Last to update on June 11th, 2021Pour plate an approach is commonly the an approach of choice for counting the number of colony-forming bacteria current in a liquid specimen. Because the sample is mixed with the molten agar medium, a bigger volume can be supplied than v the spread out plate. In this method, a addressed amount of inoculum (generally 1 ml) indigenous a broth/sample is inserted in the center of a sterile Petri dish making use of a sterile pipette. Molten cooled agar (approx. 15mL) is climate poured right into the Petri dish containing the inoculum and also mixed well. After the solidification that the agar, the key is inverted and also incubated in ~ 37°C because that 24-48 hours.Microorganisms will thrive both top top the surface and within the medium. Swarms that prosper within the medium usually are little in size and also maybe confluent; the couple of that thrive on the agar surface room of the same size and appear choose those on a streak plate. Every (both large and small) swarm is closely counted (using magnifying swarm counter if needed). Each swarm represents a “colony-forming unit” (CFU).The variety of microorganisms existing in the particular test sample is established using the formula:CFU/mL= CFU * dilution variable * 1/aliquot

Pouring the molten agar medium

You are watching: Where will the colonies be located in the pour plate

Collect one bottle of sterile molten agar (containing 15 mL the melted Plate counting Agar or any other standard culture media) from the water bathtub (45°C).Hold the party in the appropriate hand; eliminate the cap v the tiny finger the the left hand.Flame the neck the the bottle.Lift the lid that the Petri dish slightly with the left hand and pour the sterile molten agar into the Petri dish and also replace the lid.Flame the neck that the bottle and replace the cap.Gently swirl the key on the benchtop come mix the culture and the tool thoroughly. Ensure the the tool covers the plate evenly and do not slip the agar end the edge of the Petri dish.Allow the agar to fully gel there is no disturbing it, it will take around 10 minutes.Seal and also incubate the plate in an inverted position at 37°C because that 24-48 hours.
Overview of pour plate an approach and spread plate method

See more: What Developer To Use With Loreal Hicolor Hilights Review, Instructions For Loreal Excellence Hicolor


After 24-48 hours, count all the colonies (again: keep in mind that the embedded colonies will be much smaller 보다 those which happen to form on the surface). A magnifying swarm counter can aid in counting tiny embedded colonies.Calculate CFU/mL using the formula: CFU/mL= CFU * dilution element * 1/aliquot(the volume of diluted specimen (aliquot) is one of two people 0.1 or 1.0 mL)

Disadvantages of to water plate method

Preparation for the pour plate method is time-consuming contrasted with the streak plate/and or spread plate technique.Loss the viability the heat-sensitive organisms comes into call with hot agar.Embedded colonies are lot smaller than those which occur to be on the surface. Thus, one have to be careful to counting these so the none space overlooked.Reduced growth rate of obligate aerobes in the depth the the agar.References and also further readingsBasic handy Microbiology A manual by culture for basic Microbiology (SGM)