An enrichment culture is a medium

Growth medium

A growth medium or culture medium is a liquid or gel designed to support the growth of microorganisms or cells, or small plants like the moss Physcomitrella patens.There are different types of media for growing different types of cells....

 with specific and known qualities that favors the growth of a particular microorganism

Microorganism

A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

. The enrichment culture's environment will support the growth of a selected microorganism, while inhibiting the growth of others. Lourens Bass Becking

Lourens Bass Becking

Lourens G. M. Bass Becking was a Dutch botanist and microbiologist. He is known for the Baas-Becking hypothesis, which he originally formulated as "Everything is everywhere, but the environment selects"....

 succinctly summarized enrichment cultures' abilities when he said "everything is everywhere; the environment selects."

The botanist Martinus Beijerinck

Martinus Beijerinck

Martinus Willem Beijerinck was a Dutch microbiologist and botanist. Born in Amsterdam, Beijerinck studied at the Technical School of Delft, where he was awarded the degree of Chemical Engineer in 1872. He obtained his Doctor of Science degree from the University of Leiden in 1877...

 is credited with developing the first enrichment cultures. Sergei Winogradsky

Sergei Winogradsky

Sergei Nikolaievich Winogradsky was a Ukrainian-Russian microbiologist, ecologist and soil scientist who pioneered the cycle of life concept. He discovered the first known form of lithotrophy during his research with Beggiatoa in 1887...

 also experimented on bacteria using different cultures.

Examples

High salt concentration will select for halophile

Halophile

Halophiles are extremophile organisms that thrive in environments with very high concentrations of salt. The name comes from the Greek for "salt-loving". While the term is perhaps most often applied to some halophiles classified into the Archaea domain, there are also bacterial halophiles and some...

s. High temperatures will select for thermophile

Thermophile

A thermophile is an organism — a type of extremophile — that thrives at relatively high temperatures, between 45 and 122  °C . Many thermophiles are archaea...

s.