TB Broth media are based on the medium formulated by Dubos and Davis (1) and are used as liquid media for the cultivation of Mycobacterium tuberculosis. This medium provides dispersed growth of tubercle bacilli which is free of excessive clumps and so it can be used to prepare a uniform suspension of Mycobacteria. The medium can be used without additives and supplements; however, sterile dextrose and sterile serum can be added for the enrichment. Glycerol addition helps in the cultivation of Mycobacterium tuberculosis though some bovine strains are inhibited by it.
Proteose peptone and yeast extract provide nitrogenous nutrients like amino acids and peptides, vitamin B complex and other essential nutrients. The medium is well buffered by phosphates. The salts present in the medium supply ions required for the mycobacterial metabolism. Sodium citrate inhibits gram-positive organisms and coliforms. Polysorbate 80, an oleic acid ester provides essential fatty acids for the replication of Mycobacteria.
Storage and Shelf-life:
Store below 30°C in tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the label.
Reference:
1. Dubos and Davis, 1946, J. Exp. Med., 83:409.