Adaptive evolution improves acid tolerance and succinic acid production in Actinobacillus succinogenes |
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| Institution: | 1. State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211800, PR China;2. Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, PR China;1. State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;2. University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, China;3. China National Center for Biotechnology Development, Beijing 100036, China;1. Guangxi Key Laboratory of Subtropical Bio-resource Conservation and Utilization, College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530005, China;2. National Non-grain Bio-energy Engineering Research Center, Guangxi Academy of Sciences, Nanning, Guangxi 530007, China;3. Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China;1. State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211816, PR China;2. Department of Biology, College of Natural and Computational Science, Mizan-Tepi University, P.o.box 121, Tepi, Ethiopia;3. Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, PR China |
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| 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 speci?c 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. |
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| Keywords: | Adaptive evolution Acid tolerance Succinic acid Membrane composition |
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