Sinorhizobium sp. KT55 was the first Gram-negative isolate to be capable of utilizing benzothiophene as the sole source of sulfur. By GC-MS analysis of metabolites of benzothiophene by this strain, benzothiophene sulfone, benzo[e][1,2]oxathiin S-oxide and o-hydroxystyrene were detected, suggesting that the benzothiophene desulfurization pathway of this strain is benzothiophene --> benzothiophene sulfoxide --> benzothiophene sulfone --> benzo[e][1,2]oxathiin S-oxide --> o-hydroxystyrene, Desulfurization activity of this strain was significantly repressed by methionine, cysteine, sulfate, dimethyl sulfoxide, and Casamino acids.