TABLE 2.

Mean retention rates of bacteria on three types of 5-μm-pore filters^a

Strain	LSWP filters		SVLP filters		TMTP filters
	No. of cells filteredb	% Retained (mean ± SD)c	No. of cells filtered	% Retained (mean ± SD)	No. of cells filtered	% Retained (mean ± SD)
Pseudomonas fluorescens PF130A	9.57 × 107	0.03 ± 0.01	9.03 × 107	0.31 ± 0.03	9.65 × 107	<0.001d
Pseudomonas putida MC1-100	1.37 × 108	1.91 ± 0.15	1.33 × 108	1.32 ± 0.24	1.40 × 108	0.004 ± 0.003
Corynebacterium aquaticum MC1-098	1.01 × 108	0.04 ± 0.01	9.50 × 107	2.29 ± 0.13	9.75 × 107	0.004 ± 0.002
Corynebacterium aquaticum MC1-108	8.17 × 107	0.04 ± 0.01	8.03 × 107	0.34 ± 0.03	7.95 × 107	<0.001d
Hafnia alvei MC1-057	6.17 × 107	0.52 ± 0.03	6.60 × 107	0.54 ± 0.00	5.55 × 107	<0.002d

^aThe filters are described in Table 1. Retention rates were determined for bacterial suspensions prefiltered across SVLP filters. 

^bValues represent the mean number of bacteria in three 50-ml aliquots of suspensions passed across each type of filter. Each suspension had been prefiltered across polyvinylidene fluoride filters (5-μm-diameter pores) before the population sizes were determined. 

^cValues represent the mean and standard deviation (SD) of the percentage of bacteria retained on the filters for three independent filtrations. 

^dThe number of bacteria on the filters was below the detection limit (1,000 CFU/filter) for all filters in this test. Hence, the percent retention rate was estimated by using the detection limit.