Although yeast has the function to change glucose into alcohol (namely, the action of fermentation), in order to make rice ferment in such large amounts that are handled in a brewery, one or two yeasts, that are microorganisms, are quite insufficient and yeasts in the order of several tens or hundreds of billions are required corresponding to the amount of rice.
酵母にはグルコースをアルコールに変える働き、すなわち発酵作用があるものの、酒蔵で扱うような大量の米を発酵させるためには、微生物である酵母が一匹や二匹ではまったく不十分で、米の量に見合っただけの何百億、何千億匹もの酵母が必要となる。