Fig. 4
Analysis of GFP expression in KpPPEPCKGFP (A)and KpPGDH2GFP (B) cultured in YNB-MSG, YNBE and YNBE-MSG for 6 h, 24 h and 48 h by live cell imaging under a fluorescence microscope. See text for details. C Schematic representation of biochemical events taking place during ethanol-MSG co-feeding. Ammonia generated during the conversion of glutamate to α-ketoglutarate (α-KG) by GDH2 combines with H+ generated during ethanol metabolism and the resulting NH4+ is utilized for biochemical reactions such as glutamine biosynthesis catalyzed by glutamine synthetase. Oxaloacetate (OAA) synthesized from α-KG induces synthesis of PEPCK and the recombinant proteins via the PPEPCK-translational regulatory circuit [4]. PEPCK converts OAA to phosphoenolpuruvate (PEP) which is utilized in gluconeogenesis. Acetyl Co-A and OAA generated from ethanol and glutamate metabolism enter mitochondrial TCA cycle and contribute to ATP which is utilized for growth and generation of biomass