A common pathway of sulfide oxidation by sulfate-reducing bacteria

Abstract

The pathway of sulfide oxidation with oxygen as electron acceptor was studied with five strains of freshwater, marine and alkaliphilic sulfate‐reducing bacteria. Electrode measurements with washed cells indicated that all strains oxidized sulfide to elemental sulfur. In a second step, the elemental sulfur formed was disproportionated to sulfate and sulfide. During this phase, most of the disappeared sulfide was formed back. Since oxygen could be replaced by nitrate or nitrite as electron acceptor, the described biphasic reaction was independent of molecular oxygen. With Desulfobulbus propionicus and the alkaliphilic strain Z‐7935, sulfide back‐formation started after oxygen was consumed completely. By contrast, with the freshwater strains Desulfovibrio desulfuricans CSN (DSM 9104) and Essex 6 (DSM 2032) and the marine strain P1B, sulfide back‐formation already started before oxygen was consumed. The addition of hydrogen as electron donor increased simultaneously the rate of aerobic respiration and sulfide back‐formation. Both reactions stopped when the oxygen was consumed, indicating that the electron transport to oxygen and sulfur was coupled. Sulfide‐oxidizing activity (84 nmol O2 min−1 (mg protein)−1) was found in the periplasmic fraction prepared by osmotic shock treatment of suspensions of D. desulfuricans CSN. This fraction oxidized sulfide with oxygen to elemental sulfur. It is concluded that in different sulfate‐reducing bacteria sulfide oxidation proceeds via a common pathway with the formation of elemental sulfur as intermediate and its disproportionation to sulfate and sulfide. The process is independent of molecular oxygen.

Oxygen-dependent growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough

“…The mechanism by which oxygen-dependent growth occurs is not yet clear. Fuseler et al (7) recently reported that oxygen consumption in Desulfovibrio desulfuricans CSN was coupled to the oxidation of sulfide to sulfur, after which the sulfur underwent disproportionation to sulfide and sulfate. Oxygen was also reduced in a separate reaction, possibly involving a periplasmic cytochrome c capable of both reducing sulfur and being autoxidized by oxygen.…”

Linked Redox Precipitation of Sulfur and Seleniumunder Anaerobic Conditions by Sulfate-Reducing BacterialBiofilms

“…As such, SRB comprise a functional group within a sulfuretum, linking broad-scale cycling between sulfate and sulfide by ecological communities of SRB and sulfide-oxidizing bacteria (12,28). Biological reoxidation of reduced sulfur species typically occurs at oxic-anoxic transition zones and is attributed largely to phototrophs and chemolithotrophs.…”

Thiosulfate as a metabolic product: the bacterial fermentation of taurine

“…Thiosulfate is found naturally in anoxic environments (Höll 1979) and is widely used as an electron acceptor or as an electron donor (Jørgensen 1990;Jørgensen and Bak 1991). Despite this importance, no significant biological source of thiosulfate has been reported [see also Fuseler and Cypionka (1996)]. We thus believe that we have detected a potential biological source of thiosulfate, namely the widespread taurine (Huxtable 1992).…”