Fluid Thioglycolate Medium

 Principle

• A fluid thioglycollate medium is used for detecting microorganisms in normally sterile materials. Media support the growth of a wide variety of fastidious microorganisms having a wide range of growth requirements.
• Media is composed of tryptone, yeast extract, dextrose, sodium chloride, L-cystine, sodium thioglycolate, resazurin, and a small amount of agar. Tryptone provides nitrogen, carbon, amino acids, and vitamins.
• Yeast extract is the source of essential carbon, vitamin, nitrogen, and amino acids. Dextrose serves as a carbon and energy source and is included in the media for the early and vigorous growth of many organisms. Sodium chloride is used to maintain the osmotic balance.
• L-cystine and sodium thioglycollate allow anaerobic organisms to grow in aerobic conditions. Sodium thioglycollate also acts as a reducing agent and neutralizes the toxic effects of mercurial preservatives and peroxides formed in the medium, thereby promoting anaerobiosis, and making the medium suitable to test materials containing heavy metals.
• Resazurin is a redox indicator and helps to detect an increase in oxygen content by changing color to pink. The small amount of agar helps in maintaining a low redox potential for stabilizing the medium. favors the growth of aerobes as well as anaerobes in the medium.

 Use: Recommended for sterility testing of biologicals and for the cultivation of anaerobes, aerobes, and microaerophiles from pharmaceutical and clinical samples.