Differential modulation of human intestinal bifidobacterium populations after consumption of a wild blueberry (Vaccinium angustifolium) drink

Bifidobacteria are gaining increasing interest as health-promoting bacteria. Nonetheless, the genus comprises several species, which can exert different effects on human host. Previous studies showed that wild blueberry drink consumption could selectively increase intestinal bifidobacteria, suggesting an important role for the polyphenols and fiber present in wild blueberries. This study evaluated the modulation of the most common and abundant bifidobacterial taxonomic groups inhabiting the human gut in the same fecal samples. The analyses carried out showed that B. adolescentis, B. breve, B. catenulatum/pseudocatelulatum, and B. longum subsp. longum were always present in the group of subjects enrolled, whereas B. bifidum and B. longum subsp. infantis were not. Furthermore, it was found that the most predominant bifidobacterial species were B. longum subsp. longum and B. adolescentis. The results obtained revealed a high interindividual variability; however, a significant increase of B. longum subsp. infantis cell concentration was observed in the feces of volunteers after the wild blueberry drink treatment. This bifidobacterial group was shown to possess immunomodulatory abilities and to relieve symptoms and promote the regression of several gastrointestinal disorders. Thus, an increased cell concentration of B. longum subsp. infantis in the human gut could be considered of potential health benefit. In conclusion, wild blueberry consumption resulted in a specific bifidogenic effect that could positively affect certain populations of bifidobacteria with demonstrated health-promoting properties.

Short-chain fructo-oligosaccharides modulate intestinal microbiota and metabolic parameters of humanized gnotobiotic diet induced obesity mice

Prebiotic fibres like short-chain fructo-oligosaccharides (scFOS) are known to selectively modulate the composition of the intestinal microbiota and especially to stimulate Bifidobacteria. In parallel, the involvement of intestinal microbiota in host metabolic regulation has been recently highlighted. The objective of the study was to evaluate the effect of scFOS on the composition of the faecal microbiota and on metabolic parameters in an animal model of diet-induced obesity harbouring a human-type microbiota. Forty eight axenic C57BL/6J mice were inoculated with a sample of faecal human microbiota and randomly assigned to one of 3 diets for 7 weeks: a control diet, a high fat diet (HF, 60% of energy derived from fat)) or an isocaloric HF diet containing 10% of scFOS (HF-scFOS). Mice fed with the two HF gained at least 21% more weight than mice from the control group. Addition of scFOS partially abolished the deposition of fat mass but significantly increased the weight of the caecum. The analysis of the taxonomic composition of the faecal microbiota by FISH technique revealed that the addition of scFOS induced a significant increase of faecal Bifidobacteria and the Clostridium coccoides group whereas it decreased the Clostridium leptum group. In addition to modifying the composition of the faecal microbiota, scFOS most prominently affected the faecal metabolome (e.g. bile acids derivatives, hydroxyl monoenoic fatty acids) as well as urine, plasma hydrophilic and plasma lipid metabolomes. The increase in C. coccoides and the decrease in C. leptum, were highly correlated to these metabolic changes, including insulinaemia, as well as to the weight of the caecum (empty and full) but not the increase in Bifidobacteria. In conclusion scFOS induce profound metabolic changes by modulating the composition and the activity of the intestinal microbiota, that may partly explain their effect on the reduction of insulinaemia.

Use of bifidobacterial specific terminal restriction fragment length polymorphisms to complement next generation sequence profiling of infant gut communities

Bifidobacteria are intestinal anaerobes often associated with gut health. Specific bifidobacterial species are particularly common in the gastrointestinal tract of breast-fed infants. Current short read next-generation sequencing approaches to profile fecal microbial ecologies do not discriminate bifidobacteria to the species level. Here we describe a low-cost terminal restriction fragment length polymorphism (TRFLP) procedure to distinguish between the common infant-associated bifidobacterial species. An empirical database of TRF sizes was created from both common reference strains and well-identified isolates from infant feces. Species-specific quantitative PCR validated bifidobacterial-specific TRFLP profiles from infant feces. These results indicate that bifidobacterial-specific TRFLP is a useful method to monitor intestinal bifidobacterial populations from infant fecal samples. When used alongside next generation sequencing methods that detect broader population levels at lower resolution, this high-throughput, low-cost tool can help clarify the role of bifidobacteria in health and disease.

