title: Improved hydrogen production under microaerophilic conditions by overexpression of polyphosphate kinase in Enterobacter aerogenes.
abstract: Effects of different microaerophilic conditions on cell growth, glucose consumption, hydrogen production and cellular metabolism of wild Enterobacter aerogenes strain and polyphosphate kinase (PPK) overexpressing strain were systematically studied in this paper, using NaH(2)PO(4) as the phosphate sources. Under different microaerophilic conditions, PPK-overexpressing strain showed better cell growth, glucose consumption and hydrogen production than the wild strain. In the presence of limited oxygen (2.1%) and by PPK overexpression, the hydrogen production per liter of culture, the hydrogen production per cell and the hydrogen yield per mol of glucose increased by 20.1%, 12.3% and 10.8%, respectively, compared with the wild strain under strict anaerobic conditions. Metabolic analysis showed that the increase of the total hydrogen yield was attributed to the improvement of NADH pathway. The result of more reductive cellular oxidation state balance also further demonstrated that, under proper initial microaerophilic conditions and by PPK overexpression, the cell could adjust the cellular redox states and make more energy flow into hydrogen production pathways.
authors: Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
authors: Yuan
authors: Y
authors: Lu
authors: Chong
authors: C
authors: Zhang
authors: Qiheng
authors: Q
authors: Lai
authors: Hongxin
authors: H
authors: Zhao
authors: Xin-Hui
authors: XH
authors: Xing
mesh_terms: D000693:Anaerobiosis; D021902:Enterobacter aerogenes / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005947:Glucose / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D007218:Industrial Microbiology / Q000379:methods; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000235:genetics / Q000378:metabolism*
chemical_list: D006859:Hydrogen; D017856:Phosphotransferases (Phosphate Group Acceptor); C022424:polyphosphate kinase; D005947:Glucose; D010100:Oxygen