Error-prone PCR of global transcription factor cyclic AMP receptor protein for enhanced organic solvent (toluene) tolerance

► We have isolated three toluene-tolerant Escherichia coli mutant strains via engineering its global transcription factor cAMP receptor protein (CRP). ► The mutant isolation was achieved within 3-5 days through directed evolution of CRP. ► The best mutant M2 was also tolerant against other organic solvents such as n-hexane, cyclohexane and p-xylene. ► qRT-PCR proved the differential expression of certain organic-solvent stress related genes in the mutant.