Effects of feeding finisher pigs with chicory or lupine feed for one week or two weeks before slaughter with respect to levels of Bifidobacteria and Campylobacter

This study aimed to assess whether inclusion of chicory or lupine (prebiotics) in the diet of pre-slaughter pigs for just 1 or 2 weeks could change the composition of their intestinal microbiota, stimulate the growth of bifidobacteria and help to lower the amount of thermoplilic Campylobacter spp. (mainly Campylobacter jejuni and Campylobacter coli), which are a major cause of food-borne infections in humans. A total of 48 pigs that had an initial live weight of 90 kg were fed with either a lupine (organic concentrate with 25% blue lupine seeds), chicory (organic concentrate with 10% dried chicory roots) or control (100% organic concentrate) diet for 1 week (24 pigs) or 2 weeks (24 pigs) before slaughter. The Campylobacter spp. level in rectal faecal samples after 0, 1 and 2 weeks of feeding and in the luminal content from ileum, caecum and colon at slaughter was determined by direct plating on modified charcoal-cefoperazone-deoxycholate agar plates. DNA extracted from the luminal content of distal ileum and caecum was used for terminal restriction fragment length polymorphism (T-RFLP) analysis of the composition of intestinal microbiota and for measuring the amount of bifidobacterial and total bacterial DNA by quantitative real-time PCR (qPCR). Campylobacter spp. were excreted by all pigs and present in the luminal content from distal ileum to midway colon with particularly high numbers in the caecum, but the excretion was reduced by 10-fold in pigs fed lupines for 1 week as compared with control- and chicory-fed pigs (mean log(10) 2.9 v. 4.1 CFU/g; P < 0.05). The qPCR analysis showed that feeding with lupines resulted in higher levels of bifidobacteria in caecum as compared with the other diets (P < 0.05). T-RFLP analysis showed that four of the most abundant bacteria with terminal restriction fragment values >5% relative to the intensity of total abundance differed between the feed treatments (P < 0.05). Therefore, this study showed that even a short-term alternative feeding strategy with prebiotics in the diet of pre-slaughter pigs elicited changes in the composition of the intestinal microbiota, where lupine increased the level of bifidobacteria in caecum and reduced the Campylobacter spp. excretion level after 1 week.

[Phenotypic and genotypic characterization of probiotic bacterial strains used in medicinal products]

INTRODUCTION

The optimization of quality testing strategy of products containing probiotics might allow to general improvement of its safer use in humans. The goal of the study was the evaluation of quality expressed by identity, colony forming unit (CFU) and antibiotic sensitivity ofprobiotics used in medicinal products available in Poland using the appropriate and validated procedures.

METHODS

The medicinal products containing L. rhamnosus, L. acidophilus, L. delbrueckii subsp. bulgaricus and B. animalis subsp. lactis, L. helveticus, and L. gasseri were tested for species identity performed with validated rep-PCR (BOXA 1R) method. The antimicrobial susceptibility of working seeds and strains isolated to 26 antibiotics were tested by disk diffusion and E-test methods using relevant references as recommended by EUCAST. The numbers of probiotic strains, expressed as cfu count per package, was done using plating plunge method.

RESULTS

All strains tested, except B. lactis, were found to be resistant to trimethoprim-sulphamethoxazole, nalidixic acid, metronidazole, and colistin. B. lactis was resistant to aminoglycosides. L. rhamnosus strains were found to be resistant to vancomycin, (MIC > 256 microg/ml) similarly to ATCC strains (L. rhamnosus GG 53103 and 244). The sensitivity to other antibiotics was strain specific. The rep-PCR method was found species and strain specific. All products tested fulfilled declared countent as measured by cfu count/package.

