New genotypes of aflatoxigenic fungi from Egypt and the Philippines

Abstract

Aflatoxins (AFs), mainly produced by Aspergillus section Flavi, are the major natural toxins of crops and commodities in hot climatic geographic regions. These toxins are considered as type A carcinogens. One hundred and sixty single spore isolates of A. section Flavi were isolated from two different geographical places, Egypt and the Philippines. A quarter (26.5%) of the isolates was able to produce AFs. Four chemotypes of aflatoxin-producing fungi were obtained. Surprisingly, all aflatoxin-producing A. nomius isolates produced higher amounts (2400-40400 ng ml-1) of total AFs (AFB1, AFB2, AFG1 and AFG2) than the toxigenic A. flavus isolates (<1200 ng ml-1). All isolates producing AFs gave PCR products with the ver-1/ver-2 and ordAF/ordAR primers, which amplify ver-1 and ordA genes in the aflatoxin biosynthetic pathway. Based on PCR products of ver-1 gene, new genotypes of aflatoxigenic fungi were found which revealed the variability of AFs production between different isolates depending on the region of the isolation.