RESUMO
We first cloned the dsz operon of Pseudomonas delafieldii R-8 into the expressing plasmid (pPR9TT) to construct the recombinant plasmid pPR-dsz, and then reintroduced it into strain R-8 to obtain a muti-copy dsz operon engineering strain R-8-1. Compared with the wild-type, strain R-8-1 showed a higher desulfurization activity for dibenzothiophene (DBT). Initial rates of DBT removal by strain R-8-1 were 6.25 micromol/g dry cell/h, about 2-fold higher than that for wild-type strain. The recombinant cells were also applied in the desulfurization of diesel. It resulted in a 68% reduction of total sulfur from 310.8 mg/L to 100.1 mg/L, whereas only 53% of sulfur was removed by strain R-8. The stability of pPR-dsz in strain R-8-1 was studied. The results revealed the first obtain a muti-copy dsz operon engineering strain are helpful for further development in biodesulfurization.