MICROBIAL CULTURE MEDIA, CLASS 12

A growth medium or culture medium is a solid, liquid or semisolid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation

Culture media contain all the elements that most bacteria need for growth and are not selective, so they are used for the general cultivation and maintenance of bacteria kept in laboratory culture collections.

An undefined medium (also known as a basal or complex medium) contains:

·         a carbon source such as Glucose

·         water

·         various salts

·         a source of amino acids and nitrogen (e.g., beef, yeast extract)

o    This is an undefined medium because the amino-acid source contains a variety of compounds with the exact composition being unknown.

A defined medium (also known as chemically defined medium or synthetic medium) is a medium in which

·         all the chemicals used are known

·         no yeast, animal, or plant tissue is present

In a synthetic media, the exact chemical composition is known while it may not be so clearly known in case of a complex media. Synthetic media usually contains peptone water medium while complex media usually contains materials of biological origin such as blood or milk, peptone yeast extract and beef extract.

What is the importance of culture media?

Culture media is of fundamental importance for most microbiological tests: to obtain pure cultures, to grow and count microbial cells, and to cultivate and select microorganisms. Without high-quality media, the possibility of achieving accurate, reproducible, and repeatable microbiological test results is reduced