The short incubation step at 98
°
C of the dilution protocol
should denature cellular proteins including cytoplasmic
enzymes. PBS, proteinase K, and sterile water aid direct PCR
in different ways: PBS is non-toxic to cells and can maintain
the pH of the PCR; proteinase K aids cell lysis and degrades
nucleases, thereby minimizing DNA degradation; and sterile
water results in cell lysis through osmotic shock. Surpris-
ingly, the highest amplification success rate was found in the
samples that were treated with PBS (95 %); thus it was
chosen for further analysis