Biodesulfurization of Alkylated Forms of Dibenzothiophene and Benzothiophene by Sphingomonas subarctica T7b

Sphingomonas subarctica T7b was isolated from soil in Toyotomi, Hokkaido, Japan as an organism capable of desulfurizing aromatic hydrocarbons in light gas oil (LGO) through enrichment culture. S. subarctica T7b could grow on mineral salt sulfur-free (MSSF) medium with the n-tetradecane oil phase containing dibenzothiophene (DBT), alkyl dibenzothiophenes (alkyl DBTs) or alkyl benzothiophenes (alkyl BTs) as the sole sulfur source and desulfurize these compounds, but could not utilize the tetradecane as a carbon source. This is the first report of a gram-negative bacterium which can desulfurize 4,6-dibutyl DBT and 4,6-dipentyl DBT. The desulfurized product of DBT produced by this strain was 2-hydroxybiphenyl, as in the case of other DBT-desulfurizing bacteria. S. subarctica T7b could desulfurize LGO and the sulfur content was decreased to 41% within 36 h.