DMSO RESPIRATION BY THE ANAEROBIC RUMEN BACTERIUM WOLINELLA-SUCCINOGENES

The anaerobic rumen bacterium Wolinella succinogenes was able to grow by respiration with dimethylsulphoxide (DMSO) as electron acceptor and formate or H-2 as electron donors. The growth yield amounted to 6.7 g and 6.4 g dry cells/mol DMSO with formate or H-2 as the donors, respe ctively. This suggested an ATP yield of about 0.7 mol ATP/mol DMSO. Ce ll homogenates and the membrane fraction contained DMSO reductase acti vity with a high K-m (43 mM) for DMSO. The electron transport from H-2 to DMSO in the membranes was inhibited by 2-(heptyl)-4-hydroxyquinoli ne N-oxide, indicating the participation of menaquinone. Formation of DMSO reductase activity occurred only during growth on DMSO, presence of other electron accepters (fumarate, nitrate, nitrite, N2O, and sulp hur) repressed the DMSO reductase activity. DMSO can therefore be used by W. succinogenes as an acceptor for phosphorylative electron transp ort, but other electron accepters are used preferentially.