Expression of TolC and Organic Solvent Tolerance of Escherichia Coli Ciprofloxacin Resistant Mutants

AcrAB-TolC is a major efflux pump in Escherichia coli. It was reported that tolC is overexpressed and involves in improving the organic solvent tolerance level in Escherichia coli marR mutants that are resistant to several antibiotics, such as ciprofloxacin. Low and intermediate levels resistance did not improve organic solvent tolerance. Thus, it was decided to measure tolC expression and organic solvent tolerance in high level ciprofloxacin resistant mutants. tolC expression was measured by real time PCR and organic solvent tolerance assay was conducted by counting bacterial colonies on LBGMg agar. Results showed that tolC expression was increased significantly (P<0.05) and organic solvent tolerance was slightly improved in high resistant mutants. It was concluded that high organic solvent tolerance may need higher expression of tolC.