ISSN:
1432-072X
Keywords:
Key words Electron transport phosphorylation
;
Respiration
;
Membrane vesicles
;
Anaerobic degradation
;
Glyoxylate
;
Glycolate
;
Hydrogen
;
Syntrophy
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The syntrophically glycolate-fermenting bacterium in the methanogenic binary coculture FlGlyM was isolated in pure culture (strain FlGlyR) with glyoxylate as sole substrate. This strain disproportionated 12 glyoxylate to 7 glycolate, 10 CO2, and 3 hydrogen. Glyoxylate was oxidized via the malyl-CoA pathway. All enzymes of this pathway, i.e. malyl-CoA lyase/malate: CoA ligase, malic enzyme, and pyruvate synthase, were demonstrated in cell-free extracts. Glycolate dehydrogenase, hydrogenase, and ATPase, as well as menaquinones as potential electron carriers, were present in the membranes. Everted membrane vesicles catalyzed hydrogen-dependent glyoxylate reduction to glycolate [86–207 nmol min–1 (mg protein)–1] coupled to ATP synthesis from ADP and Pi [38–82 nmol min–1 (mg protein)–1)]. ATP synthesis was abolished entirely by protonophores or ATPase inhibitors (up to 98 and 94% inhibition, respectively) indicating the involvement of proton-motive force in an electron transport phosphorylation driven by a new glyoxylate respiration with hydrogen as electron donor. Measured reaction rates in vesicle preparations revealed a stoichiometry of ATP formation of 0.2–0.5 ATP per glyoxylate reduced.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00393379
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