Enhancing Corynebacterium glutamicum robustness by over-expressing a gene, mshA, for mycothiol glycosyltransferase

Over-expression of the gene, mshA, coding for mycothiol glycosyl transferase improved the robustness of Corynebacterium glutamicum to various stresses. Intracellular mycothiol (MSH) content was increased by 114 % in WT(pXMJ19-mshA) compared to WT(pXMJ19). Survival rates increased by 44, 39, 90, 77, 131, 87, 52, 47, 57, 85 and 33 % as compared to WT(pXMJ19) under stress by H2O2 (40 mM), methylglyoxal (5.8 mM), erythromycin (0.08 mg ml(-1)), streptomycin (0.005 mg ml(-1)), Cd(2+) (0.01 mM), Mn(2+) (2 mM), formic acid (0.05 %), acetic acid (0.15 %), levulinic acid (0.25 %), furfural (7.2 mM), and ethanol (10 % v/v), respectively. Increased MSH content also decreased the concentration of reactive oxygen species in the presence of the above stresses. Our results may open a new avenue for enhancing robustness of industrial bacteria for production of commodity chemicals.