TABLE 3.

Nitrospira 16S rRNA genes per liter in a DNA sample spiked with a plasmid containing a Nitrospira 16S rRNA gene

Assayb	Nitrospira 16S rRNA genes per litera
	1 × Sample	2 × Sample	5 × Sample	10 × Sample
1	5.2 × 109 (± 0.90 × 109)	3.7 × 1010 (± 0.33 × 1010)	9.2 × 1010 (± 1.0 × 1010)	1.2 × 1011 (± 0.28 × 1011)
2	3.1 × 1010 (± 0.72 × 1010)	3.5 × 1010 (± 0.41 × 1010)	9.2 × 1010 (± 1.5 × 1010)	1.6 × 1011 (± 0.18 × 1011)
3	2.2 × 1010 (± 0.54 × 1010)	7.5 × 1010 (± 0.89 × 1010)	1.6 × 1011 (± 0.45 × 1011)	3.0 × 1011 (± 0.47 × 1011)
4	4.5 × 1010 (± 0.94 × 1010)	3.9 × 1010 (± 1.0 × 1010)	1.6 × 1011 (± 0.12 × 1011)	2.9 × 1011 (± 0.11 × 1011)
5	4.1 (± 0.90 × 1010)	3.1 × 1010 (± 0.53 × 1010)	1.3 × 1011 (± 0.09 × 1011)	1.7 × 1011 (± 0.94 × 1011)
Meanc	3.6 × 1010 (± 0.38 × 1010)	4.5 × 1011 (± 2.9 × 1011)	1.4 × 1010 (± 0.46 × 1010)	2.3 × 1011 (± 0.99 × 1011)

^aNitrospira 16S rRNA genes per liter; mean of three PCR values (± SD).

^bNitrospira 16S rRNA gene assay calculated as copies/liter of MLSS.

^cMean of Nitrospira 16S rRNA genes per liter of MLSS for five assays.