Abstract: One hundred and sixty isolates of Bacillus thuringiensis were screened by PCR, and 94 of these isolates were zmaR-positive. It was found that 67 zmaR-positive isolates showed inhibitory effects on the growth of Erwinia herbicola OS, and the inhibitory activity of 21 isolates were higher than those of others. Bacillus thuringiensis isolate G03, which has cry1Ac, cry1Aa, cry1Ca and cry2Ab genes, was identified with zmaR gene and highly active to Erwinia herbicola OS. The zmaR gene was cloned from G03, and sequence analysis showed that zmaR consisted of 1 125 bp DNA fragment and encoded a protein containing 375 amino acids with 43.5 kD. The isoelectric point was pI4.945. The zmaR gene was inserted into pET-21b to generate pET-21b::zmaR, and then this recombinant plasmid was introduced into E. coli BL21 (DE3) for high-level expression. The 43.5 kD peptide could be detected by SDS-PAGE in the transformants with Zwittermicin A resistance.

Key words: zmaR gene, Bacillus thuringiensis, Zwittermicin A, Inhibition activity, Gene cloning