Alteration of hydrogen metabolism of ldh-deleted Enterobacter aerogenes by overexpression of NAD(+)-dependent formate dehydrogenase
Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China. Applied Microbiology and Biotechnology
(Impact Factor: 3.34).
10/2009; 86(1):255-62. DOI: 10.1007/s00253-009-2274-3
The NAD+-dependent formate dehydrogenase FDH1 gene (fdh1), cloned from Candida boidinii, was expressed in the ldh-deleted mutant of Enterobacter aerogenes IAM1183 strain. The plasmid of pCom10 driven by the PalkB promoter was used to construct the fdh1 expression system and thus introduce a new dihydronicotinamide adenine dinucleotide (NADH) regeneration pathway from formate in the ldh-deleted mutant. The knockout of NADH-consuming lactate pathway affected the whole cellular metabolism, and the hydrogen yield increased by 11.4% compared with the wild strain. Expression of fdh1 in the ldh-deleted mutant caused lower final cell concentration and final pH after 16 h cultivation, and finally resulted in 86.8% of increase in hydrogen yield per mole consumed glucose. The analysis of cellular metabolites and estimated redox state balance in the fdhl-expressed strain showed that more excess of reducing power was formed by the rewired NADH regeneration pathway, changing the metabolic distribution and promoting the hydrogen production.
Available from: Hao Zheng
- "Metabolic engineering has recently been recognized as one of the most important potential technologies to improve fermentative hydrogen yield. Some researches have aimed at improving the yield of originally good hydrogen producers (wild-type Clostridium sp., Enterobacter sp.), but the genetic manipulation is relatively hard     . Escherichia coli, the best-characterized bacterium, was chosen as the starting model strain to study ways of improving the hydrogen yield by the manipulation of its metabolism . "
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ABSTRACT: Metabolic engineering is recognized as one of the most important technologies for improving fermentative hydrogen yield. A vector with hydrogenase genes (hoxEFUYH) from Synechocystis sp. PCC 6803 under an alkB promoter was constructed, and introduced into Escherichia coli DH5α to alter the hydrogen metabolism with glucose as the sole carbon source. The recombinant strain reached a highest hydrogen yield of 1.89 mol/mol glucose, which was 95% of the theoretical hydrogen yield of E. coli. Hydrogenase activities for hydrogen evolution were increased and formic acid assimilation was accelerated with the expression of hoxEFUYH. The expression of hoxEFUYH suppressed the transcription of native hydrogenase 1 and hydrogenase 2, which were responsible for hydrogen uptake activity, while it had no influence on the transcription of the hydrogenase 3. Moreover, as the electron donor of HoxEFUYH is NADH, the expressed HoxEFUYH expanded the substrate specificity of the hydrogen-evolving hydrogenase in E. coli.
Biochemical Engineering Journal 01/2012; 60:81-86. DOI:10.1016/j.bej.2011.10.006 · 2.47 Impact Factor
Available from: You-Kwan Oh
- "Zhang et al. (2009) suggested that the exogenous addition of NADH or NAD + could change the intracellular redox state of E. aerogenes and, subsequently, the H 2 production through formate and NADH pathways. In a consecutive study, Lu et al. (2010) improved the H 2 yield in E. aerogenes IAM 1183 to 1.70 from 0.91 mol H 2 /mol glucose by inactivating NADH-consuming lactate dehydrogenase and overexpressing NAD + -dependent formate dehydrogenase. However, detailed genetic and biochemical characterizations for NADH-dependent H 2 production machineries in E. aerogenes sp. "
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ABSTRACT: The improvement of H2 production capabilities of hydrogen (H2)-producing microorganisms is a challenging issue. Microorganisms have evolved for fast growth and substrate utilization rather than H2 production. To develop good H2-producing biocatalysts, many studies have focused on the redirection and/or reconstruction of cellular metabolisms. These studies included the elimination of enzymes and carbon pathways interfering or competing with H2 production, the incorporation of non-native metabolic pathways leading to H2 production, the utilization of various carbon substrates, the rectification of H2-producting enzymes (nitrogenase and hydrogenase) and photophosphorylation systems, and in silico pathway flux analysis, among others. Owing to these studies, significant improvements in the yield and rate of H2 production, and in the stability of H2 production activity, were reached. This review presents and discusses the recent developments in biohydrogen production, with a focus on metabolic pathway engineering.
Bioresource Technology 09/2011; 102(18):8357-67. DOI:10.1016/j.biortech.2011.04.054 · 4.49 Impact Factor
1974 Ultrasonics Symposium; 02/1974
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