Reduction of aflatoxin production by exposing Aspergillus flavus to CO۲

Aspergillus flavus is a saprophytic fungus contaminating different food and nut products by aflatoxin which is a major problem worldwide. Modified atmosphere packaging (MAP) could be an effective method for control of saprophytic fungi and their toxins and secondary metabolites production. This study gives the consequences of fungal isolates growing under MAP condition on potato dextrose agar (PDA). Two isolates of A. flavus (A۴۲ and CHAO۵۰) were packed under ۱۰۰% CO۲, ۱۰۰% O۲ and vacuum conditions. The mycelial growth of fungal isolates on PDA was controlled up to ۸۰% with CO۲ treatment. Under the vacuum condition, mycelial growth of the isolates was inhibited up to ۳۰%, while ۱۰۰% oxygen had no inhibition on mycelial growth. Examination of isolates A۴۲ and CHAO۵۰ under UV light showed that both isolates produced yellow pigments on aflatoxin producing ability (APA) medium after ۱۰ days. The levels of aflatoxin B۱, B۲, G۱, G۲ and total aflatoxin were analyzed chromatographically. The results revealed that the highest concentration of total aflatoxin was produced by fungal isolates grown in an atmosphere of ۱۰۰% O۲, while the level of aflatoxins was significantly reduced in ۱۰۰% CO۲.