Aflatoxin biosynthetic pathway extrolites in airborne Aspergilli series Versicolores

The Aspergilli of the series Versicolores include airborne species that produce sterigmatocystin, a mycotoxin possibly carcinogenic to humans (IARC group 2B). Molecular identification of 116 fungal isolates by benA gene amplification and sequencing revealed 8 species belonging to this series in French bioaerosols. All these isolates and a reference strain of each species were extracted using ethyl acetate + acetic acid 1% (v/v). In each extract, 10 extrolites of the aflatoxin biosynthetic pathway were investigated by UPLC-HRMS: norsolorinic acid, versicolorin A, 6-demethylsterigmatocystin, sterigmatocystin, 8-O-methylsterigmatocystin, 5-methoxysterigmatocystin and aflatoxins (B1/B2/G1/G2). All extrolites except aflatoxins were found. Sterigmatocystin was found in extracts of these species, including A. sydowii and A. tabacinus for which the ability to produce sterigmatocystin was questioned or unknown, respectively.