Note: for the detailed description regarding the use of pipette, inoculation of the sample, dilution technique, etc, follow reference 1. Inoculate labeled empty Petri dish with specified mL (0.1 or 1.0 mL) of diluted specimen.Prepare the dilution of the test sample expected to contain between 30-300 CFU/mL.01, 1.0 and 2.0 mL) Procedure of Pour plate technique Plate count agar (PCA) or nutrient agar.It has the advantage of not requiring previously prepared plates and is often used to assay bacterial contamination of foodstuffs. The pour plate technique can determine the number of microbes/mL in a specimen. On average, it will give a lower count as heat-sensitive microorganisms may die when they come in contact with a hot molten agar medium. The pour plate method of counting bacteria is more precise than the streak plate method. To ensure a countable plate, plate a series of dilutions. The number of microorganisms present in the particular test sample is determined using the formula:ĬFU/mL= CFU * dilution factor * 1/aliquotįor accurate counts, the optimum count should be within 30-300 colonies/plate. Each colony represents a “colony-forming unit” (CFU). Each (both large and small) colony is carefully counted (using magnifying colony counter if needed). Colonies that grow within the medium generally are small in size and maybe confluent the few that grow on the agar surface are of the same size and appear like those on a streak plate. Microorganisms will grow both on the surface and within the medium. 15mL) is then poured into the Petri dish containing the inoculum and mixed well. After the solidification of the agar, the plate is inverted and incubated at 37☌ for 24-48 hours. In the pour plate method, a fixed amount of inoculum (generally 1 ml) from a broth/sample is placed in the center of a sterile Petri dish using a sterile pipette. Disadvantages of Pour plate method Principle.
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