Probiotic bacteria, mostly belonging to the genera Lactobacillus and Bifidobacterium, confer a number of health benefits to the host, including vitamin production. With the aim to produce folate-enriched fermented products and/or develop probiotic supplements that accomplish folate biosynthesis in vivo within the colon, bifidobacteria and lactobacilli have been extensively studied for their capability to produce this vitamin. On the basis of physiological studies and genome analysis, wild-type lactobacilli cannot synthesize folate, generally require it for growth, and provide a negative contribution to folate levels in fermented dairy products. Lactobacillus plantarum constitutes an exception among lactobacilli, since it is capable of folate production in presence of para-aminobenzoic acid (pABA) and deserves to be used in animal trials to validate its ability to produce the vitamin in vivo. On the other hand, several folate-producing strains have been selected within the genus Bifidobacterium, with a great variability in the extent of vitamin released in the medium. Most of them belong to the species B. adolescentis and B. pseudocatenulatum, but few folate producing strains are found in the other species as well. Rats fed a probiotic formulation of folate-producing bifidobacteria exhibited increased plasma folate level, confirming that the vitamin is produced in vivo and absorbed. In a human trial, the same supplement raised folate concentration in feces. The use of folate-producing probiotic strains can be regarded as a new perspective in the specific use of probiotics. They could more efficiently confer protection against inflammation and cancer, both exerting the beneficial effects of probiotics and preventing the folate deficiency that is associated with premalignant changes in the colonic epithelia.

The utilization of fructooligosaccharides (FOS) and inulin by 55 Bifidobacterium strains was investigated. Whereas FOS were fermented by most strains, only eight grew when inulin was used as the carbon source. Residual carbohydrates were analyzed by high-performance anion-exchange chromatography with pulsed amperometric detection after batch fermentation. A strain-dependent capability to degrade fructans of different lengths was observed. During batch fermentation on inulin, the short fructans disappeared first, and then the longer ones were gradually consumed. However, growth occurred through a single uninterrupted exponential phase without exhibiting polyauxic behavior in relation to the chain length. Cellular β-fructofuranosidases were found in all of the 21 Bifidobacterium strains tested. Four strains were tested for extracellular hydrolytic activity against fructans, and only the two strains which ferment inulin showed this activity. Batch cultures inoculated with human fecal slurries confirmed the bifidogenic effect of both FOS and inulin and indicated that other intestinal microbial groups also grow on these carbon sources. We observed that bifidobacteria grew by cross-feeding on mono- and oligosaccharides produced by primary inulin intestinal degraders, as evidenced by the high hydrolytic activity of fecal supernatants. FOS and inulin greatly affected the production of short-chain fatty acids in fecal cultures; butyrate was the major fermentation product on inulin, whereas mostly acetate and lactate were produced on FOS.

The ability of 76 Bifidobacterium strains to produce folate was investigated. In order to evaluate folic acid productivity, bifidobacteria were cultivated in the folate-free semisynthetic medium SM7. Most of the tested strains needed folate for growth. The production and the extent of vitamin accumulation were not a function of species but were distinctive features of individual strains. Six strains among the 17 that grew without folate produced significantly higher concentrations of vitamin (between 41 and 82 ng ml ⁻¹ ). The effects of exogenous folate and p -aminobenzoic acid (PABA) concentrations on folate production were evaluated. In contrast to most of the other strains, the folate yield of B. adolescentis MB 239 was not negatively affected by either PABA or exogenous folic acid. Folate production by B. adolescentis MB 239 was studied in the pH range of the colonic environment, and a comparison of folate production on raffinose, lactose, and fructo-oligosaccharides, which belong to three important groups of fermentable intestinal carbon sources, was established. Differences in folate biosynthesis by B. adolescentis MB 239 were not observed as a function either of the pH or of the carbon source. Fecal culture experiments demonstrated that the addition of B. adolescentis MB 239 may increase the folate concentration in the colonic environment.

Background: : Pouchitis is the major long‐term complication after ileal pouch‐anal anastomosis for ulcerative colitis. About 15% of patients have a chronic, treatment‐resistant disease.Aims: : To evaluate the efficacy of an antibiotic combination for chronic active, treatment‐resistant pouchitis.Patients and Methods: : Eighteen patients were treated orally with rifaximin 1 g b.d. + ciprofloxacin 500 mg b.d. for 15 days. Symptoms assessment, endoscopic and histological evaluations were performed at screening and after 15 days using the Pouchitis Disease Activity Index (PDAI). Improvement was defined as a decrease of at least 3 points in PDAI score, and remission as a PDAI score of 0. Systemic absorption of rifaximin was determined by high performance liquid chromatography. Faecal samples were collected before and after antibiotic treatment for stool culture.Results: : Sixteen out of 18 patients (88.8%) either improved (n=10) or went into remission (n=6); the median PDAI scores before and after therapy were 11 (range 9–17) and 4 (range 0–16), respectively (P < 0.002). No side‐effects were reported. Rifaximin plasma levels and urinary excretion were negligible, confirming its mainly topical activity. A significant decrease in total anaerobes and aerobes, enterococci, lactobacilli, bifidobacteria and bacteroides in faecal samples was observed, while the reduction in number of coliforms and Clostridium perfringens did not reach a statistical significance.Conclusions: : A combination of rifaximin and ciprofloxacin was effective in patients with active chronic, treatment‐resistant pouchitis, suggesting the need, in these patients, for treatment using antibiotic agents with wide antibacterial spectrum of activity.

Summary: Cereal fibres such as wheat bran are considered to offer human health benefits via their impact on the intestinal microbiota. We show here by 16S rRNA gene‐based community analysis that providing amylase‐pretreated wheat bran as the sole added energy source to human intestinal microbial communities in anaerobic fermentors leads to the selective and progressive enrichment of a small number of bacterial species. In particular, OTUs corresponding to uncultured L achnospiraceae ( F irmicutes) related to E ubacterium xylanophilum and B utyrivibrio spp. were strongly enriched (by five to 160 fold) over 48 h in four independent experiments performed with different faecal inocula, while nine other Firmicutes OTUs showed > 5‐fold enrichment in at least one experiment. Ferulic acid was released from the wheat bran during degradation but was rapidly converted to phenylpropionic acid derivatives via hydrogenation, demethylation and dehydroxylation to give metabolites that are detected in human faecal samples. Pure culture work using bacterial isolates related to the enriched OTUs , including several butyrate‐producers, demonstrated that the strains caused substrate weight loss and released ferulic acid, but with limited further conversion. We conclude that breakdown of wheat bran involves specialist primary degraders while the conversion of released ferulic acid is likely to involve a multi‐species pathway.