Etudiant : MDAGHRI ALAOUI OULAYA

Filière : Master d'excellence: Biotechnologie Alimentaire et Management de la Qualité (BAEMQ)

Encadrant : Pr. ADIL LAAZIZ

Annèe : 2026

Résumé : A number of Aspergillus species, including A. carbonarius, A. niger, and A. tubingensis, generateochratoxin A (OTA), a nephrotoxic and carcinogenic mycotoxin that regularly contaminates food products such cereals, coffee, and grapes. Controlling OTA production and fungus growth is still a significant problem for food safety. This study used an integrative method integrating in silico and in vitro investigations to assess the combined impact of water activty (aw) and essential oils (EOs) on the growth of Aspergilus spp. and OTA production. Molecular docking was applied to two significant enzymatic targets: CYP51B and OtaC. Pulegone, carvacrol and cinnemaldehyde were docked against both targets. Carvacrol showed the highest affinity for CYP51B (ΔG = -7,231 kcal/mol) as well as the best biding to OtaC (ΔG = -7,316 kcal/mol). The possible inhibitory effect of these drugs was supported by 2D/3D interaction studies that identified important hydrophobic interactions and hydrogen bonding with conserved active-site residues. In vitro antifungal assays were conducted using the EO of Mentha Pulegium, Origanum Vulgare and Cinnamomum Cassia at six concentrations (25–500 µL/L), on five Aspergillus strains, under three aw levels (0.99, 0.95, 0.90). The percentage of inhibition of radial growth (PICR) increased with EO concentration and was significantly enhanced at 0.90 aw, with Cinnamomum Cassia EO showing the best antifungal activity, with total inhibition at 100 µL/L at 0.99 and 0.95 aw, and 50 µL/L at 0.90 aw. A two way ANOVA revealed significant effects of concentration, aw, and strain on fungal growth (p < 0,01) in Mentha Pulegium and Origanum vulgare, but strains were not significant in Cinnamomum Cassia EO. The lag phase was also extended at higher EO concentrations, particularly under water stress conditions. Overall, this study highlights the synergistic effect of aw reduction and EO application as a promising strategy for controlling Aspergillus growth and OTA contamination. These findings open new perspectives for the development of natural and eco friendly preservation methods in the food industry.