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Microbiology Concept Inventory
Please note, you must be an educator in higher ed or maybe high school to qualify to recieve the MCI
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|A practical and common laboratory technique used in isolating pure cultures or enumerating the living microorganisms in water, milk, foods, and other materials is the pour plate technique.
To aseptically transfer liquid into a pour plate, raise one side of a Petri plate lid only just enough to allow access of the sample (from a tube or pipette). Transfer a known amount of the sample to the dish and cover immediately with the lid. Then pour 15-20 ml of sterile agar culture medium which has been melted and cooled to 45-50°C into the plate as shown in Figure 2-5. The inoculum and medium are mixed by gentle rotation ten times in one direction and ten times in the other direction. The agar must be allowed to solidify completely before the plates are inverted for incubation. After incubation both surface and subsurface colonies will be observed.
Figure 2.5. Pour plates. Pour plates allow the addition of larger amounts of liquid (1-5 ml) to an agar dish. The sample is added to the bottom of a sterile Petri plate. Molten agar is then added to the plate aseptically. It is important to only open the cover enough to allow the pouring of the agar. This prevent contamination from the environment.
Above is a movie demonstrating the pour plate technique.