TABLE 1.

Percentages of permeabilized river bacteria and cells remaining on membrane filters after various cell permeabilization treatments for in situ RCA^a

Sample	Treatment				Mean % of cells (SD)b
	Lysozyme	Achromopeptidase	Proteinase K	Heat	Totalc	Permeabilizedd	Remaininge
1	Not treated	Not treated	Not treated	Not treated	100 (2)	2 (0.3)	100 (7)
2	Not treated	Not treated	Not treated	94°C, 10 min	97 (4)	49 (6)	96 (4)
3	0.5 mg/ml, 15 min	Not treated	10 μg/ml, 5 min	Not treated	90 (8)	2 (0.6)	28 (4)
4	0.5 mg/ml, 15 min	Not treated	10 μg/ml, 5 min	94°C, 10 min	78 (7)	39 (12)	32 (10)
5	10 mg/ml, 60 min	Not treated	Not treated	Not treated	102 (10)	5 (2)	98 (7)
6	10 mg/ml, 60 min	Not treated	Not treated	94°C, 10 min	99 (8)	95 (3)	100 (8)
7	10 mg/ml, 60 min	Not treated	10 μg/ml, 45 min	Not treated	102 (10)	4 (0.8)	68 (8)
8	10 mg/ml, 60 min	Not treated	10 μg/ml, 45 min	94°C, 10 min	77 (6)	96 (8)	24 (3)
9	Not treated	65 U/ml, 30 min	Not treated	Not treated	82 (10)	3 (0.7)	19 (3)
10	Not treated	65 U/ml, 30 min	Not treated	94°C, 10 min	47 (5)	3 (1)	10 (1)
11	Not treated	65 U/ml, 30 min	10 μg/ml, 45 min	Not treated	81 (12)	1 (0.3)	11 (1)
12	Not treated	65 U/ml, 30 min	10 μg/ml, 45 min	94°C, 10 min	43 (7)	13 (6)	5 (1)

^aRiver water samples were collected at Juhachijo on the Kanzakigawa river (9 July 2004). All enzymatic reactions were carried out at 37°C.

^bMeans and standard deviations for triplicate determinations.

^cPercentage of total bacteria remaining on membrane filter.

^dPercentage of bacteria stained with Cy3-labeled rabbit phosphorylase used for examination of cell permeability.

^ePercentage of E. coli O157:H7 cells added to the river water remaining on the membrane filter to investigate the possibility of a selective loss of specific bacterial species.