Study of desulfurization rate in Rhodococcus FMF native bacterium

The Rhodococcus FMF (R. FMF) native bacterium was isolated from soil contaminated with oil in Tabriz refinery. This bacterium carries three genes sox (dszA, B, C) on its genomic DNA. Preliminary studies have proved that R. FMF strain possess desulfurization activity. In this work soxA and B genes were amplified by PCR, after designing a pair of suitable primers. Analysis of PCR products on agarose gel electrophoresis showed a sharp band in the 2.46 kb region, belonging to soxA and B genes. In addition, dot blotting using the sox4 probe, confirmed the presence of sox operon in the PCR product. The standard Gibbs test was designed for desulfurization activity assay in which production of 2HBP (µM) in four bacterial strains [R. FMF, P. aeruginosa (pESOX4), E.coli DH5α (pESOX3) and E. coli CC118λpir (pESOX4)] was recognized and compared. After 41h of dibenzothiophene (DBT) addition, Pseudomonas aeruginosa (pESOX4) produced 4.8 µM 2HBP and the local R. FMF produced 3.8 µM of DBT. Comparison of 2HBP production in the standard strain of P. aeruginosa (pESOX4) with the isolated R. FMF strain from Tabriz refinery revealed that the later is equally capable of desulfurizing DBT.