MODIFICATION OF ORGANOSULFUR COMPOUNDS AND WATER-SOLUBLE COAL-DERIVEDMATERIAL BY ANAEROBIC MICROORGANISMS

The transformation of organosulfur compounds by anaerobic microorganis ms may be of interest for coal desulfurization. An anaerobic microbial community indigenous to cyanobacterial mats of a Yellowstone National Park hot spring was assessed for the ability to evolve volatile sulfu r compounds from benzyl methyl sulfide, benzyl methyl disulfide, methi onine and water-soluble lignite-derived material. The addition of meth ionine or benzyl methyl disulfide stimulated the production of methane thiol by slurries made with cyanobacterial mat material. Transformatio n of methionine appeared to be the direct result of microbial activity . However, the evolution of methanethiol from benzyl methyl disulfide appeared to be the indirect result of microbial activity, that is, the cleavage of the disulfide linkage may have resulted from the reductio n by microbially produced hydrogen sulfide. Results indicated a transi ent interaction of hydrogen sulfide and methanethiol with the coal mat erial. In separate studies, sulfate-reducing bacteria were examined fo r the modification of water-soluble lignite-derived material. As expec ted, the sulfur content of the soluble material increased under condit ions of sulfate respiration. However, when grown fermentatively withou t the production of sulfide, two of the nine cultures examined reduced the sulfur content of the soluble material. Most of the cells in all the cultures immediately lysed upon the addition of the soluble materi al. By 2 weeks, cell densities were greater in cultures amended with s oluble coal material than in control cultures.