A microorganism that produces D-aspartate-oxidizing enzyme by induction was isolated from soil, and identified as Fusarium sacchari var. elongatum Y-105. The enzyme catalyzed the oxidative deamination of D-aspartate (D-Asp) and produced oxaloacetate, ammonia, and hydrogen peroxide, stoichiometrically. The enzyme is designated "D-Asp oxidase" (EC 1.4.3.1). In addition to D-Asp, the enzyme oxidized D-glutamate (D-Glu) and N-methyl-D-aspartate (NMDA). N-Acetyl-D-Asp and other D- or L-amino acids, however, were inert as substrates. The optimum pH and temperature were 7.5 and 40 degrees C, respectively. The enzyme was stable at pH9.0 and temperature of 50 degrees C, respectively. The enzyme activity was not inhibited by sodium benzoate which is a specific inhibitor of D-amino acid oxidase from mammals. The enzyme activity was also not affected by carboxylates such as meso- or D-tartarate, citrate, and fumarate which inhibit D-Asp oxidase from rabbits.