Growth medium

A growth medium or culture medium is a solid or liquid containing nutrients. It is designed to support the growth of microorganisms or cells,^[1] or small plants like moss.^[2] There are different types of media for growing different types of cells.^[3]

An agar plate – an example of a bacterial growth medium. It is a 'streak plate': the orange lines and dots are bacterial colonies

There are a wide range of growth media used in biology. Some of the basic types are:

1. Undefined versus defined media: with defined media we know exactly what chemicals are in them.
2. Selective media: for example, a medium with an antibiotic added. The only things which grow are those resistant to the antibiotic.
3. Differential media: these distinguish one microorganism type from another growing on the same plate.
4. Transport media: these have just enough to let organisms survive.
5. Enriched media: contain extra amino acids and other building blocks. Used to harvest a wide range of organisms from a particular source.