Final answer:
The fungus used for making sake and soy sauce is Aspergillus oryzae, a species within the Ascomycota phylum that efficiently converts rice starch into fermentable sugars.
Step-by-step explanation:
The fungus used in the production of sake and soy sauce is Aspergillus oryzae. This fungus is part of the Ascomycota phylum, which includes many commercially important fungi. Aspergillus oryzae is adept at converting the starch present in rice into sugars, which can then be fermented to create alcohol and flavorings found in these traditional Japanese products.
In contrast, Aspergillus fumigatus and Aspergillus nidulans are known for their roles as causes of allergy and infection as well as their use in research, while Saccharomyces cerevisiae is commonly known as brewer's or baker's yeast and is used in the making of bread, wine, and beer.