Enrichment cultures and selective cultures are two techniques used to isolate and grow specific microorganisms, but they have distinct methodologies and goals.
The aim of enrichment cultures is to increase the abundance of a target microorganism within a mixed population. This is achieved using a non-selective medium where conditions are tailored to promote the growth of the desired organism, resulting in a diverse mixture with higher concentrations of the target species.
In contrast, selective cultures focus on suppressing the growth of non-target microorganisms while allowing the desired species to thrive. This is accomplished by utilizing a selective medium that contains specific agents that inhibit the growth of unwanted organisms. The outcome is a culture predominantly composed of the intended microorganism.
In summary, while both methods are geared toward isolating specific microorganisms, enrichment cultures enhance the population of a target organism in a mixed setting, whereas selective cultures create conditions that favor the growth of its target by limiting competitors.