A Role of the cspA Gene Encoding a Mycolyltransferase in the Growth under Alkaline Conditions of Corynebacterium glutamicum

Corynebacterium glutamicum is widely used in the industrial production of amino acids. Producer strains are generated by classical random mutagenesis, and therefore have detrimental characteristics caused by unnecessary mutations. Increased alkali sensitivity is one of those undesired characteristics. We found that one of the laboratory strains, AJ12036 Delta cspA Delta cspB, showed decreased growth under alkaline conditions. To clarify which mutation is responsible for alkali sensitivity, we constructed mutant strains carrying the Delta cspA and/or Delta cspB mutations from wild-type strain ATCC13869. We found that disruption of cspA encoding a mycolyltransferase alone caused increased alkali sensitivity. The Delta cspA mutant also showed increased susceptibility to ethambutol, penicillin, and rifampicin. Disruption of cspB had no effect on alkali sensitivity or drug sensitivity. These results indicate that the mycolate layer is important for alkali sensitivity as well as drug susceptibility in this bacterium.