Plate count agar (PCA), also called standard methods agar (SMA), is a microbiological growth medium commonly used to assess or to monitor "total" or viable bacterial growth of a sample.
The medium contains casein which provides nitrogen, carbon, amino acids, vitamins and minerals to aid in the growth of the organism.
The molten agar is cooled to about 45 degrees Celsius and is poured using a sterile method into a petri dish containing a specific diluted sample.
From here, the plates are rotated to ensure the samples are uniformly mixing with the agar.
Incubation of the plates is the next step and is carried out for about 3 days at 20 to 30 degrees Celsius.
"Streak Plate Method- Principle, Methods, Significance, Limitations".