What is the Difference Between Enriched Media and Enrichment Media

The main difference between enriched media and enrichment media is that enriched media are used to grow nutritionally-exacting (fastidious) bacteria whereas enrichment media inhibit the growth of unwanted commensal or contaminating bacteria. Furthermore, enriched media are agar-based while enrichment media are liquid in consistency.

Enriched media and enrichment media are two types of culture media which provide nutrients necessary for microbial growth.

Key Areas Covered

1. What are Enriched Media
     – Definition, Characteristics, Function
2. What are Enrichment Media
     – Definition, Characteristics, Function
3. What are the Similarities Between Enriched Media and Enrichment Media
     – Outline of Common Features
4. What is the Difference Between Enriched Media and Enrichment Media
     – Comparison of Key Differences

Key Terms

Agar-Based, Enriched Media, Enrichment Media, Fastidious Bacteria, Selective Media

What are Enriched Media

Enriched media are a type of media used to grow a wide variety of microorganisms including fastidious organisms. Therefore, these media contain extra nutrients in the form of egg yolk, blood, serum, etc. in addition to the basal medium. Thus, enriched media are capable of providing nutrients to nutritionally exacting organisms as well. Most importantly, enriched media can be used to harvest different types of microorganisms present in a particular specimen.

Figure 1: Blood Agar

Furthermore, some examples of enriched media are blood agar, chocolate agar, Loeffler’s serum, etc. Blood agar contains 5-10% blood by volume to a blood agar base. Also, heated or lysed blood agar is known as chocolate agar.

What are Enrichment Media

Enrichment media are a type of highly selective media which allows the growth of only a particular type of microorganism in the medium. That means; these media inhibit the growth of unwanted, commensal or contaminating microorganisms. Therefore, enrichment media can be used to concentrate on a relative type of microorganisms while recovering them from other microorganisms in a medium.

Figure 2: Salmonella Bacteria in Tetrathionate Enrichment Broth

Generally, enrichment media have a liquid consistency. When agar-based, the media performing the same purpose are known as selective media. Moreover, the selectivity of these media can be obtained by either adding antibiotics, dyes, chemicals, alteration of pH or a combination of these.

Similarities Between Enriched Media and Enrichment Media

• Enriched media and enrichment media are two types of culture media used to grow microorganisms in the laboratory.
• They provide a medium as well as nutrients for the growth of microorganisms.
• Also, both enriched media and enrichment media are classified based on their functional use.

Difference Between Enriched Media and Enrichment Media

Definition

Enriched media refers to the media which contain the nutrients required to support the growth of a wide variety of organisms, including some fastidious ones, while enrichment media refers to the liquid media that inhibits the growth of the unwanted bacteria.

Type of Growth

While enriched media allow the growth of a wide variety of microorganisms, enrichment media allow the growth of a particular type of microorganism in the medium. Thus, this is the main difference between enriched media and enrichment media.

Solid or Liquid

Apart from that, an important difference between enriched media and enrichment media is that enriched media are solid media as they are agar-based while enrichment media are liquid media.

Composition

Moreover, enriched media contain extra nutrients in the form of egg yolk, blood, serum, etc. in addition to the basal medium while enrichment media contain added antibiotics, dyes, chemicals or altered pH. Hence, this is also a difference between enriched media and enrichment media.

Purpose

The purpose of each is another important difference between enriched media and enrichment media. That is; the enriched media facilitate the growth of fastidious microorganisms while the enrichment media inhibit the growth of unwanted commensal or contaminating bacteria.

Examples

Some examples of enriched media are blood agar, chocolate agar, Loeffler’s serum, etc. while Selenite F broth, tetrathionate broth, alkaline peptone water (APW), etc. are the examples of enrichment media.

Conclusion

Enriched media are a type of agar-based media which allow the growth of a wide variety of microorganisms including fastidious organisms. Generally, enriched media are solid media. In contrast, enrichment media are liquid media, which inhibit the growth of unwanted microorganisms in the media. Therefore, the main difference between enriched media and enrichment media is the type of microorganisms.

References:

1. tankeshwar. “Bacterial Culture Media: Classification, Types and Uses.” Microbe Online, 26 Nov. 2018, Available Here.

Image Courtesy:

1. “Agarplate redbloodcells edit” By Bill Branson – (Edited by Fir0002)(Edited by Drhx) – This image was released by the National Cancer Institute, an agency part of the National Institutes of Health, with the ID 2230. (Public Domain) via Commons Wikimedia  
2. “Salmonella bacteria in tetrathionate enrichment broth stained using direct FA staining technique.” By Thomason (Public Domain) via Public Domain Files