Hermetia illucens (black soldier fly) larvae (HIL) are considered useful industrial insects for the production of feed for livestock, eco-friendly fertilizer from organic wastes, and biodiesel. Therefore, we evaluated the antimicrobial activity in the extract of crude-oil-extracted crushed HIL powder prepared from HIL fed organic waste containing fermented effective micro-organisms for biodiesel production. The result showed that antimicrobial activity was not fully induced in HIL fed L. casei-containing feed. In contrast, increased antimicrobial activity was observed in defatted HIL extract prepared from crude-oil-extracted crushed HIL powder. We found that the extract effectively inhibited the growth of pathogens and antimicrobial-peptide-resistant bacteria, such as three kinds of Salmonella species, and Enterococcus faecalis, Streptococcus mutans, Candida albicans, Serratia marcescens, and Pseudomonas tolaasii, with a minimum inhibitory concentration of 200-1000 µg/100 µL. Furthermore, no cytotoxicity to CaCO-2 human intestinal cells was observed in the extract. We also found that the production fee of extract equivalent to the antimicrobial activity of melittin was approximately 25-fold less than the production fee of melittin. Therefore, the results demonstrate that crude-oil-extracted crushed HIL powder prepared from HIL fed organic waste containing fermented effective micro-organisms for biodiesel production should be used as the feedstock for synthetic, preservative-free livestock feed and food additives. Taken together, the present study supports the usefulness of HIL as an eco-friendly feedstock in the biodiesel, agricultural, food, and feed industries.
Keywords: Hermetia illucens larvae; antimicrobial peptide; ecofriendly feedstock; food additives; natural antimicrobial substance.