Cystine Tryptone Agar is a solid medium recommended for the maintenance, subculture, motility detection, and detection of fermentation reactions of fastidious microorganisms. Motility can be detected in semisolid Agar, since motile cultures grow away from the line of inoculation, while non-motile organisms grow along the stab line. Addition of carbohydrates allows its use to study fermentation reactions through color shift of the pH indicator Phenol Red. Casein Enzymatic Hydrolysate and L-Cystine provide essential nutrients for bacterial growth. Sodium Chloride maintains the osmotic balance. Agar is the gelifying agent.
