Strain (biology)

Strain (biology) refers to a genetic variant, subtype or culture within a biological species. Strains are often seen in microorganisms, viruses, bacterium, and fungus, but can also occur in higher organisms, such as mammals and plants.

Overview

In microbiology, strains are a genetic variant or subtype of a microorganism (e.g. virus or bacterium or fungus). For example, a "flu strain" is a certain biological form of the influenza or "flu" virus. These flu strains are characterized by their differing isoforms of surface proteins. New viral strains can be created through the process of mutation or by reassortment of genes through genetic recombination.

Escherichia coli is a bacterium that has many different strains, some of which can cause illness in humans.

Strains in Bacteria

In bacteriology, a strain is a genetic variant of a bacterium. Bacterial strains can have vastly different properties. For example, one strain of the bacterium Escherichia coli, E. coli O157:H7, is a major cause of foodborne illness, while other strains of E. coli are essential for human digestion.

Strains in Viruses

In virology, a strain is a genetically unique version of a virus. This can be caused by changes in the virus's genome. These changes can result in a new strain that can cause more severe disease, or a strain that can spread more easily.

Strains in Fungi

In mycology, a strain is a genetic variant or subtype of a fungus. The different strains of fungi are often used in scientific research.

Strains in Higher Organisms

In higher organisms, strains are often referred to as breeds or cultivars in the case of plants. These are usually artificially selected for certain traits.

See Also

• Genotype
• Phenotype
• Subspecies
• Variety (botany)