Mutation of genes for cell membrane synthesis in Corynebacterium glutamicum causes temperature-sensitive trait and promotes L-glutamate excretion

A temperature-sensitive mutant of Corynebacterium glutamicum is widely used as the fermentation strain in L-glutamate industrial production. Rapid synthesis of L-glutamate in this type of strain can be triggered by raising the culture temperature. However, the molecular mechanism of the temperature-sensitivity trait and L-glutamate excretion has not been clarified. In this study, we compared the genome sequence of an industrial L-glutamate-producing strain C. glutamicum TCCC11822 with the wild-type strain C. glutamicum ATCC13032. Seven mutant genes related to cell membrane synthesis were screened and separately integrated into the genome of C. glutamticum ATCC13032 to replace the corresponding genes. All the recombinant strains showed temperature-sensitivity and increased L-glutamate excretion. Electron microscopy showed that there was no significant change in cell morphology of recombinant strains at different temperatures. Genotypes found in this article can be applied to the construction of temperature-sensitive engineering strains and the regulation of cell permeability.