Lactose is used in preparing microbiological culture media in a laboratory setting. Lactose is not intended for use in the diagnosis of disease or other conditions in humans.

A basic characteristic of a microorganism is its nutritional requirements, and without the proper nutrients the organism cannot survive. An essential variety of ingredients are used in the preparation of dehydrated culture media to ensure optimal growth of the microorganism. Carbohydrates, including Lactose, play an important role as an energy source to increase the growth of bacteria and fungi.