In order to expend the host system,plasmid in B. sphaericus was eliminated and then was transformed with plasmid pE9 cop为了扩大芽孢杆菌属的受体系统范围，对球形芽孢杆菌进行了质粒消除，并用含有溶葡球菌酶基因的质粒pE9cop－转化。