TABLE 2.
Power analysis predictions for sample size required to detect 2-, 5-, and 10-fold differences in bacterial and Nitrospira 16S rRNA gene copies per litera
| Reactor typeb | Target | No. of ext.c | SD | No. of samples per group required for effect size
|
||
|---|---|---|---|---|---|---|
| 2-Fold | 5-Fold | 10-Fold | ||||
| High biomass | Bacteria | 3 | 0.0707 | 3 | 2 | 2 |
| Bacteria | 1 | 0.0707 | 3 | 2 | 2 | |
| Nitrospira | 3 | 0.1732 | 7 | 3 | 2 | |
| Nitrospira | 1 | 0.1789 | 7 | 3 | 2 | |
| Low biomass | Bacteria | 3 | 0.632 | 3 | 2 | 2 |
| Bacteria | 1 | 0.1342 | 5 | 3 | 2 | |
| Nitrospira | 3 | 0.3479 | 22 | 5 | 4 | |
| Nitrospira | 1 | 0.3478 | 22 | 5 | 4 | |
Copies of each target per liter of mixed liquor measured using real-time PCR assays.
Power analysis predictions were divided into two groups based on biomass (MLVSS) concentration. High- and low-biomass predictions utilize one-way ANOVA comparisons of 10- and 20-day SRT reactor data and 2- and 5-day SRT reactor data, respectively.
Number of DNA extractions used for power analysis. Three extraction-parameters results were obtained from one-way ANOVA for three extractions for three sample dates within each reactor grouping. One extraction-parameter results were obtained from one-way ANOVA of triplicate real time results for the first extraction only for each sample date within each reactor grouping. Power predictions were for the log10-transformed copies of the target per liter of mixed liquor and met the assumptions of homogeneity of variance between groups and within group normality. The significance level was 0.05, and the power was 80%.