What unit of measurement is used for bacterial colonies?

Answer 1

Many aspects of bacterial colonies may be measured for example colony size or appearance can be useful. The measurement which is perhaps the most useful however, is the colony forming units per ml (or cfu) which indicates how many bacterial cells are present to form colonies on the medium. This is a relatively simple calculation which is done by initially counting the number of colonies present on the medium. this number is then multiplied by the inverse of the dilution used. For example, if the dilution of the bacterial broth was 10-2 and the number of colonies on the medium was 60, then the calculation would be 60 x 102. This result is then divided by the volume of sample used in ml and will give you the number of colony forming units per ml present on the medium.

Ben McD