LAUSR

The FEt and FGl derivatives of the E. coli K-12 MG1655 and YA1461 strains with improved ethanol and glycerol utilization, respectively, under aerobic conditions were obtained by laboratory adaptive evolution. These fitness strains have a shorter lag-phase and higher growth rate on glucose, xylose, and their mixture as compared with the parental strains. DNA sequencing and cross-transduction analysis showed that the change in the growth rate of the rifampicin-resistant fitness mutants FGl and YA1461 RifRII are caused by mutations in the rpoB gene encoding the RNA polymerase β-subunit. These mutations affect conservative amino acid segments, which leads to the amino acid substitutions of RpoBD483G and RpoBH526N, respectively.