Primary metabolism of Aspergillus parasiticus in relation to aflatoxin biosynthesis

Summary The uptake of various ¹⁴C labelled compounds like (1-¹⁴C) glucose, (1-¹⁴C) acetate, (2-¹⁴C) uracil, (1-¹⁴C) leucine and (¹⁴C–CH₃) methionine was studied in Aspergillus parasiticus. A comparative study of asparagine deficient, zinc deficient and SLS cultures revealed different growth patterns. High lipid levels under zinc and asparagine deficiency were observed. During the stationary phase the synthesis of proteins and DNA declined. The uptake of ¹⁴C labelled glucose, methionine and acetate was maximum in asparagine deficient cultures during the transitional and stationary phase of growth. Maximum uptake of labelled methionine and glucose occured during the exponential growth phase (45 h). The uptake of labelled leucine was highest under asparagine deficiency during the exponential and transitional phases but reached a minimum during stationary phase. The uptake of labelled uracil remained high throughout in the asparagine deficient cultures. The mechanism of inhibition of aflatoxin biosynthesis in the absence of zinc and asparagine seems to be different.