The Study of Biodesulfurization Activity in Recombinant E. coli Strain by Cloning the dsz Genes Involve in 4S Pathway

Several research groups have attempted to make recombinant bacteria capable of efficient desulfurization of oil fraction. The main aim of this study was to design a recombinant strain in order to desulfurize dibenzothiophen (DBT) and its components found in petroleum. In this study the pVLT31 vector harboring dszABC genes was transferred into recombinant E. coli BL21 which contained the dszD gene previously. We found that the recombinant E. coli BL21 containing the pVLT31 plasmid harboring dszABC genes and the pET21a plasmid harboring dszD gene had the highest capability for desulfurization of dibenzothiophen, when these four genes co-expressed. The data obtained in this study were confirmed by using Gibbs test, High-performance liquid chromatography (HPLC) and measuring of dry Cell weight. These analyses showed that dszABC and dszD genes co-express under the heterologous promoter in the strains which are stable in oil and petroleum compounds. In the next step the pUC18 plasmid harboring dszAB genes of Rhodococcous FMF was transferred into E. coli DH5? in order to evaluate the Effect of elimination of dszC gene in the rate of biodesulfurization process. This analysis demonstrated that 2-hydroxybiphenyl (2-HBP) production of recombinant E. coli DH5? using broken 4s pathway was less than that of Rhodococcous FMF in comparison. In this report we showed that the existence of the third gene (dszC) is necessary for enhancement of desulfurization activity.