CONCLUSIONS

Quality of medicinal products containing probiotics was found undoubted and confirmed. The optimized strategy of quality monitoring of probiotics used in medicinal products can be used in dietary supplements and foodstuffs intended for particular nutritional uses.

Comparison and evaluation of molecular methods used for identification and discrimination of lactic acid bacteria

BACKGROUND

Lactobacillus and Bifidobacterium strains are present in a great variety of habitats, including fermented products, probiotic concoctions and the human colon. Some species are so closely related that it is difficult to distinguish them by microbiological techniques. Nevertheless, discrimination of isolates is an important issue in respect of application, and molecular methods such as restriction fragment length polymorphism (RFLP), random amplification of polymorphic DNA (RAPD) or species-specific polymerase chain reaction (PCR) might help in resolving this problem. In this study, PCR, RFLP and sequencing were applied to identify lactobacilli and bifidobacteria originating from various sources and the DSMZ strain collection.

RESULTS

The microbiological composition of foods was analysed by molecular methods. Using species-specific PCR primers, three restriction enzymes (AluI, HhaI and RsaI) and sequencing, three Bifidobacterium and six Lactobacillus reference strains could be distinguished and four additional lactobacilli of food origin were identified.

CONCLUSION

A combination of three molecular methods resulted in successful discrimination of nine reference strains and four isolates of food origin. Since these methods are not always accurate owing to their high genetic homogeneity, it is advisable to use more than one method for the identification of L. casei and closely related species.

Diversity of bifidobacteria within the infant gut microbiota

Background

The human gastrointestinal tract (GIT) represents one of the most densely populated microbial ecosystems studied to date. Although this microbial consortium has been recognized to have a crucial impact on human health, its precise composition is still subject to intense investigation. Among the GIT microbiota, bifidobacteria represent an important commensal group, being among the first microbial colonizers of the gut. However, the prevalence and diversity of members of the genus Bifidobacterium in the infant intestinal microbiota has not yet been fully characterized, while some inconsistencies exist in literature regarding the abundance of this genus.

Methods/Principal Findings

In the current report, we assessed the complexity of the infant intestinal bifidobacterial population by analysis of pyrosequencing data of PCR amplicons derived from two hypervariable regions of the 16 S rRNA gene. Eleven faecal samples were collected from healthy infants of different geographical origins (Italy, Spain or Ireland), feeding type (breast milk or formula) and mode of delivery (vaginal or caesarean delivery), while in four cases, faecal samples of corresponding mothers were also analyzed.

Conclusions

In contrast to several previously published culture-independent studies, our analysis revealed a predominance of bifidobacteria in the infant gut as well as a profile of co-occurrence of bifidobacterial species in the infant’s intestine.

[Differences in fecal Bifidobacterium species between patients with type 2 diabetes and healthy individuals]

OBJECTIVE

To determine the changes in fecal Bifidobacterium species in patients with type 2 diabetes in comparison with healthy individuals.

METHODS

The bacterial DNA were extracted from the fecal samples from 50 type 2 diabetic patients and 30 healthy individuals. Real-time quantitative PCR was employed to determine the copy numbers of the bacteria in the fecal samples using 16S rRNA-targeted genus- and species-specific PCR primers for a selected group of fecal Bifidobacterium species including total Bifidobacterium, B.longum, B.breve, B.adolescent, and B. infantis.

RESULTS

The diabetic group had significantly lower copy numbers of total Bifidobacterium and B.adolescent compared to the healthy individuals (P<0.05).

CONCLUSION

Type 2 diabetic patients have a lowered number of Bifidobacterium species in the gut microflora.

