Some Factors Influencing the Enumeration of Metabolizing Aquatic Bacteria

Effects of incubation time, temperature, and organic substrate on the enumeration of total and metabolizing aquatic bacteria were evaluated with a reduction technique using 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride and formazan. Data indicated that there were no apparent differences in metabolizing bacterial numbers when water samples were incubated for up to 24 h at 4 or 20°C with or without the addition of glucose. However, increasing numbers of detectable metabolizing bacteria were noted when the water samples were incubated at 37°C for 4 h with or without added glucose. Implications of the observations as they relate to point source nutrient discharges on the nearshore-offshore bacterial populations are discussed.