Cotton plug making experiment

Summary

The role of cotton plugs is twofold: one is to prevent contamination by stray bacteria, and the other is to ensure good aeration. Therefore, the quality of the cotton plug has a great impact on the results of the experiment. The correct cotton plug requires shape, size, tightness and test tube mouth (or triangular flask mouth) is completely suitable, too tight to prevent air circulation, operation is inconvenient; too loose can not achieve the purpose of filtering bacteria.

Operation method

Cotton plug making

Materials and Instruments

cotton
water
test tube

Move

Add plug, should make the cotton plug length of 1/3 in the test tube outside the mouth, 2/3 in the test tube mouth, as shown in Figure 1, do plug the cotton to choose the longer fiber, generally do not use skimmed cotton to do cotton plug. Because it is easy to absorb water and become wet, resulting in contamination, and expensive, do cotton plug process as shown in Figure 2.

Figure 1 Cotton plug

Figure 2 Cotton plug making process
In addition, in microbiological experiments and scientific research, often need to use the ventilation plug, the so-called ventilation plug, is a few layers of gauze (usually 8 layers) overlap each other, or in the two layers of gauze evenly spread between a layer of cotton and become. This vent plug is usually added to the mouth of a triangular flask containing liquid baking medium. After inoculation, it is placed on a shaker for shaking culture, in order to obtain good aeration to promote the growth or fermentation of the bacteria, the shape of the aeration plug is shown in Figure 3.
Figure 3 Ventilator plugA. Gauze plug method during preparation; B. Kraft paper wrapped during sterilization; C. Gauze turned out for incubation

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