Comparative transcriptomic analysis revealed the key pathways responsible for organic sulfur removal by thermophilic bacterium Geobacillus thermoglucosidasius W-2.

Biodesulfurization is a promising method to desulfurize sulfur-containing compounds in oil with its unique advantages, such as environment-friendly treatments and moderate reaction conditions. In this study, a thermophilic bacterium Geobacillus thermoglucosidasius W-2 was reported to show nearly 40% and 55% desulfurization rates on heavy oil with 2.81% and 0.46% initial total sulfur content, respectively. Subsequently, comparative transcriptome analysis indicated that several possible key desulfurization-related genes of this strain were found to be differentially up-regulated induced by benzothiophene and dibenzothiophene, respectively. These desulfurization-related genes were considered to conduct key step to convert organic sulfur to inorganic sulfur. Moreover, the characterization of thermophilic alkanesulfonate monooxygenase systems SsuD/SsuE and SsuD/SsuE revealed that the enzymes exhibit considerable thermal and pH stability and wide substrates applicability. These enzymes probably endowed the strain W-2 with the ability to desulfurize oil and eliminate the sulfur-containing surfactants. Thus, this study provides novel alkanesulfonate monooxygenase systems that have the application potential for heavy oil biodesulfurization, oil demulsification and other biocatalytic processes.