TABLE 1.

Effects of 1 ppm of ClOH on the hybridization efficiency of Universal 342 probe to 16S rRNA in planktonic bacteria^a

Time (min)	% of cells positive after hybridizationc
	E. coli control	E. coli, 1 ppm of ClOH	TWb control	TW, 1 ppm of ClOH
0	108.5 ± 2.12	104.5 ± 2.12	20.7 ± 15.3	31.7 ± 7.14
10	103.5 ± 0.707	0.63 ± 0.891	25.8 ± 11.5	4.25 ± 4.60
30	98.2 ± 0.848	1.69 ± 2.39	39.9 ± 22.3	4.32 ± 2.66

^aThe E. coli isolate, obtained from Thames Water Utilities, was grown to log phase in BHI broth and washed twice prior to treatment. The distribution system bacteria were treated and analyzed directly after they were sampled.

^bTW, bacteria present in tap water filter concentrates.

^cTwo experiments were averaged, and the mean ± standard deviation is shown.