title: Insights into the global regulation of anaerobic metabolism for improved biohydrogen production.
abstract: To improve the biohydrogen yield in bacterial dark fermentation, a new approach of global anaerobic regulation was introduced. Two cellular global regulators FNR and NarP were overexpressed in two model organisms: facultatively anaerobic Enterobacter aerogenes (Ea) and strictly anaerobic Clostridium paraputrificum (Cp). The overexpression of FNR and NarP greatly altered anaerobic metabolism and increased the hydrogen yield by 40%. Metabolic analysis showed that the global regulation caused more reducing environment inside the cell. To get a thorough understanding of the global metabolic regulation, more genes (fdhF, fhlA, ppk, Cb-fdh1, and Sc-fdh1) were overexpressed in different Ea and Cp mutants. For the first time, it demonstrated that there were approximately linear relationships between the relative change of hydrogen yield and the relative change of NADH yield or ATP yield. It implied that cellular reducing power and energy level played vital roles in the biohydrogen production.
authors.affiliation: Key Lab of Industrial Biocatalysis of Ministry of Education (Tsinghua University), China; Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Key Lab of Industrial Biocatalysis of Ministry of Education (Tsinghua University), China; Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China; Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, China; College of Chemistry and Life Sciences, Shenyang Normal University, Shenyang 110034, China.
authors.forename: Hongxin
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Key Lab of Industrial Biocatalysis of Ministry of Education (Tsinghua University), China; Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Chong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Key Lab of Industrial Biocatalysis of Ministry of Education (Tsinghua University), China; Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China. Electronic address: xhxing@tsinghua.edu.cn.
authors.forename: Xin-Hui
authors.initials: XH
authors.lastname: Xing
mesh_terms: D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D056804:Biofuels; D001709:Biotechnology / Q000379:methods; D003013:Clostridium / Q000378:metabolism* / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004734:Energy Metabolism; D021902:Enterobacter aerogenes / Q000378:metabolism* / Q000502:physiology; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D006859:Hydrogen / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D056804:Biofuels; D004268:DNA-Binding Proteins; D007506:Iron-Sulfur Proteins; D006859:Hydrogen
keywords: Clostridium paraputrificum; Enterobacter aerogenes; Global regulation; Hydrogen production; Metabolic analysis