The expressions of antimicrobial peptides (AMPs) in the larvae of the black soldier fly, Hermetia illucens, were significantly increased by pathogen or stimulant induced innate immunity activation. We immunized H. illucens fifth instar larvae with five different Lactobacillus species, that is, Lactobacillus acidophilus, L. brevis, L. casei, L. fermentum, or L. delbrueckii, to induce the mass production of AMPs and selected optimal immune inducers. Antimicrobial activities in hemolymph and H. illucens larvae (HIL) extract were evaluated against three salmonella species (Salmonella pullorum, Salmonella typhimurium, and Salmonella enteritidis). Highest antimicrobial activity was shown by the hemolymph of HIL immunized by L. casei and its activity was closely linked with the inductions of cecropin 1 (HiCec1) and defensin 1 (HiDef1) gene expressions. Furthermore, antimicrobial activity in hemolymph was stable to heat and pH and the growth of three Salmonella species were dramatically suppressed by HIL hemolymph and extract after immunization with L. casei. The minimal inhibitory concentration (MICs) of L. casei-immunized HIL extract against Staphylococcus aureus, Escherichia coli, and Salmonella species ranged from 100~200 µg/100 µL and no cytotoxicity to CaCo-2 and L929 cells were observed in the concentration range 100~40,000 µg/100 µL. Taken together, the present investigation demonstrates that L. casei-immunized HIL extract is a powerful natural antibiotic and preservative that can prevent contamination by Salmonella species.

中文翻译：

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用干酪乳杆菌免疫的黑水虻幼虫提取物对沙门氏菌的抗菌活性


黑水虻 ( Hermetia illucens ) 幼虫中抗菌肽 (AMP) 的表达因病原体或刺激物诱导的先天免疫激活而显着增加。我们用嗜酸乳杆菌、短乳杆菌、干酪乳杆菌、发酵乳杆菌和德氏乳杆菌等5种不同的乳杆菌对H. illucens 5龄幼虫进行免疫，诱导AMPs的大量产生，并筛选出最佳的免疫诱导剂。评估了血淋巴和H. illucens幼虫 (HIL) 提取物针对三种沙门氏菌（白痢沙门氏菌、鼠伤寒沙门氏菌和肠炎沙门氏菌）的抗菌活性。干酪乳杆菌免疫的 HIL 血淋巴显示出最高的抗菌活性，其活性与天蚕素 1 (HiCec1) 和防御素 1 (HiDef1) 基因表达的诱导密切相关。此外，血淋巴中的抗菌活性对热和 pH 值稳定，并且在用干酪乳杆菌免疫后，HIL 血淋巴和提取物显着抑制了三种沙门氏菌的生长。干酪乳杆菌免疫 HIL 提取物对金黄色葡萄球菌、大肠杆菌和沙门氏菌的最低抑菌浓度 (MIC) 范围为 100~200 µg/100 µL，在此浓度范围内未观察到对 CaCo-2 和 L929 细胞的细胞毒性100~40,000 µg/100 µL。 总而言之，本研究表明，干酪乳杆菌免疫的 HIL 提取物是一种强大的天然抗生素和防腐剂，可以防止沙门氏菌污染。