AN OVERVIEW OF THE BACTERIA AND ARCHAEA INVOLVED IN REMOVAL OF INORGANIC AND ORGANIC SULFUR-COMPOUNDS FROM COAL

Of special importance for biohydrometallurgy are acidophilic chemolith otrophic bacteria from a number of different taxonomic groups, namely: the genera of Thiobacillus and Leptospirillum, moderately thermophili c bacteria which we combined into the group Sulfobacillus-Alicyclobaci llus, and archaea of the genera Sulfolobus, Acidianus, Metallosphaera, and Sulfurococcus. These bacteria are able to oxidize one or more of the following compounds Fe+2, S-0 and sulfide minerals and to grow und er extreme environmental conditions. Growth pH varies in the range fro m 1 to 5, growth temprature - from 2 to 90 degrees C. They can tolerat e high concentration of metal ions. They possess a great physiological , biochemical and genetic variability. Some of them are important for removal of inorganic sulfur compounds from coals. Some types of coals and oils contain aromatic heterocyclic compounds with the C-S bond. Al though a wide range of mostly heterotrophic and some chemolithotrophic bacteria, from bacteria and archaea to eucaryotes, participate in its transformation, only certain organisms have a unique capability of sp litting this bond, which is impossible to be done by chemical means. T hey can remove organic sulfur-containing compounds from coal. The poss ibilities of application of bacteria in biological processing of coals is discussed.