Bifidobacteria

Sucrose caramels have been produced under anhydrous thermal conditions that are designed to maximize the content of fructose-rich oligosaccharides.100-102 These sucrose thermal oligosaccharide caramels (STOC) have been tested in animals as a nutritional supplement. Improved weight gains and feed conversion, and increased levels of bifidobacteria (see section VIII) were observed in broiler chickens that were fed this supplement.103... 

Di-D-fructose dianhydrides have been claimed to promote the growth of bifidobacteria in vitro.134 Bifidobacterium spp. are found in the large intestines of most vertebrates.135 The benefits attributed to the presence of a healthy population of bifidobacteria in the gut include inhibition of carcinogenesis,136 suppression of putrefactive substances,137 lowering of blood pressure and blood... 

GIBSON G R, BEATTY E B, WANG X, CUMMINGS J H (1995) Selective stimulation of bifidobacteria in the hiunan colon by oligosaccharides and inulin. Gastroenterology 108 975-82. 

Several bacteria in the natural gut flora or non-pathogenic bacteria which can colonise the gut have been shown to have preventive or even therapeutic effects on pathogens. Most commonly used and studied are bifidobacteria and lactobacilli (see Fig. 13.2) they have been shown to stimulate the innate immune system to produce cytokines, antimicrobial compounds and other metabolites affecting either the host and/or enteric bacteria (Aattouri et al., 2001 Xuan et al., 2001 Kralik et al, 2004 Scharek et al., 2005 Tannock, 2005 Davis et al., 2006). 

The results of many studies (Perin et al, 2000 Schrezenmeir and de Vrese, 2001 Shin et al, 2000 Gmeiner et al, 2000) point to a synergistic effect of probiotic and prebiotic combinations on the faecal microbiota of experimental animals. This effect was demonstrated by increased total anaerobes, aerobes, lactobacilli and bifidobacteria counts as well as by decreased Clostridia, Enterobacteriaceae and E. coli counts. The combination of probiotics and non-digestible carbohydrates may be a way of stabilisation and/or improvement of the probiotic effect. 

The idea that inulin-type fructans are fermented by bacteria colonising the large bowel is supported by many in vitro (both analytic and microbiological) and in vivo studies, which, in addition, confirm the production of lactic and short-chain carboxylic acids as end products of the fermentation (Tanner, 2005). Furthermore, it was shown inhuman in vivo studies that this fermentation leads to the selective stimulation of growth of the bifidobacteria population, making inulin-type fructans the prototypes of prebiotics (Roberfroid, 1997 Roberfroid, 2001). 

Gibson G.R. and Wang X. (1994). Inhibitory effects of bifidobacteria on other colonic bacteria . J Appl Bacteriol, 77, 412-420. 

To understand the role of antibiotics, it is important to understand their effects on the fecal flora. The normal flora consists of a complex bacterial population with 400-500 distinct species of bacteria (table 2a). More than 99% of the total organisms are accounted for by non-sporeforming anaerobic rods [28] the four major species are Bacteroides, bifidobacteria, eubacteria and peptostrepto-cocci [29], Other common species are Escherichia coli, Streptococcus viridans, Streptococcus salivarius and lacto-bacilli. Mette et al. [30] clarified the prevalence of species in fecal flora by listing the four most common anaerobes Bacteroides spp., Eubacterium spp., Bifidobacterium spp. and anaerobic cocci) and three common aerobes E. coli spp., Enterococcus spp. and Lactobacillus spp.) (table 2b). 

As diarrhea is a known and common complication of antibiotic therapy, many approaches have been used for prevention. The use of probiotics administered with the antibiotic is appealing. A probiotic is a live microbial food supplement that beneficially affects the host animal, improving its microbial balance [67], Certain probiotics can reduce the risk and duration of diarrhea [68]. Agents used in prevention of AAD include lactobacilli, such as Lactobacillus GG, Streptococcus faecium, bifidobacteria and the yeast S. boulardii. 

