Measurement of Active Cells in Environmental Samples

Several approaches have been considered for assessing microbial viability/activity in environmental samples. Epifluorescence microscopy, in combination with the use of oxido-reduction dyes, is used to determine the percent of active cells in aquatic environments. The most popular oxido-reduction dyes are INT (2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride) and CTC (cyanoditolyl tetrazolium chloride) (Poschet al., 1997; Pyle et al., 1995a). A good correlation was found between