Bacteria tract microflora

Both pirlimycin and its sulfoxide metabolite were partially converted to ribonucleotide adducts by gastrointestinal tract microflora and excreted in feces. Such adducts have been well documented as products of antibiotic inactivation by bacteria for a variety of substances including lincomycin and clindamycin (117-119). 

Fiber components are the principal energy source for colonic bacteria with a further contribution from digestive tract mucosal polysaccharides. Rate of fermentation varies with the chemical nature of the fiber components. Short-chain fatty acids generated by bacterial action are partiaUy absorbed through the colon waU and provide a supplementary energy source to the host. Therefore, dietary fiber is partiaUy caloric. The short-chain fatty acids also promote reabsorption of sodium and water from the colon and stimulate colonic blood flow and pancreatic secretions. Butyrate has added health benefits. Butyric acid is the preferred energy source for the colonocytes and has been shown to promote normal colonic epitheUal ceU differentiation. Butyric acid may inhibit colonic polyps and tumors. The relationships of intestinal microflora to health and disease have been reviewed (10). 

Microflora Microorganisms such as bacteria that normally inhabit the gastrointestinal tract. 

Strains of obligately anaerobic bacteria in rat (and human) intestinal microflora have been shown to produce iodothyronine glucuronidase and sulfatase activities [22,23]. This explains why T4 and T3 appear in feces of rats as free iodothyronines [24] although they are excreted in bile mainly as glucuronide conjugates. Recent studies indicate that a large fraction of T3G introduced in the rat intestinal tract is resorbed as free T3 liberated by bacterial hydrolysis [25,26]. In rats, therefore, glu-curonidation does not seem an irreversible pathway for the elimination of T4 and T3 but an essential step in the enterohepatic cycle of these compounds. 

The gut microflora consist of microorganisms, mainly bacteria, of the gastrointes linal tract. The small intestine of the adult human is about 4.0 m long. The large intestine, or colon, is about one-third this length (1.5 m). Hie colon receives 1.5-2.U liters of water per day, most of which is absorbed- Only lott-200 mi of water is lost in the feces. The colon also absorbs sodium and chloride originating from the diet and from secretions of the small intestine. The lumenal surface of the large intestine secretes mucus, as docs the small intestine. However, the mucosa of the colon contains crypts but lacks villi. 

The microflora of the gastrointestinal tract, which develop shortly after birth, are found in the lumen, associated with remnants of food, on the mucosal surface, and in the crypts. These microorganisms, including prokaryotic and eukaryotic species, tend not to use oxygen in their energy metabolism since they exist in an environment that is essentially anaerobic. Over 99.9% of the bacterial cells are anaerobic, meaning they are unable to use oxygen even when it is provided for them. Of these bacteria, 5-20% are unable to tolerate O2 and die in its presence. 

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