Advantages and disadvantages of the serial dilution agar plate technique

#Advantages and disadvantages of the serial dilution agar plate technique series

Note: for the detailed description regarding use of pipette, inoculation of sample, dilution technique etc, follow the 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 food stuffs. The pour plate technique can be used to determine the number of microbes/mL in a specimen.

5 Disadvantages of Pour plate method Uses:.

#Advantages and disadvantages of the serial dilution agar plate technique series

To insure a countable plate a series of dilutions should be plated.The pour plate method of counting bacteria is more precise than the streak plate method, but, on average, it will give a lower count as heat-sensitive microorganisms may die when they come contact with hot, molten agar medium. The number of microorganisms present in the particular test sample is determined using the formula:Д¬FU/mL= CFU * dilution factor * 1/aliquotДЇor accurate counts, the optimum count should be within the range of 30-300 colonies/plate.

Each colony represents a вЂњcolony-forming unitвЂќ (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.В After the solidification of the agar, the plate is inverted and incubated at 37вЊ for 24-48 hours. In this 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. Because the sample is mixed with the molten agar medium, a larger volume can be used than with the spread plate. Pour plate method is usually the method of choice for counting the number of colony-forming bacteria present in a liquid specimen.