"A. oryzae" is an aerobic fungus and is the most active fermenting agents in koji as it produces amylolytic, and proteolytic enzymes which are essential to creating the final miso product. Amyloytic enzymes such as amylase aid in the breakdown of starch in the grains to sugar and dextrin, while proteolytic enzymes such as protease catalyze the breakdown of proteins into smaller peptides or amino acids. These both aid in the enzymatic digestion of the mixture of rice and soybeans. Depending on the strain of "A. oryzae", enzymatic composition varies thereby changing the characteristics of the final miso product. For example, the strain used to create the sweeter white miso would likely produce a higher content of amylolytic enzymes, while comparatively a soybean miso might have a higher content of proteolytic enzyme.