GROWTH AND AFLATOXIN PRODUCTION IN FUNGI DEVELOPING ON CEREAL AND CRUDE DRUG SAMPLES

Abstract

Powdered dry samples of unpolished rice and ginseng (Khumsan) infected with aflatoxinogenic strains of aspergilli were used to measure the courses of growth and aflatoxin production. Estimation of fungal growth on such plant materials was performed by following the incorporation of ¹⁴CO₂ into cellular macromolecules such as nucleic acid and protein. Continuous labeling with ¹⁴CO₂ could be adopted more preferably than pulse labeling for the estimation of fungal growth.
The results of experiments using either sample infected with Aspergillus parasiticus and A. toxicarius clearly showed that the incorporation of radioactivity into cellular macromolecules ran almost parallel with that of aflatoxin production. The amount of radioactivity incorporated and aflatoxin produced in either sample was equally affected by the atmospheric relative humidity, being the highest under saturated humidity and exhibiting essentially no signs of growth and aflatoxin production under less than 90% relative humidity. Among one cereal and four crude drugs examined, the highest amount of aflatoxin was produced on unpolished rice and ginseng root (Khumsan), and none on Scutellaria root, irrespective of abundant growth of the fungi.