Role of intestinal microbes on body nitrogen accumulation in germfree, gnotobiotic and conventional mice.

In order to observe the influence of intestinal microbes, nitrogen (N) of the carcasses and of the gut contents of 80-day-old germfree (GF), Escherichia coil (E. coil) or Staphylococcus epidermidis (Staph.) mono contaminated (at 56 days of age) gnotobiotic (GB) and conventional (CV) mice was estimated. The body weight of CV mice was greater than that of GF and both GB mice. The same tendencies were also shown in the weights of liver and kidney. However, there were no remarkable differ ences between GF and GB mice. Total N of the whole carcass per 100 g of body weight (except for intestinal contents) of CV mice was higher than that of other mice. The rank was CV, Staph., E. coli and GF mice. There was no major difference in 15N accumulation in the whole carcass, liver and leg muscles of three mice in each group two days after they were given a 0.2% "N-labelled secondary ammonium phosphate-supplemented diet in any group, but accumulation in CV mice tended to be higher than in GF and GB mice. Total N of the whole intestinal contents per 100 g of body weight was high in GF, E. coil, Staph. and CV mice in that, order. N in cecal contents in GF and both GB mice was remarkably higher than that in CV mice. The ratio of pro tein N to total N of gut contents showed almost the same tendencies in all groups until the lower part of the small intestine, however from the cecum the tendencies were different. CV mice showed an especially high protein N ratio and high total N per unit chromic oxide of intestinal contents until the cecum, but they decreased in the colon and rectum, which might suggest more reabsorption of non-protein N in the cecum, colon and rectum than in GF and both GB mice.