Assimilation of sulfur from alkyl- and arylsulfonates by Clostridium spp.

Abstract

Organisms able to utilize one of several alkyl- and arylsulfonates as sole source of sulfur under anoxic conditions were enriched. Three fermenting bacteria, all putative Clostridium spp., were isolated in pure culture. All three organisms had wide substrate ranges for alkylsulfonates, taurine and arylsulfonates, presumably due to three different enzyme systems. One organism, strain KNNDS (DSM 10612) was selected for further characterization. The organism was possibly a new Clostridium sp., with Clostidium intestinalis as its nearest neighbor (97.6% similarity of rDNA). Strain KNNDS catalyzed complete sulfonate utilization concomitant with growth. Growth yields of approximtely 3 kg protein/mol sulfur were observed, independent of the sulfur source [e.g. sulfate, sulfide, 4-(phenyl)butyl-1-sulfonate, 2,6-naphthyldisulfonate or 4-nitrocatechol sulfate]. We failed to detect significant amounts of either an arylsulfonatase or an arylsulfatase, and we hypothesize different arylsulfatases [EC 3.1.6.1] in aerobes and in Clostridium spp.