文献类型：期刊文献

英文题名：Modular Engineering Intracellular NADH Regeneration Boosts Extracellular Electron Transfer of Shewanella oneidensis MR-1

作者：Li, Feng[1];Li, Yuanxiu[1];Sun, Liming[2];Chen, Xiaoli[1];An, Xingjuan[1];Yin, Changji[1];Cao, Yingxiu[1];Wu, Hui[3];Song, Hao[1]

机构：[1]Tianjin Univ, Collaborat Innovat Ctr Chem Sci & Engn, Sch Chem Engn & Technol, Key Lab Syst Bioengn,Minist Educ,SynBio Res Platf, Tianjin 300072, Peoples R China;[2]PetroChina Co Ltd, Petrochem Res Inst, Beijing 102206, Peoples R China;[3]East China Univ Sci & Technol, China Natl Light Ind Council, Key Lab Biobased Mat Engn, State Key Lab Bioreactor Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China

年份：2018

卷号：7

期号：3

起止页码：885

外文期刊名：ACS SYNTHETIC BIOLOGY

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000428003700016)】；

基金：This research was supported by the National Natural Science Foundation of China (NSFC 21376174, 21621004), and the National Basic Research Program of China ("973" Program: 2014CB745102).

语种：英文

外文关键词：Shewanella oneidensis; extracellular electron transfer; NADH regeneration; reducing equivalents; cofactor engineering; microbial fuel cells

摘要：Efficient extracellular electron transfer (EET) of exoelectrogens is essentially for practical applications of versatile bioelectrochemical systems. Intracellular electrons flow from NADH to extracellular electron acceptors via EET pathways. However, it was yet established how the manipulation of intracellular NADH impacted the EET efficiency. Strengthening NADH regeneration from NAD(+), as a feasible approach for cofactor engineering, has been used in regulating the intracellular NADH pool and the redox state (NADH/NAD(+) ratio) of cells. Herein, we first adopted a modular metabolic engineering strategy to engineer and drive the metabolic flux toward the enhancement of intracellular NADH regeneration. We systematically studied 16 genes related to the NAD(+)-dependent oxidation reactions for strengthening NADH regeneration in the four metabolic modules of S. oneidensis MR-1, i.e., glycolysis, Cl metabolism, pyruvate fermentation, and tricarboxylic acid cycle. Among them, three endogenous genes mostly responsible for increasing NADH regeneration were identified, namely gapA2 encoding a NAD(+)-dependent glyceraldehyde-3-phosphate dehydrogenase in the glycolysis module, mdh encoding a NAD(+)-dependent malate dehydrogenase in the TCA cycle, and pflB encoding a pyruvate-formate lyase that converted pyruvate to formate in the pyruvate fermentation module. An exogenous gene fdh* from Candida boidinii encoding a NAD(+)-dependent formate dehydrogenase to increase NADH regeneration in the pyruvate fermentation module was further identified. Upon assembling these four genes in S. oneidensis MR-1, similar to 4.3-fold increase in NADH/NAD(+) ratio, and similar to 1.2-fold increase in intracellular NADH pool were obtained under anaerobic conditions without discharge, which elicited similar to 3.0-fold increase in the maximum power output in microbial fuel cells, from 26.2 +/- 2.8 (wild-type) to 105.8 +/- 4.1 mW/m(2) (recombinant S. oneidensis), suggesting a boost in the EET efficiency. This modular engineering method in controlling the intracellular reducing equivalents would be a general approach in tuning the EET efficiency of exoelectrogens.