Alteration of hydrogen metabolism of ldh-deleted Enterobacter aerogenes by overexpression of NAD+-dependent formate dehydrogenase.
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.
Lu
Yuan
Y
Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Zhao
Hongxin
H
Zhang
Chong
C
Lai
Qiheng
Q
Wu
Xi
X
Xing
Xin-Hui
XH
D000693:Anaerobiosis; D001709:Biotechnology / Q000379:methods*; D002175:Candida / Q000201:enzymology / Q000235:genetics; D003001:Cloning, Molecular; D021902:Enterobacter aerogenes / Q000201:enzymology* / Q000235:genetics; D005285:Fermentation; D005560:Formate Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015971:Gene Expression Regulation, Enzymologic; D005818:Genetic Engineering / Q000379:methods; D006859:Hydrogen / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000235:genetics*; D009243:NAD / Q000378:metabolism; D015854:Up-Regulation
D009243:NAD; D006859:Hydrogen; D007770:L-Lactate Dehydrogenase; D005560:Formate Dehydrogenases