Elucidation of the mechanisms of environmental adaptation of Escherichia coli in murine intestine

The mammalian gastrointestinal microbiota is robust to exogeneous perturbation and adapts to the intestinal environment, during which, advantageous mutations could be accumulated. In this study, we focused on the genomic mutation of gut microbes during intestinal colonization. To identify advantageous mutations, we inoculated Escherichia coli K-12 hypermutator strain to germ-free (GF) mice. After 3 months of colonization, mutations on six sugar metabolism-related genes accumulated in the bacterial genome. In order to determine the gene most responsible for adaptive colonization, we performed a competition assay using single mutants of the six genes and wild type strain in the murine intestine. As a result, gatC mutant overcame other strains. To elucidate the mechanism of gatC mutant dominance, we performed RNA-seq with WT and gatC mutant strain.