Growth and aflatoxin production of Aspergillus flavus in fig-based medium: Effect of minerals and chelating agents

Abstract

In this study, minerals required for the growth and aflatoxin production of A. flavus were determined. Then, the effectiveness of some chelating agents such as citric acid, phytic acid and ethylenediaminetetraacetic acid (EDTA) in preventing mold growth and toxin production was investigated in a fig-based medium and in two synthetic media, called Czapek-dox agar (CZA) and potato dextrose agar (PDA). A. flavus did not grow in CZA without sodium nitrate during 6-day incubation at 30 degrees C. The absence of the other components (magnesium sulfate, iron sulfate, potassium chloride and potassium phosphate) did not significantly (p>0.05) affect the growth of the mold. However, the mold produced significantly (p<0.05) higher amounts of aflatoxins in the media without magnesium sulfate and iron sulfate. A. flavus grew faster on fig-based medium and produced higher amounts of aflatoxins in PDA. In all media tested in this study, EDTA was found to be more effective than the other agents in controlling the growth of A. flavus. It was also effective in inhibiting the production of aflatoxins. It was determined that 1.75 mM EDTA reduced aflatoxin production up to 97\% in PDA. Citric and phytic acids could inhibit the growth of the mold only in PDA. All chelating agent reduced aflatoxin production over 90\% in fig-based medium.