Fermentation of acetylene by an obligate anaerobe,Pelobacter acetylenicus sp. nov.

Four strains of strictly anaerobic Gram-negative rod-shaped non-sporeforming bacteria were enriched and isolated from marine and freshwater sediments with acetylene (ethine) as sole source of carbon and energy. Acetylene, acetoin, ethanolamine, choline, 1,2-propanediol, and glycerol were the only substrates utilized for growth, the latter two only in the presence of small amounts of acetate. Substrates were fermented by disproportionation to acetate and ethanol or the respective higher acids and alcohols. No cytochromes were detectable; the guanine plus cytosine content of the DNA was 57.1±0.2 mol%. Alcohol dehydrogenase, aldehyde dehydrogenase, phosphate acetyltransferase, and acetate kinase were found in high activities in cell-free extracts of acetylene-grown cells indicating that acetylene was metabolized via hydration to acetaldehyde. Ethanol was oxidized to acetate in syntrophic coculture with hydrogen-scavenging anaerobes. The new isolates are described as a new species in the genusPelobacter, P. acetylenicus.Dedicated to Professor Dr. Norbert Pfennig on occasion of his 60th birthday