Biodesulfurization of dibenzothiophene by a newly isolated Rhodococcus erythropolis strain.

A new dibenzothiophene (DBT) desulfurizing bacterium was isolated from oil-contaminated soils in Iran. HPLC analysis and PCR-based detection of the presence of the DBT desulfurization genes (dszA, dszB and dszC) indicate that this strain converts DBT to 2-hydroxybiphenyl (2-HBP) via the 4S pathway. The strain, identified as Rhodococcus erythropolis SHT87, can utilize DBT, dibenzothiophene sulfone, thiophene, 2-methylthiophene and dimethylsulfoxide as a sole sulfur source for growth at 30 degrees C. The maximum specific desulfurization activity of strain SHT87 resting cells in aqueous and biphasic organic-aqueous systems at 30 degrees C was determined to be 0.36 and 0.47 micromol 2-HBP min(-1) (gdrycell)(-1), respectively. Three mM DBT was completely metabolized by SHT87 resting cells in the aqueous and biphasic systems within 10h. The rate and the extent of the desulfurization reaction by strain SHT87 suggest that this strain can be used for the biodesulfurization of diesel oils.