THE PRESENCE OF ACONITASE AND “ACONITIC HYDRASE” IN ASPERGILLUS NIGER

Abstract

Cell-free extracts of sonic disintegrated mycelium of A. niger grown in a non-citrate accumulating malt-yeast extract medium contain two enzymes capable of utilizing cis-aconitate. One resembles the aconitase of animal tissue. The other, "aconitic hydrase", is precipitated between 0.25 and 0.42 saturation with (NH4)2SO4 and forms only citrate from cis-aconitate. Extracts of mycelium grown in the defined medium of Tomlinson (J. Bacteriol. 61, 17-25) contain neither enzyme. Increasing the Mn content of this medium to 3 [mu]g% and omitting the Cu permits the formation of "aconitic hydrase" but not aconitase.