p < 0.001 for both patient groups) and reduction in the frequency of Lactobacillus fermentus (p < 0.001 for group LC and p < 0.01 for group LT). Our findings on the frequency of lactobacilli population suggested decreased diversity in groups LC and LT (compared with the healthy controls (p < 0.001 and p < 0.01, respectively)). Patients tended to have less complex fecal lactobacilli composition than the healthy controls, especially in the group LC.

Diversity of Lactobacillus and Bifidobacterium in feces of herbivores, omnivores and carnivores

The Lactobacillus and Bifidobacterium population in the feces of 26 animals (16 species) were studied by culture-dependent and culture-independent techniques. Lactobacilli were detected from a few herbivores, all carnivores and some omnivores. Lactobacillus johnsonii, Lactobacillus reuteri, Lactobacillus salivarius, Lactobacillus vaginalis and Lactobacillus ingluviei were the most dominant lactobacilli in carnivores. These species were, however, not predominant in herbivores and omnivores. Lactobacillus brevis, Lactobacillus casei, Lactobacillus parabuchneri, Lactobacillus plantarum, Lactobacillus sakei, Leuconostoc mesenteroides and Leuconostoc pseudomesenteroides, usually present in raw plant material, were present in omnivores but not in carnivores. Bifidobacteria were detected in only four herbivores and two omnivores. Bifidobacterium pseudolongum was the only Bifidobacterium species detected in herbivores. Bifidobacteria detected in the two omnivores are phylogenetically not closely related to known species and are possible novel species in the genus.

Determining the genetic diversity of lactobacilli from the oral cavity

Several methods for determining the diversity of Lactobacillus spp were evaluated with the purpose of developing a realistic approach for further studies. The patient population was comprised of young children with an oral disease called severe early childhood caries. The ultimate goal of these studies was to ascertain the role of lactobacilli in the caries process. To accomplish that goal, we evaluated several methods and approaches for determining diversity including AP-PCR, chromosomal DNA fingerprinting, denaturing gradient gel electrophoresis, and 16S rRNA gene sequencing. Central to these methods was the gathering and screening of isolates from cultivation medium. Using various estimates of diversity, we addressed the question as to how many isolates represent the overall diversity and how cultivation compares to non-cultivation techniques. Finally, we proposed a working approach for achieving the goals outlined framed by both practical constraints in terms of time, effort and efficacy while yielding a reliable outcome.

Characterisation and response of intestinal microflora and mucins to manno-oligosaccharide and antibiotic supplementation in broiler chickens

1. An experiment was conducted to characterise and evaluate, in comparison to zinc bacitracin (ZnB), the response of intestinal microflora and mucins to manno-oligosacchares (MOS, Bio-MOS®, Alltech Biotechnology, Nicholasville, Kentucky, USA). 2. Supplementation of MOS and ZnB selectively increased the intensity of sulphomucins. As revealed by the plate culture method, MOS accelerated the maturation of gut microflora by promoting the growth of lactobacilli in the ileal mucosa and vice versa on ileal and caecal clostridia. Unlike MOS, ZnB suppressed the growth of intestinal bacteria, especially those of lactobacilli and clostridia. Use of T-RFLP further revealed that MOS increased the diversity of lactobacilli in the ileum and ileal mucosa but the opposite was observed for ZnB. It also appears that MOS and ZnB possessed a common property in differentially favouring the growth of certain Lactobacillus species. There was also evidence to show that both MOS and ZnB also increased the homogeneity of the gut microflora, possibly through the regulation of the overall gut bacterial communities. 3. Improvement in intestinal microbial homogeneity and mucin synthesis, coupled with the differential selections for certain specific beneficial bacterial species, may ultimately be proven to be the target mechanisms in the search for more effective alternatives to antibiotics.

Microbial community composition of the crop and ceca contents of laying hens fed diets supplemented with Chlorella vulgaris

It is generally accepted that the intestinal microbiota plays an important role in sustaining health and productivity of animals. Chlorella vulgaris, a naturally occurring green microalga, is believed to influence performance and health, including bird reproduction and egg quality. The nutritive value of open or indoor cultured C. vulgaris depends upon the technological process used to treat the algal mass. In the present paper, it is presented and discussed how 2 differentially processed C. vulgaris powders (spray-dried: SD-CV; bullet-milled and spray-dried: BMSD-CV) affected crop and cecal microbiota in laying hens. Polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) of bacterial 16S rRNA gene fragments was applied. The diversity of the crop universal bacterial DGGE fingerprints was not affected (6.4 +/- 1.65, 5.4 +/- 1.19, and 5.5 +/- 1.35 in the control, SD-CV, and BMSD-CV, respectively). Most of the bands from the corresponding positions in the gels were closely related to Lactobacillus sp. The DGGE fingerprints of V2-V3 fragments of 16S rRNA of crop lactobacilli had lower diversity in the control hens (8.7 +/- 1.22) than in the SD-CV (9.2 +/- 1.77) and BMSD-CV (9.9 +/- 1.88); thus, feeding C. vulgaris resulted in increased lactobacilli diversity in crop. A band closely related to Lactobacillus ingluviei was present in 9 out of 12 hens in the control group but in only 1 bird in the SD-CV and in 5 out of 11 birds in the BMSD-CV, suggesting a negative effect of C. vulgaris on this lactobacillus. Feeding C. vulgaris to laying hens also resulted in increased bacterial community diversity in the ceca. No effect of the technological processing of the microalgae on the microbial diversity could be observed. The diversity of the ceca universal bacterial DGGE fingerprints was lower in the control group than in the SD-CV and BMSD-CV (5.6 +/- 1.72 vs. 9.16 +/- 2.64 and 9.31 +/- 2.41, respectively). Most of the sequences retrieved from the DGGE bands formed ceca that were closely related to Ruminococcaceae, Lachnospiraceae, and lactobacilli, giving further insight into still poorly discovered intestinal microbiota of laying hens.

