Potensi Bakteri Asam Laktat (BAL) dari Larva Hermetia illucens dalam Menghambat Methicillin-resistant Staphylococcus aureus (MRSA)

Abstract

Larvae of Hermetia illucens, commonly known as maggots, are known to decompose various organic materials such as vegetables and fruits. This ability creates a body and gut environment rich in microorganisms, including lactic acid bacteria (LAB). LAB are capable of producing bioactive compounds such as lactic acid and bacteriocins, which possess antibacterial properties against pathogenic bacteria. This study aimed to isolate LAB from Hermetia illucens larvae and to assess their antagonistic activity against Methicillin-resistant Staphylococcus aureus (MRSA). LAB were isolated from both the body surface and the gut of the larvae, then characterized morphologically, subjected to Gram staining, motility test and biochemical assay. The isolated LAB strains were tested for their antagonistic ability against MRSA using the dual culture method and by assessing the inhibitory activity of the culture supernatant. The LAB culture supernatants underwent four treatments: untreated (normal condition), heating at 100°C, autoclaving, and pH neutralization. The isolation yielded 13 LAB strains, consisting of 5 isolates from the body surface and 8 from the gut of the larvae. Morphological characterization revealed diversity in colony shapes, colors, margins, and elevations among the isolates. All isolates were Gram-positive and exhibited bacillus and coccus cell forms. Biochemical tests indicated that all isolates were non-motile, catalase-negative, and capable of fermenting sugars without producing hydrogen sulfide (H₂S) or carbon dioxide (CO₂). Antagonistic tests against MRSA identified 6 isolates with inhibitory potential. The antimicrobial activity indices of these 6 isolates ranged from 0.3 to 3.525. The isolate with the highest activity index was Mi01 under natural conditions although its inhibitory activity decreased after heat and autoclaving treatments, it remained effective to inhibit MRSA. These results suggest that isolate Mi01 has potential as a candidate antimicrobial-producing bacterium in inhibiting MRSA infections that are resistant to conventional antibiotics and that it produces antimicrobial compounds that remain stable under high-temperature conditions.