Another focus in the laboratory is to develop new strategies for microbial desulfurization of coals from Turkey and Bulgaria. Coal is a major source of energy for centuries. During coal combustion sulfur content of coal combines with oxygen to form sulfur oxides leading to hazardous environmental problems such as acid rains. Sulfur emissions can be controlled either removing the sulfur by pre-combustion or converting the sulfur dioxides to sulphate salts by post-combustion. It is believed that the best method to decrease the sulfur dioxide emission into atmosphere is to reduce the amount of coal before combustion. Sulfur content of various coals differs worldwide between 0.5% and 11% and the increasing amount of universal coal utilization necessitates limitation and ultimately elimination of the present sulfur in coal before combustion. The removal of sulfur from coal is a complicated process due to the presence of mainly different inorganic and organic forms of sulfur as pyrite, sulfate, inorganic sulfite, organic sulfur compounds and elemental sulfur, each requiring specific separation methods. These techniques include physical, chemical and biological processes. Removal of inorganic sulphur is easier than to that of organic sulfur compounds. The inability of physical and chemical methods to completely remove even the inorganic sulfur has led to the development of biodesulfurization processes which have significant advantages over the conventional technologies.Since high efficiency on the removal of certain impurities can be obtained with this method under milder reaction conditions. Our research mainly aims to optimize and improve the biological conditions of the microbial desulfurization process specifically for the removal of organic sulfur. In addition, our goal is to apply basic recombinant DNA technologies to enhance the efficiency of biodesulfurization reactions.