It is one of the different koji molds ニホンコウジカビ (日本麹黴) (Japanese: nihon kōji kabi) used for food fermentation.

[4] Genomic analysis has led some scholars to believe that the Japanese domesticated the Aspergillus flavus that had mutated and ceased to produce toxic aflatoxins, giving rise to A.

[13] A. oryzae secretes a number of salt-tolerant alkaline proteases which makes it particularly stable in the high-sodium conditions required for the production of miso and soy sauce.

[16][17][18] Genichirō Kawachi (1883 -1948), who is said to be the father of modern shōchū and Tamaki Inui (1873 -1946), a lecturer at University of Tokyo succeeded in the first isolation and culturing of aspergillus species such as A. kawachii, A. awamori, and a variety of subtaxa of A. oryzae, which led to great progress in producing shōchū in Japan.

The genome of A. oryzae is thus one-third larger than that of two related Aspergillus species, the genetics model organism A. nidulans and the potentially dangerous A.

[28] The increased number of genes in Aspergillus oryzae are responsible for the function of proteins and cellular processes such as hydrolase, transporters, and metabolism.

The extensive array of secretory hydrolase and transporters allows the mold to break down or secrete various compounds effectively.

Transformed types can produce: polyketide synthase-derived 1,3,6,8-tetrahydroxynaphthalene, alternapyrone, and 3-methylorcinaldehyde; citrinin; terrequinone A; tennelin, pyripyropene, aphidicolin, terretonin, and andrastin A by plasmid insertion; paxilline and aflatrem by co-transformation; and aspyridone, originally from A. nidulans, by Gateway cloning.

[36][37] 麹 (Chinese qū, Japanese kōji) which means mold used in fermented foods, was first mentioned in the Zhouli (Rites of the Zhou dynasty) in China in 300 BCE.