Dibenzothiphene (DBT) was used as a model organic sulfur in solubilized coal and the degradation mechanism by Rhocococcus rhodochrous IGTS8 was studied. Optimum conditions for desulfurization were investigated with respect to cultivation. Under the optimum conditions, desulfurization of solubilized coal was performed.
Final product of DBT conversion by the bacteria was identified as 2-hydroxybiphenyl (2-HBP). DBT degradation was inhibited by sulfates.
Optimum conditions were summarized as follows; pH 7, glycerol 1.2%(v/v), ammonium chloride 0.4%(w/v), 200rpm, 28℃ Over 100ppm DBT, the cell growth was repressed. Surface tension of medium was declined during cultivation and it was probably due to surfactants produced by the bacteria. Addition of surfactant(Tween80) promoted the cell growth.
1% (w/v) of solubilized coal was treated with bacteria. After microbial treatment, elemental analysis showed little compositional difference. From the titration experiment, solubilized coal is supposed to have folded structure and this seems to interfere microbial attack on organic sulfur moieties in coal.