DIMETHYLSULFOXIDE REDUCTION BY MARINE SULFATE-REDUCING BACTERIA

Dimethylsulfoxide (DMSO) reduction occurred in five out of nine strain s of sulfate-reducing bacteria from marine or saline environments, but not in three freshwater isolates. DMSO reduction supported growth in all positive strains. In Desulfovibrio desulfuricans strain PA2805, DM SO reduction occurred simultaneously-with sulfate reduction and was no t effectively inhibited by molybdate, a specific inhibitor of sulfate reduction. The growth yield per mol lactate was 26% higher with DMSO t han with sulfate as electron acceptor. In extracts of cells of strain PA2805 grown on sulfate, a low level of DMSO-reducing activity was pre sent (0.013 mu mol (mg protein)(-1) min(-1)); higher levels were found in cells grown on DMSO (0.56 mu mol (mg protein)(-1) min(-1)). In ano xic marine environments DMSO reduction by sulfate-reducing bacteria ma y lead to enhanced dimethylsulfide emission rates.