at 4 °C. Amplification products were diluted 10 times with deionized H2O, and 5 μL were used for selective amplification in a total volume of 20 μL containing 1X PCR buffer [750 mM TrisHCl (pH 8.8 at 25 °C), 200 mM (NH4)2SO4 0.1% (v/v)], 0.25 μM of each E-specific and M-specific primer extended by each of three selective nucleotides (Table 3), 0.2 mM dNTPs, and 1 U of Taq DNA polymerase. PCR was performed using a touchdown protocol with initial denaturation of a cycle of 30 s at 94 °C, annealing for 30 s at 65 °C for the first cycle, after which the temperature was lowered by 0.7 °C following each cycle until it reached 56 °C, with extension for 1 min at 72 °C, followed by 30 cycles of 30 s at 94 °C, 30 s at 56°C and 1 min at 72 °C.