Plate count

Definition

Plate count is a method used to estimate the number of viable microorganisms in a sample by counting the number of colonies that grow on an agar plate. It is commonly used to assess microbial load in various substances.

5 Must Know Facts For Your Next Test

1. Plate counts are often expressed as colony-forming units per milliliter (CFU/mL).
2. Serial dilution is typically performed before plating to ensure colony counts fall within a countable range, usually 30-300 colonies per plate.
3. Incubation conditions, such as temperature and time, significantly affect the outcome of a plate count.
4. Selective media can be used in plate counts to isolate specific types of microorganisms.
5. Accuracy in pipetting and proper mixing during serial dilutions are critical for reliable results.

Related terms

Serial Dilution: A stepwise dilution of a substance in solution to reduce its concentration.

Colony-Forming Unit (CFU): A unit used to estimate the number of viable bacteria or fungal cells in a sample.

Selective Media:

A type of agar media designed to support the growth of specific microorganisms while inhibiting others.