Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

A rapid identification method for aflatoxin-producing strains of Aspergillus flavus and A. parasiticus by ammonia vapor.

Abstract

The colony reverse of aflatoxin (AF)-producing strains of A. flavus and A. parasiticus turned pink when their cultures were exposed to ammonia vapor. The color change was visible for colonies grown on media suitable for AF production such as potato dextrose, coconut and yeast extract sucrose agars after 2 d incubation at 25°C. Of the 120 strains of A. flavus, A. parasiticus and 2 related species (A. oryzae and A. sojae), only the AF-producing strains of A. flavus and A. parasiticus showed the pink pigmentation. The color change occurred immediately after the colony was contacted with ammonia vapor. It is suggested that this method could be useful for rapid screening the AF-producing strains of A. flavus and A. parasiticus.