Fig. 2.

Standard curves of C_q values from multiplex qPCR using the six Pseudomonas probes P1–P6 (a–f), correlated with cell counts of artificially spiked raw milk samples. 26 representative target strains (9 strains for P1; 8 for P2; 3 for P3, P4 and P5; 26 for P6) were chosen, and cells were serially diluted in fresh raw milk (1:5²–1:5⁹). Cell counts of diluted samples were determined by cultivation, and in parallel, DNA of the milk samples was isolated and applied as templates in the two triplex qPCR assays. Averaged C_q values from two technical replicates of each strain were plotted against the respective Pseudomonas counts given in log cfu/ml. Regression equation, coefficient of determination (R²), and amplification efficiency (E) are given for each standard curve