Title
Oligofructose contributes to the protective role of bifidobacteria in experimental necrotising enterocolitis in quails.
Author
Catala I; Butel MJ; Bensaada M; Popot F; Tessedre AC; Rimbault A; Szylit O
Source
J Med Microbiol, 1999 Jan, 48:1, 89-94
Abstract
Bifidobacteria are dominant in the gut of full-term infants, although colonisation by them is often delayed in preterm neonates. Bifidobacteria are recognised to have beneficial effects on digestive disorders and they might prevent neonatal necrotising enterocolitis (NEC), a gastrointestinal disease that predominantly affects premature infants. They have been shown to protect gnotobiotic quails against NEC-like lesions when the birds were inoculated with faecal flora from preterm infants, decreasing the clostridial population. The present study was designed to investigate whether oligofructose, which stimulates the activity of bifidobacteria, may enhance their protective role. Experiments were done in eight groups of germ-free quails for 28 days. The groups differed as to their bacterial status, diet and environment. Quails were inoculated with one of two flora from premature twins. The first flora included Bifidobacterium pseudo-catenulatum, Escherichia coli and no clostridia. The second flora included clostridial species and was associated with B. infantis-longum. Caecal bacterial population and metabolism changes were investigated with a lactose (6%) diet versus a lactose-oligofructose (3%-3%) diet, either in a gnotobiotic environment or in an ordinary environment permitting post-colonisation by exogenous bacteria. In both environments and with both flora, oligofructose significantly increased the level of bifidobacteria and this was associated with a decrease of E. coli or C. perfringens and C. ramosum. The bacterial changes in the ordinary environment depended on the initial composition of the microflora and the colonisation resistance against exogenous bacteria was more efficient with the flora that included B. pseudo-catenulatum. The changes in caecal pH and short-chain fatty acids were minimal. It was demonstrated that, irrespective of the environmental conditions, the use of oligofructose helped to prevent the overgrowth of bacteria implicated in necrotising enterocolitis in preterm neonates.

Title
Administration of transgalacto-oligosaccharides increases fecal bifidobacteria and modifies colonic fermentation metabolism in healthy humans.
Author
Bouhnik Y; Flourié B; DAgay Abensour L; Pochart P; Gramet G; Durand M; Rambaud JC
Source
J Nutr, 1997 Mar, 127:3, 444-8
Abstract
Transgalacto-oligosaccharides are a mixture of oligosaccharides consisting of glucose and galactose; they are not digested in the human small intestine. In vitro, they specifically stimulate the growth of bifidobacteria. The aim of the present work was to assess tolerance of transgalacto-oligosaccharides and the effects of their prolonged administration on bifidobacteria and fermentative activity of colonic flora. Eight healthy subjects were given 10 g of transgalacto-oligosaccharides per day for 21 d in two daily doses. A breath test and stool sample collection were carried out on d 1, 7, 14 and 21 of transgalacto-oligosaccharides ingestion. The stools of three subjects were collected and mixed before the study, and then inoculated in vitro into a fermentor to which 10 g transgalacto-oligosaccharides was added daily for 14 d. In the eight volunteers, administration of transgalacto-oligosaccharides led to a significant decrease in breath hydrogen excretion (P < 0.01) and a significant increase in fecal concentrations of bifidobacteria from (means +/- SEM) 8.6 +/- 0.6 to 9.7 +/- 0.5, 9.7 +/- 0.6 and 9.5 +/- 0.6 log colony-forming units (CFU)/g on d 1, 7, 14 and 21, respectively (P < 0.05). Fecal concentrations of enterobacteria, as well as stool weight, fecal water and pH did not change during the study. In vitro, transgalacto-oligosaccharides fermentation became more efficient and faster with time. In addition, metabolic alterations such as a rise in acetate proportion and lactate formation after 7 d of fermentation were observed, indicating the transformation of the inoculated fecal flora into an acid-resistant lactic flora. Prolonged administration of transgalacto-oligosaccharides, at a dose which does not induce digestive symptoms, increases the number of bifidobacteria and alters the fermentative activity of colonic flora in humans.

