dilution platingthe number of MICROORGANISMS in a given sample can be determined by plating dilutions of the sample on to a suitable MEDIUM. Measured amounts of each dilution can be plated on AGAR plates. After incubation, the number of colonies growing is counted. It is assumed that each microorganism in the original sample will give rise to a single colony on the plate. Thus by allowing for the dilution factor, the number of colony-forming units per cm3 (cfu.cm-3) in the sample can be obtained. Although this plating technique is not a very exact method for the enumeration of microorganisms, it is generally satisfactory for routine use.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005