Aflatoxigenic potential of Aspergillus quadrilineatus: implications for food safety in arid climates

Mycotoxins produced by Aspergillus species pose a major threat to food safety, particularly in warm and arid regions where environmental conditions favor fungal persistence and toxin biosynthesis. Aspergillus quadrilineatus, a member of Aspergillus section Nidulantes, is a documented producer of sterigmatocystin, the penultimate precursor of aflatoxin biosynthesis, yet its food-colonization potential remains poorly characterized. In this study, we investigated the growth characteristics, sporulation capacity, and mycotoxigenic potential of nine A. quadrilineatus isolates recovered from agricultural soils, compost, and poultry farm environments in Kuwait. Species identity was confirmed by morphological examination and ITS sequencing. All isolates exhibited optimal growth between 35 and 40°C, with several strains retaining growth above 45°C, indicating pronounced thermotolerance. All strains successfully colonized peanuts and strawberries under experimental conditions and produced high conidial loads. Sterigmatocystin was detected in all isolates, with maximal production observed on day 7 of incubation. High-performance liquid chromatography analysis demonstrated that multiple isolates produced substantial quantities of aflatoxins B1, B2, G1, and G2 on infected food commodities. In peanuts, total aflatoxin concentrations reached 7.38, 6.51, and 6.32 ppm in the highest-producing strains, exceeding international regulatory limits by several orders of magnitude. In strawberries, aflatoxin production was generally lower but remained significant, with G-type aflatoxins frequently predominating. Collectively, these results demonstrate that indigenous A. quadrilineatus strains can survive arid climatic conditions, infect food commodities, and contaminate them with carcinogenic mycotoxins, identifying this species as an under-recognized food safety risk in arid and semi-arid regions.