Study On Iducement And Abtivity Of Antibacterial Peptides In Tenebrio Molitor Larvae

Study on insect antibacterial peptides had been made great progress in recent years. In this paper, antibacterial substances were acquired from the larvae of Tenebrio molitor. Induction, isolation, antibacterial activity and antibacterial mechanism of antibacterial substances of Tenebrio molitor were studied.The larvae of Tenebrio molitor were induced by E.ciol, ultrasonic wave, ultraviolet light, all of them could induce the production of antibacterial peptide. The bacteriostasis ring was used to test the antimicrobial activity, while the E.ciol was treated as indicator bacterium. The results showed that the size of bacteriostasis ring increased along with the inducing level increased, and the tendency was raise before, then drop down. After 3-5 d, it would reach the peak-hour. Different inducing methods had different results:after pricking with E.ciol, the highest size of bacteriostasis ring advanced while the inducing concentration increased, but there were no change of ultrasonic wave and ultraviolet light induction. With the increasing of inducing level,there was an increasing of corrected mortality after using different inductions..The binary regression equation was figured out by the quadratic regression orthogonal rotary composite experimental design coded level of three factors, it showed as:Y=2.0611-2.4559×10-19×Z12+1.6524×103×Z22+3.0030×10-3×Z32+1.2776×10-9×Z1-6.5769×10-2×Z2- 7.174910-2×Z3-3.2568×10-11×Z1Z2-3.2087×10-11×Z1Z3.The F-test indicated that the concentration of the E.ciol had more effect on bacteriostasis ring, but there were no significant effect on ultrasonic wave and ultraviolet light induction. According to the regression equation, the experiment was based on this condition:E.ciol (1.47×108-4.06×108 germ/ml), ultrasonic wave(18.3-21.8 min) and ultraviolet light (10.7-13.6 min).This combination was the best inducing method from the orthogonal experiments.The antibacterial peptide of Tenebrio molitor had a broad antimicrobial activity.In this experiment we choose 8 kinds of germ to test its activities.2 kinds G+. the antibacterial peptide could prevent and kill the Streptococcus, but had no inhibitive effect on Staphyloccocus aureus.6 kinds G-,the antibacterial peptide had highly effect on inhibiting and killing E. coli, Bacillus subtilis, Aeromonas hydrophilia, R.solanacearum, but mainly had inhibitive effect on Xanthomonas oryzae pv.oryzae, and there was no significant bacteriostatic effect on P.Aeruginosa. The results showed that:the antibacterial peptide of Tenebrio molitor had wide spectrum and antimicrobial activity against germs, but had no significant effect on some germs.The result of Tricine-SDS-PAGE showed that the molecular weights of 18,21,24 and 90 KD increased for macromolecular proteins of Tenebrio molitor, the protein bands of 55 and 36 KD were thickened and 70 KD were thined than induced by E.ciol. The band of the antibacterial peptides were same.