两阶段pH控制和碳氮源协同补加促进谷氨酸棒杆菌高产L-谷氨酰胺OACSTPCD

To improve the fermentation level,sugar-acid conversion rate,and productivity of L-glutamine production by Corynebacte-rium glutamicum,the contents of glucose,ammonium sulfate,and corn syrup in fermentation medium were optimized using response sur-face methodology.Then the kinetic models for cell growth,substrate consumption and L-glutamine production of batch fermentation in 50 L fermenter were constructed.Furthermore,the strategy of two-stage pH control combined with coordinating the concentrations of car-bon and nitrogen sources by adding glucose and ammonium sulfate in 50 L fermenter was adopted to promote L-glutamine production.The results showed that the optimized fermentation medium contained 167 g/L glucose,61 g/L(NH4)2SO4,and 31 g/L corn syrup,respec-tively.L-Glutamine yield in shaking flask fermentation reached 38.13 g/L,an increase of 34.12％compared with that before optimiza-tion.After 80 h of batch fermentation in 50 L fermenter,L-glutamine yield reached 42.06 g/L,the sugar-acid conversion rate reached 25.85％,and the productivity was 0.53 g/(L·h).The strategy of two-stage pH control combined with synergistic addition of carbon and nitrogen sources in 50 L fermenter significantly promoted L-glutamine production,shortening the fermentation period to 52 h,achieving 68.01 g/L of L-glutamine,33.93％of sugar-acid conversion and 1.31 g/(L·h)of productivity.This study provides valuable guidance for promoting industrial production of L-glutamine by C.glutamicum.