Tryptone Soy Agar (TSA) also known as trypto-casein soy agar or trypticase soy agar is a culture medium used in microbiology for aerobic and anaerobic low-demand bacteria. It is a versatile, non-selective medium that provides sufficient nutrients to allow the growth of a wide variety of microorganisms. It is used for a wide range of applications, including culture storage, cell counting (counting), isolation of pure cultures or simply general culture. This medium also exists without agar as a broth as an enrichment medium. TSA agar contains enzymatic digestions of casein and soybean meal, which provide amino acids and other nitrogenous substances, making it a nutrient medium for a variety of organisms. Glucose is the source of energy. Sodium chloride maintains osmotic balance, while dipotassium phosphate acts as a buffer to maintain pH. Agar extracted from any number of organisms is used as a gelling agent.

The medium can be supplemented with blood to facilitate the growth of more demanding bacteria or with antimicrobial agents to allow the selection of various microbial groups from pure microbiota.