Fluid Thioglycollate Medium is used for determining the presence of aerobic and anaerobic bacteria in normally sterile materials. Pancreatic Digest of Casein is the nitrogenous source. Yeast Extract supplies B-complex vitamins. Dextrose is the fermentable carbohydrate. L-Cystine and Sodium Thioglycollate allow Clostridium spp. to grow in this medium even under aerobic conditions. The latter also neutralizes the toxic effect of mercurial preservatives and peroxides. Resazurin indicates increases in the oxygen content by shifting to pink-red. The small amount of Agar maintains a low redox potential to stabilize the medium.
