Effects of fructose and maltose as aerobic carbon sources on subsequently anaerobic fermentation by Escherichia coli NZN111 / 生物工程学报

ABSTRACT

To understand the effects of sugar whose uptake is dependent or independent on the phosphotransferase system (PTS), two-stage culture of Escherichia coli strain NZN111 that was constructed by disruption of IdhA and pflB encoding the fermentative lactate dehydrogenase (LDH) and pyruvate formate lyase (PFL) of E. coli W1485, was carried out for organic acids production. When NZN111 was aerobically cultured on fructose (PTS dependent) or maltose (PTS independent), it fermented glucose with succinic acid and pyruvic acid as the major products in subsequent anaerobic culture. The experiments were also performed in a 5-L fermentor. The yields of succinic acid by the fructose-and maltose-grown NZN111 were 0.84 and 0.75 mol/mol, whereas the yields of pyruvic acid were 0.65 and 0.83 mol/mol, respectively. The final ratio of succinic acid to pyruvic acid in the anaerobic stage reached 1.731 and 1.211, respectively. The different behaviors in anaerobic fermentation by the fructose-, maltose- and glucose-grown NZN111 were likely caused by the regulation of catabolite repression in the aerobic culture stage.