International Journal of Biotechnology & Biochemistry

Rhodococcus FMF isolated from Iran is an indigenous, gram-positive bacterium with the biological desulfurization activity. This bacterium has capability to utilizing Dibenzothiophen(DBT) as the sole source of sulfur and converts the DBT to 2-hydroxybiphenyl (2-HBP) using 4 Enzymes (DszA,B,C,D,) in a pathway which is named 4s pathway. Previously dszABC genes of this bacterium were isolated, sequenced and expressed in different heterologus hosts. In this study for the first time the dszD gene of Rhodococcus FMF was amplified and sequenced. The data obtained showed that there was a high similarity between dszD gene sequences of Rhodococcus FMF and that of R. erythropolis IGTS8. In addition, the dszD gene was cloned into pET21a plasmid and expressed in E. coli BL21. This result demonstrated that dszD gene could be over expressed and supported the biodesulfurization process. The biodesulfurization activity of two Rhodococcus species, Rhodococcus FMF isolated in Iran and Rhodococcus erythropolis IGTS8, were compared using HPLC analysis and Quantitative Gibb's assay. The results demonstrated that the Biodesulfurization activity of Rhodococcus FMF is lower than that of Rhodococcus erythropolis IGTS8. This research emphasized that the low BDS activity of R. FMF is not related to dszD (oxidoreductase) gene because this gene has 100% homology in Rhodococcus FMF and Rhodococcus erythropolis IGTS8 and the amount of dszD gene expression in these bacteria is the same.