R2A Agar (Reasoner´s 2A agar) is designed to promote the growth of aerobic, heterotrophic microorganisms that are adapted to low nutrient environments such as water. The low amount of nutrients in the agar allows the growth of aerobic, heterotrophic microorganisms, which are adapted to low nutrient content. The Gram-negative, Gram-positive bacteria, and several yeast colonies appear red due to the chromogenic agent, which facilitates the evaluation of the plates. However, molds are not affected by the chromogenic agent.

R2A Agar chromogenic - LI in 90 mm settle plates is designed for the determination of the total microbial count in water for injections in bulk, highly purified water, and purified water in bulk.