Amazing, famous places of interest are grown in culture medium! Let's learn about the in vitro culture of "little elves under the mirror"

Most pathogenic microorganisms such as bacteria, fungi, and actinomycetes are invisible to the naked eye and can only be seen after being magnified by a microscope. We call them "elves under the microscope."

They are everywhere. Some of them can be used in agriculture or industry and are beneficial to humans, but there are also naughty bad guys who can cause human infection and lead to disease.

How can people know which pathogen they are infected with?

In addition to conducting relevant clinical tests, we can also find the source of infection through culture. Because pathogenic microorganisms are really too small, it is difficult to find the real "culprit" of infection in the human body without culture. So, can they be cultured in vitro? The answer is yes.

Clinical laboratory personnel place pathogens in an adaptive environment in vitro and allow them to grow in large quantities, thereby reaching the lower limit of detection. They then use laboratory methods to test them, which can further provide clinicians with effective information and guide which antibiotics are most effective.

Not only that, these little elves that have been cultured in vitro, after breeding under suitable temperature and humidity, can also create a different kind of beauty and cultivate "historical sites".

The following beautiful pictures are their masterpieces:

Students from Anqing Normal University used fungi to paint the Songhe Great Wall and named it "National Soul", showing the beauty of the microscopic world

These breathtaking works show common bacteria or fungi growing on culture media, with multiple bacterial cells fused together.

1 What is culture medium?

Careful friends may find that these elves of different colors and shapes can all grow on round or square small boards. Why is this? In fact, this magical board is the culture medium .

The culture medium is a plate for artificially culturing bacteria in vitro, which provides all the nutrients needed by the elves, including water, carbon source, nitrogen source, inorganic salts, growth factors, etc. Its basic ingredient is agar powder , and the culture medium is bouncy and similar to jelly.

There are many types of culture media used in laboratories. According to their different uses, they can be divided into basic nutrient media , selective media and identification media .

What is the difference between these media?

Basic nutrient medium: Add some special nutrients to the basic medium, such as glucose, blood, growth factors, etc., so that bacteria with higher nutritional requirements can grow in it;

Selective culture medium: It contains antibacterial agents. After the specimen is inoculated in this type of culture medium, due to the selective inhibition of the antibacterial agent, non-target bacteria are inhibited to varying degrees, which is conducive to the proliferation or separation of target bacteria;

Identification culture medium: A certain reaction substrate and indicator are added into it to distinguish the characteristics of certain microorganisms and identify them.

Agar powder

Laboratory Part Culture Medium

2 Why do different patterns form on the culture medium?

How come the elves appear in different colors and shapes on the culture medium?

This is because the colors and shapes of the bacteria and fungi vary depending on the type of bacteria or fungus.

For example, the picture we see is colorful, and the color- developing culture medium (an identification culture medium) used is: the green one is Candida albicans, the blue one is Candida tropicalis, the purple one is Candida glabrata, and the pink one is Candida krusei.

3 How to prepare culture medium?

The culture medium provides an important foundation for the various forms of the elves and is the source of nutrition for the elves. The quality of the culture medium will have a direct impact on the elves, so the production of the culture medium is particularly important.

The preparation of culture medium requires the steps of "weighing - melting - sterilization - cooling - pouring into plates". Special attention should be paid to aseptic operation throughout the process. The pH and thickness of the culture medium are important factors affecting the quality. After preparation, corresponding quality control is required to verify whether the prepared culture medium is effective and whether there is any contamination before it can be used clinically.

Also, be sure to use the culture medium within its validity period. Ordinary culture media can be sealed and sterilized and placed in a refrigerator at 2 to 8°C for 2 to 6 months ; homemade culture media in the laboratory can generally be stored for about 4 weeks ; and some culture media need to be prepared before use.

When taking the culture medium, you need to check whether there is any bacteria growing in the culture medium, whether the color and texture have changed, and whether it has become dry. If these abnormalities occur, do not continue to use it.

Weighing

melt

Sterilization

cool down

Inverted plate

Of course, in addition to the culture medium, the atmospheric environment such as oxygen and carbon dioxide also plays a vital role in the in vitro cultivation of elves.

We must remind everyone here that not all “little elves under the microscope ”** can be cultured in vitro. For example, Pneumocystis jiroveci cannot be cultured in vitro. Some viruses also require avian embryo or cell culture medium. I will continue to share their testing points with you when the opportunity arises!

Editor: Liu Yang and Zhao Na

Proofreading: Li Na, Li Yule, Dong Zhe, Li Huiwen

Producer: Wu Wenming

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