Biodesulfurization of dibenzothiophene and its derivatives through the selective cleavage of carbon-sulfur bonds by a moderately thermophilic bacterium Bacillus subtilis WU-S2B

Heterocyclic organosulfur compounds such as dibenzothiophene (DBT) in petro leum cannot be completely removed by hydrodesulfurization using chemical ca talysts. A moderately thermophilic bacterium Bacillus subtilis WU-S2B, whic h could desulfurize DBT at 50 degreesC through the selective cleavage of ca rbon-sulfur (C-S) bonds, was newly isolated. At 50 degreesC, growing tells of WU-S2B could degrade 0.54 mM DBT within 120 h to produce 2-hydroxybiphen yl, and the resting cells could also degrade 0.81 mM DBT within 12 h, The D BT-desulfurizing ability of WU-S2B is high over a wide temperature range fr om 30 to 50 degreesC, and highest at 50 degreesC for both the growing and r esting cells, and this is an extremely advantageous property for the practi cal biodesulfurization. In addition, WU-S2B could also desulfurize DBT deri vatives such as 2,8-dimethylDBT, 4,6-dimethylDBT and 3,4-benzoDBT, Therefor e, S. subtilis WU-S2B is considered to have more beneficial properties than other desulfurizing bacteria such as Rhodococcus strains previously report ed, particularly from the viewpoint of its capacity for thermophilic desulf urization through the C-S bond cleavage.