was added to the mixture and centrifuged at 8000×g for 10 min at 25 °C. The aqueous phase was transferred in fresh tube to which 0.6 volumes of ice-cold isopropanol was added for the precipitation of DNA and was stored at −20 °C for 30 min. The precipitated DNA was centrifuged at 8000×g for 10 min at 4 °C. The supernatant was discarded and the pellet was washed with 80% ethanol twice and dried at room temperature for 15 min. The DNA pellet was dissolved 30 µl of TE RNase.