MacCONKEY BROTH (as per USP/EP/JP/BP)

Lactose fermenting ability has been utilized as a key feature for differentiating coliforms from other bacteria for a long time. MacConkey Broth is based on this principle to facilitate the detection and presumptive identification of coliform bacteria in water, raw materials, and other samples of sanitary significance. The medium is commonly employed in quality control and microbiological analysis in which presence of coliform organisms serves as an indicator of contamination.
The nutrients in the formulation promote the growth of bacteria while bile salts inhibit the growth of many Gram-positive bacteria, making the medium more selective. Lactose acts as the fermentable carbohydrate, and bromocresol purple functions as a pH indicator. Production of acid as a result of lactose fermentation turns the medium from purple to yellow. Non lactose fermenters like some species of Salmonella and Shigella do not produce this colour change. This distinct visual reaction makes MacConkey Broth a convenient medium for routine coliform detection and enumeration procedures.

Selective broth medium for detecting and enumerating coliform bacteria in water and sanitary samples.