The spread plate technique is used for the enumeration of aerobic microorganisms from the given sample. This can be done by serial diluting the samples, placing 0.1ml of the diluted sample in the middle of an agar plate and spreading the sample over the surface with a help of an L-rod. After incubating it in a suitable temperature for a period of time the colonies can be counted.
Before start the experiments always spray 70% alcohol on the table and inside laminar hood. While performing the experiments always wear lab safety glasses to prevent chemical irritants from entering the eyes and facemask for protecting spores from entering your body. Use lab gown to avoid damage of your clothes. Wear lab shoes or slippers to prevent any cut or burns that may occur while handling chemicals and lab equipments. Gloves must be removed or changed before touching any other laboratory surfaces or equipment and washing your hand before leave from lab room. Take care while handling the microorganisms. They can cause diseases if not taken good care of.
Countable limit of this procedure is 30 to 300 colonies per plate. If the number of colonies in the plate is less than 30, centrifuge the suspension and increase the concentration and repeat the experiment again. If the colonies in the plate is more than 300, dilute the sample 10 folds and repeat the experiment again.
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