Brewer thioglycollate medium is prepared as per the original formula of Brewer (1, 2).
It contains highly nutritious proteose peptone and beef infusion, which support luxuriant growth of even fastidious bacteria. Sodium thioglycollate helps to create anaerobic condition as well as neutralizes toxicity of mercurial compounds if present in the inoculum of the test material. Sodium chloride maintains the osmotic equilibrium while dipostassium phosphate buffers the medium. Very small amount of agar present maintains anaerobic conditions at the bottom of the broth. Methylene blue indicates oxygen content of the medium by exhibiting bluish-green colour to the medium in presence of oxygen.
The uninoculated medium shows bluish green colour at the top indicating presence of oxygen in that part. Organisms that ferment dextrose and lower the pH to critical levels may not survive in this medium after growth has taken place.
Storage and Shelf-life:
Store below 30°C in tightly closed container and prepared medium at 2 to 8°C. Use before expiry date on the label.
References:
1. Brewer J. H., 1940, J. Bacteriol., 39:10
2. Brewer J. H., 1940, J.A.M.A., 115:598.