Petri dish

November 1, 2021

Laboratories require a wide variety of instruments in order to carry out all kinds of experiences, observations and evaluations. The Petri dish is one such instrument and is used in microbiology laboratories, where it is used to deposit cells, observe seed germination, or examine microorganisms.

What is it?

It is a round container made of glass or plastic. It has a cover in the same shape as the plate, but with a larger diameter so that it can be placed on top and close the container. Although not airtight. It is part of the laboratory glassware.

It is used in microbiology to grow cells, examine the behavior of microorganisms in cultures, and observe seed germination.

It was designed in 1877 by the German bacteriologist Julius Richard Petri when he was working as an assistant to Robert Koch, known for receiving the Nobel Prize for discovering the tuberculosis bacillus.

What is it for?

  • It is used to observe different types of both biological and chemical samples. These samples are enclosed within the plate.
  • It is used to grow bacteria and other microorganisms.
  • It is also used to mass solids on a balance.

How is it used?

In the case of cultures of bacteria, molds and microorganisms, the bottom is covered with culture media, such as agar, depending on the microorganism that we want to cultivate.

If it is desired to observe a colony, the plate is left upside down resting on the lid during the incubation time of the seeded microorganism.

In this way, the agar remains on top and the water vapor produced by the microorganisms due to their metabolism condenses and falls on the lid, preventing the microorganisms from being diluted. Thus, they remain fixed to the substrate.


  • It should be used with caution because contact with microorganisms should be avoided when working with them. Some can cause illness.
  • The necessary protective implements must be used to work with biological organisms.
Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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