They incorporate chemical compounds that, following inoculation and incubation, produce a characteristic change in the appearance of bacterial growth and/or the medium surrounding the colonies, which permits differentiation.

• 它们纳入化合物，因此在接种与培养后细菌生长的外观或者在菌落的四周形成一种具有特色的改变，这种改变具有分辨能力。