Sulfur metabolism in Rhodococcus species and their application in desulfurization of fossil fuels.

Organosulfur compounds in fossil fuels have been a major concern in the process of achieving zero-sulfur fuel production. Biodesulfurization (BDS) is an environmentally friendly strategy for the removal of refractory organosulfur compounds from fossil fuels. Even though researchers are committed to engineering the desulfurization specific pathway for improving BDS efficiency, the industrial application of BDS is still difficult. Recently, sulfur metabolism of Rhodococcus has begun to attract attention due to its influences on BDS process. In this review, we introduce the sulfur metabolism in Rhodococcus, including sulfur absorption, reduction, and assimilation; and summarize desulfurization in Rhodococcus, including the desulfurization mechanism, the regulation mechanism of the 4S pathway and the strategies of optimizing the 4S pathway to improve BDS efficiency. In particular, the influence of sulfur metabolism on BDS efficiency is discussed. In addition, we consider the latest genetic engineering strategies in Rhodococcus. An improved understanding of the relationship between sulfur metabolism and desulfurization will enable the industrial application of BDS.