(515ak) Deep Biodesulfurization of Diesel Oil by Recombinant Rhodococcus Erythropolis LSSE8-1

Rhodococcus are important actinomyces and play important roles in biodegradation, biotransformation and biocatalysis. Despite their importance in the environmental and technological application, there have been short of expression vectors for Rhodococcus. Here, we developed an expression vector, pBSGT, for a specific desulfurization bacterium Rhodococcus erythropolis LSSE8-1 based on the E.coli-R.erythropolis shuttle vector pBS305 and the promoter of the thiostrepton resistance gene (tsr). The fluorescence data showed that GFP (green fluorescent protein) expressed under the promoter of tsr more effectively than the expression of gfp driven by the dsz (desulfurization genes) native promoter. Furthermore, the strain was not restrained any more by the sulfate. The dsz operon from LSSE8-1 was cloned into pBSGT and the dsz expression vector, pBSGT-dsz, was constructed. Then, it was transformed into LSSE8-1. The growth curve indicated that the transformation of the expression vector did not affect the host physiology. The results of the HPLC analysis revealed that the DBT (dibenzothiophene) desulfurization activities of the recombinants were increased remarkably. The recombinant strains were also applied in the desulfurization process of diesel oil (sulfur content 497 mg l-1). After 4 h, about 82% of sulfur in disel oil was removed by the recombinant, whereas the wild strain removed only 61% of sulfur in the system.