Influence of pH and neutralizing agent on anaerobic succinic acid production by a Corynebacterium crenatum strain

Environmental conditions, particularly pH, have significant effects on the efficiency and final titers of bio-based products. Therefore, these factors need to be identified to ensure the fermentation process is economically attractive. In this study, strategies for controlling pH were optimized to enhance succinic acid production by Corynebacterium crenatum J-2. The results indicate that pH 6.8 is the optimal value for anaerobic succinic acid production by C. crenatum J-2 in terms of productivity and titer. The use of Mg(OH)2 as the neutralizing agent for pH control resulted in the highest levels of succinic acid concentration, yield, and productivity; superior to the levels obtained with Ca(OH)2, KOH, and NaOH. Under conditions of pH 6.8 and Mg(OH)2 as the neutralizing agent, 45.7 g/L succinic acid was produced within 12 h during the prophase of anaerobic fermentation, resulting in a succinic acid productivity of 3.8 g/(L·h). Succinic acid concentration reached 53.8 g/L at 22 h, with a productivity of 2.45 g/(L·h). The results of this study will be useful for the development of highly efficient succinic acid production processes utilizing industrial Corynebacterium spp. strains.