Comparative genomics of Bifidobacterium, Lactobacillus and related probiotic genera

Six bacterial genera containing species commonly used as probiotics for human consumption or starter cultures for food fermentation were compared and contrasted, based on publicly available complete genome sequences. The analysis included 19 Bifidobacterium genomes, 21 Lactobacillus genomes, 4 Lactococcus and 3 Leuconostoc genomes, as well as a selection of Enterococcus (11) and Streptococcus (23) genomes. The latter two genera included genomes from probiotic or commensal as well as pathogenic organisms to investigate if their non-pathogenic members shared more genes with the other probiotic genomes than their pathogenic members. The pan- and core genome of each genus was defined. Pairwise BLASTP genome comparison was performed within and between genera. It turned out that pathogenic Streptococcus and Enterococcus shared more gene families than did the non-pathogenic genomes. In silico multilocus sequence typing was carried out for all genomes per genus, and the variable gene content of genomes was compared within the genera. Informative BLAST Atlases were constructed to visualize genomic variation within genera. The clusters of orthologous groups (COG) classes of all genes in the pan- and core genome of each genus were compared. In addition, it was investigated whether pathogenic genomes contain different COG classes compared to the probiotic or fermentative organisms, again comparing their pan- and core genomes. The obtained results were compared with published data from the literature. This study illustrates how over 80 genomes can be broadly compared using simple bioinformatic tools, leading to both confirmation of known information as well as novel observations.

Changes of fecal Bifidobacterium species in adult patients with hepatitis B virus-induced chronic liver disease

The beneficial effects of Bifidobacteria on health have been widely accepted. Patients with chronic liver disease have varying degrees of intestinal microflora imbalance with a decrease of total Bifidobacterial counts. Since different properties have been attributed to different Bifidobacterium species and there is no information available for the detailed changes in the genus Bifidobacterium in patients with chronic liver disease heretofore, it is meaningful to investigate the structure of this bacterium at the species level in these patients. The aim of this study was to characterize the composition of intestinal Bifidobacterium in patients with hepatitis B virus-induced chronic liver disease. Nested-PCR-based denaturing gradient gel electrophoresis (PCR-DGGE), clone library, and real-time quantitative PCR were performed on the fecal samples of 16 patients with chronic hepatitis B (CHB patients), 16 patients with hepatitis B virus-related cirrhosis (HBV cirrhotics), and 15 healthy subjects (Controls). Though there was no significant difference in the diversity among the three groups (P = 0.196), Bifidobacterium dentium seems to be specifically enhanced in patients as the PCR-DGGE profiles showed, which was further validated by clone library and real-time quantitative PCR. In contrast to the B. dentium, Bifidobacterium catenulatum/Bifidobacterium pseudocatenulatum were detected less frequently in the predominant profile and by quantitative PCR in HBV cirrhotics than in the controls, and the level of this species was also significantly different between these two groups (P = 0.023). Although having no quantitative difference among the three groups, Bifidobacterium longum was less commonly detected in HBV cirrhotics than in CHB patients and Controls by quantitative PCR (P = 0.011). Thus, the composition of intestinal Bifidobacterium was deeply altered in CHB and HBV cirrhotic patients with a shift from beneficial species to opportunistic pathogens. The results provide further insights into the dysbiosis of the intestinal microbiota in patients with hepatitis B virus-induced chronic liver disease and might potentially serve as guidance for the probiotics interventions of these diseases.

[Bifidobacterial species composition of digestive tract of people of different age groups]

The quantitative and species composition of bifidoflora of intestinal content of people of different age groups has been studied. It was established that B. longum subsp. infantis, B. bifidum, B. brev, B. longum subsp. longum and B. dentium were the dominant species of intestinal bifidoflora of people of all ages. The dependence of the species composition of intestinal bifidobacteria on the human age was shown. A decrease of species diversity of bifidobacteria in elderly people was observed.

