Metabolic Analysis of a Corynebacterium glutamicumIdhA Mutant During an Efficient Succinate Production Using pH-Control Under Oxygen Deprivation

Corynebacterium glutamicum produce succinate and lactate from glucose under oxygen deprivation without growth. By deleting the lactate dehydrogenase genes (ldhA), lactate formation could be completely abolished and yield of succinic acid increased up to 0.78 g g−1. With increasing concentration of carbonate, which could regular the pH of culture, the glucose consumption rate has been improved, leading to increase the succinic acid production rates. Interestingly, depending on the pH conditions, there is a sharp increase in the presence of higher concentration carbonate. This phenomenon was investigated by the key metabolic enzymes analysis during different pH condition. A pyruvate carboxylase and malate dehydrogenase played a significant role in succinic production under oxygen deprivation. Succinic acid production by a ldhA mutant was investigated with free pH and constant pH 8.0. Succinic acid production and yield were higher under constant pH 8.0 conditions compared with culture with free pH. In an efficient succinic acid production process, C. glutamicum ATCC 13032 ΔldhA accumulated 67.2 g l−1 succinic acid within 48 h with an average succinic production rate 0.14 g l−1 per cells (dry weight) (cdw) per hour.