Microbiological evaluation of jejunal aspirates and faecal samples after oral administration of bifidobacteria and lactic acid bacteria

Comparative evaluation of Lactobacillus strains with different adhesion ability on growth performance and immunomodulatory activity in broiler chickens

The study was designed to assess the effect of 2 Lactobacillus strains (Lactobacillus kefiri 1.3207 and Lactobacillus plantarum 1.2567) with different adherence ability on growth performance and immunomodulatory activity in broiler. The BW and FCR were higher in L. kefiri 1.3207 and L. plantarum 1.2567 groups compared to control group at 42 days of age, and BW of broilers in L. kefiri 1.3207 group was significantly higher than that in L. plantarum 1.2567 group. IgA and IgG contents and the spleen and bursa of Fabricius indices in significantly increased in the L. kefiri 1.3207 group, but not in the L. plantarum 1.2567-treated group. L. kefiri 1.3207 had more significant effect on growth performance, plasma IgA and IgG levels and immune organs indices because it had better adhesion ability.

The underlying microbial mechanism of epizootic rabbit enteropathy triggered by a low fiber diet

Epizootic rabbit enteropathy (ERE) is reproduced successfully in the present study by feeding rabbits a low-fibre diet, and high-throughput sequencing and quantitative real-time PCR (qPCR) analysis were applied to examine the microbial variations in the stomach, small intestine and caecum. The evenness was disturbed and the richness was decreased in the ERE groups. When the rabbits were suffering from ERE, the abundance of the Firmicutes was decreased in three parts of the digestive tract, whereas the Proteobacteria was increased in the stomach and caecum, the Bacteroidetes and Verrucomicrobia were increased in the small intestine. Correlation analysis showed that the reduced concentrations of TVFA and butyrate in the caeca of the ERE group were attributed to the decreased abundances of genera such as Lactobacillus, Alistipes and other fibrolytic bacteria and butyrate- producing bacteria such as Eubacterium and Faecalibacterium. It is concluded that, in terms of microorganisms, the overgrowth of Bacteroides fragilis, Clostridium perfringen, Enterobacter sakazakii and Akkermansia muciniphila and inhibition of Bifidobacterium spp. and Butyrivibrio fibrisolvens in the stomach, small intestine and caecum resulted in a decrease in butyrate yield, leading to the incidence of ERE, and the probability of developing ERE could be manipulated by adjusting the dietary fibre level.

Application of sequence-dependent electrophoresis fingerprinting in exploring biodiversity and population dynamics of human intestinal microbiota: what can be revealed?

Sequence-dependent electrophoresis (SDE) fingerprinting techniques such as denaturing gradient gel electrophoresis (DGGE) have become commonplace in the field of molecular microbial ecology. The success of the SDE technology lays in the fact that it allows visualization of the predominant members of complex microbial ecosystems independent of their culturability and without prior knowledge on the complexity and diversity of the ecosystem. Mainly using the prokaryotic 16S rRNA gene as PCR amplification target, SDE-based community fingerprinting turned into one of the leading molecular tools to unravel the diversity and population dynamics of human intestinal microbiota. The first part of this review covers the methodological concept of SDE fingerprinting and the technical hurdles for analyzing intestinal samples. Subsequently, the current state-of-the-art of DGGE and related techniques to analyze human intestinal microbiota from healthy individuals and from patients with intestinal disorders is surveyed. In addition, the applicability of SDE analysis to monitor intestinal population changes upon nutritional or therapeutic interventions is critically evaluated.

Probiotics used in human studies

GOAL

To investigate the literature from 1980 to 2004 for the types of studies and organisms used as probiotics in human studies and diseases.

METHODS

PubMed search for probiotic organisms used in studies from 1980 to August 2004. The data from those papers were evaluated for organisms used, dose, vehicle, frequency, and investigator's report of positive or negative results.

RESULTS

A total of 185 manuscripts were identified. Investigators reported results of both single and multiple organisms in the same manuscript. A single organism was used in 125 reports, and multiple organisms, ranging from 2 to 9, were used in 60 reports. Positive results were reported in 239 clinical situations and negative results reported in 49 in a total of 288 clinical conclusions drawn by the respective investigators. The studies are tabulated in this review.

CONCLUSION

There is a large literature available in credible journals that report benefit of probiotic administration using a wide range of doses, organisms, and clinical situations. Most of the studies are simple reports of a clinical situation and require additional evaluation.