Title
Improvement of lactose digestion in humans by ingestion of unfermented milk containing Bifidobacterium longum.
Author
Jiang T; Mustapha A; Savaiano DA
Source
J Dairy Sci, 1996 May, 79:5, 750-7
Abstract
Fifteen lactose malabsorbers were studied to evaluate the effects of consumption of milk containing different strains of Bifidobacterium longum on lactose digestion. Influences of different growth substrates, bile sensitivity, and lactose transport on lactose digestion by bifidobacteria were also investigated. Lactose malabsorption was determined by measuring breath hydrogen excretion of subjects fed four different test milks (three of which contained 5 x 10(8) cfu/ml of B. longum) on 4 different d using a randomized, double-blinded trial. Test milks included 1) 400 ml of lowfat milk (control), 2) 400 ml of milk containing B. longum B6 that had been grown with lactose, 3) 400 ml of milk containing B. longum B6 grown with lactose plus glucose, or 4) 400 ml of milk containing B. longum ATCC 15708 grown with lactose. beta-Galactosidase activity was highest in milk containing B6 grown with lactose but was extremely low in milk containing B6 grown with lactose and glucose. Consumption of milk containing B6 grown with lactose resulted in significantly less hydrogen production and flatulence than occurring after consumption of control milk or the milk containing B6 grown with both lactose and glucose. Hydrogen production after ingestion of 15708 was also significantly lower than hydrogen production after ingestion of the control milk. We concluded that milks containing B. longum might reduce breath hydrogen response and symptoms from lactose malabsorption when the culture is grown in a medium containing only lactose to induce a higher beta-galactosidase level and increase rate of lactose uptake.

Title
Feeding human milk to rats increases Bifidobacterium in the cecum and colon which correlates with enhanced folate status.
Author
Krause LJ; Forsberg CW; OConnor DL
Source
J Nutr, 1996 May, 126:5, 1505-11
Abstract
The purpose of this investigation was to determine if feeding diets containing human milk resulted in increased numbers of microorganisms implicated in increased folate production and the effect on folate availability. Following a folate-depletion period (5 wk), 30 rats were fed folate-repletion diets (4 wk) with or without 20% milk solids (human, cow or goat) and containing either 906 or 4530 nmol folic acid/kg. At the end of the test period, the cecum and colon were removed in an anaerobic chamber, homogenized, diluted (10(-2) -10(-8)), and the contents of each plated on selective and nonselective media. In addition to enumeration of the total anaerobic load, five genera of bacteria were counted (Bacteroides, Bifidobacterium, Clostridium, Escherichia and Streptococcus). Rats fed human milk solids had at least a seven- and onefold mean increase in the Bifidobacterium concentration in the cecum (P < 0.006) and colon (P < 0.04), respectively, compared with rats fed other diets. The total anaerobic bacterial concentration in the cecum and the colon of rats fed human milk solids was also greater than that of rats fed the other diets (P < 0.05). The single exception was the total anaerobic count in the cecum of rats consuming goat milk solids, which did not differ from that of rats consuming human milk solids. Further, rats fed human milk solids had at least a 42 and 48% higher mean plasma folate concentration and total cecal material folate content, respectively, than rats in other dietary treatments containing 906 nmol/kg folic acid. Therefore, the improved folate status of rats fed human milk-containing diets appears to be due, at least in part, to increased folate synthesis by Bifidobacteria and other folate-synthesizing microbes in the cecum and colon.

Title
Adhesion of different bifidobacteria strains to human enterocyte-like Caco-2 cells and comparison with in vivo study.
Author
Crociani J; Grill JP; Huppert M; Ballongue J
Source
Lett Appl Microbiol, 1995 Sep, 21:3, 146-8
Abstract
The validity of the in vitro adhesion tests performed with cultured cell lines, was determined in this study by comparison with results obtained in vivo, in a previous study. To make this experiment the in vitro adhesion tests were performed during a long period by utilization of an appropriate medium, to determine the capacity of the adhered strain to colonize the intestinal tract. It was demonstrated that the ability of the strain to adhere and colonize the intestinal cell in vivo or the cultured intestinal cells in intro was similar.

Title
Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics.
Author
Gibson GR; Roberfroid MB
Source
J Nutr, 1995 Jun, 125:6, 1401-12
Abstract
Because the human gut microbiota can play a major role in host health, there is currently some interest in the manipulation of the composition of the gut flora towards a potentially more remedial community. Attempts have been made to increase bacterial groups such as Bifidobacterium and Lactobacillus that are perceived as exerting health-promoting properties. Probiotics, defined as microbial food supplements that beneficially affect the host by improving its intestinal microbial balance, have been used to change the composition of colonic microbiota. However, such changes may be transient, and the implantation of exogenous bacteria therefore becomes limited. In contrast, prebiotics are nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacterial species already resident in the colon, and thus attempt to improve host health. Intake of prebiotics can significantly modulate the colonic microbiota by increasing the number of specific bacteria and thus changing the composition of the microbiota. Nondigestible oligosaccharides in general, and fructooligosaccharides in particular, are prebiotics. They have been shown to stimulate the growth of endogenous bifidobacteria, which, after a short feeding period, become predominant in human feces. Moreover, these prebiotics modulate lipid metabolism, most likely via fermentation products. By combining the rationale of pro- and prebiotics, the concept of synbiotics is proposed to characterize some colonic foods with interesting nutritional properties that make these compounds candidates for classification as health-enhancing functional food ingredients.

