Figure 5.

Effect of the amplicon length on the suppression of false positive signals by v-dPCR. Apple branch macerates prepared in AMB were inoculated with E. amylovora live (10⁶ CFU mL⁻¹), dead (10⁶ dead cells mL⁻¹) or a defined ratio of live (10³ CFU mL⁻¹) and dead cells (10⁶ dead cell mL⁻¹). Samples were sub-aliquoted for total (purple) and live (green) cell quantification by dPCR and v-dPCR, respectively, using primer combinations targeting a 74, 325, 627 and 966 bp DNA sequence. Data are mean values of three biological repeats of the same experiment. Error bars show the SD. Different letters denote statistically significant differences between live cell counts of samples treated with PMA. Non-statistically significant (ns) differences were detected between dPCR total cell counts regardless of the amplicon length.