FIG. 1.
(A) 5′-Nuclease PCR analysis of serial 10-fold dilutions of L. monocytogenes DNA. CT values are plotted against the calculated CFU (i.e., 10-fold dilutions of the bacterial DNA from 3.125 × 106 CFU/μl). The straight line, which is calculated by linear regression (y = −3.56x [CFU] + 40.7) shows a square regression coefficient of R2 = 0.993. The standard deviations based on three PCR reactions are indicated. (B) 5′-Nuclease PCR analysis of serial 10-fold dilutions of L. monocytogenes cells. CT values plotted against the number of CFU of L. monocytogenes. Template DNA was extracted from samples of cells containing serial 10-fold dilutions of approximately (5.0 ± 0.3) × 107 CFU of L. monocytogenes. The straight line, which is calculated by linear regression (y = −4.12x [CFU] + 45.5) shows a square regression coefficient of R2 = 0.995. The standard deviations based on three PCR reactions are indicated.