Abstract:The mycolic acid layer in Corynebacterium glutamicum (C. glutamicum) plays important role in maintain cell permeability, however, its synthesis consumes substantial energy and substrate in the synthesis process. A mutant strain, Δpks13, was constructed by deleting the polyketide synthase gene pks13 in C. glutamicum ATCC13869. Compared to the wild type, the mutant strain Δpks13 cells were larger, more rounded, and with a loosely bound cell wall that tended to detach easily,while the L-glutamate yield increased 8-fold. Thin layer chromatography and liquid chromatography mass spectrometry analysis revealed that phospholipids were the primary cell wall lipids in Δpks13. Quantitative real-time PCR analysis revealed that, compared with wild-type strain,the transcript level of the glutamate efflux-related gene mscCG was upregulated, while the transcription levels of the α-ketoglutarate dehydrogenase-encoding gene odhA and the downstream arginine synthesis-related gene (argB, argC, argD, argF, argG, argH and argJ) were downregulated in Δpks13 cells. These changes in genes transcription levels explain the mechanism underlying the enhanced L-glutamate production in Δpks13.
