Mature seeds of Sorghum contain proteins toxic to aflatoxin-producing Aspergillus flavus

Crude acid extract of mature Sorghum seeds showed partial inhibition of spore germination and growth of aflatoxin-producing Aspergillus flavus strains. To find the protein components involved in this mechanism of inhibition, the crude extract was fractionated by differential precipitation followed by ion exchange chromatography in carboxymethyl cellulose. Five proteins of low molecular weight were isolated. The ability of each of the five proteins to inhibit the spore germination and hyphal extension of aflatoxin-producing Aspergillus flavus strains was tested. Protein 5 did not show any inhibition. Proteins 1, 2 and 4 showed complete inhibition of spore germination (1500–2000 spores/100 μl of medium) at a concentration of 15 μg/100 μl. Protein 3 showed partial inhibition only.