A Simple, Rapid Method for Enumerating Total Viable and Metabolically Active Bacteria in Groundwater

Abstract
We report here a new staining procedure which uses both the enzymatic dehydrogenation of 2-( p -iodophenyl)-3- p -(nitrophenyl)-5 phenyltetrazolium chloride to a pink intracellular formazan and the DNA-specific fluorochrome 4′,6′-diamidino-2-phenylindole. Application of this staining procedure to cells concentrated on filters and then transferred to microscope slides by the filter-transfer-freeze technique has proven valuable for statistically accurate enumeration of the total viable and metabolically active cells in groundwaters.