EFFECTS OF TUNGSTATE ON THE GROWTH OF DESULFOVIBRIO-GIGAS NCIMB-9332 AND OTHER SULFATE-REDUCING BACTERIA WITH ETHANOL AS A SUBSTRATE

Growth of Desulfovibrio gigas NCIMB 9332 in mineral, vitamin-supplemen ted media with ethanol as substrate was strongly stimulated by the add ition of tungstate (optimal level approximately 10(-7) M). At suboptim al tungstate concentrations, up to 1.0 mM acetaldehyde was detected in the culture supernatant and growth was slow. Omission of both tungsta te and molybdate from the media prevented growth and ethanol utilizati on. Tung state-deprived cultures that were grown on lactate had much l ower aldehyde dehydrogenase (benzylviologen as acceptor; BV-AlDH) leve ls than tungstate-supplemented cultures. These data suggest that tungs tate is required for the synthesis of active BV-AlDH. The characterist ics of the enzyme activities in cell-free extracts show that the BV-Al DH activity present in tungstate-supplemented cultures is not due to t he recently characterized molybdenum-containing aldehyde dehydrogenase of D. gigas. Out of 13 other strains of ethanol-oxidizing, gram-negat ive, sulfate-reducing bacteria tested, most strains grew well with eit her tungstate or molybdate supplementation. In contrast to a recent re port, good growth on ethanol of two D. baculatus (Desulfomicrobium) st rains (DSM 1741 and DSM 1743) was observed.