Sporomusa silvacetica sp, nov., an acetogenic bacterium isolated from aggregated forest soil

Sporomusa silvacetica sp. nov. DG-1T (= DSMZ 10669T) (T = type strain) was isolated from well-drained, aggregated forest soil (pH 6.0) in 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 by 0.7 micron. Cells stained weakly gram positive, but thin sections revealed a complex multilayer cell wall. Spores were spherical and distended the sporangia. Growth and substrate utilization occurred with ferulate, vanillate, fructose, betaine, fumarate, 2,3-butanediol, pyruvate, lactate, glycerol, ethanol, methanol, formate, and H2-CO2. With most substrates, acetate was the primary reduced end product and was produced in stoichiometries indicative of an acetyl-coenzyme A pathway-dependent metabolism. Fumarate was dismutated to succinate and acetate. Methoxyl and acrylate groups of various aromatic compounds were O-demethylated and reduced, respectively. Yeast extract was not required for growth. 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 growth was between 5 and 10 degrees C. The carbon monoxide dehydrogenase and hydrogenase activities were approximately 9 and 102 mumol 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-1T was most closely related to members of the genus Sporomusa in the Clostridium subphylum of the gram-positive bacteria.