Sterilization: Stack the bottom cover in one direction, wrap it with cloth or kraft paper according to the usage amount, or directly put it into the sterilization disinfection bucket. Sterilize at 121 ℃ for 20 minutes or 115 ℃ for 30 minutes. After sterilization, dry in a 50 ℃ oven for later use;

Pouring culture medium: In a sterile room, the temperature of the sterilized culture medium is controlled between 50 ℃ and 70 ℃. About 11ml of culture medium is poured onto a contact plate (the height of the contact plate is 3.5mm, and the height of the culture medium is 1mm higher, with an area of 25cm2). The culture medium protrudes 1mm from the contact plate mouth and must be covered after solidification (so the bottom cover should be separated during sterilization, and the bottom of the contact plate should be placed on the table before pouring the culture medium. Only after pouring the culture medium and solidifying can the contact plate cover be covered, otherwise the culture medium will flow out and will not protrude from the contact plate mouth). Spot check some (or all) pre cultured samples for 48 hours, and those that grow aseptically can be used immediately;

Contact the flat culture medium with the tested surface for about 10 seconds, cover and culture (at a specified temperature and time), and count;

After use, remove the culture medium, clean and drain for future use.