IrrE Improves Organic Solvent Tolerance and Delta(1)-Dehydrogenation Productivity of Arthrobacter simplex

During steroid bioconversion, organic solvents are widely used for facilitating hydrophobic substrate dissolution in industry. Thus, strains that tolerate organic solvents are highly desirable. IrrE, a global transcriptional factor, was introduced into Arthrobacter simplex with Delta(1)-dehydrogenation ability. The results evidenced that IrrE did not affect cell biological traits and biotransformation performance under non-stress conditions. However, the recombinant strain achieved a productivity higher than that of the control strain in systems containing more ethanol and substrate, which coincided with cell viability under ethanol stress, the major stress factor during biotransformation. It also demonstrated that IrrE caused genome-wide transcriptional perturbation, and several defense proteins or systems were linked with higher organic solvent tolerance. IrrE simultaneously enhanced cell resistance to various stresses, and its horizontal impacts showed strain and stress dependence. In conclusion, the introduction of exogenous global regulators is an efficient approach to enhance organic solvent tolerance in steroid-transforming strains, resulting in higher productivity.