Alcohol tolerance of Escherichia coli acrR and marR regulatory mutants

We investigated the alcohol tolerance of Escherichia coli acrR and marR regulatory mutants. The local repressor gene acrR and the global repressor gene marR were deleted either separately or together from the genomic DNA of E. coli for overexpression of AcrAB-TolC. Mutants with ΔacrR background indicated no growth difference in the exponential growth phase and modestly better growth in the stationary growth phase than the parental strain under various concentrations of alcohol. However, single marR mutant did not show any better growth than the parental strain in the presence of butanol and isobutanol although the efflux pump AcrAB-TolC was upregulated.