Lack of inhibitory effects of Lactic acid bacteria on 1,2-dimethylhydrazine-induced colon tumors in rats

AIM: A myriad of healthful effects has been attributed to the probiotic lactic acid bacteria, perhaps the most controversial issue remains that of anticancer activity. This study was aimed at investigating the putative anti-cancer effects of lactic acid bacteria strains on the progression of colon tumor in 1,2-dimethylhydrazine (DMH)-treated animals.

METHODS: The strain of lactic acid bacteria used in this study was lactic acid bacteria NZ9000 that conformed to the characteristics of plasmid free. Sixty male Wistar rats were given subcutaneous injections of DMH at a dose of 40 mg/kg body wt or saline once a week for 10 wk. The rats were divided into 6 experimental groups. After the last DMH injection, animals in groups 1 and 4 were gavaged with 1 mL of lactic acid bacteria at a dose of 5 × 10⁹ per day or vehicle until sacrifice at the end of week 22 or week 52. Animals in groups 1-3 were killed at the end of week 22 for histopathological examination. The whole period of experimental observation was 52 wk.

RESULTS: By the end of 22nd week, final average body weights of the rats treated with DMH alone and all animals receiving lactic acid bacteria were significantly decreased compared with the vehicle control (P < 0.05). No differences in tumor incidence, multiplicity, dimensions and stage in the colonic mucosa were observed among the groups. At week 52, the survival rate of the rats administered lactic acid bacteria was lower than that of the rats treated with DMH that were fed on control fluids of non-lactococcus lactis. The mean survival time of lactic acid bacteria-treated animals was 39 wk.

CONCLUSION: These results indicate that lactic acid bacteria lacks inhibitory effects on the progression of colon tumor in DMH-treated animals, and does not support the hypothesis that alteration of colonic flora may exert an influence on the progression of colon tumor.

A review of the role of the gut microflora in irritable bowel syndrome and the effects of probiotics

Irritable bowel syndrome (IBS) is a multi-factorial gastrointestinal condition affecting 8-22 % of the population with a higher prevalence in women and accounting for 20-50 % of referrals to gastroenterology clinics. It is characterised by abdominal pain, excessive flatus, variable bowel habit and abdominal bloating for which there is no evidence of detectable organic disease. Suggested aetiologies include gut motility and psychological disorders, psychophysiological phenomena and colonic malfermentation. The faecal microflora in IBS has been shown to be abnormal with higher numbers of facultative organisms and low numbers of lactobacilli and bifidobacteria. Although there is no evidence of food allergy in IBS, food intolerance has been identified and exclusion diets are beneficial to many IBS patients. Food intolerance may be due to abnormal fermentation of food residues in the colon, as a result of disruption of the normal flora. The role of probiotics in IBS has not been clearly defined. Some studies have shown improvements in pain and flatulence in response to probiotic administration, whilst others have shown no symptomatic improvement. It is possible that the future role of probiotics in IBS will lie in prevention, rather than cure.

Adaptation of bacteria to the intestinal niche: probiotics and gut disorder

The gastrointestinal tract is a complex ecosystem host to a diverse and highly evolved microbial community composed of hundreds of different microbial species. The interactions that occur between this complex microbial community and the human host have become the focus of scientific research due to increases in the incidence of illnesses associated with deficient or compromised microflora (e.g., gastrointestinal tract infections, inflammatory bowel disease (Crohn's disease and ulcerative colitis), irritable bowel syndrome, antibiotic-induced diarrhea, constipation, food allergies, cardiovascular disease, and certain cancers). Effective multidisciplinary research programs now complement conventional microbiology with molecular ecology techniques to provide culture-independent analysis of the gastrointestinal ecosystem. Furthermore, as we acquire an understanding of gut microflora composition and processes such as intestinal adherence, colonization, translocation, and immunomodulation, we are also elucidating mechanisms by which these can be influenced. This knowledge not only allows scientists to define the activities and interactions of "functional food"-borne beneficial bacteria in the gut, but will also provide the scientific basis for the development of innovative biotechnology-based products tailored to prevent specific diseases and promote overall human gastrointestinal health.

