title: A systematic analysis of TCA Escherichia coli mutants reveals suitable genetic backgrounds for enhanced hydrogen and ethanol production using glycerol as main carbon source.
abstract: Biodiesel has emerged as an environmentally friendly alternative to fossil fuels; however, the low price of glycerol feed-stocks generated from the biodiesel industry has become a burden to this industry. A feasible alternative is the microbial biotransformation of waste glycerol to hydrogen and ethanol. Escherichia coli, a microorganism commonly used for metabolic engineering, is able to biotransform glycerol into these products. Nevertheless, the wild type strain yields can be improved by rewiring the carbon flux to the desired products by genetic engineering. Due to the importance of the central carbon metabolism in hydrogen and ethanol synthesis, E. coli single null mutant strains for enzymes of the TCA cycle and other related reactions were studied in this work. These strains were grown anaerobically in a glycerol-based medium and the concentrations of ethanol, glycerol, succinate and hydrogen were analysed by HPLC and GC. It was found that the reductive branch is the more relevant pathway for the aim of this work, with malate playing a central role. It was also found that the putative C4-transporter dcuD mutant improved the target product yields. These results will contribute to reveal novel metabolic engineering strategies for improving hydrogen and ethanol production by E. coli.
authors.affiliation: Department of Biomedicine, Biotechnology and Public Health-Biochemistry and Molecular Biology. Campus de Excelencia Internacional Agroalimentario (ceiA3), Institute of Biomolecules (INBIO), University of Cádiz, Puerto Real (Cádiz), Spain. antonio.valle@uca.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Valle
authors.affiliation: Department of Chemical Engineering and Food Technology. Campus de Excelencia Internacional Agroalimentario (ceiA3), University of Cádiz, Puerto Real (Cádiz), Spain.
authors.forename: Gema
authors.initials: G
authors.lastname: Cabrera
authors.affiliation: Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, United Kingdom.
authors.forename: Howbeer
authors.initials: H
authors.lastname: Muhamadali
authors.affiliation: Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, United Kingdom.
authors.forename: Drupad K
authors.initials: DK
authors.lastname: Trivedi
authors.affiliation: Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, United Kingdom.
authors.forename: Nicholas J W
authors.initials: NJ
authors.lastname: Ratray
authors.affiliation: Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, United Kingdom.
authors.forename: Royston
authors.initials: R
authors.lastname: Goodacre
authors.affiliation: Department of Chemical Engineering and Food Technology. Campus de Excelencia Internacional Agroalimentario (ceiA3), University of Cádiz, Puerto Real (Cádiz), Spain.
authors.forename: Domingo
authors.initials: D
authors.lastname: Cantero
authors.affiliation: Department of Biomedicine, Biotechnology and Public Health-Biochemistry and Molecular Biology. Campus de Excelencia Internacional Agroalimentario (ceiA3), Institute of Biomolecules (INBIO), University of Cádiz, Puerto Real (Cádiz), Spain. jorge.bolivar@uca.es.
authors.forename: Jorge
authors.initials: J
authors.lastname: Bolivar
mesh_terms: D002952:Citric Acid Cycle / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D000431:Ethanol / Q000032:analysis / Q000378:metabolism*; D005285:Fermentation; D005990:Glycerol / Q000378:metabolism*; D006859:Hydrogen / Q000032:analysis / Q000378:metabolism*; D009154:Mutation / Q000235:genetics
chemical_list: D000431:Ethanol; D006859:Hydrogen; D005990:Glycerol
keywords: Bioethanol production; Biohydrogen production; Escherichia coli; Glycerol feed-stocks; Tricarboxylic acid (TCA) cycle