The probiotic properties ofLactobacillus buchneriP2

To isolate new lactobacilli strain with cholesterol-lowering effect and analyse its probiotic properties and possible mechanisms of cholesterol removal. The strain with cholesterol-lowering effect was isolated from pickled juice. The acid and bile tolerance and antimicrobial activity were tested. The free cholalic acid, the cholesterol in supernatant fluid, washing buffer and cell extract, the cholesterol removed by growing, dead and resting cells were quantified. The isolated strain with high cholesterol-reducing rate of 43.95% was identified as Lactobacillus buchneri (Lact. buchneri) P2. It had acid and bile tolerance and antimicrobial activity. Moreover, it could remove cholesterol via coprecipitating with deconjugated bile salts, assimilating and adsorbing by cells. And the assimilation was considered to be the main reason of cholesterol removal. The isolated Lact. buchneri P2 showed probiotic properties of cholesterol reduction, acid and bile tolerance and antimicrobial activity and could remove cholesterol via different ways. A new strain of Lact. buchneri P2 with efficient cholesterol-reducing ability was isolated to provide species diversity of lactobacilli for functional dairy products. And the possible mechanism of cholesterol removal by Lact. buchneri was discussed.

Phenotypic and genotypic characterization of lactobacilli from Churpi cheese

The aim of this study was to investigate the diversity of lactobacilli in Churpi cheese, a traditional variety of cheese made from yak milk. Thirty-five lactobacilli isolated from five different samples procured from different parts of Arunachal Pradesh (India) were analyzed by phenotypic and genotypic methods. The 16S rDNA sequencing for all the isolates was performed. Five different species of lactobacilli were isolated from Churpi cheese with the predominance of Lactobacillus paracasei followed by Lactobacillus plantarum. All the isolates were further evaluated for their technological properties such as citrate utilization, exopolysaccharide (EPS), bacteriocin, and acid production. Forty-three percent isolates were found positive for citrate utilization, while 14% were found good acid producer, and 11% for EPS production. Lactobacillus coryniformis was an uncommon species found in Churpi cheese. Isolates obtained in this study can be potentially used for the development of defined strain starter for Churpi cheese.

Impacts of Piglet Age and Route of Delivery on Ileal Lactobacillus Diversity

Lactobacilli are inhabitants of the human and porcine gastrointestinal tract. Herein, Lactobacillus diversity in piglets that were either Cesarean ‐ (CD, n = 11) or vaginally delivered (VD, n=9) was characterized. Piglets were weaned on d21 and samples obtained on d3, 14, 21 and 28. Total lactobacilli increased from d3 to 14, were stable until d21 and decreased at d28. Ten random isolates per piglet were identified by partial (499‐bp) hsp60 gene sequencing using Lactobacillus specific primers and 7 species were identified: L. johnsonii, L. thermotolerans, L. reurteri, L. amylovorus, L. delbrueckii, L. salivarius and L. vaginalis. At d3, VD and CD piglets had 3‐5 Lactobacillus species, but the composition differed between the groups. At d14 and 21, L. johnsonii dominated in both CD and VD piglets (&gt;75%). At 28 days, L. johnsonii remained dominant with VD (91%) piglets, whereas CD piglets had both L. johnsonii (72%) and L. thermotolerans (21%). Carbohydrate utilization profiles of 200 Lactobacillus isolates demonstrated intraspecies diversity confirming that several strains may be present for each Lactobacillus species. Terminal restriction fragment length polymorphism patterns (T‐RFLP) generated from ileal contents confirmed the Lactobacillus species composition identified by cultivation. Thus, piglet age and route of delivery impacts the ileal Lactobacillus community. (BMS Freedom to Discover Award).Grant Funding SourceFSHN

Administration of Lactobacillus casei and Lactobacillus plantarum affects the diversity of murine intestinal lactobacilli, but not the overall bacterial community structure

