In a recent article, Korean researchers aimed to produce a natural food preservative using a crude extract from edible, immunized Tenebrio molitor larvae (iTME), injected with edible bacteria using an edible solvent.

iTME had concentration-dependent inhibitory activity against food-poisoning bacteria E. coli, Bacillus cereus, Staphylococcus aureus, as well as against harmful fungi Aspergillus flavus, A. parasiticus, and Pichia anomala (a biofilm yeast related to the reduction in quality of the sauce).

Moreover, iTME showed antimicrobial activity against beneficial microorganisms Bacillus subtilis and Aspergillus oryzae (which are used in Korean traditional sauce fermentation), but not Lactobacillus acidophilus. The inhibition level against A. oryzae was lower than that against harmful fungi.

Insects produce a variety of antimicrobial peptides (AMPs), which aggregate, penetrate the cell membrane, and form channels, resulting in cytoplasmic leakage. In severe cases, AMPs induce cell membrane disruption, leading to cell death. Owing to these properties, AMPs do not generate resistant strains unlike conventional antibiotics.

To date, no studies have reported the direct application of insect-derived AMPs to food, since insects have been officially recognized as new raw food materials only recently, and interest in edible insects is increasing worldwide. The preparation of Meju (Korean traditional sauce) with TML has been previously reported.

In previous reports, insect-derived AMPs have been industrially applied by expressing or synthesizing every single peptide, but only one peptide has a narrow spectrum of antimicrobial activity. Therefore, in this study, the production of various AMPs in the insect body was induced through the injection of edible lactic acid bacteria.

It was also studied whether the antibacterial activity of iTME under human intestinal protease was maintained. These results indicate that iTME would lose its inhibitory activity when introduced into the intestine. Therefore, when ingested, iTME may not remain in the intestine due to proteolytic enzymes. Therefore, iTME is predicted to be safe for the human body.