Aflatoxigenic fungus has ability to produce eight kinds of aflatoxins （aflatoxins B₁, B₂, G₁, G₂, M₁, M₂, GM₁, and GM₂）

Abstract

  Aflatoxigenic fungi produce aflatoxins B₁ （AFB₁）, B₂ （AFB₂）, G₁ （AFG₁）, G₂ （AFG₂） as major aflatoxins, and some of them also produce one or a few of aflatoxins M1 （AF M₁）, M₂ （AFM₂）, GM₁ （AFGM₁）, GM₂ （AFGM₂） as minor aflatoxins, which are 12 c-hydroxy derivatives of the major aflatoxins. Although biosynthetic pathway of the major aflatoxins has been mostly clarified, that of the minor ones has not been done. Aspertoxin is the 12c-hydroxy derivative of O-methylsterigmatocystin, which is a precursor of both AFB₁ and AFG₁. We recently reported that both AFM₁ and AFGM₁ were produced from aspertoxin in both feeding and cell-free experiments, and aspertoxin was produced from OMST through hydroxylation catalyzed by OrdA enzyme encoded by ordA gene in the aflatoxin gene cluster. On the other hand, AFM₁ was not significantly produced from AFB₁ in feeding experiment. These results demonstrated that the biosynthetic pathway of the minor aflatoxins in fungi is different from that of AFM₁ from AFB₁ in animal livers.