A basal medium containing a single carbohydrate used to determine whether bacteria can ferment the specific carbohydrate. The medium contains a pH indicator that changes from red to yellow if the bacteria can ferment the carbohydrate.

• May be used with Durham tubes to determine if gas is produced during the fermentation process

To prepare media, add 20 g of phenol red lactose broth to a liter of distilled or de-ionized water. The media will not be sterile until autoclaved prior to use.