Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 program), Center for Systems and Synthetic Biotechnology, Institute for the BioCentury, KAIST, Daejeon, Republic of Korea.
Metab Eng. 2012 Sep;14(5):477-86. doi: 10.1016/j.ymben.2012.07.006. Epub 2012 Aug 1.
An engineered Escherichia coli strain that produces 1-propanol under aerobic condition was developed based on an L-threonine-overproducing E. coli strain. First, a feedback resistant ilvA gene encoding threonine dehydratase was introduced and the competing metabolic pathway genes were deleted. Further engineering was performed by overexpressing the cimA gene encoding citramalate synthase and the ackA gene encoding acetate kinase A/propionate kinase II, introducing a modified adhE gene encoding an aerobically functional AdhE, and by deleting the rpoS gene encoding the stationary phase sigma factor. Fed-batch culture of the final engineered strain harboring pBRthrABC-tac-cimA-tac-ackA and pTacDA-tac-adhE(mut) allowed production of 10.8 g L(-1) of 1-propanol with the yield and productivity of 0.107 g g(-1) and 0.144 g L(-1) h(-1), respectively, from 100 g L(-1) of glucose, and 10.3 g L(-1) of 1-propanol with the yield and productivity of 0.259 g g(-1) and 0.083 g L(-1) h(-1), respectively, from 40 g L(-1) glycerol.
基于产 L-苏氨酸大肠杆菌，开发了一株在好氧条件下生产 1-丙醇的工程大肠杆菌菌株。首先，引入了编码苏氨酸脱水酶的反馈抗性ilvA 基因，并删除了竞争代谢途径基因。进一步的工程改造通过过表达编码柠檬酸合酶的 cimA 基因和编码乙酰激酶 A/丙酰激酶 II 的 ackA 基因，引入修饰的编码好氧功能型 AdhE 的 adhE 基因，以及敲除编码静止期σ因子 rpoS 基因来实现。最终工程菌株在含有 pBRthrABC-tac-cimA-tac-ackA 和 pTacDA-tac-adhE(mut) 的条件下进行分批补料培养，从 100 g/L 葡萄糖中分别获得了 10.8 g/L 的 1-丙醇，产率和生产率分别为 0.107 g/g 和 0.144 g/L/h；从 40 g/L 甘油中分别获得了 10.3 g/L 的 1-丙醇，产率和生产率分别为 0.259 g/g 和 0.083 g/L/h。
