MacConkey Broth W/ Bromo Cresol Purple

 Principle

• MacConkey Broth is composed of peptone, lactose, Oxgall, and bromocresol purple. Peptone provides nitrogen and other nutrients necessary for the growth of microorganisms.
• Lactose is a carbon source and plays an important role for the selection of lactose-fermenting microbes. Oxgall is a selective agent, that inhibits the growth of gram-positive organisms.
• Bromocresol purple is a pH indicator dye. Lactose-fermenting organisms show prominent growth and produce acid and gas, causing the medium to turn yellow. Non-fermenting organisms produce good growth but will not produce acid or gas.

 Use: Recommended for cultivating gram-negative, lactose-fermenting bacilli in water and foods as a presumptive test for coliform organisms.