rpoS gene function is a disadvantage for Escherichia coli BJ4 during competitive colonization of the mouse large intestine

The ability of Escherichia coli to survive stress during growth in differen t environments is, in large part, dependent on rpoS and the genes that comp rise the rpoS regulon. E. coli BJ4 and an isogenic BJ4 rpoS mutant were use d to examine the influence of the rpoS gene on E. coli colonization of the streptomycin-treated mouse large intestine. Colonization experiments in whi ch the wild-type E. coli BJ4 and its rpoS mutant were fed individually as w ell as simultaneously to mice suggested that E. coli BJ4 does not face prol onged periods of nutrient starvation in the mouse large intestine and that the rpoS regulon is not expressed during long-term colonization after adapt ation of the bacteria to the gut environment.