2. Materials and Methods
2.1. The culture medium
The culture media was corn juice which contained all necessary nutrition to yeast. Corn was used in food
fermentation industry for its low-cost, rich-source and none yeast smell. It was made as follow: corn flour
which crossed 60 mesh mixed with water at a 1:5 ratio, and was liquefied in the role of -amylase at 90 for
10 mins, then the glucoamylase catalyzed liquid to generate small molecules of sugar at 55 for about 1 hour,
until it could not react with iodine solution. In the previous of centrifugation, it needed to heat to 100 for 10
mins to inactivate enzymes. At last, the corn juice with 13 Brix was obtained and sterilized, spared.
2.2. The soy sauce yeasts
Soy sauce yeasts were provided by culture collection of Tianjin University of Science and Technology.
The mutant strains (S3-2, T3-5) were obtained by genome rearrangement on the basis of the original ones.
The mutant strains have more advantages than the original strains in the tolerance of salt.