Study of enzymes and relative genes coding for activities involved in polysaccharide degradation in the rumen bacteria Ruminococcus flavefaciens and influence of tannins and flavonoids on Ruminococcus flavefaciens cultures.

Mammals do not secrete the enzymes required to hydrolyse structural polysaccharides therefore they depend upon microbes, which do secrete such enzymes, to utilize fibre as a source of energy. Ruminants have evolved a particularly efficient way of obtaining energy from fibrous materials. Ruminants differ from other herbivores because anaerobic microbial fermentation of the feed occurs prior to chemico-enzymic digestion in the lower gut. This process is primarily affected by degradation rate of the feed and its rate of passage through the rumen. Fibre is extensively colonized by microbes after entering the rumen. This is a mechanism by which the microbes are prevented from being washed out from the rumen and at the same time are attached to an energy source.The most important fibre-degrading microbes are cellulolytic bacteria. These bacteria can degrade substrates by different pathways, consequently producing different end-products. The close association between primary cellulolytic microbes with symbiotic species which remove fibre degradation end-products from the medium is important in maximising efficiency of fibre degradation in the rumen.The rumen is one of the most well studied ecosystems where the microflora is composed of obligate anaerobic bacteria, fungi and protozoa. The plant cell wall polysaccharides are an important renewable energy source and its degradation in the rumen is a very important pathway to reach human. Polysaccharide degradation is carried out by a concerted action of many different hydrolytic enzymes produced by rumen microorganisms (Flint H.J., 1997). These enzyme activities and a good microbial balance among microbe species into the rumen will bring about nutritional, health and animal production through an improvement in nutrient absorption. Many enzymes are involved in polysaccharide degradation, they include cellulases, xylanases and debranching enzymes such as ?-arabinosidases, acetyl xylan esterases, ?-glucuronidases (Aurilia, V., et al. 2000a).It is here reported the study, at molecular level, of polysaccharidase activities from the rumen anaerobic bacterium Ruminococcus flavefaciens and preliminary results on the action of tannins and flavonoids on two strains of Ruminococcus flavefaciens.