Fig. 2.

The mechanism of glutamate production in C. glutamicum during biotin limitation. a Metabolic flow under the normal culture and biotin limitation conditions. The activity of the 2-oxoglutarate dehydrogenase complex (ODHC) inhibits the synthesis of glutamate and the lipid synthesis is also inhibited by the reduced activity of acetyl-CoA carboxylase, a complex of DtsR and AccBC, under biotin limitation. Under glutamate-producing conditions, oxaloacetate is supplied from phosphoenolpyruvate (Hasegawa et al. 2008). b The ratio of the saturation and unsaturated membrane lipids. c The ratio of membrane lipid components under the normal culture (blue) and biotin limitation conditions (orange) are shown. Note that the plasma membrane of C. glutamicum is exceptional, being exclusively composed of negatively charged phospholipids, phosphatidylglycerol (PG), phosphatidylinositol (PI), phosphatidylinositol mannoside (PIM), phosphatidic acid (PA), and cardiolipin (DPG), respectively