A colony-forming unit (CFU, cfu, Cfu) is a unit used in microbiology. It estimates the number of bacteria or fungal cells in a sample which are viable, able to multiply via binary fission under the controlled conditions. Counting with colony-forming units requires culturing the microbes and counts only viable cells, in contrast with microscopic examination which counts all cells, living or dead. The visual appearance of a colony in a cell culture requires significant growth, and when counting colonies it is uncertain if the colony arose from one cell or a group of cells. Expressing results as colony-forming units reflects this uncertainty.
Colony forming unit density
Biological property
Number density