The thoroughness of media sterilization is directly related to the accuracy and reliability of experimental data. In order to ensure the sterilization of the medium, we need to focus on several factors. In addition to the type and number of bacteria in the medium, the choice of sterilization time and temperature is also crucial. Today, Mr. Xiaowei will work with you to ** these main factors that affect the sterilization of culture media to help you better control the experimental process.
Physical or chemical methods to kill or remove viable bacterial trophic bodies and their spores from the culture medium.
Kills microorganisms in the medium and creates aseptic conditions for subsequent fermentation processes.
Achieve the required degree of sterility – 10-3
Minimize nutrient destruction.
Chemical sterilization. Filter sterilization.
Moist heat sterilization. The heat-lethal temperature of the organism (above which should generally prevail) should be considered;
On the premise of ensuring the sterilization effect, the destruction of nutrients in the medium should be reduced as much as possible
Follow media manufacturer's recommendations.
, medium components
High concentrations of organic compounds such as oils, sugars, and proteins form a thin film around the cell, which affects heat conduction. However, the high concentration of salts and pigments weakens its heat resistance and makes it easier to sterilize. Generally, when the sugar content is large, it is best to use 115 for 30 minutes;The general medium can be selected for 121-20 minutes.
2. PH value
pH has a great influence on the heat resistance of microorganisms. The pH is at 60~8.At 0, microorganisms are the least likely to die. pH 6At 0, the microorganism is relatively easy to die, and the pH can easily penetrate into the cells of the microorganism, thereby changing the physiological response of the cell and promoting its death. So the lower the pH of the medium, the shorter the time required.
3. Particles in the medium
Small particles are easy to sterilize, and large particles are difficult to sterilize. Mass clumping can lead to incomplete media sterilization.
4. Foam
The air in the foam forms an insulating layer, which makes it difficult for heat to penetrate and kill the bacteria in it, thus affecting the sterilization effect of the medium.
5. Whether the cold air in the sterilizer is discharged
When the autoclave is in use, the cold air is drained clean to achieve saturated steam. When water vapor contains air in it, the pressure shown on the pressure gauge is not the actual pressure of the water vapor but the sum of the water vapor pressure and the air pressure. At the same pressure, the temperature of the steam containing air is lower than the temperature of the saturated steam, so when the sterilizer is heated to the required sterilization pressure, if it contains air, the sterilizer cannot reach the required sterilization temperature, and the due sterilization effect cannot be achieved.
The microsterilizer system automatically monitors the cold air discharge to ensure a pure steam sterilization environment and ensure the best sterilization effect. It has specific media sterilization procedures such as liquid, liquid with heat preservation, agar dissolution, etc., to meet the needs of media sterilization.