Abstract

Ladan Rashidi*, Ghasemali Mohebali, Jafar Towfighi darian, Behnam Rasekh

RIPI-S81 is a new dibenzothiophene (DBT)-desulfurizing bacterium, which was isolated by Research Institute of Petroleum Industry in Iran. Resting cells and growing cells of RIPI-S81 was able to convert alkylated dibenzothiophenes (Cx-DBTs) to hydroxybiphenyls such that they were almost stoichiometrically accumulated as the dead-end metabolites of Cx-DBTs desulfurization in the medium containing minimal salt (MSM) and nutrients. RIPI-S81 could desulfurize up to 80% of 4,6-dimethyldibenzothiophene and 50% of methyldibenzothiophene in the MSM containing 40 mg/l of a sulfur source. The molecular structures of metabolites and the reduction of Cx-DBTs were analyzed using GC-MS and HPLC. The position of alkyl substitutes and the sulfur substrate affected desulfurization rates.