Coal is decomposing plant or animal material that has been altered by a biological process and a geological process over a long period of time. Biological processes have the capacity to remove organic sulfur but have not been used commercially (Ohtsuka, 2000). An advantage that biological processes retain over other methods is that the temperature and pressure required can be very low, thereby reducing energy, whereas other processes can have a temperature of up to 1,350 °C and a pressure of 140 atm (Faison, 1991). . The biological process of removing pyritic sulfur is generally thought to involve two methods: indirect and direct methods. The indirect method removes pyritic sulfur by oxidation of pyritic sulfur through the use of ferric ions. This route is 106 times slower than the direct route (Groppo, Parekh, 1993). The direct method is defined as a process in which microorganisms attach themselves to the surface of the pyrite and oxidize the sulfur enzymatically, proving much more efficient with