TABLE 3.

Effects of cell density, CFDA/SE concentration, and incubation procedure on fluorescence intensity of stained Comamonas sp. strain DA001 cells^a

Expt	Mixing conditions	Cell density (cells/ml)	CFDA/SE final concn (μM)	Fluorescence intensity (relative fluorescence units)b
A	Stirred, 42°C	1.0 × 109	100	30.2 ± 0.3
		1.0 × 1010	100	72.7 ± 1.6
A	Shaken, 35–42°C	1.0 × 1010	50	25.6 ± 0.5
			100	38.5 ± 0.4
		2.5 × 1010	50	15.9 ± 0.5
			100	25.2 ± 0.5
B	Stirred, room temp	1.0 × 1010	100	47.4 ± 0.9
	Stirred, 40°C	1.0 × 1010	100	82.7 ± 1.9

^aAll cells were stained in PBS, washed, incubated at 15°C for 48 h, washed, and resuspended in NCAGW to a final optical density at 550 nm of 0.003 for experiment A and in Oyster groundwater to a final optical density at 550 nm of 0.005 for experiment B prior to microplate spectrofluorimetry. Experiment B samples were also adjusted to pH 8.0 (0.01 mM phosphates). 

^bMeasured with the SPECTRAmax GEMINI scanning microplate spectrofluorometer.