Composition

*  Dehydrated powder, hygroscopic in nature, store in a dry place, in tightly-sealed containers below 25°C and protect from direct Sunlight.

Instructions for Use

Dissolve 77.40gms in 1000ml distilled water. Gently heat to boiling with gentle swirling and dissolve the medium completely. DO NOT AUTOCLAVE. Cool below 45°C and add 20 ml iodine solution (Iodine 6gms and Potassium Iodide 5g in 20 ml distilled water). Mix well and dispense in 10 ml quantities.

Note: Due to the presence of calcium carbonate, the prepared medium forms opalescent solution with white precipitate.

Appearance: Light green colour solution

pH (at 25°C): 7.8 ± 0.2

Principle

TETRATHIONATE BROTH BASE is used for selective isolation of Salmonellae from faecal samples, sewage and other samples. Medium contains Peptic digest of animal tissue, Meat extract & Yeast extract as the sole sources of carbon, nitrogen, vitamins and minerals. Sodium thiosulphate is the selective agent, to suppress commensal coliform organism. Terathionate is produced from Sodium thiosulphate by adding iodine to the culture medium. Such organisms are Salmonellae & Proteus species; those are having luxuriant growth in the medium and possess the enzyme tetrathionate reductase while other fecal organisms are inhibited due to production of tetrathionate. Calcium carbonate helps in neutralizing the acidic tetrathionate decomposition products. Salmonella present in food samples may be sublethally damaged during various stages of food processing where they may be exposed to low temperatures, heat drying, radiations, and various chemicals. These damaged cells are able to cause spoilage, and if ingested cause diseases under favourable conditions. Therefore it is important to resuscitate these damaged bacteria before enumeration.

Interpretation

Cultural characteristics observed after incubation at 35 – 37°C for 18 – 72 hours.

Reference

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5. MacFaddin J. F., Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. 1, Williams and Wilkins, Baltimore. (1985).
6. Downes F. P. and Ito K., (Eds.), Compendium of Methods For The Microbiological Examination of Foods, 4th Ed., APHA, Washington, D.C. (2001).
   1. Eaton A. D., Clesceri L. S. and Greenberg A. W., (Eds.), Standard Methods for the Examination of Water and Wastewater, 21st Ed., APHA, Washington, D.C. (2005).
   2. FDA Bacteriological Analytical Manual, 18th Ed., AOAC, Washington, DC. (2005).