Utilization of Dibenzothiophene and Desulfurization of Crude Oil by a New Klebsiella sp. Strain BDS24 and the Proposed Metabolic Pathway

A strain capable of efficient biodesulfurization of dibenzothiophene was isolated from oil-contaminated soil samples. The strain, designated BDS24, was a rod-shaped gram-negative bacterium. Molecular identification based on its 16S rDNA gene sequence showed that this strain belonged to the genus Klebsiella. Examining its ability to desulfurize dibenzothiophene by gas chromatography revealed that this isolate consumed 0.5 mM of dibenzothiophene within 72 h. Evaluation of growth characteristics by the tetrazolium chloride assay showed that BDS24 isolate reached its maximum growth in the exponential phase after 60 h of growth with DBT. Compared to the reported 4S metabolic pathway, an extended 4S pathway was proposed for the desulfurization of dibenzothiophene, which has not been formerly reported in the literature. A decrease of 88% of the total sulfur content of crude oil sample by a Klebsiella strain has not been achieved previously. These results indicate that Klebsiella sp. BDS24 is an adequate candidate for deep biodesulfurization of crude oil.