Microbial removal of organic sulfur from coal (degradation of sulfur-containing heterocyclic compounds). Final report, July 1, 1984-June 30, 1985

The presence of substantial levels of sulfur in coal is a major source of air pollution, and considerable efforts are being made to devise a cost-effective way of removing the sulfur. One promising method is the microbial desulfurization of coal. Recent research has shown that it is possible to remove almost all of the inorganic sulfur from coal using the bacteria Thiobacillus or Sulfolobus. These organisms convert sulfide to sulfate but leave the organic sulfur untouched. Since certain coals, including those in the Illinois Basin, contain high levels of organic sulfur, its removal is also necessary. If a strain of bacteria could be found or developed which would effectively remove organic sulfur from coal, then, when used in conjunction with an organism which removes inorganic sulfur, it could result in an effective desulfurization method. Several approaches are used in developing bacteria which remove organic sulfur. One method is to isolate suitable naturally occurring bacterial species; another is to mutate a laboratory species, Escherichia coli, an organism which is genetically well understood and whose pathways for the metabolism of sulfur-containing amino acids have been extensively investigated. The objectives of this study were threefold: (1) to isolate thiophene-oxidizing bacteria from the naturalmore » environment and to identify the optimal growth conditions for thiophene oxidation; (2) to construct novel biosynthetic pathways for organic sulfur utilization in Escherichia coli via successive cycles of mutation; and (3) from objectives 1 and 2, to construct a bacterial organism that will be efficient in the removal of organic sulfur from coal. 3 refs., 13 figs., 9 tabs.« less