Commonly used physical disinfection and sterilization methods include: thermal disinfection and sterilization, pressure steam sterilization, ultraviolet sterilization, filtration sterilization and ultrasonic sterilization.
Thermal sterilization is mainly achieved by protein denaturation, cell membrane destruction and nucleic acid degradation. It can be divided into dry heat sterilization and wet heat sterilization. At the same temperature, the effect of moist heat sterilization is better than that of dry heat sterilization.
Pressure steam sterilization or pressure saturated steam sterilization is one of the most effective and reliable methods to sterilize experimental materials, which is suitable for sterilization of medical instruments, laboratory supplies and equipment with high temperature and humidity resistance.
The commonly used equipment includes downward pressure steam sterilizer and pre-vacuum pressure steam sterilizer, among which pre-vacuum and pulsating vacuum pressure sterilizer are suitable for the sterilization of porous articles, but not for the sterilization of liquids.
Introduce physical disinfection and sterilization methods;
1. Sterilize in a dry heat sterilization box. The sterilization conditions are:160℃ for 2 hours; Or 170℃, 1 hour; Or180℃ for 30 minutes. Mechanical convection ovens are often used.
2. Ultraviolet rays with bactericidal wavelength of 240 ~ 280 nm (265 ~ 266 nm has the strongest bactericidal effect) make two adjacent thymines on a DNA chain covalently combine to form dimers, which interferes with the transcription and replication of DNA, thus affecting protein synthesis and leading to microbial death.
3. Filtration sterilization method: remove bacteria in liquid or air by physical retention method to achieve aseptic purpose. Using a bacterial filter, the pore size of the filter membrane or sieve plate of the bacterial filter is (0.22 ~ 0.45 micron), and only liquid or gas is allowed to pass through, while particles such as bacteria larger than the pore size are blocked on the sieve plate or sieve plate.