Phenol Red Broth Base
Phenol Red Broth Base is a medium without added carbohydrates used as a base for the addition of the carbohydrates for determining the fermentation reactions of microorganisms. It must be capable of supporting the growth of test organisms. Casein peptone provides nitrogen, vitamins, minerals and amino acids essential for growth, and allows the abundant growth of a wide variety of
fastidious microorganisms. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Phenol red is the pH indicator. Vera recommended using Casein peptone in fermentation test media since she found that it could be used with the pH indicator Phenol red in fermentation tests with a high degree of accuracy. Phenol Red Broth Base is used for the carbohydrate fermentation studies of many microorganisms. Control tubes of the uninoculated medium should be run parallel with inoculated tubes. Tubes should be examined frequently because different carbohydrates are utilized at variable speeds. Phenol Red Broth Base is an excellent substrate for streptococci, as well for other less fastidious bacteria. For anaerobes the medium should be used on the day of preparation. If not, the medium must be heated and cooled before use.
