The increasing global human population has been associated with the development of high-density urban communities. This has led to increase in fossil energy consumption and posed serious threats to the environment and human health. Organosulfur compounds found in crude oil and transportation fuels such as diesel have gained strong attention because they are hazardous to human and the ecosystem. Moreover, the sulfur oxide gases resulting from fuel combustion are a major cause of acid rain. Governments and environmental organizations worldwide have recognized the problem and implemented strict regulations and legislations that limit the amount of sulfur in diesel. Hydrodesulphurization (HDS) is commonly used by oil refineries to reduce sulfur content in refined fuels. However, HDS has many disadvantages. It is costly, environmentally polluting, and not sufficiently efficient. Accordingly, there has been increasing interest in the development of alternative desulfurization technologies to circumvent the problems associated with the conventional HDS. Biodesulfurization (BDS) has emerged as an alternative or a complement technology to overcome the drawbacks of the conventional HDS. BDS exploits the ability of dedicated microorganisms to remove sulfur from many organosulfur compounds that are commonly found in crude oil and refined fuels. As compared to thermochemical treatments like HDS, BDS is environmentally friendly, cost-effective and active towards organosulfur compounds that escape the conventional HDS. Nonetheless, lack of deep understanding of the physiology and metabolism, particularly sulfur metabolism, of biodesulfurizing microbes has impeded the development and implementation of a commercially viable BDS process. In this project, we apply metabolomics and proteomics to better understand the physiological adaptations and sulfur metabolism of in a model biodesulfurization-competent strain Rhodococcus qingshengii IGTS8.