Base on the successful expression of pks gene by cits857 controlled lambda promoter, an e . coli expression vector phz330, an e . coli and streptomyces bi-functional vector phz1060 were constructed containing the dts857-pr for inducible expression in both hosts . both vector 根据受cits857调控的p_r能引导pks基因的成功表达,构建了大肠杆菌表达载体phz330以及在大肠杆菌和链霉菌两种宿主中都能表达外源基因的双功能表达载体phz1060。