Influences of chemical fertilizers (in vitro) on aflatoxin and citrinin synthesis by two strains of aspergilli.

The selective effect of various levels of phosphate and nitrate (as fertilizers) on biosynthesis of aflatoxin by Aspergillus parasiticus var. globosus, and citrinin by A. terreus var. aureus was studied in defined culture medium. Phosphate at 35-175 mmol per 50 mL decreased aflatoxin production, but increased citrinin synthesis. Nitrate at 73-365 mmol per 50 mL stimulated the synthesis of aflatoxin but depressed that of citrinin. A rise in the levels of nitrate and phosphate led to a decrease in aflatoxin production, an increase in citrinin production and an accumulation of mycelial phosphate and nitrate contents.