MacConkey agar (麦康凯培养基) lngredients: peptone, lactose, bile salts sodium chloride and pH indicator(neutral red) aBacteria that ferment lactose in the medium will produce acid byproducts, which will change the color of the ph indicator from vellow to redMacConkey Agar （麦康凯培养基） Ingredients : peptone, lactose, bile salts, sodium chloride and pH indicator (neutral red). Bacteria that ferment lactose in the medium will produce acid byproducts, which will change the color of the pH indicator from yellow to red