The biological properties of an antimicrobial peptide extracted from Tenebrio molitor

[Objectives] To determine the concentration and antibacterial activity of an antimicrobial peptide(AMPs) extracted from Tenebrio molitor Linnaeus larvae, and to explore its biological properties. [Methods] AMP production was induced in five-day old Tenebrio molitor larvae by Escherichia coli at a concentration of 1×108 CFU/m L. AMPs were extracted from the larvae at 12, 24, 36, 48, 60, and 72 h respectively, their concentration detected by coomassie brilliant blue stain and their antibacterial activity measured using the filter paper method. In addition, other features, such as thermal stability, stability after repeated freezing and thawing, proteinase stability, effect of different p H and coagulation, were also measured. [Results] The results show that inducing the production of AMPs with E. coli resulted in a significantly higher concentration of AMPs being extracted from T.molitor(P 0.01). AMP levels were highest at 48 h. Moreover, the diameter of bacterial inhibition caused by AMPs induced by E. coli was significantly larger(P 0.05). AMPs extracted from T. molitor were stable with respect to variation in temperature, proteinase and p H. Repeated freezing and thawing had little effect on the biological properties of AMPs, including coagulation. Therefore, the immune system of T. molitor produces a higher concentration of AMPs with better biological stability and antibacterial activity, and no coagulation, following induction by E. coli. [Conclusion] These results have laid a theoretical basis for further utilization of antibacterial peptides extracted from T. molitor.