Sodium dodecyl sulfate and proteinase K were added to a final concentration of 0.5% and 100 g ml-1, respectively. The mixture was incubated for 1 h at 37°C. Precipitation was then performed by adding 0.8 M NaCl and 0.5% hexadecyltrimethyl ammonium bromide solution and incubating for 20 min at 65°C. The solution was extracted with an equal volume of Roti® phenol-CHCl3 mixture. DNA was precipitated with 0.6 volume of isopropanol. The resulting DNA pellet was washed with 70% ethanol, centrifuged at 8,000 rpm for 30 min at 4°C and air dried. DNA pellet was then dissolved in TE buffer