[The innate ability of Rhodococcus sp. SDUZAWQ to tolerate sulfur in petroleum]

Abstract

Removal of sulfur from petroleum can be accomplished by various means. One method is to use microorganisms, such as bacteria. In the present study, strain Rhodococcus sp. SDUZAWQ was employed to test the effects of various concentrations of dibenzothiophene (DBT) and sulfate, had on this removal process. Desulfurization was accomplished, using Basal Salts Medium (BSM), supplemented with 0.2mmol/L DBT and different concentrations of Na2SO4. Growth of SDUZAWQ was pronounced, even when the concentration of DBT was increased to 6mmol/L. Furthermore, it should be noted that the end product of DBT desulfurization, 2 hydroxybiphenyl (2-HBP), was detected as well. This finding was significant because it demonstrated the bacteria' s ability to withstand high concentrations of organosulfur. Dibenzothiophene was utilized when both DBT and Na2SO4 were present in the culture medium. Additionally, 2-HBP was produced. These data are in contrast to previous studies that indicated that DBT could not be metabolized by Rhodococcus sp. in the presence of sulfate. Finally, cloning and sequencing of the gene cluster dszABC, its upstream regulatory sequence and dszD, demonstrated that they share 99%, 100% and 100% with those of R. erythropolis IGTS8, respectively.