Abstract: The gene sequence of Cecropin D mature peptide was obtained from the fat body of common cutworm, Spodoptera litura by RT-PCR. Amino acid sequence analysis showed that there was a two-amino-acid-residue difference between the mature peptides of Cecropin D and Cecropin B from S. litura. The target gene was cloned into a prokaryotic expression vector pGEX-4T-1, and a fusion protein was obtained from E. coli BL21 after IPTG induction; but no protein expression was detected without induction. The fusion protein could be detected 1 h after IPTG induction, and the amount of the fusion protein kept a relatively constant level from 1 h to 5 h. Growth curve showed that the growth of host bacteria with recombinant vector was restrained distinctly when IPTG was added into the culture medium. The results indicated that the purified fusion protein could restrain growth of bacteria.

Key words: Spodoptera litura, antibacterial peptide, fusion expression