Why should China 90mm petri dish be turned upside down during plate culture?
In daily experiments, laboratory workers often use China 90mm petri dishes, culture bottles and other types of experimental utensils, but in plate culture,China 90mm petri dishes need to be inverted. What are the main reasons?
01. Avoid pollution
When China 90mm petri dish is placed upright, the water evaporated from the culture medium will condense on the lid of the dish, and may cause bacteria to fall back to the surface of the culture medium, causing pollution and affecting the culture results.
However, if China 90mm petri dish is inverted, the evaporated water will condense evenly on the surface of the medium, and the evaporation and condensation will form a balance, which will not affect the culture results. Because the air in the plate is not easy to flow, the infection of foreign bacteria can be reduced as much as possible, and the medium and culture medium can be prevented from being polluted by bacteria.
02. Easy access
If it is placed upright, because the lid of the petri dish is large and the bottom is small, it is easy to only pick up the lid when taking it, exposing the culture medium to the air, causing pollution or dropping the petri dish. The inverted plate can keep its original shape when it is taken, and it is not easy to separate the bottom and cover of the plate, so as to avoid the contamination of bacteria in the environment.
03. Slow down evaporation
In the forced convection incubator, inverting China 90mm petri dish can reduce the air flow on the surface of the medium, reduce the evaporation rate of water, and make the medium not easy to crack and not affect the growth of microorganisms. Inverted China 90mm petri dishes are more conducive to the growth and reproduction of strains.
04. Easy to observe
Inverting China 90mm petri dish can control the spread of colonies to a certain extent, which is conducive to the formation of single colonies and is convenient for observation and counting.
05. Good for collection
If the goal of culture is to collect metabolites of bacteria, and some metabolites are easily soluble in water, if the evaporated water falls back to the culture medium, it will also cause bacterial colonies to form flakes, making it difficult to collect metabolites. Inverted China 90mm petri dishes do not exist this problem.
China 90mm petri dish