Novel probiotic Bifidobacterium longum subsp. infantis CECT 7210 strain active against rotavirus infections

Rotavirus is the leading cause of severe acute gastroenteritis among children worldwide. It is well known that breast-feeding and vaccination afford infants protection. Since breast-feeding has drastically decreased in developed countries, efforts have been focused on the potential use of probiotics as preventive agents. In this study, a novel Bifidobacterium longum subsp. infantis strain was isolated from infant feces and selected, based on its capacity to inhibit in vitro rotavirus Wa replication (up to 36.05% infectious foci reduction) and also to protect cells from virus infection (up to 48.50% infectious foci reduction) in both MA-104 and HT-29 cell lines. Furthermore, studies using a BALB/c mouse model have proved that this strain provides preliminary in vivo protection against rotavirus infection. The strain has been deposited in the Spanish Type Culture Collection under the accession number CECT 7210. This novel strain has the main properties required of a probiotic, such as resistance to gastrointestinal juices, biliary salts, NaCl, and low pH, as well as adhesion to intestinal mucus and sensitivity to antibiotics. The food safety status has been confirmed by the absence of undesirable metabolite production and in acute ingestion studies of mice. Overall, these results demonstrate that Bifidobacterium longum subsp. infantis CECT 7210 can be considered a probiotic able to inhibit rotavirus infection.

Immune response to Bifidobacterium bifidum strains support Treg/Th17 plasticity

In this work we analyzed the immune activation properties of different Bifidobacterium strains in order to establish their ability as inductors of specific effector (Th) or regulatory (Treg) responses. First, we determined the cytokine pattern induced by 21 Bifidobacterium strains in peripheral blood mononuclear cells (PBMCs). Results showed that four Bifidobacterium bifidum strains showed the highest production of IL-17 as well as a poor secretion of IFNγ and TNFα, suggesting a Th17 profile whereas other Bifidobacterium strains exhibited a Th1-suggestive profile. Given the key role of Th17 subsets in mucosal defence, strains suggestive of Th17 responses and the putative Th1 Bifidobacterium breve BM12/11 were selected to stimulate dendritic cells (DC) to further determine their capability to induce the differentiation of naïve CD4⁺ lymphocytes toward different Th or Treg cells. All selected strains were able to induce phenotypic DC maturation, but showed differences in cytokine stimulation, DC treated with the putative Th17 strains displaying high IL-1β/IL-12 and low IL-12/IL-10 index, whereas BM12/11-DC exhibited the highest IL-12/IL-10 ratio. Differentiation of naïve lymphocytes confirmed Th1 polarization by BM12/11. Unexpectedly, any B. bifidum strain showed significant capability for Th17 generation, and they were able to generate functional Treg, thus suggesting differences between in vivo and vitro responses. In fact, activation of memory lymphocytes present in PBMCS with these bacteria, point out the presence in vivo of specific Th17 cells, supporting the plasticity of Treg/Th17 populations and the key role of commensal bacteria in mucosal tolerance and T cell reprogramming when needed.

Bifidobacterium population analysis in the infant gut by direct mapping of genomic hybridization patterns: potential for monitoring temporal development and effects of dietary regimens

A bifidobacterial mixed-species microarray platform was used in a proof-of-principle study to address the composition and development of bifidobacteria in DNA extracted from faecal samples. These were collected in a time-course of 2 years since birth and derived from human infants that were breastfed, standard formula-fed or received a prebiotic formula during their weaning period. A set of over 50 samples was analysed, testifying for the throughput of the designed platform for multiple genome hybridizations. The generated data revealed that faecal samples of breastfed infants contained a high abundance of genomic DNA homologous to Bifidobacterium breve. In contrast, faecal samples from standard formula-fed infants lacked detectable amounts of this B. breve DNA but contained genes with high similarity to B. longum. Remarkably, infants that received breastmilk and later a prebiotic formula consisting of a standard formula milk containing a mixture of specific galacto- and fructo-oligosaccharides, continued to harbour a B. breve-dominant faecal population. One infant that received standard formula in combination with the additional B. lactis Bb12 culture, contained significant amounts of faecal DNA belonging to Bb12 but only during the period of ingestion. The microarray platform showed sufficient sensitivity to analyse the B. breve group at the strain level. Overall, the B. breve populations observed in the faecal samples of the studied infants showed a stable composition over time and were unique per infant. In conclusion, our results show the applicability of comparative genome hybridization to study bifidobacterial populations in infant faecal samples without the use of any amplification step.

