Antimicrobial Compounds From Aspergillus chevalieri Associated With the Gut Microbiota of Hermetia illucens Larvae Targeting Salmonella enterica Serovar Pullorum

Background: The gut microbiota of insects represents an underexplored reservoir of bioactive compounds with potential antimicrobial applications. This study is aimed at identifying antimicrobial compounds from fungi associated with the gut microbiota of Hermetia illucens (black soldier fly) larvae active against Salmonella enterica serovar Pullorum, an important poultry pathogen. Methods: Fungi isolated from H. illucens larval gut were screened for antimicrobial activity against S. enterica serovar Pullorum. The active fungus was identified through molecular analysis of ITS, benA, and CaM regions. Ethyl acetate extract from the fungal culture was assessed for antimicrobial activity, followed by bioguided fractionation using preparative and semipreparative chromatography. Active fractions were analyzed using UHPLC/HRMS, and putative compound identification was performed through mass spectrometry and molecular networking. Result: Aspergillus chevalieri was identified as active against S. enterica serovar Pullorum, with the ethyl acetate extract exhibiting moderate antimicrobial activity (MIC = 4.00 mg/mL; IC₅₀ = 3.00 ± 0.58 mg/mL). Bioguided fractionation resulted in several active fractions. UHPLC/HRMS analysis putatively annotated 10 compounds, previously shown to be bioactive, including diketopiperazines (Neoechinulin A and echinulin), peptide derivatives (cyclo(L-Tyr-L-Pro) and N-acetyltyramine), a benzofuran derivative, an isocoumarin (diaporthin), a flavin (lumichrome), an aminopurine (isopentenyladenine), and two diterpenoids (4-deoxyphorbol-13-acetate and austinoneol). Conclusion: This study represents the first report of A. chevalieri associated with H. illucens larvae and demonstrates its potential as a source of antimicrobial compounds against S. enterica serovar Pullorum. The identified bioactive compounds provide promising leads for the development of new antimicrobial agents for poultry health.