Temperature Limits for Production of Aflatoxin by Twenty-five Isolates of Aspergillus flavus and Aspergillus parasiticus

Abstract

Aflatoxicogenic isolates of Aspergillus were tested for their aflatoxin production after 8 weeks of growth on wort agar medium at high (41, 46 ± 1 C) and low (2, 7 ± 0.5 C) temperatures. Controls were grown at approximately 22 C, a temperature known to be favorable for aflatoxin production. There were two replications of each treatment. All replicate cultures of the 25 isolates grown at 22 C were positive for aflatoxin. Aflatoxins were not detected in wort agar when cultures were incubated at other test temperatures. It appears that both Aspergillus flavus and Aspergillus parasiticus will not produce aflatoxins when grown at ⩽ 7.5 C or at ⩾ 40 C.