Enrichment Culture : Definition, Composition, Advantages

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.
Yeast Extract6
Peptic digest of Animal Tissue40
Dipotassium phosphate3
Distilled Water1000 ml
pH7.0 ± 0.2

Advantages of Enrichment Culture 

  1. Enrichment culture is an isolation technique designed for growth and Development of particular microorganisms by providing favorable Nutrients and Environment.
  2. Enrichment culture techniques are used to increase the small number of organisms to high number of molecules.
  3. One of the most important  advantage of enrichment culture media is the it increase the chance of isolation of particular bacteria from mixed culture.
  4. The advantages of Enrichment culture is it provide natural conditions, 
  5. Enrichment culture is easy to replace without changing the container, 
  6. Easy to sterilize with ultra-filtration.
  7. Enrichment media are used for various purposes such as propagation of a large number of organisms, fermentation studies, and various other Microbiological tests.

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