Abstract:Antimicrobial peptide which plays a key role in the innate immune system of insect, is a kind of cationic alkaline peptide with low molecule weight. It is so effective against bacteria that it can be expected to develop as a new antibiotic. In this study, the authors compared the inhibitory effect of antimicrobial peptides of Blaps rhynchoptera Fairmaire larvae at induced treatment with non-induced treatment during isolation and purification procedures. The result indicated that both crude extracts of the two groups had no inhibitory effect on indicator bacteria at first. But after gel chromatography, the fraction DZP1 from non-induced group showed anti-bacteria activities against Staphylococcus aureus and Bacillus subtilis. Meanwhile the fraction YDP1 from induced group displayed anti-bacteria activities against Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa. Moreover, YDP1 had stronger activity than DZP1 and its anti-bacteria spectrum was broadened. Based on the analysis of Tricine-SDS-PAGE, the components of DZP1 and YDP1 were similar, both composed of small peptides no less than 20 kD. The results suggested that the antimicrobial peptide could be obtained from both induced and non-induced insects and the inhibitory effect against microbes would be stronger after challenging with bacteria.