ANTIBIOTIC ASSAY MEDIUM NO. 36 (SOYA BEAN CASEIN DIGEST AGAR) (TRYPTONE SOYA AGAR) (as per USP)

Tryptone Soya Agar, also known as Soyabean Casein Digest Agar, is used for enrichment and isolation of fastidious microorganisms with or without blood. It is a widely used medium, which supports the growth of a wide variety of organisms, even that of fastidious ones such as Neisseria, Listeria, Brucella, etc. The medium with the addition of blood provides perfectly defined haemolysis zones while preventing the lysis of erythrocytes due to its sodium chloride content. Its simple and inhibitor-free composition makes it suitable for the detection of antimicrobial agents in food and other products. It has been frequently used in the pharma industry to produce antigens, toxins, etc. It is also recommended by various pharmacopoeias as a sterility-testing medium. It conforms as per USP and is used in microbial limit tests and antimicrobial preservative-effectiveness tests.

The combination of tryptone and soya peptone makes this medium highly nutritious, supplying amino acids and long-chain peptides that support the growth of microorganisms. Sodium chloride helps maintain osmotic balance within the medium.

This medium does not contain X and V growth factors, making it suitable for determining the specific growth requirements of Haemophilus isolates. This can be achieved by adding X-factor, V-factor, and X+V factor discs to inoculated TSA plates and observing the growth response.

for enrichment and isolation of fastidious microorganisms with or without blood