Iron-molybdenum interaction in Aspergillus niger

Abstract

Aspergillus niger was grown in a solution, from which iron and molybdenum had been eliminated as far as possible, with deficient (0.002 p.p.m.), subnormal (0.04 p.p.m.) and sufficient (1 p.p.m.) iron, each with deficient (0.02 p.p.b.), normal (1 p.p.b.) and excess (400 p.p.b.) molybdenum. The deficiency of molybdenum accentuated the effects of iron deficiency by further lowering the dry weight, soluble protein and specific activities of nitrate reductase, catalase, peroxidase, succinic dehydrogenase, aconitase, aldolase and acid phosphatase. The specific activity of ribonuclease was stimulated by both the deficiency and excess of molybdenum with deficient and subnormal iron. Excess molybdenum with deficient iron depressed the specific activities of succinic dehydrogenase, aconitase, acid phosphatase, aldolase, nitrate reductase and increased that of peroxidase.