DESULFUROMONAS PALMITATIS SP-NOV, A MARINE DISSIMILATORY FE[III] REDUCER THAT CAN OXIDIZE LONG-CHAIN FATTY-ACIDS

Studies on the microorganisms living in hydrocarbon-contaminated sedim ents in San Diego Bay, California led to the isolation of a novel Fe(I II)-reducing microorganism. This organism, designated strain SDBY1, wa s an obligately anaerobic, non-motile, non-flagellated, gram-negative rod. Strain SDBY1 conserves energy to support growth from the oxidatio n of acetate, lactate, succinate, fumarate, laurate, palmitate, or ste arate. Hz was also oxidized with the reduction of Fe(III), but growth with H-2 as the sole electron donor was not observed. In addition to v arious forms of soluble and insoluble Fe(III), strain SDBY1 also coupl ed growth to the reduction of fumarate, Mn(IV), or S-o. Air-oxidized m inus dithionite-reduced difference spectra exhibited peaks at 552.8, 5 23.6, and 422.8 nm, indicative of c-type cytochrome(s). Strain SDBY1 s hares physiological characteristics with organisms in the genera Geoba cter, Pelobacter, and Desulfuromonas. Detailed analysis of the 16S rRN A sequence indicated that strain SDBY1 should be placed in the genus D esulfuromonas. The new species name Desulfuromonas palmitatis is propo sed. D. palmitatis is only the second marine organism found (after D. acetoxidants) to oxidize multicarbon organic compounds completely to c arbon dioxide with Fe(III) as an electron acceptor and provides the fi rst pure culture model for the oxidation of long-chain fatty acids cou pled to Fe(III) reduction.