Antimicrobial peptides (AMPs) are effective molecules produced by the innate immune system of most organisms to fend off invading microbes and regarded as promising alternatives to conventional antibiotics due to their potent antimicrobial activities. The larvae of black soldier fly (BSF), Hermetia illucens, inhabit microbe-rich environments and its insect genome encodes a broad repertoire of AMPs. In the present study, three AMPs encoded by BSF Hidefensin-1, Hidiptericin-1 and HiCG13551 were cloned, expressed and purified in a recombinant Escherichia coli expression system. In vitro, both Hidefensin-1 and Hidiptericin-1 inhibited the growth of Streptococcus pneumoniae and Escherichia coli, while HiCG13551 inhibited the growth of Staphylococcus aureus and E. coli. Transmission electron microscopy showed that Hidiptericin-1 inhibited bacterial growth through bacterial membrane lysis. We also constructed a transgenic silkworm line constitutively expressing an AMP cassette HiAMP4516 encoding all the three AMPs, and the silkworms showed an increased resistance to both gram-positive and gram-negative entomopathogenic bacteria. These results provide insights into the antibacterial activities of BSF AMPs both in vitro and in vivo and suggest a great potential of exploiting insect-derived AMPs in silkworm disease resistance breeding.

抗菌肽（AMPs）是大多数生物体的先天免疫系统产生的有效分子，可以抵御入侵的微生物，由于其强大的抗菌活性，被认为是常规抗生素的有希望的替代品。黑兵苍蝇（BSF）的幼虫（Hermetia illucens）栖息在富含微生物的环境中，其昆虫基因组编码广泛的AMPs。在本研究中，由BSF Hidefensin-1，Hipiptericin-1和HiCG13551编码的三个AMPs在重组大肠杆菌表达系统中被克隆，表达和纯化。在体外，Hidefensin-1和Hidiptericin-1均抑制肺炎链球菌的生长和大肠杆菌，而HiCG13551抑制金黄色葡萄球菌和大肠杆菌的生长。透射电子显微镜显示Hidiptericin-1通过细菌膜裂解抑制细菌生长。我们还构建了组成型表达编码所有三个AMP的AMP盒HiAMP4516的转基因蚕品系，该家蚕对革兰氏阳性和革兰氏阴性昆虫致病菌均显示出更高的抗性。这些结果提供了对BSF AMPs体外和体内抗菌活性的见识，并表明在昆虫抗病育种中利用昆虫衍生的AMPs具有巨大的潜力。