Selective cleavage of the two C-S bonds in asymmetrically alkylated dibenzothiophenes by Rhodococcus erythropolis KA2-5-1

The Rhodococcus erythropolis strain KA2-5-1 was characterized by its abilit y to cleave carbon-sulfur bonds in the dibenzothiophene (DBT) ring by asymm etrically alkyl substitution, such as C-2-DBTs (e.g., dimethyl and ethyl DB Ts) and C-3-DBTs (e.g., trimethyl and propyl DBTs), which are known to rema in in hydrodesulfurization-treated diesel fuels. After treatment by solid-p hase extraction (SPE) of solvents from microbial reactions of alkylated DBT s (Cx-DBTs), we used gas chromatography (GC), GC-atomic emission detection, GC-mass spectrometry and H-1 nuclear magnetic resonance spectroscopy to id entify and quantitatively evaluate the Cx-DBT metabolites. Molar ratios of metabolic isomers of the desulfurization products suggested that resting-ce ll reactions of KA2-5-1 against these Cx-DBTs occurrs through specific carb on-sulfur-bond-targeted cleavages, yielding alkylated hydroxybiphenyls, and that the manner of the attack on the DBT skeleton is affected not only by the position but also by the number and length of the alkyl substituents.