Plate Count Agar

Description

Product Description

STANDARD METHODS AGAR (P.C.A.) (PLATE COUNT AGAR) is recommended by APHA when enumerating bacteria of sanitary interest, which are indicators of contamination or microbial load in foods. Enzymatic Digest of Casein provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is source of vitamins, particularly the B-group. Dextrose is the fermentable carbohydrate providing carbon and energy. Bacteriological agar is the solidifying agent. In general, 1 ml of the appropriate test dilution is added to the sterile medium at a temperature of 44 – 45°C, mixed gently and poured into sterile Petri dishes. Alternatively, dispense a portion of each test dilution (e.g., 0.1, 0.01 ml) into separate sterile Petri dishes. Add 10 – 12 ml of tempered (45°C) Standard Methods Agar to Petri dishes containing test dilutions. Swirl the dishes to thoroughly mix the medium and test dilution. Allow plates to cool and solidify. Incubate the Petri dishes at 32 ± 2°C for 18 – 48 hours and count the developed colonies. Consult the specifi c texts of APHA for the particular sample applications.

This medium is recommended by the ISO normative 4833 for the colony count technique of microorganisms at 30ºC. Inoculate 1ml of the sample, (if necessary 2 continuous decimal dilutions to be able to count between 15 – 300 colonies per plate), put 12 – 15 ml per plate of agar cooled to 44 – 47ºC in each Petri dish. The time of preparation should not exceed 45 minutes. Invert the plates and incubate at 30 ± 1ºC for 72 ± 3 hours. Post incubation count the colonies.

MICROBIOLOGICAL TEST
The following results were obtained in the performance of the medium from type cultures after incubation at a temperature of 32 ± 2ºC and observed after 18 – 48 hours.

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