Aspergillus luchuensis

Aspergillus luchuensis (previous names A. foetidus and A. acidus) is a species of fungus in the genus Aspergillus. It belongs to the group of black Aspergilli which are important industrial workhorses. The fungus has been used to make awamori, a distilled spirit in Okinawa Island, Japan, and is also used to make shōchū and sake. This species was first isolated and described by Tamaki Inui of the University of Tokyo in 1901. For more than 100 years there has been confusion between this species and Aspergillus awamori and Aspergillus niger with regard to scientific names and classification.

The scientific name for this species is derived from "Ryukyu", the historical name for Okinawa, Japan. It is authorized as a "national fungi" (国菌) along with Aspergillus oryzae, Aspergillus sojae and Aspergillus kawachii by the Scientific Conference of Brewing Society Japan because it is used not only in brewing but also in a variety of foods and is useful in the lives of Japanese people.

In 1918, Genichiro Kawachi isolated an albino mutant of Aspergillus luchuensis (black kōji) and named it Aspergillus kawachii (white kōji). This mutant is now also called 'Aspergillus luchuensis mut. kawachii'. In shōchū brewing, Aspergillus oryzae (yellow kōji) was traditionally used, but black and white kōji produced more citric acid and were more effective in preventing microorganism growth, so the use of black kōji was recommended from the 1940s and white kōji from the 1950s. Brewing with each type of kōji brings different flavors to shōchū. Sake was also traditionally brewed with yellow kōji, but from the 21st century sake brewed with white or black kōji began to appear. The black kōji variants and white kōji that Kawachi discovered and isolated have been used in makgeolli and soju in Korea since the 1940s.

Its genome has been sequenced by two different research groups, first in 2016, and then in 2017. The first sequencing of the A. luchuensis genome reported a genome assembly size of 34.7 Mbp and reported the presence of 11,691 genes.