Studies on the Autolysis of Aspergillus oryzae

Abstract

Aspergillus oryzae was autolyzed at pH 5.4 at 30°C. The morphological changes during autolysis were observed with a phase-contrast microscope, and the degradation products of proteins, nucleic acids, and sugars were analyzed. 1) The cytoplasmic materials disappeared during three days of autolysis, and the cell wall remained after autolysis. Under an aerobic condition, mycelia lived for a while consuming the reserve materials, and vacuoles were formed in the midst of the cell, becoming larger till they occupied the whole space of the cell. Under an anaerobic condition, the cytoplasmic materials began to dissolve at the marginal site contacting with the cell wall, and the whole cell became empty leaving a few particles. 2) Seventy-five per cent of proteins were excreted into medium during autolysis, 60% as free amino acids, 15% as peptides. Protein itself was hardly present in the autolyzate. 3) Glucose, ribose and three other sugars were detected in the autolyzate, and glucosamine was also detected in the hydrolyzate of the autolyzate. 4) Eighty-one per cent of the cellular nucleic acids was excreted into medium as uridine (28%), xanthine (24%), and hypoxanthine (17%). Nucleotides were hardly present in the autolyzate.