Desulphurization of Dibenzothiophene by Different Bacterial Strains: An Eco-Friendly Approach to Obtain Clean Fuel from Coal

Coal is an important energy resource and many deposits contain a significant quantity of organic sulfur compounds. Combustion of coal releases SO2, CO2 and other gases into atmosphere and causes negative impact on the environment. Biodesulphurization of dibenzothiophene could be a prominent method for the removal of sulfur from coal. Here we successfully employed bacterial strains to degrade dibenzothiophene, and characterized through chromatography, high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Strains of Ralstonia sp., Pseudoxanthomons sp. and Rhodococcus sp. were used in the present investigation. Only Rhodococcus sp. converted dibenzothiophene (DBT) into 2-hydroxy biphenyl (2-HBP) and was able to additionally break the C-S bond without disturbing heterocyclic structure of DBT ring. This is also complemented by blue color of Gibb's assay which is indicative of DBT conversion into 2-HBP while brown color indicates complete consumption of DBT by bacteria. After two days of bacterial treatment, there was no further removal of DBT. DBT conversion into 2-HBP was monitored through HPLC during six days of experiment. Thus Rhodococcus sp. could be a proficient candidate for biodesulphurization of dibenzothiophene and eventually for biodesulphurizing organic sulfur rich coal with an eco-friendly and energy economical process. Though it is encouraging technique for desulphurization however more studies on coal are still required to support the industrial scale biodesulfurization.

Automated summary

This study successfully employed bacterial strains to degrade dibenzothiophene, with Rhodococcus sp. exhibiting the best desulfurization performance by breaking the C-S bond without disrupting the heterocyclic structure of DBT.