Qualitative PCR analysis. For the species-specific qualitative PCR, DNA was
isolated as described previously (16) earlier. PCRs were carried out as described
previously (37, 40, 41) by using a PTC-200 Peltier Thermal Cycler (Biozym,
Landgraaf, The Netherlands). Amplification products were checked by agarose
gel electrophoresis and ethidium bromide staining.