[Lactose--a potential dietary fiber. The regulation of its microecologic effect in the intestinal tract. 3. Dietary fiber actions of lactose due to microbial activity].

The activity of the mucosal beta-galactosidase of caecum and colon is low in both germfree and conventional rats. beta-Galactosidase activity occurs also in the chymus of germfree rats. It increases after monoassociation and is higher in conventional than in germfree animals. Lactose entering caecum and colon acts like dietary fibre and is hydrolysed mainly by the intestinal flora. Aerobe lactobacilli and bacteroides predominate in the microflora of rat caecum and colon. A lactose-containing diet increases the total number of germs and stimulates the growth of bifidobacteria. After special diets, rich in lactose and low in protein and phosphate (e.g. human milk and similar formulae), the number of bacteroides and other putrefactive germs decreases. Moreover, a lactose-containing diet alters the metabolic activity of intestinal microorganisms (activity of microbial beta-galactosidase, acidification and lowering of ph in the chymus, production of hydrogen, proteolytic activity.) Lactose as dietary fibre decreases the nitrogen excretion in the urine and increases the N-excretion in the faeces of conventional rats.