CFU

Colony-forming unit: a viable cell, or a cluster of cells, that grows into one visible colony on solid medium. Because clumps of cells can form a single colony, a CFU count estimates viable organisms rather than counting individual cells. Results are expressed per volume or area sampled, such as CFU/mL for water, CFU/m³ for air or CFU/plate for surfaces. Countable ranges, such as 25–250 colonies for TAMC plates, keep counts reliable.