Genetically switched D-lactate production in Escherichia coli
Genetically switched D-lactate production in Escherichia coli
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DOI：
10.1016/j.ymben.2012.05.004
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发表时间：
2012-09-01
影响因子：
8.4
通讯作者：
Wang, Zheng-Xiang
中科院分区：
文献类型：
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作者：
Zhou, Li;Niu, Dan-Dan;Wang, Zheng-Xiang
在发酵过程中，在细胞生长期形成所需产物与生物质竞争底物或直接抑制细胞生长，这导致生产效率降低。需要一个基因开关来精确地分离生长和生产，并简化发酵过程。ldhA启动子，其在乳酸生产者大肠杆菌CICIM B 0013 -070中编码发酵D-乳酸脱氢酶（LDH）（ack-pta pps pflB dld poxB adhE frdA）被λ p（R）和p（L）启动子替换（作为遗传开关）使用基因组重组和热可控菌株B 0013 - 070 B（B 0013 -070，ldhAp：：kan-cl（ts）857-p（R）-p（L）），其在42 ℃下可产生比B 0013 -070菌株高两倍的LDH活性。当在33 ℃关闭遗传开关时，菌株B 0013 - 070 B产生比菌株B 0013 -070多10%的好氧生物量，并且仅产生痕量水平的乳酸，这可以减少大规模发酵中由氧不足引起的生长抑制。然而，42摄氏度是开启乳酸盐生产的最有效温度。与菌株B 0013 - 070相比，当其在33 ° C有氧生长并在42 ° C进行短的热诱导，然后在42 ° C转换到生产阶段时，B 0013 - 070 B的体积生产率提高了9%。在使用在摇瓶实验中优化的放大条件的生物反应器实验中，菌株B 0013 - 070 B产生122.8 g/l D-乳酸盐，具有0.89 gig的增加的氧限制生产率。H.结果揭示了使用基因开关调节细胞生长和代谢化合物产生的有效性。(C)2012 Elsevier Inc. All rights reserved.
During a fermentation process, the formation of the desired product during the cell growth phase competes with the biomass for substrates or inhibits cell growth directly, which results in a decrease in production efficiency. A genetic switch is required to precisely separate growth from production and to simplify the fermentation process. The ldhA promoter, which encodes the fermentative D-lactate dehydrogenase (LDH) in the lactate producer Escherichia coli CICIM B0013-070 (ack-pta pps pflB dld poxB adhE frdA), was replaced with the lambda p(R) and p(L) promoters (as a genetic switch) using genomic recombination and the thermo-controllable strain B0013-070B (B0013-070, ldhAp::kan-cl(ts)857-p(R)-p(L)), which could produce two-fold higher LDH activity at 42 degrees C than the B0013-070 strain, was created. When the genetic switch was turned off at 33 degrees C, strain B0013-070B produced 10% more biomass aerobically than strain B0013-070 and produced only trace levels of lactate which could reduce the growth inhibition caused by oxygen insufficiency in large scale fermentation. However, 42 degrees C is the most efficient temperature for switching on lactate production. The volumetric productivity of B0013-070B improved by 9% compared to that of strain B0013-070 when it was grown aerobically at 33 degrees C with a short thermo-induction at 42 degrees C and then switched to the production phase at 42 degrees C. In a bioreactor experiment using scaled-up conditions that were optimized in a shake flask experiment, strain B0013-070B produced 122.8 g/l D-lactate with an increased oxygen-limited productivity of 0.89 gig . h. The results revealed the effectiveness of using a genetic switch to regulate cell growth and the production of a metabolic compound. (C) 2012 Elsevier Inc. All rights reserved.