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 ␤-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.Bifidobacteria constitute a significant portion of the intestinal microflora and have beneficial effects on their host (52). These obligate anaerobes (43) compete with other species of intestinal flora and transient organisms for nutrients and attachment sites in the gut (45). Bifidobacteria produce lactic and acetic acids which acidify the large intestine and restrict putrefactive and potentially pathogenic bacteria (46). Bifidobacteria also play an important role in immunostimulation (10, 18), anticarcinogenic activity (21), human pathogen growth inhibition (47), vitamin and amino acid production (8,12,30), and the reduction of the conversion of primary bile salts to secondary bile salts (21,29).Like most intestinal bacteria, bifidobacteria are saccharolytic: they obtain carbon and energy through fermentation of host and dietary carbohydrates. Bifidobacteria catabolize a variety of mono-and oligosaccharides (9, 43) released by glycosyl hydrolases acting on nondigestible plant polysaccharides or host-derived glycoproteins and glycoconjugates (44). Fructooligosaccharides (FOS) and inulin occur naturally in many foods of vegetable origin, such as onions, Jerusalem artichokes, asparagus, leeks, and garlic. They consist of mixtures of fructose moieties linked by ␤-(231)-glycosidic bonds with a terminal glucose unit. FOS have a degree of polymerization (DP) of 2 to 10 and can be produced from sucrose by transfructosylation and from inulin by controlled hydrolysis. Inulin, extracted from chicor...

Thirty-four strains of lactic acid bacteria (seven Bifidobacterium, 11 Lactobacillus, six Lactococcus, and 10 Streptococcus thermophilus) were assayed in vitro for antioxidant activity against ascorbic and linolenic acid oxidation (TAA(AA) and TAA(LA)), trolox-equivalent antioxidant capacity (TEAC), intracellular glutathione (TGSH), and superoxide dismutase (SOD). Wide dispersion of each of TAA(AA), TAA(LA), TEAC, TGSH, and SOD occurred within bacterial groups, indicating that antioxidative properties are strain specific. The strains Bifidobacterium animalis subsp. lactis DSMZ 23032, Lactobacillus acidophilus DSMZ 23033, and Lactobacillus brevis DSMZ 23034 exhibited among the highest TAA(AA), TAA(LA), TEAC, and TGSH values within the lactobacilli and bifidobacteria. These strains were used to prepare a potentially antioxidative probiotic formulation, which was administered to rats at the dose of 10(7), 10(8), and 10(9) cfu/day for 18 days. The probiotic strains colonized the colon of the rats during the trial and promoted intestinal saccharolytic metabolism. The analysis of plasma antioxidant activity, reactive oxygen molecules level, and glutathione concentration, revealed that, when administered at doses of at least 10(8) cfu/day, the antioxidant mixture effectively reduced doxorubicin-induced oxidative stress. Probiotic strains which are capable to limit excessive amounts of reactive radicals in vivo may contribute to prevent and control several diseases associated with oxidative stress.

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.

Restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) is a well-established surgical procedure for the management of ulcerative colitis and familial adenomatous polyposis. 1,2 Pouchitis, a non speci®c in¯ammation of the ileal reservoir, is the most frequent long-term complication following pouch surgery for ulcerative colitis. 3 Its cumulative frequency varies between 7 and 50% depending on the duration of follow-up and de®nition of pouchitis used. 4±6 This syndrome is characterized clinically by the presence of diarrhoea, rectal bleeding, faecal urgency, abdominal cramping, malaise and fever, endoscopically by oedema, granularity, mucus exudate and ulcerations, and histologically by neutrophil in®ltration, crypt abscesses and ulcerations in addition to chronic in¯ammatory in®l-trate. 7,8 Its exact cause(s) are poorly understood and pathogenetic theories abound, including faecal stasis with SUMMARY 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 ef®cacy of an antibiotic combination for chronic active, treatment-resistant pouchitis. Patients and Methods: Eighteen patients were treated orally with rifaximin 1 g b.d. + cipro¯oxacin 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 de®ned 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.