soxRS gene increased the level of organic solvent tolerance in Escherichia coli

Escherichia coli strain JA300 grows in the presence of n-hexane, but not in the presence of cyclohexane. We isolated a 10.5-kb DNA fragment that provided cyclohexane tolerance on a multi-copy plasmid, from the chromosomal DNA of JA300. In this fragment, there were found C-terminal 10-amino acids truncated soxR (soxR') and soxS which control the superoxide response regulon genes. Characterization of subclones found that both the soxR' and overexpression of the soxS increased the levels of organic solvent tolerance in several E. coli strains.