A novel spectrophotometric method for simultaneous estimation of dibenzothiophene and 2-hydroxybiphenyl in their mixed spectrum and its application in screening of specific biodesulfurizing microbes

The desulfurization of fuel is currently enforced to meet environmental legislation and prevent pollution. The use of specific biodesulfurizing microbes with a unique 4S pathway allows the desulfurization without compromising the quality of fuel. These specific microbes can be screened by the detection of 2-hydroxybiphenol (2-HBP) in desulfurizing mixture of dibenzothiophene (DBT). At present, colorimetric Gibb's assay is the most commonly employed screening method which requires a specific reagent, i.e., 2,6-dichloroquninone-4-chloramide. In the present study, a novel and simple spectrophotometric method was developed for the detection of 2-HBP for screening purpose based on dual wavelength method. The developed method facilitates the simultaneous analysis of DBT desulfurization and 2-HBP production in a sample by merely measuring the absorbance differences at two specified wavelengths, i.e., Delta A (lambda(320)-lambda(247)) for DBT and Delta A (lambda(286)-lambda(324)) for 2-HBP. The developed method was used to screen 57 microbes and two specific desulfurizing microbes Bacillus flexus MS-5 and Bacillus cereus BR-31 were selected based on 2-HBP production. The outcomes of developed method were validated by HPLC analysis. The strains MS-5 and BR-31 were employed in biodesulfurization and resulted in 54.88 +/- 1.12% and 55.72 +/- 1.32% desulfurization of 1.0 mM DBT, respectively. The developed method for screening of specific desulfurizing microbes does not require any specific reagent or sophisticated instrument in spite of being quick and reliable. The microbes selected by developed method exhibited excellent potential for biodesulfurization of fuel.