Novel probiotic Bifidobacterium bifidum CECT 7366 strain active against the pathogenic bacterium Helicobacter pylori

Helicobacter pylori is considered one of the major risk factors underlying the development of gastritis and gastric and duodenal ulcers. Moreover, 50% of the population carries this bacterium, and consequently, when it is detected, eradication of H. pylori is strongly recommended. Regarding the use of probiotics as functional agents, several studies have shown that there is a direct relationship between the addition of certain probiotic bacteria and in vitro inhibition of H. pylori; however, in vivo studies showing bifidobacterial activity against H. pylori remain scarce. In this study, a Bifidobacterium bifidum strain which proved active in vitro against H. pylori has been isolated, with inhibition levels reaching 81.94% in the case of the supernatant and even 94.77% inhibition for supernatant purified by cationic exchange followed by an inverse phase. In vivo studies using a BALB/c mouse model have proved that this strain partially relieves damage to gastric tissues caused by the pathogen and also decreases the H. pylori pathogenicity ratio. This novel strain fulfills the main properties required of a probiotic (resistance to gastrointestinal juices, biliary salts, NaCl, and low pH; adhesion to intestinal mucus; and sensitivity to antibiotics). Furthermore, the absence of undesirable metabolites has been demonstrated, and its food safety status has been confirmed by acute ingestion studies in mice. In summary, the results presented here demonstrate that Bifidobacterium bifidum CECT 7366 can be considered a probiotic able to inhibit H. pylori both in vitro and in vivo.

Isolation and characterisation of an oxygen, acid and bile resistant Bifidobacterium animalis subsp. lactis Qq08

BACKGROUND

Currently, bifidobacteria are recognised as one of the most important bacteria used as probiotics, which promote human health. However, their commercial application has been limited by their anaerobic nature. The purpose of this study was to select an oxygen, acid and bile resistant strain of bifidobacterium for use as a new probiotic.

RESULTS

A total of 10 strains of bifidobacteria from different sources were analysed for their relative bacterial growth ratio (RBGR) in different oxygen concentrations. Three strains with high RBGR values were selected and their survival rates in acid environment and bile salt conditions were investigated in vitro. One strain showed high tolerance to low pH, giving a survival rate of 84% at pH 2 after 4 h incubation, and high tolerance to bile, more than 90% after 4.5 h incubation at 0.01 g mL(-1) bile concentration. This strain was identified as Bifidobacterium animalis subsp. lactis strain Qq08 based on polyphasic taxonomy approaches, such as phenotype analysis and 16S rRNA and 16S to 23S internally transcribed spacer sequence analyses.

CONCLUSION

We isolated an aerotolerant bifidobacterium and identified it as Bifidobacterium animalis subsp. lactis Qq08. This strain has characteristics more favourable than the commercial probiotic strain, Bifidobacterium lactis Bb12.

Lactobacillus and Bifidobacterium diversity in horse feces, revealed by PCR-DGGE

Lactobacillus equi, Lactobacillus hayakitensis, Lactobacillus johnsonii, and Weissella confusa/cibaria were the dominant species in 12 South African horses. The Bifidobacterium-group was detected in the feces of only one of the 12 horses. Sequencing of the nested-PCR amplicon identified the Bifidobacterium-group as Parascardovia denticolens. Cell numbers of L. equi, L. hayakitensis, and W. confusa/cibaria were consistent in all samples. P. denticolens, Bifidodobacterium pseudolongum, and a phylogenetic relative of Alloscardovia omnicolens were rarely detected. L. equigenerosi, a dominant species in Japanese horses, was detected in the fecal samples of only one horse.

