Characterization of aflatoxin-producing fungi outside of Aspergillus section Flavi
Most aspergilli that produce aflatoxin are members of Aspergillus section Flavi, however isolates of several Aspergillus species not closely related to sec- tion Flavi also have been found to produce aflatoxin. Two of the species, Aspergillus ochraceoroseus and an undescribed Aspergillus species SRRC 1468, are mor- phologically similar to members of Aspergillus section Circumdati. The other species have Emericella teleo- morphs (Em. astellata and an undescribed Emericella species SRRC 2520) and are morphologically distinc- tive in having ascospores with large flanges. All these aflatoxin-producing isolates were from tropical zones near oceans, and none of them grew on artificial me- dia at 37 C. Aflatoxins and sterigmatocystin produc- tion were quantified by high-pressure liquid chro- matography (HPLC) and confirmed by HPLC-mass spectrometry (LC-MS) detection. Phylogenetic anal- yses were conducted on these four species using A. parasiticus and Em. nidulans, (which produce afla- toxin and the aflatoxin precursor sterigmatocystin, respectively) for comparison. Two aflatoxin/sterig- matocystin biosynthesis genes and the beta tubulin gene were used in the analyses. Results showed that of the new aflatoxin-producers, Aspergillus SRRC 1468 forms a strongly supported clade with A. ochra- ceoroseus as does Emericella SRRC 2520 with Em. as- tellata SRRC 503 and 512.
, vol. 97, no. 2, pp. 425-432, 2005