TABLE 2.

Determination of the detection and quantification limits of the Q-PCR assay with genomic DNA from C. tyrobutyricum strain CECT 4011^a

Approx no. of genome equivalents/reaction	Confidence interval limitb		Signal ratioc	CTd
	Lower	Upper
fla
1 × 105	99,643	100,358	9/9	21.98 ± 0.05
1 × 104	9,887	10,113	9/9	25.18 ± 0.09
1 × 103	964	1,036	9/9	28.93 ± 0.08
1 × 102	89	111	9/9	32.32 ± 0.11
1 × 101	7	14	30/30	35.63 ± 0.19
2	0	4	24/30	37.84 ± 0.06
1	0	2	12/30	38.52 ± 0.25
fla-IAC
1 × 105	99,643	100,358	9/9	21.99 ± 0.02
1 × 104	9,887	10,113	9/9	25.35 ± 0.04
1 × 103	964	1,036	9/9	28.85 ± 0.06
1 × 102	89	111	9/9	32.44 ± 0.06
1 × 101	7	14	30/30	35.74 ± 0.15
2	0	4	21/30	37.75 ± 0.16
1	0	2	11/30	39.95 ± 0.56

^aNontemplate controls for both Q-PCR systems were negative (C_T values of 50 in all replicates). The overall slopes of the regression curve were −3.4436 and −3.4595 for the fla and fla-IAC Q-PCR systems, respectively, indicating PCR E of 0.952 and 0.946, respectively; the R² were 0.9995 and 0.9998, respectively.

^bCalculated for the expected number of template molecules at each dilution at the 95% confidence level.

^cNumber of positive results out of 9 reactions (30 reactions for those containing 10, 2, and 1 genome equivalent per reaction).

^dCycle number at which fluorescence intensity equals a fixed threshold. Mean values ± standard errors of the mean are shown. The experimental results were statistically significant (P < 0.05), taking into account the unavoidable error associated with serial dilutions.