Toxigenic potential of Aspergillus flavus tested in different culture conditions

The objective of the present work was to evaluate the capacity of three isolates of Aspergillus flavus to produce aflatoxin under different culture conditions. This experiment was based on a 2³ factorial design, in which the independent variables were temperature (20-40 °C), incubation time (7-21 days), and the pH (2.0-6.0) in two different synthetic media. The optimal conditions were applied to non-aflatoxigenic isolates previously tested in coconut agar. Aflatoxin B1 was extracted directly from the synthetic cultures with chloroform. Thin Layer Chromatography (TLC) and Photographic Photometry were utilized to identify and quantify the compounds. Preliminary results showed that YES agar was an alternative medium for detecting the toxigenic potential of Aspergillus flavus in the following conditions: pH of 5.2, temperature of 25 °C, and incubation time of 11 days producing 206.05 ng.CFU-1 of aflatoxin B1. Of the 30 non-aflatoxigenic isolates, 12 presented a positive result in the optimal media and conditions tested.