Iron nutrition of four Aspergillus species

Abstract

For normal growth and sporulation, the iron requirement of Aspergillus sulphureus was at least 20 p.p.m., whereas, for A. niger, A. flavus and A. terreus it was 0.2 p.p.m. Iron deficiency, in the four Aspergillus species, reduced the dry weight, alcohol insoluble nitrogen and soluble protein but there was accumulation of sugars and alcohol soluble nitrogen except in A. sulphureus where the latter was depressed. In all the species of Aspergillus studied, the deficiency of iron depressed the specific activities of catalase, peroxidase, succinic dehydrogenase, aconitase, nitrate reductase and acid phosphatase except nitrate reductase in A. terreus and acid phosphatase in A. sulphureus . The specific activity of ribonuclease was stimulated in A. flavus, A. terreus and A. sulphureus by iron deficiency. Eighteen hours after the addition of iron aseptically to 60 h old iron deficient cultures of A. niger , there was an increase in dry weight, alcohol insoluble nitrogen, soluble protein and in restoration of the specific activities of catalase, peroxidase, succinic dehydrogenase, aconitase, nitrate reductase but not of acid phosphatase. Cycloheximide, when added together with iron reduced dry weight, alcohol insoluble nitrogen, soluble protein and inhibited the recovery of the specific activities of succinic dehydrogenase, aconitase and nitrate reductase but not the activities of catalase and peroxidase.