DESULFUROMONAS ACETEXIGENS SP-NOV, A DISSIMILATORY SULFUR-REDUCING EUBACTERIUM FROM ANOXIC FRESH-WATER SEDIMENTS

Five strains of obligate anaerobic sulfur-reducing eubacteria that exc lusively use acetate as energy and carbon source have been enriched an d isolated from anoxic sulfide-containing freshwater mud. The strains were unable to grow in the presence of 2% NaCl. Morphologically the st rains were not uniform, cells were either rod-shaped or elongated ovoi d. All strains were flagellated with a single polar to subpolar flagel lum. They stained gram-negative. Two of the strains were studied in de tail. Malate or fumarate was used alternatively to elemental sulfur as electron acceptor. The capacity to grow on acetate as sole organic su bstrate and to reduce elemental sulfur or polysulfide to sulfide are t raits in common with the genus Desulfuromonas. The strains differ from Desulfuromonas acetoxidans by their freshwater origin, morphology, me tabolic specialization and their DNA base ratio. Therefore we consider the new isolates as a new species for which the name Desulfuromonas a cetexigens is proposed.