For sterility testing of biologicals and for cultivation of aerobic, anaerobic and microaerophilic organisms. FLUID THIOGLYCOLLATE MEDIUMis used for sterility testing of biological and for cultivation of anaerobic, and microaerophilic organisms.This dehydrated medium is irradiated with dosage **25 kGy – 68kGy which is sufficient and adequate to eliminate sterility assurance level (SAL) of 10-6(5-7). Whereas, a minimum dose of 25 kGy is desired for microbial control or sterilization7. The media is also used for sterility testing of antibiotics, biologicals and foods and also for determining the phenol coefficient and sporicidal effect of disinfectants. However, it is intended for the examination of clear liquid or water-soluble materials. Fluid Thioglycollate Medium is also routinely used to check the sterility of stored blood in blood banks. The medium contains Pancreatic digest of casein and Yeast extract those provides the nitrogen and essential growth enhancers necessary for bacterial multiplication. Sodium thioglycollate and L- Cystineacts as a reducing agent which maintains a low oxygen tension by removing molecular oxygen from the environment. Indicator Resazurin dispensed throughout the media causing the media to appear brown or pink in colour. Dextrose is a fermentable energy source. Addition of small amount of agar helps in maintaining low redox potential for stabilizing the medium. Addition of agar in small amount of agar favors the growth of aerobes as well as anaerobes which retards dispersion of CO2, diffusion of oxygen, and reducing substances. On incubation period of 30 - 350C for 48- 72 hours shown luxuriant growth in all the culture strains tested. Sodium chloride helps maintaining the osmotic balance.