Lactobacilli MRS Agar, also referred to asLactobacillusMRS Agar or LMRS Agar, is an agar medium used for the selective isolation and enumeration ofLactobacillifrom various sources which include feces and dairy. Proteose Peptone, Beef Extract, and Yeast Extract provide nitrogenous sources, carbohydrates, vitamins, and minerals. Dextrose is the main fermentable carbohydrate. Sodium Acetate and Ammonium Citrate serve as both selective agents and energy sources. Potassium Phosphate acts as pH buffer, while Magnesium and Manganese Sulfates provide cations essential for bacterial metabolism. Tween 80 is a surfactant to facilitate nutrient uptake by theLactobacilli. Agar is the gelifying agent.