Plate Count Agar

Plate Count Agar is a growth medium used in microbiology in order to assess or monitor bacterial growth of samples. It is not a selective medium, but the bacteria can be identified by using a PCA, which serves as a substrate in which bacteria can grow. PCA contains casein, which provides an environment rich in nitrogen, carbon, amino acids, vitamins and minerals where the organism can grow easily. Meanwhile the yeast extract is the source where the vitamins come from. Agar acts as the solidifying agent and glucose fulfills the function of a fermentable carbohydrate. In this method, bacterias are counted as colony forming units per gram. Plate Count Agar is most commonly used by the technique of plate pouring. In this process, the inoculum is added to the agar before pouring the plate, then the agar is cooled to 45°C and poured into a petri dish containing diluted samples, by using a sterile method. Moving forward, the plates are rotated to mix the samples as uniformly as possible with the agar itself. Finally, the plates are incubated for a period of 3 days at 20-30°C. The typical PCA composition is made of enzymatic digest of casein, yeast extract, glucose, and agar.

Plate Count Agar (PCA) is the commonly used medium for plate counts of mesophilic aerobes. Plate Count Agar (PCA) is a culture medium for counting aerobic microorganisms on a plate by the contact method of the plate with the surface to be sampled. It can be used both on surface and in depth. This medium contains glucose and yeast extract, these components are used in food bacteriology to enumerate bacteria in the food industry, pharmaceutical and cosmetic industry as well as in their associated raw materials. This method is also used for the control of psychrotrophic microorganisms.Contact plates are used to monitor the effectiveness of cleaning and disinfection systems on surfaces in factory and laboratory environments.

Plate Count Agar is a medium that is recommended in the enumeration of aerobic bacteria in water, dairy products and foods, cosmetics, and pharmaceuticals. PCA is non-selective and rich in nutrients, trytone, vitamin factor from yeast extract and glucose used as an energy source to promote the growth of bacteria. This medium is also known by the name of Tryptone Glucose Yeast Agar, or Casein-Peptone Dextrose Yeast Agar. It meets the specifications and standards provided by the American Public Health Association and ISO 4833.

Using Plate Count Agar has its benefits for a number of reasons. First, it is easy to perform in microbiology laboratories. Second, it allows for a larger sample volume than other testing methods, and therefore detects lower microbiological concentrations. Third, the agar surface does not need to be pre-dried in order to carry on with the test. Fourth, you can determine the number of microbes per milliliter within a given specimen, and the plates do not need to be pre-prepared. Finally, it is a method that can be used to determine bacterial contamination of foods. PCA is used to obtain isolated colonies. When the plate has been prepared, agar cells will grow into colonies which can be isolated to determine their cell type. The forming unit is a good way to determine the colony’s origin.

TAAG Life Sciences offers a Plate Count Agar that comes with 500g per bottle. The use of this agar is to determine a total bacterial count. It is a non-selective medium for the plate count of microorganisms in water, milk and other dairy products. The principle is that tryptone provides carbon and nitrogen. Meanwhile, yeast extract powder provides B vitamins, glucose provides energy, and agar is the solidifying agent. The instructions of usage are to suspend 23.5g in 1L of distilled water, bringing the boil to dissolve completely, then sterilization by autoclaving at 121°C for 15 minutes. Finally, the agar must be poured into sterile petri plates, and the surface dried of the gel before inoculation. It must be stored by keeping the container closed tightly, in a cool, dry environment, away from bright light, for a period of 3 years. The formulation per liter is 5.0g of tryptone, 2.5g of yeast extract powder, 1.0g glucose, 15.0g agar.