Enumeration of active cells in the bacterioplankton of the Rybinsk Reservoir using 5-cyano-2,3-ditolyl tetrazolium chloride: A comparison with other methods

The enumeration of actively respiring bacterial cells in different biotopes of the littoral zone of the Rybinsk Reservoir during the spring period of ice thaw using the fluorescent dye 5-cyano-2,3-ditolyl tetrazolium. chlorid e showed that bacterial communities growing on the bottom surface of the ic e cover and in water overgrown by higher aquatic plants were most active. T he number of active cells among individual bacterial cells averaged 20% and reached about 40% among aggregated and filamentous bacterial cells. The re sults of the count of active bacteria by this method were compared with tho se obtained by other methods.