Antibacterial peptides exist in earthworms with low concentrations in normal environments. In order rnto test the quantitative and active variation of peptides with environmental situation surrounding earthworms,rna set of antibacterial peptide assay were used on 3 stressed earthworm ways to verify the possibility of induced rnantibacterial peptides (IAP) as a novel candidate biomarker used for risk assessment in earthworm ecotoxicolorngy. Stress - peptides characterized with strong bacteriostatic activities, high heat stability and less than 10Kd rnmolecular weight was separated from the extract of coelomic fluid by methods of heat treatment, ultrafilter and rnmolecular sieve. The physicochemical and antibacterial properties of antibacterial peptides were verified by usrning the methods of plate growth inhibition assay, bactericidal assay and belt growth inhibition assay with polyrnacrylamide gel electrophoresis. The result showed that peptide A3-4-2, a Gly rich acid tetradecapeptide,rnseems to be a suitable candidate biomarker. It has wide antibacterial chart and bacteriostatic activities and a rnhigh level of concentration response to stresses. However, there are differences among various bacterial strains rnin antibacterial efficiency.rnThree stresses, including biological treatment (bacteria injection), physical treatments (γ- ray and mernchanical injury) and chemical treatments (heavy metal and pesticide pollution) were used to test the sensitivity rnof induced earthworm antibacterial peptides. The result showed that antibacterial peptides can be induced by rnalmost all inducing treatments used, but there were differences in sensitivity to various stress treatments. The rnhigher sensitivities are alive E coli injection, mechanical injury and heavy metal treatment. In the limited rnscope that earthworm can tolerate, the stronger the stress to worms, the higher the antibacterial activities of rnthe peptide. It seems that certain target antibacterial substances can be induced by given matters or methods.rnAntibacterial peptide (tetradecapeptide), as a component of antibacterial system in the earthworm coelomic rnfluid, can be gotten by many inducing methods and with sensitive non - specialization - immune response to rnenvironmental stressors.%正常情况下,蚯蚓含有低量的抗菌肽.为了验证周围生活环境对蚯蚓抗菌肽量和活性的诱导作用,检测了在3种应激处理下蚯蚓的诱导抗菌肽变化,以探讨利用诱导抗菌肽(IAP)作为一种新的生化标记用于蚯蚓生态毒理风险评价的方法.应激肽用热处理、超滤和分子筛方法从蚯蚓体液中获得.它具有强的抑菌活性和热稳定性,分子量低于10KD.用抑菌圈测定,溶菌活力测定及聚丙酰凝胶电泳抑菌带显示试验的方法分析抗菌肽的抗菌特征和理化特性.结果表明:抗菌肽A3-4-2为一种适宜的候选生物标记.它是一种富含甘基酸的四十肽,具有广泛的抗菌谱和抑菌活性,对应激条件表现高的浓度水平.但对不同菌株具有不同的抗菌效力.3种应激处理用于检测诱导蚯蚓抗菌肽的敏感性.这3种处理包括生物处理(细菌注射)、物理处理(γ射线和机械损伤)和化学处理(重金属和农药污染).结果表明,几乎各种应激处理都能诱导产生抗菌肽,但蚯蚓对不同的应激其敏感性有区别.对大肠杆菌注射敏感性高.其次是机械损伤重金属处理.蚯蚓在一定的耐受范围内,随着应激强度加大,抗菌肽活性增强.一定的物质和方法似乎能诱导出定向的目标抗菌物.抗菌肽(四十肽)作为蚯蚓体液中的抗菌成分可以被多种方法诱导获得并具有对环境应激物非专一性的免疫应答.
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