The role of trehalose biosynthesis on mycolate composition and L-glutamate production in Corynebacterium glutamicum

Corynebacterium glutamicum has been widely utilized for the industrial production of various amino acids. Trehalose is a prerequisite for the biosynthesis of mycolates which are structurally important constituents of the cell envelope in C. glutamicum. In this study, C. glutamicum mutant ASYA, which is unable to synthesize trehalose was constructed by deleting genes treS, treY and otsA in the three pathways of trehalose biosynthesis. In the fermentation medium, ASYA grew as well as the control C. glutamicum ATCC13869, synthesized similar levels of glucose monocorynomycolate, trehalose dicorynomycolate, and phospholipids to ATCC13869, but produced 12.5 times more L-glutamate than ATCC13869. Transcriptional levels of the genes relevant to L-arginine biosynthesis, encoding ODHC and relevant to the biosynthesis of sulfur-containing amino acids were down -regulated in ASYA. In minimal medium with different concentrations of glucose, ASYA grew worse than ATCC13869 but excreted more L-glutamate. When grown in minimal medium, phospholipids are the major lipid in ASYA, while glucose monocorynomycolate, trehalose dicorynomycolate, and phospholipids are the major lipid in ATCC13869. The transcriptional levels of mscCG in ASYA was significantly up-regulated when grown in minimal medium.