#cottonplug #microbiologylab #autoclave
Cotton plugs are best filters of microbes. The required amount of non- absorbent cotton should be rolled tightly to fit the mouth of the flask or tube. It must be possible to lift the flask or tube by holding the plug without the plug slipping off.
What Are Cotton Plugs?
Tight plugs are not advisable for plant and bacterial cultures, which require the maintenance of an aerobic environment, which is characterized by the presence of free oxygen. Loose-fitting caps, like cotton plugs, permit the free passage of air over the edge of tubes and flasks and prevent the lack of air flow that causes semi-anaerobic conditions in the culture.
In general, cotton plugs are used to stop air movement that might carry microbes. They are sometimes used in equipment when sterilized in an autoclave, as well as in the tops of agar flasks in the autoclave. They are used in test tubes, again to prevent contamination through the air.
Culture vessels like flasks and tubes must stay aerated in order to prevent accumulation of certain gaseous compounds, such as ethylene. A plant hormone, ethylene is normally produced and released in the general proximity of a plant. As ethylene accumulates, Accumulation of ethylene leads to certain developmental abnormalities that can be observed in plant culture when the vessels are not properly aerated. Cotton plugs are usually sufficient to keep fungal infection from penetrating inside the vessel while still allowing for proper aeration.