What are the basic classes of media?
Posted November 6, 2023
The six basic classes of media include: basal, indicator, selective, enriched, storage, and transport media.
- Basal media consists of glucose, amino acids, and ions required for cellular growth. This type of media is used for the survival of cells in vitro which imitates the optimum physiological environment vivo and does not require the enrichment of bacteria. Examples of basal media include nutrient agar, peptone water, and nutrient broth. Bacteria such as enterobacteria and staphylococcus are able to grow in basal media.
- Enriched media consists of nutrients which induce the growth of a wide range of organisms including fastidious ones. They are utilized to grow as many different types of microbes which are found in the specimen. Blood agar and Loweinstein-Jensen media are examples of enriched media.
- Storage media is used for storing bacteria for extended periods of time. Examples of this type of media include chalk cooked meat broth, and egg saline medium.
- Transport media are solutions of buffers with peptones, carbohydrates, and nutrients (without growth factors), made to preserve viability of bacteria during transport without permitting their multiplication. Examples of transport media include Cary-Blair medium, Stuart medium, and Amies medium.
- Indicator media consist of substances which cause colonies of bacteria to have a unique appearance. This type of media permits researchers to differentiate multiple types of bacteria on the same agar plate. Examples of indicator media include blood agar and MacConkey agar.
- Selective media are used to select the growth of a specific microorganism by inhibiting the growth of unwanted bacteria. For example, if a specific microbe is resistant to an antibiotic, that antibiotic can be added to the medium to inhibit other microorganisms (which are not resistant) from growing.