Aspergillus flavus and Soil Fungi Aflatoxin Production Potential Using Coconut Medium in Al Ahsa Oasis, Saudi Arabia

Abstract

Aflatoxins are potent carcinogenic mycotoxins produced primarily by Aspergillus flavus and represent a severe threat to food safety, with contamination potentially originating in agricultural soil. This study aimed to isolate, characterise, and evaluate the aflatoxigenic potential of Aspergillus spp. in agricultural soils from the Al-Ahsa oasis, Saudi Arabia. One hundred soil samples were collected, and fungi were isolated on Sabouraud Dextrose Agar at 27 °C and 37 °C. Identification was based on macroscopic and microscopic morphological characteristics. Aflatoxin production was screened using Coconut Agar Medium (CAM) under ultraviolet light (365 nm). Among 122 primary isolates, Rhizopus spp. was the most prevalent (46 isolates), followed by Aspergillus fumigatus (30) and A. flavus (10). Further subculturing yielded 17 pure A. flavus isolates for aflatoxin testing. The CAM formulation containing coconut powder was effective, whereas the coconut oil formulation failed. Fourteen A. flavus isolates (82.4%) were aflatoxigenic, with production classified as high (3), medium (7), or low (4). Chi-square, Kruskal-Wallis, and binary logistic regression analyses found no significant association between aflatoxin production and geographical origin (p > 0.05), suggesting that toxigenicity may be strain-specific rather than environmentally determined. The high prevalence of toxigenic A. flavus indicates a substantial pre-harvest contamination risk for key crops in Al-Ahsa, particularly date palms. The study supports CAM as a cost-effective screening tool and highlights the need for integrated soil-management strategies in the region.