The range of application of flow cytometry has expanded over the last four decades far beyond the initial successes in blood cell analysis. Flow cytometry is an analytical method for measuring rapidly multiple properties of biological particles primarily by quantifying fluorescence emissions from dyes bound to specific constituents of the particles as they pass through a focused laser beam. Using techniques developed to improve the instrumental sensitivit, it is possible to measure the size of individual DNA fragments. After staining, the fragments are passed individually through a focused laser beam that excites the bound dye molecules. The number of photons detected as the fragment traverses the laser beam is proportional the fragment length.
Conventional analyses require micrograms of DNA and tens of hours to derive the same information.
Details of DNA fragment size analysis and its application to bacterial discrimination will be discussed.