Research note: Antimicrobial properties of commercial black soldier fly (Hermetia illucens) meal against gram-positive and gram-negative bacteria

Black soldier fly larvae meal (BSFM) is increasingly recognised as a sustainable and functional protein source in the livestock feed industry, owing to its high crude protein and rich fatty acid content. Beyond its nutritional value, BSFM has demonstrated antibacterial properties, enhancing resistance in animals to pathogens such as Salmonella species. These findings are critical as antimicrobial resistance continues to rise in the livestock sector. The black soldier fly (BSF) genome encodes antimicrobial peptides (AMPs) that can be classified under families such as cecropins, defensins, and attacins. The presence and functionality of these AMPs in the commercial BSFM remain underexplored. This study investigates the AMP content and antimicrobial properties of BSFM produced industrially. The water-soluble peptides from the complex BSFL biomatrix were extracted with acidic methanol and defatted with hexane. Attacin, cecropins, defensins and related peptides were identified with liquid chromatography-mass spectrometry (LC-MS). Bioassays against five bacterial strains relevant to animal health revealed that the antimicrobial activity of AMPs was preserved even after undergoing industrial processing that involved heat and mechanical compression. These findings confirmed BSFM as a nutritious antimicrobial feed ingredient in livestock production.