DszC is a flavin reductase dependent enzyme, which catalyzes the first two steps of DBT desulfurization in mesophilic bacteria. DszC converts DBT to DBT-sulfoxide, which is then converted to DBT-sulfone. Bacteria with this enzyme are candidates for the removal of organic sulfur compounds from fossil fuels, which pollute the environment. An equivalent enzyme tdsC, is found in thermophilic bacteria. This alignment also contains a closely related uncharacterized subgroup.