Adaptive evolution improves acid tolerance and succinic acid production in Actinobacillus succinogenes. (November 2020)

• Record Type: Journal Article
• Authors: Zhang, Wenming; Tao, Yuxuan; Wu, Min; Xin, Fengxue; Dong, Weiliang; Zhou, Jie; Gu, Jiacheng; Ma, Jiangfeng; Jiang, Min
• Is Part Of: Process biochemistry. Volume 98(2020)
• Page Start: 76
• Page End: 82
• Publication Date: 2020-11
• Subjects: Adaptive evolution -- Acid tolerance -- Actinobacillus succinogenes -- Succinic acid -- Membrane composition; Biochemical engineering -- Periodicals; Biotechnology -- Periodicals; Biochemistry -- periodicals; Biotechnology -- periodicals; Chemical Engineering -- periodicals; Génie biochimique -- Périodiques; Biotechnologie -- Périodiques; Biochemical engineering; Biotechnology; Periodicals; 660.63
• DOI: 10.1016/j.procbio.2020.08.003
• Languages: English
• ISSNs: 1359-5113

Abstract

Graphical abstract: Highlights: An acid-tolerant mutant of A. succinogenes was obtained by adaptive evolution. A 20.77 g/L of succinic acid titer with a yield of 0.63 g/g was achieved at pH 5.8. The activities of specific enzymes with ATP generation were significantly increased. Membrane unsaturated fatty acids of mutant were increased under low pH condition. Abstract: Fermentation at low pH is an efficient way to improve the competitiveness of biological succinic acid-producing process. Actinobacillus succinogenes shows good performance of succinic acid production under anaerobic conditions, but its succinic acid production capability at the low-pH is inefficient due to the poor acid resistance. Herein, a mutant A. succinogenes BC-4 with improved cell growth and succinic acid production under weak acid conditions was obtained by adaptive evolution. The specific growth rate and succinic acid production of BC-4 reached 0.13 g/L/h and 20.77 g/L, which were increased by 3.25- and 2.95- fold, respectively compared with the parent strain under anaerobic condition at pH 5.8. The activities of specific enzymes with ATP generation were significantly enhanced under weak acidic conditions, resulting in 1.28-fold increase in the maximum ATP level. Membrane fatty acid composition analysis demonstrated that the ratio of saturated to unsaturated fatty acids was decreased from 1.62 to 1.44 in mutant BC-4, leading to improved intracellular pH homeostasis. Furthermore, the change from long-chain to median-chain fatty acid might lower the permeability of H + into cytoplasm for survival under acid stress. These results indicated that A. succinogenes BC-4 is a promising candidate for succinic acid production under weak acid condition.