Expression And Antibacterial Activity Test Of Insect Antimicrobial Peptides Gene Cercropin B

Insect antimicrobial peptides are a kind of bioactive peptides in the blood lymph after immunization and have wide range antibacterial activities against bacteria,fungi,viruses,protozoa and cancer cells without harming natural mammalian cell.These peptides,usually smaller than 10 kDa,can directly kill bacteria rather than the inhibition mechanism of antibiotics.Usage of these peptides may be gradually appreciated since more bacteria may develop the ability to resist conventional antibiotics due to the abuse of these drugs worldwide.In this study,Cecropin B gene of Plutella xylostella was fused with ubiquitin gene of P.xylostella.The fusion gene was cloned into the prokaryotic expression vector pQE30 and constructed the recombinant plasmid pQEUBI-CB.The plasmid was then transformed into E.coli M15 and induced with IPTG.The dissolubility analysis revealed that the fusion protein dissolved in the supernatant fluid after cell lysis.The fusion protein was then post-translated by ubiquitin C-terminal hydrolase and released intact.Finally,antibacterial activity test of Cercropin B towards E.coli TG1,Staphylococcus aureus and Vibrio parahemolyticus was processed.The results showed that ubiquitin-Cecropin B fusion gene has been expressed in the E.coli M15,and the product has antibacterial activity after post-translation.