Sucrase metabolism in germfree rats.

We studied degradation of the intestinal brush-border protein sucrase-isomaltase in germfree animals as well as in ex-germfree animals and conventional controls to determine the mechanism by which intestinal bacteria alter disaccharidase levels. Our results indicate that sucrase-isomaltase turnover is as rapid in germfree animals as in the other groups and are consistent with surface removal of disaccharidases by pancreatic proteases under physiological conditions. Our results also suggest that elevated disaccharidase levels in germfree animals are in large part the consequence of an increased number of mature enterocytes, which persists for at least 2 wk after exposure of animals to a conventional microbial flora.