Table 2.

Effects of PCR amplification conditions on formation of PCR artifacts

TreatmentNo. of clones examinedMean % chimeras ± SDMean error ratea ± SD (%)Mean % heteroduplexes ± SDMean % total PCR artifacts ± SD
DNA polymerase
 Z-Taq1628.7 ± 2.29.3 ± 0.0d 3.7 ± 1.120.4 ± 0.0d
 LA-Taq1626.2 ± 2.26.8 ± 0.61.2 ± 1.214.8 ± 3.2
 AmpliTaq1622.5 ± 1.23.7 ± 1.1d 1.2 ± 0.67.4 ± 1.1d
Elongation time
 20 s16210.3 ± 1.5d 12.8 ± 2.11.8 ± 1.025.5 ± 3.9
 2 min1688.5 ± 2.610.6 ± 2.33.0 ± 1.622.1 ± 1.1
 4 min1653.7 ± 1.1d 9.6 ± 2.13.0 ± 1.016.1 ± 3.2
Template concn (ng/ml)b
 0.11626.8 ± 2.22.5 ± 1.2d 1.3 ± 0.610.5 ± 2.2
 1.01628.6 ± 1.26.2 ± 1.61.2 ± 1.216.1 ± 2.7
 101626.2 ± 0.68.0 ± 0.6d 3.1 ± 1.617.3 ± 1.2
PCR cycle no.
 221622.5 ± 0.6d 8.0 ± 1.62.5 ± 0.613.0 ± 1.9
 251624.3 ± 0.68.7 ± 1.63.1 ± 1.616.0 ± 1.2
 281558.2 ± 2.0d 9.9 ± 3.32.7 ± 0.820.8 ± 3.0
PCR cycle no.c
 15162NDd, f 2.5 ± 1.60.6 ± 0.63.1 ± 1.6
 201620.6 ± 0.6a 1.9 ± 1.10.6 ± 0.63.1 ± 1.6
 251623.7 ± 1.91.9 ± 1.12.5 ± 2.56.2 ± 3.3
 301624.3 ± 0.6d, e 3.7 ± 1.11.9 ± 1.19.9 ± 1.6
  • a Error rate is the percentage of total clones examined that had artificial RFLP patterns caused by the misincorporated base at the HhaI site.

  • b Template concentration of each strain was equivalent to 30 ng of genomic DNA per ml.

  • c Amplification was carried out with AmpliTaq.

  • d Student t test shows significant difference at the 0.05 level.

  • e Student t test shows significant difference at the 0.05 level.

  • f ND, not detected.