Incubate at 35C for 48 hours. ISO method 48322006 enumerates typical coliform colonies on Violet Red Bile Lactose VRBL agar with confirmation of atypical colonies. Pin On Knowledge For accurate counts the optimum count should be within 30-300 coloniesplate. . 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. Being kept in one place the resulting cells have accumulated to form a visible patch. The spread plate can be used for quantitative work colony counts but see Note 1. This plate features a new indicator technology that makes colonies easier to interpret. Add 12-15 ml plate count agar cooled to 45 1C to each plate within 15 min of. Thomas et al 2015. An agar suspension 03 agar containing colony-forming cells is plated over an agar underlay 20 agar. The total number of living ae