Biodesulfurization of benzonaphthothiophene by an isolated Gordonia sp. IITR100

• Gordonia sp. IITR100 mediates the desulfurization of benzo-naphtho-thiophene (BNT).
• The released sulfur is used by the bacterium for growth.
• Metabolites BNT-sulfone, BNT-sulfinite and BNT-hydroxide are formed.
• Desulfurization of BNT is strongly inhibited in the presence of dibezothiophene.

Studies on the desulfurization of three or more ringed-compounds, which are considered to inhibit biodesulfurization of crude oil, are rare. In this paper, desulfurization of a three-ringed compound benzo[b]naphtho[2,1-d]thiophene (BNT) by an isolated strain Gordonia sp. IITR100 is described. The bacterium mediates desulfurization of BNT and utilizes the released sulfur for its growth. The reaction is accompanied with the formation of metabolites BNT-sulfone and BNT-sulfinate, in addition to the reported BNT-hydroxide. Recombinant E. coli cells, harboring DszC or DszA, were also able to mediate the metabolism of BNT to BNT-sulfone, or of BNT-sulfone to BNT-sulfinate, respectively. Desulfurization of BNT, both by IITR100 and E. coli-DszC cells was strongly inhibited in the presence of dibenzothiophene. The results are discussed in the context of the biodesulfurization of petroleum fractions where several organosulfur compounds are present together.