The goal of this project is to evaluate the biodesulfuriztion/hydrodesulfurization process to determine how to meet current Environmental Protection Agency (EPA) diesel standards (15 ppm sulfur concentration) most efficiently. Specific objectives are to 1) develop a biocatalyst that will remove a large portion of the sulfur in diesel fuel at commercially acceptable rates and 2) develop design specifications and a cost estimate for a 5,000 barrel-per-day biodesulfurization demonstration unit.