More than 1 million species live on the earth. Of these, approximately 97 thousand species are known as the relative of the fungus. Mold, yeast and mushroom are also included in the fungus family. Whereas, mold is said to have around 38% proportion of the family. It is also said that the number of species includes no fewer than 30,000 species at a moderate estimate, but some researchers have estimated to be between 70,000 and 80,000 species, and further, there are predictions that it will be around 200,000 species in the future.
Among these large numbers of mold, our ancestors had selected only one mold, namely koji mold and have used it in Japanese brewing industry.
Approximately 500 species of yeast are known at present, and even there are still some possibility to find other microorganisms that can make sake, yeast is the only one that can do it among one million creatures.
Alcoholic fermentation is an enzymatic process performed with the action of the yeast, Saccharomyces cerevisiae. The scientific name is in Latin, and two words of the genus name and the species name are combined just like our family name and given name. Namely, Saccharo– , –myces and cerevisiae mean sugar, fungus and beer, respectively. Accordingly, it means a fungus that eats sugar and then produces beer.
Yeast has a diameter with the range of 5 to 7 microns and is a microorganism with a high growth rate which is estimated to be between 2 and 4 hours as its doubling time if condition is optimum. It is obvious that no alcoholic fermentation reaction by yeast occurs without glucose which was saccharified from starch by koji mold because yeast has no such activity. Aspergillus oryzae is a well-fitted koji mold for taking over the role.
In fact, during an incubation with steamed rice, koji mold produces the diastatic enzyme, which keeps saving in the rice. Then, the enzyme works to decompose starch in the rice into glucose just like cutting into small pieces with scissors.
When we look at the microbial world, we notice an interesting trend. Namely, yeast can produce alcohol but cannot degrade starch, and inversely, microorganisms that have the ability to degrade starch do not have the ability to produce alcohol.
Likewise, Koji mold has an extremely high activity to degrade starch, but cannot produce alcohol. If God had imparted both ability to a single microorganism, the birth of grain liquor may have been thousands of years earlier. It may be said that God did not give two objects to a single microorganism.