title: Biotechnological potential of respiring Zymomonas mobilis: a stoichiometric analysis of its central metabolism.
abstract: The active, yet energetically inefficient electron transport chain of the ethanologenic bacterium Zymomonas mobilis could be used in metabolic engineering for redox-balancing purposes during synthesis of certain products. Although several reconstructions of Z. mobilis metabolism have been published, important aspects of redox balance and aerobic catabolism have not previously been considered. Here, annotated genome sequences and metabolic reconstructions have been combined with existing biochemical evidence to yield a medium-scale model of Z. mobilis central metabolism in the form of COBRA Toolbox model files for flux balance analysis (FBA). The stoichiometric analysis presented here suggests the feasibility of several metabolic engineering strategies for obtaining high-value products, such as glycerate, succinate, and glutamate that would use the electron transport chain to oxidize the excess NAD(P)H, generated during synthesis of these metabolites. Oxidation of the excess NAD(P)H would also be needed for synthesis of ethanol from glycerol. Maximum product yields and the byproduct spectra have been estimated for each product, with glucose, xylose, or glycerol as the carbon substrates. These novel pathways represent targets for future metabolic engineering, as they would exploit both the rapid Entner-Doudoroff glycolysis, and the energetically uncoupled electron transport of Z. mobilis.
authors.affiliation: Biosystems Group, Department of Computer Systems, Latvia University of Agriculture, Liela iela 2, Jelgava, LV3001, Latvia. agris.pentjuss@gmail.com
authors.forename: Agris
authors.initials: A
authors.lastname: Pentjuss
authors.forename: Ilona
authors.initials: I
authors.lastname: Odzina
authors.forename: Andrejs
authors.initials: A
authors.lastname: Kostromins
authors.forename: David A
authors.initials: DA
authors.lastname: Fell
authors.forename: Egils
authors.initials: E
authors.lastname: Stalidzans
authors.forename: Uldis
authors.initials: U
authors.lastname: Kalnenieks
mesh_terms: D001483:Base Sequence / Q000235:genetics; D001709:Biotechnology; D004579:Electron Transport; D000431:Ethanol / Q000378:metabolism*; D016680:Genome, Bacterial; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D060847:Metabolic Engineering; D058977:Molecular Sequence Annotation; D019802:Succinic Acid / Q000378:metabolism; D014994:Xylose / Q000378:metabolism; D017355:Zymomonas / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000431:Ethanol; D014994:Xylose; D019802:Succinic Acid; D005947:Glucose