Lactobacilli are normal inhabitants of the gastrointestinal tract (GIT) of many mammalian hosts. Their administration as probiotics in functional foods is currently a frequent practice, mainly because of their benefits to host health. It is therefore of interest to study the impact of administration of exogenous strains of Lactobacillus normally used as probiotics upon endogenous microbial populations. For this purpose, fecal and intestinal tissue samples were analyzed in a mouse model fed with a mixture of Lactobacillus plantarum and Lactobacillus casei isolated from commercially available dairy products. The murine intestinal microbiota was studied by means of cultivation-independent 16S rRNA gene-targeted techniques, namely denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (T-RFLP) and sequence analysis of clone libraries. Multivariate statistical analysis was used to integrate datasets obtained from the different techniques applied. Whereas no differences were detected in the composition of the overall fecal bacterial community, changes were observed for intestinal tissue samples. Moreover, an increase in the diversity of gut lactobacilli was observed in fecal as well as intestinal tissue samples when mice received the mixture of L. casei and L. plantarum.

Diversity and dynamics of lactobacilli populations during ripening of RDO Camembert cheese

The diversity and dynamics of Lactobacillus populations in traditional raw milk Camembert cheese were monitored throughout the manufacturing process in 3 dairies. Culture-dependent analysis was carried out on isolates grown on acidified de Man - Rogosa - Sharpe agar and Lactobacillus anaerobic de Man Rogosa Sharpe agar supplemented with vancomycin and bromocresol green media. The isolates were identified by polymerase chain reaction - temperature gradient gel electrophoresis (PCR-TGGE) and (or) species-specific PCR and (or) sequencing, and Lactobacillus paracasei and Lactobacillus plantarum isolates were characterized by pulsed field gel electrophoresis (PFGE). Milk and cheese were subjected to culture-independent analysis by PCR-TGGE. Presumed lactobacilli were detected by plate counts throughout the ripening process. However, molecular analysis of total DNA and DNA of isolates failed to detect Lactobacillus spp. in certain cases. The dominant species in the 3 dairies was L. paracasei. PFGE analysis revealed 21 different profiles among 39 L. paracasei isolates. Lactobacillus plantarum was the second most isolated species, but it occurred nearly exclusively in one dairy. The other species isolated were Lactobacillus parabuchneri, Lactobacillus fermentum, Lactobacillus acidophilus, Lactobacillus helveticus, a Lactobacillus psittaci/delbrueckii subsp. bulgaricus/gallinarum/crispatus group, Lactobacillus rhamnosus, Lactobacillus delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, Lactobacillus brevis, Lactobacillus kefiri, and Lactobacillus perolens. Lactobacilli diversity at the strain level was high. Dynamics varied among dairies, and each cheese exhibited a specific picture of species and strains.

Comparative evaluation of three molecular typing methods in their applicability to differentiate Lactobacillus strains with human origin

We isolated a total of 49 strains of lactic acid bacteria from the faeces of healthy donors. The species in that group were determined as L. plantarum (11 strains), L. casei (11 strains), L. rhamnosus (seven strains), L. fermentum (seven strains), L. gasseri (six strains), L. delbrueckii ssp. lactis (four strains), L. salivarius (two strains), and L. acidophilus (one strain). Genotyping at strain level was performed using random amplification of polymorphic DNA (RAPD), pulsed field gel electrophoresis (PFGE) with endonucleases ApaI and XhoI and amplified fragment length polymorphism (AFLP) with enzymes XhoI and TaqI. The main objective was the comparison of three molecular typing techniques: AFLP, PFGE and RAPD in their applicability to determine the genetic diversity among the isolates. RAPD was the easiest, comparatively rapid and fairly strain discriminative tool. PFGE was the most laborious method but producing the most stable profiles with satisfactory discriminatory power. AFLP proved to be the most discriminative approach for typing of the strains. AFLP could differentiate strains with the same PFGE profiles. Therefore, AFLP successfully could replace the labor consuming PFGE. The specially developed AFLP and PFGE proved very high potential to evaluate the strain diversity of Lactobacillus spp. with human origin.

Population dynamics of lactobacilli in Grana cheese

A survey on the presence, microbial diversity, and population dynamics of lactobacilli in Grana cheese is presented. Evolution of thermophilic rod lactic acid bacteria within the first two days from cheese making and during ripening was different according to different bacterial groups, which were selectively enumerated and identified by molecular methods. Species-specific microbial counts indicated prevalence ofLactobacillus helveticus in both the whey starter and the cheese at moulding, and ofLactobacillus delbrueckii subsp.lactis in cheese after two months of ripening. In more advanced ripening, a decrease of total thermophilic lactobacilli and an increase of mesophilic lactobacilli (mostly belonging toLactobacillus casei/paracasei andLactobacillus rhamnosus) was observed. PCR fingerprinting of lactobacilli, which was performed by PCR-fingerprinting, indicated a marked microbial heterogeneity within theLactobacillus spp. populations, which enabled strain (or group)-specific fingerprints to be observed.