MEMBRANE D-LACTATE OXIDASE IN ZYMOMONAS-MOBILIS - EVIDENCE FOR A BRANCHED RESPIRATORY-CHAIN

Respiratory chain composition of the ethanol-producing bacterium Zymom onas mobilis was studied. Its membrane D-lactate oxidase was character ised. With NADH, but not D-lactate as substrate, a cytochrome o-like c omponent was seen in CO difference spectra. Chlorpromazine specificall y inhibited reduction of cytochrome d, while myxothiazol eliminated th e cytochrome o-like features in CO difference spectra. It is suggested that electrons from NADH are distributed between branches terminated by the cytochrome o-like component, cytochrome a, and cytochrome d Wit h D-lactate, electrons are transported to cytochrome a, or an unidenti fied CN--sensitive oxidase, and cytochrome d. (C) 1998 Federation of E uropean Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.