Method That Can Be Preserved With Filter Paper
Yeasts and filamentous fungi can be preserved by filter paper. The first two can be preserved for about 2 years, and some filamentous fungi can be preserved for 14 to 17 years. This method is simpler than liquid nitrogen and freeze-drying and does not require special equipment. The filter paper was cut into 0.5 cm³ 1.2 cm strips, placed in a 0.6 cm³ 8 cm ampoule tube, 1~2 sheets per tube, stoppered with a cotton plug, and sterilized at 121 °C for 30 min. The strain to be preserved is cultured on a suitable slant medium and grown sufficiently.
Sterilized degreased milk (treatment of skimmed milk: degreased by centrifugation at 2000r/min for 10min, then sterilized at 115°C for 20min, or intermittently sterilized for 3 times, after sterile inspection) 1~2mL added to the sterilized culture dish or in a test tube, take a few rings of fungus in the milk to make a concentrated suspension.
Use a sterile tweezers to take the filter paper from the ampoule tube and immerse it in the bacterial suspension, soak it up, put it back into the ampoule tube, and stuff the cotton plug. The ampoule was placed in a desiccator containing P2O5 as a water absorbing agent and evacuated by a vacuum pump to dryness. The cotton is stuffed into the tube, sealed with fire and stored at low temperature. Need to use the strain, when resurrection culture, the ampoule can be heated on the flame, drop a drop of cold water in the hot part, the glass will be broken, then use the tweezers to knock off the glass at the mouth. After the ampoule is opened, remove the filter paper, placed in a liquid medium, and incubated in a thermostat.