抄録
The modification of the formula of 0.9% trypsin broth which was devised by Gan and Tjia in 1962 for the differentiation of V. cholerae and V. eltor was investigated. According to the experimental results, the formula and method of preparation was modified as follows: trypsin (1:250, Difco) is suspended in 2% peptone water at the level of 0.4%, well mixed and stirred for 15 minutes, kept at a room temperature for one hour, then the pH of the medium adjusted to 7.4-7.6. After 1.2ml of 0.2% phenol red solution is added to 100ml of the medium, it is boiled for 10 midutes, filtrated with filter paper, and sterilized at 115°C for 15 minutes. Before using it, the medium is distributed into small test tubes in one ml quantities aseptically.
After incubation at 37°C for 18-24 hours, yellow coloration of the medium indicates V. cholerae, while deepred coloration of the surface layer of the medium indicates V. eltor. All cultural reactions are very clearcut and the reading is easy.
As the ingredient of this medium it is recommanded to use trypsin (1:250, Difco). All other samples of trypsin are inadequate for this purpose.
