Studies on the Activities of Bacteria in Soy Sauce Brewing

Thirteen strains of salt tolerant specific lactic acid bacteria were isolated from soy sauce brewing mashes, and their taxonomical characteristics investigated. These strains are spherically shaped, generally assume a tetrad form, micoaerophilic, and perform the homo-type fermentation. Eleven strains produce d-lactic and two other strains produce dl+(d) lactic acid. These characters are unaffected even when grown in salted broth containing 15% sodium chloride. They grow well in a medium containing 18% salt, and the upper limit of the salt tolerancy is approximately between 24 to 26% sodium chloride. The salt tolerant capacity seems to be a hereditable character. The strains grow within a pH range between 5.5 to 9.0, but no growth is observed at pH 5.0. The optimal temperature was from 20°C_??_30°C. Many sugars are well fermented, and this ability was not diminished in 17% salted media. From these facts, the author proposed the name Pediococcus soyae nov. sp. for this sort of organism. This bacteria requires two specific nutrients: namely, a peptide-like substance (P-factor) included in the “Polypepton” (Takeda) and a dialyzable unknown substance (S-factor) included in the “Heart infusion broth”, “Yeast extract” and “Beef extract” (Difco). This bacteria do not require leucovorin.