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Culture media sterilisation in microbiology is sterilized throughout the fermentation process for a variety of reasons. The substrate or product of the biological reaction will be lost if not sterilized, resulting in a reduction in production capacity; the bacteria also produce metabolites, making product extraction more difficult, resulting in lower yields and lower product quality; and the PH of the reaction solution can be altered by the bacteria's proliferation, resulting in abnormal reactions; some bacteria breakdown the product, causing the manufacturing to fail; phage infection causes the producing bacterium's cells to be lysed, causing the production to fail. The following are some of the most common sterilizing procedures.

1. Chemical sterilization of culture media in microbiology

Principle: The medication interacts with microbial cell components to denature enzymes and inactivate proteins. Application: sterilization of utensils, hands, and the surroundings of labs and sterile rooms, but not for culture media of microbiology.

2. Radiation sterilization of culture media in microbiology

Radiation sterilization is based on the use of high-energy electromagnetic radiation and the photochemical reaction of the bacterium's nucleic acid, which results in the bacterium's death. UV, X-rays, and -rays are commonly employed. It is used to disinfect indoor air as well as vessel surfaces.

3. Dry-heat sterilization of culture media in microbiology

The principle of sterilization is to destroy germs through oxidation, protein denaturation, and electrolyte concentration at high temperatures. 140-180°C for 1-2 hours is commonly used for cautery and electric heating. Sterilize glass and metal utensils as well as sand tubes.

4. Moist heat sterilization of culture media in microbiology

Direct steam sterilization is the principle of microbiology culture media sterilization. When steam condenses, it releases a large amount of latent heat, and steam has a strong penetrating force, destroying the chemical bonds of the bacterium's proteins and nucleic acids, inactivating enzymes, and killing microorganisms due to metabolic disorders. Atmospheric pressure sterilization with boiling water: 100°C. Alternatively, saturated steam sterilization can be done at 121°C for 30 minutes. Sterilization of culture medium and fermentation equipment is possible.

5. Filtration sterilization of culture media in microbiology
Microorganisms cannot flow through the filter membrane, which is the principle of sterilization. For the removal of microorganisms from compressed air, enzyme solutions, and other heat-resistant chemical solutions, 0.01 to 0.45 mm pore size membranes are used. In industrial production, sterilization of culture media of microbiology, pipelines, and equipment is often accomplished by heating steam to a certain temperature and maintaining it there for a length of time, a process known as moist heat sterilization. The advantages of moist heat sterilization are its ease of use, non-polluting nature, and the ability to condense the condensate directly in the culture media or drain it through a conduit.

The majority of culture media in microbiology are sterilized using moist heat. The "heat-death time", which is the time necessary to kill a given proportion of the original germs at a specific temperature, is the most often used metric of heat sterilization. The type, nature, and concentration of the microorganism, as well as the nature and concentration of the medium, all impact the temperature and time of heat sterilization.

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