|  | Healthcare Industry | Medical Facilities

What Is Sterile Nutrient Agar?

Bacteria and fungi can grow on a lot of materials, but it's not so easy to examine and study these microorganisms in their natural settings. In labs, researchers often grow microorganisms for study on a sterile growing medium instead of the soil, pond water, plants or whatever else served as their last home. Nutrient agar is a specific type of widely used growing medium.

  1. Definition

    • Nutrient agar is a gel-like substance used in laboratory tests and experiments as a medium for growing a wide variety of microorganisms, particularly bacteria and molds. It is made from a relatively simple formula that usually includes beef extract and agar, which is a gelatinous extract from seaweed and algae. Yeast extracts and a peptone also are included in nutrient agar preparations.

    Function

    • At room temperature, nutrient agar is a very stiff gel. The beef and yeast extracts in nutrient agar serve as food for the microbes that will be grown for study. The agar is the thickener that creates the gel texture, and the peptone helps control pH. Agar is preferred over regular gelatin because it is stronger and won't be eaten by the bacteria.

    Types

    • Nutrient agar may be purchased from laboratory suppliers in powdered or tablet form. Preparation includes dissolving the dry agar in water before adding to petri dishes or other similar containers. Bottled nutrient agar must be warmed in a hot water bath or the microwave before the agar can be poured into sterile dishes.

    History

    • Nutrient agar has been widely used since early in the 20th century when the American Public Health Association first published the formula. This general-purpose medium for the growth of microorganisms has been widely used since in the examination of water, waste and a broad spectrum of other materials.

    Considerations

    • Nutrient agar is suitable for growing most types of fungi and bacteria, but some bacteria find it too rich in nutrients or not rich enough. Careful handling is necessary to ensure that the nutrient agar remains sterile during storage and handling. Contamination can occur any time containers are open or when prepared petri plates are handled.

Medical Facilities - Related Articles