Trypticase soy agar

TSA contains enzymatic digests of casein and soybean meal, which provide amino acids and other nitrogenous substances, making it a nutritious medium for a variety of organisms. Sodium chloride maintains the osmotic equilibrium, while dipotassium phosphate acts as buffer to maintain pH. Agar extracted from any number of organisms is used as a gelling agent.

One liter of the agar contains:

• 15 g pancreatic digest of casein
• 5 g peptic digest of soybean
• 5 g sodium chloride
• 15 g agar

Uses

The medium may be supplemented with blood to facilitate the growth of more fastidious bacteria or antimicrobial agents to permit the selection of various microbial groups from pure microbiota. As with any media, minor changes may be made to suit specific circumstances. TSA is frequently the base medium of other agar plate types. For example, blood agar plates (BAP) are made by enriching TSA plates with defibrinated sheep blood, and chocolate agar is made through additional cooking of BAP.