Probiotic bacteria: safety, functional and technological properties

During the past two decades probiotic (health promoting) micro-organisms have been increasingly included in various types of food products, especially in fermented milks. Several aspects, including safety, functional and technological characteristics, have to be taken into consideration in the selection process of probiotic micro-organisms. Safety aspects include specifications such as origin (healthy human GI-tract), non-pathogenicity and antibiotic resistance characteristics. Functional aspects include viability and persistence in the GI-tract, immunomodulation, antagonistic and antimutagenic properties. Before probiotic strains, chosen on the basis of their good safety and functional characteristics, can benefit the consumer, they must first be able to be manufactured under industrial conditions. Furthermore, they have to survive and retain their functionality during storage, and also in the foods into which they are incorporated without producing off-flavours. Factors related to the technological and sensory aspects of probiotic food production are of utmost importance since only by satisfying the demands of the consumer can the food industry succeed in promoting the consumption of functional probiotic products in the future.

The role of probiotic bacteria in cancer prevention

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.

Some probiotic properties of chicken lactobacilli

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

The protective effects of high amylose maize (amylomaize) starch granules on the survival of Bifidobacterium spp. in the mouse intestinal tract

The possibility of using high amylose maize starch granules as a delivery system for probiotic bacteria has been investigated using Bifidobacterium spp. LaftiTM 8B and LaftiTM 13B which were isolated from a healthy human. The Bifidobacterium cells were able to adhere to the amylomaize starch granules and were also able to hydrolyse the starch during growth. Initially, in vitro studies were carried out by studying the survival of strains Bifidobacterium LaftiTM 8B and LaftiTM 13B when exposed to pH 2.3, 3.5 and 6.5 as well as 0.03 and 0.05% w/v bile acids. Both strains were grown either in the absence or presence of high amylose maize starch granules, then mixed with the high amylose maize starch granules and exposed to acidic buffers or bile acid solutions. It was shown that growth in and the presence of high amylose maize starch granules led to enhanced survival of strains LaftiTM 8B and LaftiTM 13B. Subsequently, survival in vivo was monitored by measuring the faecal level of Bifidobacterium LaftiTM 8B after oral administration of the strain to mice. A sixfold better recovery of strain LaftiTM 8B from mice faeces after oral dosage was noted for cells grown in amylose-containing medium compared with controls. It was concluded that high amylose maize starch granules contributed to enhanced survival of Bifidobacterium sp. LaftiTM 8B and LaftiTM 13B.

Overview of gut flora and probiotics

Scientific developments in recent years have opened new frontiers and enable a better understanding of the gastrointestinal tract (GIT) as a complex and delicately balanced ecosystem. This paper focuses on more recent information related to the microbial population of the GIT and its functional role in human physiology and health. Special attention is also given to modern approaches for improving or stabilising the intestinal system and its functioning by the deliberate application of viable microbial cultures, so-called 'probiotics', selected for special functional properties.

Oral supplementation with lactic acid-producing bacteria during intake of clindamycin

OBJECTIVE: To study the effect of administration of clindamycin with or without supplementation of the intestinal microflora with Bifidobacterium bifidum and Lactobacillus acidophilus. METHODS: Twenty-three healthy subjects received clindamycin by mouth for 7 days. Eleven of the subjects also received capsules containing lyophilized L. acidophilus and B. bifidum for 14 days. The other 12 subjects received placebo. RESULTS: There was a marked decrease in total numbers of anaerobic bacteria during the administration of clindamycin. In the lactic acid bacteria-supplemented group, a tendency towards delayed reduction and earlier increase in bifidobacteria was observed, and two of 11 subjects (18%) were colonized with Clostridium difficile, in comparison with five of 12 (41%) in the placebo group. The total number of microorganisms was significantly higher in the lactic acid bacteria-supplemented group than in the placebo group (p=0.02) 4 days after the end of clindamycin administration. The difference was mainly due to higher counts of Escherichia coli and enterococci. Mean levels of other enterobacteria increased less in the lactic acid bacteria-supplemented group than in the placebo group between days 0 and 14. CONCLUSIONS: The recolonization with aerobic and anaerobic microorganisms was faster in the lactic acid bacteria-supplemented group than in the placebo group. This may be of importance in preventing colonization with C. difficile.

In vitro colonization ability of human colon mucosa by exogenous Lactobacillus strains

We have tested five Lactobacillus strains for their in vitro colonization ability in a human colon epithelium culture model. Positive colonization occurred in different degrees in the presence of four Lactobacillus strains. We have found that L. casei GG and L. acidophilus NCFB 1748 induce an intermediate colonization. These two strains, largely investigated by others, have been reported to be beneficial to humans. The use of human intestinal tissue in our study partially reconstitutes the complex architectural specificity of human epithelium with the mucus layer and more closely simulates the in vivo situation.