Abstract
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, AJ12036ΔcspAΔcspB, showed decreased growth under alkaline conditions. To clarify which mutation is responsible for alkali sensitivity, we constructed mutant strains carrying the ΔcspA and/or ΔcspB mutations from wild-type strain ATCC13869. We found that disruption of cspA encoding a mycolyltransferase alone caused increased alkali sensitivity. The ΔcspA 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.
