Enrichment Culture : Definition, Composition, Advantages :
What is Enrichment Culture?
- Enrichment culture is refers to as it is a technique used to grow a particular group of microorganisms on a enrichment media.
- The media used for the enrichment culture is the enrichment media.
- The process of enrichment is usually done by addition of verious nutrients, growth factors and environmental conditions that only allow the growth of an organism of interest.
- These techniques is used to number of organism, Small to detectable levels.
- For example, if you wish to isolate a bacterium that is a halophiles (these bacteria grow at a high salt concentration), incubate the sample at that high salt concentration.
- Organisms that cannot tolerate that high salt concentration will dies or simply fail to grow, while halophiles will grow and increase in number, over time becoming a large and larger proportion of the total bacterial population in the sample. This is an example of enrichment culture by modifying the physical conditions of media.
- Enrichment can also be carried out by modifying the nutrient content of the culture medium by adding specific types of nutrients and inhibitors.
History of Enrichment Culture :
The microbiologist and virologist Martinus Beijerinck invented the enrichment culture, a fundamental method of studying microbes from the environment. Sergei Winogradsky also experimented on bacteria using different Enrichment cultures.
Media use for Enrichment Culture
- Enrichment media refers to the liquid media that allows only the growth of a particular type of microorganism and inhibits the growth of unwanted bacteria by adding inhibitors.
- Generally Enrichment media are in liquid form, so it also known as Enrichment Liquid Media/Culture.
- To stop the growth of unwanted microorganisms verious kinds of Inhibitors are usually added to enrichment media. Inhibitors such as antibiotics Penicillins, Tetracyclines, dyes, chemicals, High pH, Temperatures alteration etc.
- Examples of Enrichment media include Lowenstein Jensen medium, selenite F broth, tetrathionate broth, alkaline peptone water, pseudosel Agar etc.
- Media with a high salt concentration will select for halophiles.
- Selenite broth is used to selectively isolate Salmonella species.
- Alkaline Peptone Water is used for the cultivation of vibrio.
Composition of Enrichment Media :
- Enrichment media contains the various kinds of nutrients that required for the growth of a wide variety of organisms.
- Enrichment Medium is a highly nutritive medium which contains peptone and yeast extract which serves as source of carbons, nitrogen, amino acids, growth factors, vitamins and Dipotassium phosphate buffer for growth of bacteria.
- Agar is used as solidifying agent.
| Composition | Gms/Litre |
|---|---|
| Yeast Extract | 6 |
| Peptic digest of Animal Tissue | 40 |
| Dipotassium phosphate | 3 |
| Agar | 15 |
| Distilled Water | 1000 ml |
| pH | 7.0 ± 0.2 |
Advantages of Enrichment Culture :
- Enrichment culture is an isolation technique designed for growth and Development of particular microorganisms by providing favorable Nutrients and Environment.
- Enrichment culture techniques are used to increase the small number of organisms to high number of molecules.
- One of the most important advantage of enrichment culture media is the it increase the chance of isolation of particular bacteria from mixed culture.
- The advantages of Enrichment culture is it provide natural conditions,
- Enrichment culture is easy to replace without changing the container,
- Easy to sterilize with ultra-filtration.
- Enrichment media are used for various purposes such as propagation of a large number of organisms, fermentation studies, and various other Microbiological tests.