Geographic Profiling of Aspergillus Species and Aflatoxin Variants Across Peanut-Growing Regions of Queensland Australia

Aflatoxins are carcinogenic secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. These two fungi are ubiquitous in soil and are often found in agricultural fields. Four aflatoxin variants commonly found in infected crops are: AFB1, AFB2, AFG1, and AFG2. Aspergillus parasiticus can produce all aflatoxin variants, with A. flavus only able to produce the aflatoxin B variants. Production of aflatoxins typically occurs as pre-harvest contamination in the Australian peanut-growing regions of Queensland. This study analysed geographic variations in aflatoxin component variants using the HPLC method for the 2020–2024 season peanuts. Aflatoxin-G was found as most common aflatoxin variant across three of the four peanut-growing regions. This study also evaluated diversity of A. flavus and A. parasiticus across the four peanut-growing regions, using post-harvest soil samples from the 2023–2024 growing season. Aspergillus parasiticus was found to be most prevalent (97% isolates) across the regions, whereas A. flavus was least prevalent (3% isolates) and only found in the Tolga region. The North Burnett had no Aspergillus colonies identified from the soil samples in the current year of collection. The data suggests the aflatoxin G variant is most predominant in Australian peanuts and also that there is large variation between the growing regions for prevalence of Aspergillus species.