Fermenting agents
The wheat-soy mixture is exposed to specific strains of mold called Aspergillus oryzae or Aspergillus soyae, which break down the proteins in the mash. Further fermentation occurs through addition of specific
Soy Sauce bacteria (lactobaccillus) and yeasts which enzymatically react with the protein residues to produce a number of amino acids and peptides, including glutamic and aspartic acid, lysine, alanine, glycine, and tryptophane. These protein derivatives all contribute flavor to the end product.
Read more: http://www.madehow.com/Volume-3/Soy-Sauce.html#ixzz3odmaeRtx