Thioglycollate Medium without Indicator is an enriched general-purpose medium for the recovery of a wide variety of microorganisms. The medium is characterized by its ability to support the growth, from a minimal inoculum, of a great variety of aerobes, anaerobes and microaerophilic microorganisms. The lack of an indicator avoids possible toxicity to organisms, making this a choice medium for diagnostics, particularly useful for sterile materials which contain mercurial preservatives. Casein and Soy peptones provide nitrogen, vitamins, minerals and amino acids essential for growth. Sodium thioglycollate and L-Cystine lower the oxidation-reduction potential by removing oxygen to maintain a low Eh. Dextrose is the carbohydrate energy source and allows a rapid and vigorous growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Bacteriological agar delays the dispersion of CO2 and diffusion of O2. This medium supports a minimal inoculation with early visible signs of growth. Strict aerobes develop in the upper part, whereas anaerobes develop at the bottom of the medium tube. This medium supports the growth of aerobic microorganisms such as members of the genus Brucella, of strict anaerobes such as Clostridium acetobutyricum, Clostridium novyi, Actinomyces bovis, Bacteroides, Lactobacillus, and other bacteria. Pathogenic fungi frequently grow well in this medium. The medium can be used with the addition of 10% serum for the cultivation of Trichomonas vaginalis and other microorganisms that utilize serum for added growth.
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