Influence of indigenous microbiota on amount of protein and activities of alkaline phosphatase and disaccharidases in extracts of intestinal mucosa in mice.

The protein content and the activities of alkaline phosphatase, maltase, and sucrase were measured at 0800, 1000, 1200, 1400, and 1600 in saline extracts of the proximal small bowels of germfree and of ex-germfree mice colonized with an indigenous microbiota. In extracts prepared from germfree mice, the total activities of all of the enzymes were relatively constant throughout the sampling period. Likewise, the total activity of alkaline phosphatase in extracts prepared from associated mice varied little as a function of time. By contrast, the total activities of maltase and sucrase in the extracts from these latter animals varied significantly from sample to sample. The total activity levels in extracts from germfree mice were approximately twofold greater than the levels in extracts from associated mice. The specific activities of alkaline phosphatase and sucrase did not vary from sample to sample in extracts prepared from either type of mouse. In contrast, the specific activity of maltase in extracts prepared from both germfree and associated mice differed significantly from sample to sample. The specific activities of all three enzymes were greater in extracts from germfree animals than in those from associated animals. The protein content of extracts prepared from germfree mice also was greater than that of extracts prepared from associated animals at every sampling time. The amount of protein extractable from the mucosa of the small bowels of the former animals varied significantly at different sampling times during the day, whereas the amount of protein extractable from the tracts of associated animals remained relatively constant throughout the day. The indigenous microbiota apparently stabilizes in some way the amount of protein extractable from the mucosa of the mouse small bowel.