Selective growth inhibitory effect of biochanin A against intestinal tract colonizing bacteria

Both bifidobacteria and clostridia are part of the natural gut microflora and while clostridia may be responsible for severe intestinal infections, bifidobacteria are probiotic microorganisms belonging to the most important prospective bacteria in the bowel. The antimicrobial activity of biochanin A was tested in vitro against six Bifidobacterium spp., and eight Clostridium spp. using the broth microdilution method. Biochanin A showed an inhibition against all clostridia in the range of minimum inhibitory concentrations (MIC) from 64 microg/mL (for Cl. clostridioforme, strains DSM 933 and I3) to 1,024 microg/mL (for Cl. perfringens, DSM 11778). No bifidobacteria were suppressed at four-fold higher concentration (MICs > 4,096) than MIC of Cl. perfringens. These results indicate selective growth inhibition of biochanin A and its potential use in antimicrobial prevention and/or protection.

Molecular characterisation of the faecal microbiota in patients with type II diabetes

The investigation provides molecular analyses of the faecal microbiota in type 2 diabetic patients. In order to characterise the gut microbiota in diabetic patients and to assess whether there are changes in the diversity and similarity of gut microbiota in diabetic patients when compared with healthy individuals, bacterial DNAs from 16 type 2 diabetic patients and 12 healthy individuals were extracted from faecal samples and characterised by PCR-denaturing gradient gel electrophoresis (DGGE) with primers specifically targeting V3 region of the 16S rRNA gene, as well as been sequenced for excised gel bands. The counts of Bacteroides vulgatus, Clostridium leptum subgroup and Bifidobacterium genus were assessed using quantitative PCR. By comparing species diversity profiles of two groups, we observed that there were no significant differences between diabetic and healthy group, although a few diabetic individuals (D6, D8) exhibited a remarkable decrease in species profiles. As for the similarity index, it was lower in inter-group than that in intra-group, which showed that the composition of gut microbiota in diabetic group might be changed due to diabetes status. Sequencing results also revealed that bacterial composition of diabetic group was different from that of the healthy group. B. vulgatus and Bifidobacterium genus were low represented in the microbiota of diabetic group, and the significant decrease was observed for Bifidobacterium by real-time PCR. Taken together, in this work we observed the characterisation of gut microbiota in diabetic patients, which suggests that the gut microbiota of diabetes patients have some changes associated with occurrence and development of diabetes.

Species delineation and clonal diversity in four Bifidobacterium species as revealed by multilocus sequencing

The genus Bifidobacterium comprises several species that are important contributors to the gut microbiome, with some strains having beneficial health effects. Understanding the evolutionary emergence of advantageous biological properties requires knowledge of the genetic diversity and clonal structure of species. We sequenced seven housekeeping genes in 119 Bifidobacterium strains of Bifidobacterium animalis, Bifidobacterium bifidum, Bifidobacterium breve and Bifidobacterium longum. Phylogenetic analysis of concatenated sequences delineated sequence clusters that correspond to previously named taxa, and suggested that B. longum subsp. infantis is a nascent lineage emerging from within B. longum subsp. longum. Clear traces of recombination among distant bifidobacterial species indicate leaky species borders and warn against the practice of single gene-based identification. Multilocus sequence typing achieved precise strain genotyping, with discrimination indices above 99% in B. bifidum, B. breve and B. longum, providing a powerful tool for strain traceability, colonization dynamics and ecological studies. Frequent homologous recombination accelerates clonal diversification and may facilitate the transfer of biological properties among bifidobacterial strains.

