An efficient succinic acid production process in a metabolically engineered Corynebacterium glutamicum strain.

A Corynebacterium glutamicum strain (DeltaldhA-pCRA717) that overexpresses the pyc gene encoding pyruvate carboxylase while simultaneously exhibiting a disrupted ldhA gene encoding L-lactate dehydrogenase was investigated in detail for succinic acid production. Succinic acid was shown to be efficiently produced at high-cell density under oxygen deprivation with intermittent addition of sodium bicarbonate and glucose. Succinic acid concentration reached 1.24 M (146 g l(-1)) within 46 h. The yields of succinic acid and acetic acid from glucose were 1.40 mol mol(-1) (0.92 g g(-1)) and 0.29 mol mol(-1) (0.10 g g(-1)), respectively. The succinic acid production rate and yield depended on medium bicarbonate concentration rather than glucose concentration. Consumption of bicarbonate accompanied with succinic acid production implied that added bicarbonate was used for succinic acid synthesis.