Intestinal Metabolism Intestinal drug metabolism can occur by microflora present in the gut lumen, as well as by enzymes present in luminal fluids and in the intestinal mucosa [166], Metabolism of xenobiotics by gut microflora is low in comparison to metabolism by the gut mucosa and liver [62], However, the intestinal microflora (e.g., Bacteroides and Bifidobacteria) may play an important role in the first-pass metabolism of compounds that are poorly or incompletely absorbed by the gut mucosa, especially in the lower parts of the intestine. This bacterial metabolism is largely degradative,... 

Liepke, C., Adermann, K., Raida, M., Magert, H. J., Forssmann, W. G., and Zucht, H. D. (2002). Human milk provides peptides highly stimulating the growth of bifidobacteria. 

Mixed protein/polysaccharide micro-beads have also been found to be promising delivery vehicles for immobilized bifidobacteria (Guerin et al, 2003). Such micro-beads were made by a transacylation reaction involving the formation of amide bonds between protein and alginate (Levy and Edwards-Levy, 1996). This produces a membrane on the bead surface, protecting the immobilized bifidobacteria against both the very acidic conditions (pH 1-2) and the pepsin activity in the stomach. 

Guerin, D., Vuillemard, J.C., Subirade, M. (2003). Protection of bifidobacteria encapsulated in polysaccharide-protein gel beads against gastric juice and bile. Journal of Food Protection, 66, 2076-2084. 

Bifidobacterium in Food Products. Commonly referred to as bifidobacteria, these microorganisms were discovered by Tissiei (Pasteur Institute) in 1900 in the feces of infants. These bacteria are not true lactic add bactena, such as Lactococcus or Pediococcus, because they produce both acetic and lactic adds Early research was difficult because of the lack of effective laboratory procedures. Considerable research since the mid-1950s, however, has been conducted. Hughes and Hoover (University of Delaware) reported in 1991 on the beneficial qualities of bifidobacteria and the possibility of their use in Bifid -amended food products, notably dairy products. These therapeutic effects include ... 

Hughes, D.B. and D.G. Hoover Bifidobacteria TheirPoientialforUsein American Dairy Products." Food Tech., 74 (April 1991). 

Tsangalis D, Wilcox G, Shah NP, Stojanovska L. 2005. Bioavailability of isoflavone phytoestrogens in postmenopausal women consuming soya milk fermented with probiotic bifidobacteria. Br J Nutr 93 867-877. 

Oligofructose and inulin are known to lower plasma LDL cholesterol, but their mode of action does not involve inhibiting cholesterol absorption (Beylot, 2005 Kaur and Gupta, 2002). As mentioned earlier, oligofructose and inulin are not viscous fibers but rather serve as excellent fuel sources for beneficial intestinal bacteria, particularly lactobacilli and bifidobacteria (Boeckner et al., 2001). In this way, changes in intestinal microflora induced... 

The effects of dietary FOS on the GI microflora of poultry are well documented. Flidaka et ol. (1991) found that consumption of 8 g FOS per day increased numbers of bifidobacteria, improved blood lipid profiles and suppressed putrefactive substances in the intestine. Patterson et d. (1997) found that caecal bifidobacteria concentrations increased 24-fold and lactobacilli populations increased 7-fold in young broilers with FOS. Bifidobacteria may inhibit other microbes because of a high production of volatile fatty acids (VFAs) or the secretion of bacteriocin-like peptides (Burel and Valat, 2007). The improvement in gut health status by dietary FOS supplementation often results in improved growth performance. Ammerman et d. (1988) demonstrated that the addition of dietary FOS at a level of 2.5 or 5.0g/kg diet improved feed efficiency over the period from 1 to 46 days of age. Mortality was reduced with the higher level. However, Waldroup et d. (1993) found that supplementing the diet of broilers with 3.75 g/kg FOS had few consistent effects on production parameters or carcass Sdmonella concentrations. 

The mechanisms by which probiotics (and prebiotics) produce beneficial effects on the gut have not yet been fully elucidated. However, at least three mechanisms of action have been proposed (i) antibacterial agents produced by probiotic organisms may have an inhibitory effect on pathogenic microbes (ii) immune responses may be enhanced to suppress potential pathogens and (iii) competition in the gut epithelium may allow lactic acid bacteria and bifidobacteria to supplant pathogenic organisms. 

---