title: Respiratory behaviour of a Zymomonas mobilis adhB::kan(r) mutant supports the hypothesis of two alcohol dehydrogenase isoenzymes catalysing opposite reactions.
abstract: Perturbation of the aerobic steady-state in a chemostat culture of the ethanol-producing bacterium Zymomonas mobilis with a small pulse of ethanol causes a burst of ethanol oxidation, although the reactant ratio of the alcohol dehydrogenase (ADH) reaction ([NADH][acetaldehyde][H(+)])/([ethanol][NAD(+)]) remains above the K(eq) value. Simultaneous catalysis of ethanol synthesis and oxidation by the two ADH isoenzymes, residing in different redox microenvironments, has been proposed previously. In the present study, this hypothesis is verified by construction of an ADH-deficient strain and by demonstration that it lacks the oxidative burst in response to perturbation of its aerobic steady-state with ethanol.
authors.affiliation: Institute of Microbiology and Biotechnology, University of Latvia, Kronvalda Boulv. 4, LV-1586, Riga, Latvia. kalnen@lanet.lv
authors.forename: U
authors.initials: U
authors.lastname: Kalnenieks
authors.forename: N
authors.initials: N
authors.lastname: Galinina
authors.forename: M M
authors.initials: MM
authors.lastname: Toma
authors.forename: J L
authors.initials: JL
authors.lastname: Pickford
authors.forename: R
authors.initials: R
authors.lastname: Rutkis
authors.forename: R K
authors.initials: RK
authors.lastname: Poole
mesh_terms: D000332:Aerobiosis; D000426:Alcohol Dehydrogenase / Q000172:deficiency / Q000378:metabolism*; D002384:Catalysis; D000431:Ethanol / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007613:Kanamycin Resistance / Q000235:genetics*; D007700:Kinetics; D008954:Models, Biological; D050505:Mutant Proteins / Q000378:metabolism*; D017355:Zymomonas / Q000201:enzymology* / Q000502:physiology*
chemical_list: D007527:Isoenzymes; D050505:Mutant Proteins; D000431:Ethanol; D000426:Alcohol Dehydrogenase