Fluid Thioglycollate Medium

Trypticase and yeast extract powder provide carbon/nitrogen source, vitamins and growth factors; Glucose provide fermentable carbohydrates to facilitate growth; Sodium chloride maintains osmotic pressure; Sodium thioethanolate and L-cysteine effectively lower redox potential, preventing the accumulation of peroxides that are toxic to certain bacteria. Simultaneously, their sulfhydryl groups inhibit bacteria by passivating preservatives containing arsenic, mercury, and other heavy metals. The gelling action of a small amount of agar prevents the diffusion of carbon dioxide, oxygen, and reduction products. Methylene blue serves as a redox indicator, appearing pink in an oxidized state and colorless in a reduced state.