SPOROMUSA SILVACETICA SP-NOV, AN ACETOGENIC BACTERIUM ISOLATED FROM AGGREGATED FOREST SOIL

Sporomusa silvacetica sp. nov. DG-1(T) (= DSMZ 10669(T)) (T = type str ain) was isolated from well-drained, aggregated forest soil (pH 6.0) i n east-central Germany. The cells were obligately anaerobic, slightly curved rods and were motile by means of laterally inserted flagella on the concave side of each cell. Typical cells were approximately 3.5 b y 0.7 mu m. Cells stained weakly gram positive, but thin sections reve aled a complex multilayer cell wall. Spores were spherical and distend ed the sporangia. Growth and substrate utilization occurred with ferul ate, vanillate, fructose, betaine, fumarate, 2,3-butanediol, pyruvate, lactate, glycerol, ethanol, methanol, formate, and H-2-CO2. With most substrates, acetate was the primary reduced end product and was produ ced in stoichiometries indicative of an acetyl-coenzyme a pathway-depe ndent metabolism. Fumarate was dismutated to succinate and acetate. Me thoxyl and acrylate groups of various aromatic compounds were O-demeth ylated and reduced, respectively. Yeast extract was not required for g rowth. Cells grew optimally at approximately 30 degrees C and pH 6.8; under these conditions and with fructose as the substrate the doubling time was approximately 14 h. The lowest temperature that supported gr owth was between 5 and 10 degrees C. The carbon monoxide dehydrogenase and hydrogenase activities were approximately 9 and 102 mu mol min(-1 ) mg of protein(-1), respectively. A type b cytochrome was detected in the membrane. The G+C content was approximately 43 mol%. Phylogenetic analysis of the 16S ribosomal DNA indicated that DG-1(T) was most clo sely related to members of the genus Sporomusa in the clostridium subp hylum of the gram-positive bacteria.