Changing concepts in caries microbiology

Concepts and beliefs about the cause of dental caries have evolved over many centuries, with the involvement of microorganisms being recognized since the late 1800s. A main thrust of enquiry since then has been to tackle the question of the relative importance of different bacteria in the disease and this article will consider how technical advances in our ability to identify, cultivate and count different species has influenced our understanding. Over the last decade, molecular biological approaches have had a major impact on views of the relative contribution of particular species of plaque bacteria to the caries process. At a more detailed level, molecular genetic studies of species such as Streptococcus mutans have given new insights into the way in which particular genes and the functions that they encode may affect virulence.

[Taxonomic position of bifidobacteria and modern methods for their identification]

Literature data, concerning current state of taxonomy of microorganisms of genus Bifidobacterium are presented in the review. The question of creation of necessary conditions for accurate identification of these bacteria has been revealed, as well as the basic principles of novel molecular-genetic approaches for microorganisms' typing (as they are used for the detection and identification of bifidobacteria) have been described. Main information sources in systematics, classification and nomenclature have been listed. The paper is presented in Ukrainian.

[Species characteristic and factors of persistence of gut bifidoflora during healthy state and dysbiosis]

AIM

To determine features of species composition and factors of persistence of bifidobacteria of human gut microflora in healthy state and during dysbiosis.

MATERIALS AND METHODS

Strains of bifidobacteria isolated from feces of patients with gut dysbiosis grades I - III (24 participants) and conditionally healthy persons (14 participants) were used for the study. Isolation and identification of microorganisms were performed by conventional methods. Antilysozyme activity was determined by photometric method and antilactoferrin sign--by immunoenzyme assay.

RESULTS

Bifidobacteria isolated from intestinal biotope have differences in species composition, which depended from age and state of microbiocenosis of studied persons. Bifidobacterium bifidum was dominated between strains of bifidobacteria isolated from infants with eubiosis, whereas B. longum dominated in persons > 1 y.o. B. bifidum and B. adolescentis were mainly isolated in infants with gut dysbiosis, where as in children > 1 y.o. B. adolescentis was predominantly isolated. New characteristic of bifidoflora--antilactoferrin activity--was discovered for the first time. Expression of this sign, as well as antilysozyme activity, varied and depended from species of bifidobacteria.

CONCLUSION

Obtained data widen our views on species composition of bifidobacteria and discover possible mechanisms of persistence of these microorganisms in intestinal biotope associated with inactivation of host defense factors--lysozyme and lactoferrin.

[Screening and identification of probiotic bifidobacterium from Mongolian children]

OBJECTIVE

Bifidobacterium has important physiological activity in gastrointestinal tract of human and animals, and the tolerability of acid, intestinal juice and oxgall bile salt are the key factors that influence the function of living bacteria preparation. In this study, feces of 12 healthy Mongolian children were selected to isolate Bifidobacterium with probiotic properties.

METHODS

Bifidobacterium was isolated from feces by selective medium and identified by physiological biochemical test. The tolerability of acid, intestinal juice and oxgall bile salt of 11 Bfidobacteria were studied and B. animalis V9 was identified further by molecular biological approach 16S rDNA.

RESULTS

Eleven Bifidobacteria isolated from feces of 12 healthy Mongolian children were identified as B. adolescentis (A1, H3, G4, A8 and V10), B. longum (C6, C7 and D11), B. pseudocatenlatum (B2), B. bifidum (G5), B. animalis (V9). B. animalis V9 had the best acid tolerance with the survival rate 92.4% in artificial gastric juice at pH2.0 for 3h, whereas others had lower than 31.25%. B. animalis V9 also had good survival rate (99.7%) in artificial intestinal juice at pH8.0 for 8h after anaerobic cultured 3h in artificial gastric juice at pH2.0, and tolerated oxgall bile salt at concentration of 0.3%. B. animalis V9 was identified further by molecular biological approach 16S rDNA and result showed the homologies of B. animalis V9 was 99% with Bifidobacterium animalis subsp. lactic BB12.

CONCLUSION

B. animalis V9 had good probiotic properties to be potentiallyused in dairy products and health products.