1, inverted culture can prevent contamination: in order to prevent the distilled water appearing on the lid of the Petri dish when the positive culture flow to the Petri dish, resulting in colonies into pieces, can not be counted or separated, etc.. It also reduces the possibility of contamination.
2, convenient observation and counting: plate inverted for microbial culture, the growth of colonies on the surface of the medium is relatively not too fast diffusion, observation is conducive to identify the characteristics of the colonies.
3, conducive to the emergence of colonies: inverted, the agar surface will not remain water, otherwise there is water, bacteria grow on the surface of the bacterial film, it is difficult for colonies to appear.
Extended information
Cell culture environmental requirements
1, sterile environment: non-toxic and sterile is the first condition of in vitro cell culture. Cells in the living body, the detoxification system and the immune system can resist the invasion of microorganisms or other harmful substances, but the cells in the process of in vitro culture, the lack of the body's immune system to protect the loss of microbial defense and detoxification of harmful substances.
2, the appropriate temperature: generally mammalian and avian cells in vitro culture of the appropriate temperature is 37 ~ 38 ℃, unsuitable environmental temperature will affect the growth of cells.
3, appropriate osmotic pressure: hypertonic solution or hypotonic solution will cause cells to fold, swelling, rupture. Therefore, osmotic pressure is one of the important conditions for in vitro cell culture.
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