Culture media can be a helpful instrument in detecting and identifying the functions of various microorganisms. An ability to determine a purpose leads to a better understanding of what can be useful or harmful for the human body. This paper provides an overview of the definition, classification, and importance of culture media in microbiology laboratories.
Culture media are the media that are used in microbiology laboratories to grow various microorganisms. They are important as media help growing particular microorganisms, which allows exploring how they function. According to Marx (2016), such understanding can help to reveal “which bacterial species are key to a newborn’s immune system or coral reef health, have pathogenic traits, or might be healthful in a probiotic drink.” (p. 37). Therefore, culture contributes to the development of various fields of medicine and grows awareness of how certain microbes influence the individual’s body.
According to the composition or use, media can be divided into several categories. The two primary types of culture media are liquid culture media, which is also known as “broth,” and solid culture media, which is called “agar.” Liquid media does not contain gelatine or other gelling agents as “agar” does. Their primary function is the proliferation of a large number of microorganisms. Another purpose is various tests and fermentation studies that can be performed.
The liquid media can be divided into several categories depending on the functions they serve. Growth media are used to grow heterotrophic microorganisms; enrichment media serve to multiply the number of specific microorganisms and selective growth media. The last media is used to identify an organism, which is achieved by inhibiting the growth of the selected one.
Behera and Varma (2017) state that solid media can help microorganisms to grow in “physically informative or useful ways (e.g., as colonies or in streaks)” (p. 48). Solid medium helps to isolate bacteria or to determine the characteristics of an organism. There are also semi-solid media that are prepared with agar of concentration of 0.5 or less, compared to the solid agar with 1.5-2% concentration. The primary function of the semi-solid media is to cultivate microaerophilic bacteria. The type of use can also classify media. This classification includes defined, complex, minimal, supplementary, selective, and differential media.
Culture media should include specific criteria, and various tests can be performed to determine physical characteristics, depending on the type of media. For instance, visual tests for color and quality are one of the most common tests. Visual test for color means that the color of a sterilized medium is compared to a non-sterilized medium. Visual test for clarity identifies various optical artifacts. In determining physical characteristics, scholars should also make sure that the gel strength is not over-soft and that plates or bottles do not have defects. According to Sandle (2014), the pH of the finished media is the most critical test, as incorrect pH can lead to the inhibition of specific microbes. The inhibition can result in an inability to grow an intended microorganism, which can interfere with the experiment.
Culture media help to grow and examine various microorganisms that can help researchers to discover how they interact with the environment. Understanding the classification of different types of culture media can be useful in practice. To achieve the correct results and grow an intended microorganism, one needs to make sure that it corresponds to the most important criteria.
References
Marx, V. (2016). Microbiology: the return of culture. Nature Methods.
Sandle, T. (2014). Assessment of Culture Media in Pharmaceutical Microbiology. Bio Product Laboratory Ltd.
Behera, B. K., & Varma, A. (2017). Microbial biomass process technologies and management. Basel, Switzerland: Springer International Publishing.