Enhancement of succinic acid production by osmotic-tolerant mutant strain of Actinobacillus succinogenes

Fermentation and succinic acid production by Actinobacillus succinogenes YZ0819 was inhibited by high NaCl. To enhance the resistance of this strain to osmotic stress, an NaCl-tolerant mutant strain of A. succinogenes (CH050) was screened and selected through a continuous culture using survival in 0.7 M NaCl as the selection criterion. Using Na₂CO₃ as the pH regulator and glucose as the carbon source in batch fermentation, the isolated osmo-resistant stain, A. succinogenes CH050, produced up to 66 g/l succinic acid with a yield of 73.37% (w/w). The concentration of succinic acid and mass yield were increased by 37.5 and 4.37%, respectively, compared to the parent strain. The dry cell weight reached 10.1 g/l, which is 37% higher than that of the parent strain. The high tolerance of A. succinogenes CH050 to osmotic stress increased improved the succinic acid production from batch fermentation.