Early expression of the aflatoxin gene cluster in Aspergillus nomiae isolated from Brazil nut

Aspergillus nomiae is the most important contaminant in Brazil nut due to its high incidence in these nuts and its strong production of carcinogenic metabolites: aflatoxins (AF). Aflatoxin biosynthesis pathway in A. nomiae is poorly studied. Thus, in present investigation, aflatoxin production and gene cluster (aflC, aflQ, aflU, and aflX) expression profile were evaluated on two strains of A. nomiae isolated from Brazil nut samples collected in the Amazon region, and cultivated on Brazil nut-based medium. The results showed that the expression of the aflatoxin gene cluster in A. nomiae, started at day 2 and occurred before the production of aflatoxins. Aflatoxin production (AFB1 and AFG1) was detected on day 3 on both strains. From day 4 onwards, all four toxins were detected and their production kept at similar proportions (AFG1>AFB1>AFG2>AFB2). Thus, the anticipated information obtained through early expression profile results of aflC, aflQ, aflU, and aflX gene cluster in A. nomiae may foresee aflatoxin production before its detection in Brazil nuts. [Display omitted] •Aflatoxin was not detected until 3rd day.•AFB1 and AFG1 were detected on both strains since 3rd day.•Aflatoxin production kept at similar proportions (AFG1>AFB1>AFG2>AFB2).•qPCR showed gene expression at early stage (2nd day).•The first study that showed the early expression of genes in Aspergillus nomiae.