Biodesulfurization of organic sulfur by a newly isolated Rhodococcus sp. strain SDUZAWQ

Abstract

A strain named SDUZAWQ was isolated from soil contaminated by waste water of a refinery. Using GC/MS method, the strain was determined to biodesulfurize dibenzothiophene (DBT) via a sulfur-specific pathway, as socalled "4S pathway". This culture was identified as Rhodococcus sp. based on a partial 16S rDNA gene sequence and physiological and biochemical methods. Rhodococcus sp. SDUZAWQ can effectively desulfurize benzo[b]thiophene (BT), DBT and their derivatives. In two days, BT and DBT were degraded completely and 86% of BT was desulfurized in 24 h with the degrading rate being higher than that of DBT. The rate of 5-methyl-benzo[b] thiophene (5-MBT) was also higher than those of DBT derivatives, 4,6-dimethyldibenzothiophene (4,6-DMDBT) and 4- methyldibenzothiophene (4-MDBT). The degradation of 4-MDBT was more refractory than that of 4,6-DMDBT. In 48 h, 62% of 4,6-DMDBT was degraded, but only 36% of 4-MDBT was desulfurized under the same conditions.