title: [Isolation of high osmotic-tolerant mutants of Escherichia coli for succinic acid production by metabolic evolution].
abstract: Succinic acid production was inhibited by high osmotic pressure caused by the accumulation of sodium ions in the process of two-stage fermentation by Escherichia coli using Na2CO3 as the pH regulator. To enhance the resistance of this strain to osmotic stress, the possibility to isolate high NaCl-tolerant mutant strain of Escherichia coli for succinic acid production by metabolic evolution was investigated. The metabolic evolution system was used as a mutant-generating system, allowing the cells to be continuously cultured at the maximum specific growth rate. The mutant strain can grow at maximum rate in the condition of high osmotic by gradually improving the concentration of NaCl in a continuous culture. Then the high osmotic-tolerant mutant strain of E. coli XB4 was selected with NaCl as the osmo-regulator. When using Na2CO3 as the pH regulator, E. coli XB4 was used in a 7.0 L fermenter during two-stage fermentation. After 60 h anaerobic fermentation, the mutant strain XB4 produced 69.5 g/L succinic acid with a productivity of 1.18 g/(L x h), which were increased by 18.6% and 20% compared with that of the parent strain.
authors: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing 211816, Jiangsu, China.
authors: Changqing
authors: C
authors: Zhang
authors: Dongmei
authors: D
authors: Gou
authors: Jiajun
authors: J
authors: Mei
authors: Rongming
authors: R
authors: Liu
authors: Jiangfeng
authors: J
authors: Ma
authors: Kequan
authors: K
authors: Chen
authors: Jianguo
authors: J
authors: Zhu
authors: Min
authors: M
authors: Jiang
mesh_terms: D004361:Drug Tolerance / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D007218:Industrial Microbiology; D060847:Metabolic Engineering / Q000379:methods*; D009154:Mutation; D009997:Osmotic Pressure; D012965:Sodium Chloride / Q000494:pharmacology; D019802:Succinic Acid / Q000378:metabolism*
chemical_list: D012965:Sodium Chloride; D019802:Succinic Acid