The current approach for the crude oil desulfurizatin in refinery is hydro desulfurization in which in addition to great cost and energy, the sulfur does not get completely isolated. Therefore, the researchers have concentrated on a biodesulfurization approach which is performed with lower costs. After the isolation of existing bacteria in oil-polluted soil, they were cultured on liquid media containing mineral compounds and DBT. The growth and cell activity of the bacterium were investigated at temperatures of 20, 25, 30, 35, 40 and 45º­c; shakers of 115, 130, 145, and 160­ rpm; and at pHs of 5, 6, 7, 8, 9, 10 and 11. The obtained metabolites from the mentioned bacterium desulfurization function were examined by the Gibbs test, gas chromatography and CHONS analyzer. The isolated bacterium is coccus, gram-negative and smooth margin. The most activity and cell growth of this bacterium is 35ºc, 145 rpm and pH 8. The mentioned bacterium decreased the amount of sulfur DBT from 200 ppm to 0 during 72 hours. It also reduced the total sulfur crude oil from 5.7% to 0% during 15 days. This bacterium is capable to carry out the oxidative non-destructive desulfurization of dibenzothiophene (DBT), called 4S pathway, without carbon skeleton breakdown. The bacterium cannot decompose hydrocarbons and organic materials.

Keyword: 2-hydroxybiphenyl, dibenzothiophen, biodesulfurization