Phenol Red Broth Base is supplied by HiMedia. It is a sterile ready prepared media containing red coloured solution in bottles. Phenol Red Broth Base is generally used as a basal medium to which carbohydrates are added for determination of fermentation reactions of pure cultures of microorganisms. It is advisable to store this ready prepared media between 2-8C. Composition (in gm/L) is as follows:

Proteose peptone (10.00)

Beef extract (1.00)

Sodium chloride (5.00)

Phenol red (0.018)

Phenol Red Broth Medium is formulated as per Vera and is suggested to determine the fermentation reaction of carbohydrates for the differentiation of microorganisms. With various added carbohydrates, this medium aids in differentiation of various species and genera based on their ability to ferment the specific carbohydrate, with the production of acid or acid and gas. Phenol Red Broth Base is a complete medium without added carbohydrate, which can be used with the addition of 5-10 %, desired carbohydrate. It is used as a negative control for studying fermentations or as a base for the addition of carbohydrates. Proteose peptone and beef extract serve as sources for carbon and nitrogen. Sodium chloride is the osmotic stabilizer. Phenol red is the pH indicator, which turns yellow at acidic pH. Gas formation is seen in Durhams tubes. Enterobacteriaceae grow well in this medium. In addition to producing a pH colour shift, the production of mixed acids, notably butyric acids, often results in a pungent, foul odour from the culture medium.