APPLICATION OF SPME GC-MS TO CHARACTERIZE METABOLITES IN THE BIODESULFURIZATION OF ORGANOSULFUR MODEL COMPOUNDS IN BITUMEN/

A combined solid-phase microextraction/GC-MS analytical technique was used to monitor the formation of metabolites in the biodesulfurization of the bitumen model organosulfur compounds, dibenzothiophene (DBT) a nd the dialkylated derivative 4,6-diethyldibenzothiophene (DEDBT), by Rhodococcus sp. strain ECRD-1. In the case of DBT, the following metab olites were detected: DBT 5-oxide (sulfoxide), DBT 5,5-dioxide (sulfon e), dibenz[c,e][1,2]oxathiin 6-oxide (sultine), dibenz[c,e][1,2]oxathi in 6,6-dioxide (sultone), and the end product, 2-hydroxybiphenyl (2-HB P), whereas, with DEDBT, 4,6-DEDBT 5-oxide, 4,6-diethyldibenz[c,el[1,2 ]oxathiin 6-oxide (sultine), and 2-hydroxy-3,3'-diethylbiphenyl (HDEBP ) as the final product, were identified. A time course study for the f ormation and disappearance of DBT and DEDBT metabolites was used to co nstruct desulfurization pathways, which in both cases, involved the fo rmation of the corresponding sulfoxides.