Title
Dietary modulation of the human gut microflora using prebiotics.
Author
Gibson GR
Source
Br J Nutr, 1998 Oct, 80:4, S209-12
Abstract
The human colonic flora has both beneficial and pathogenic potentials with respect to host health. There is now much interest in manipulation of the microbiota composition in order to improve the potentially beneficial aspects. The prebiotic approach dictates that non-viable food components are specifically fermented in the colon by indigenous bacteria thought to be of positive value, e.g. bifidobacteria, lactobacilli. Any food ingredient that enters the large intestine is a candidate prebiotic. However, to be effective, selectivity of the fermentation is essential. Most current attention and success has been derived using non-digestible oligosaccharides. Types primarily being looked at include those which contain fructose, xylose, soya, galactose, glucose and mannose. In particular, fructose-containing oligosaccharides, which occur naturally in a variety of plants such as onion, asparagus, chicory, banana and artichoke, fulfil the prebiotic criteria. Various data have shown that fructo-oligosaccharides (FOS) are specifically fermented by bifidobacteria. During controlled feeding studies, ingestion of these prebiotics causes bifidobacteria to become numerically dominant in faeces. Recent studies have indicated that a FOS dose of 4 g/d is prebiotic. To exploit this concept more fully, there is a need for assessments of (a) improved determination of the gut microbiota composition and activity; (b) the use of molecular methodologies to assess accurately prebiotic identities and develop efficient bacterial probing strategies; (c) the prebiotic potential of raw and processed foods; and (d) the health consequences of dietary modulation.

Title
Antibiotic susceptibility of potentially probiotic Bifidobacterium isolates from the human gastrointestinal tract.
Author
Charteris WP; Kelly PM; Morelli L; Collins JK
Source
Lett Appl Microbiol, 1998 May, 26:5, 333-7
Abstract
Sixteen Bifidobacterium isolates from the human gastrointestinal tract were assayed for susceptibility to 44 antibiotics by soft agar overlay disc diffusion on TPY agar. Five isolates (3/7 B. bifidum and 2/3 B. breve) exhibited atypical antibiotic susceptibility profiles. Poor growth in the agar overlay accounted for susceptibility of B. bifidum but not B. breve isolates. All other isolates were resistant to cefoxitin (30 micrograms), aztreonam (30 micrograms), vancomycin (30 micrograms), amikacin (30 micrograms), gentamicin (10 micrograms), kanamycin (30 micrograms), streptomycin (10 micrograms), fusidic acid (10 micrograms), trimethoprim (5 micrograms), norfloxacin (10 micrograms), nalidixic acid (30 micrograms), metronidazole (5 micrograms), polymyxin B (300 micrograms) and colistin sulphate (10 micrograms), and they were susceptible to the six penicillins studied, cephalothin (30 micrograms), cefuroxime (30 micrograms), cefaclor (30 micrograms), ceftizoxime (30 micrograms), cefotaxime (30 micrograms), bacitracin (10 micrograms), chloramphenicol (30 micrograms), erythromycin (15 micrograms), clindamycin (2 micrograms), rifampicin (5 micrograms) and nitrofurantoin (300 micrograms). In addition, they varied in their susceptibility to cephradine (30 micrograms), cephazolin (30 micrograms), cefoperazone (75 micrograms), ceftriaxone (30 micrograms), ofloxacin (5 micrograms) and furazolidone (15 micrograms). They were resistant, or only marginally moderately susceptible, to ceftazidime (30 micrograms), netilmicin (10 micrograms), sulphamethoxazole (100 micrograms), cotrimoxazole (25 micrograms) and ciprofloxacin (5 micrograms), and susceptible or marginally moderately susceptible to tetracycline (30 micrograms). All B. bifidum isolates were susceptible to cefixime (5 micrograms). Four microorganism-drug combinations were evaluated for beta-lactamase activity but its absence suggested that cell wall impermeability was responsible for cephalosporin resistance among bifidobacteria. The antibiotic susceptibility of B. animalis 25527T was similar to that of the human isolates.