Lysozyme/SDS/proteinase K DNA extraction method
Bacterial cell pellet was resuspended in 200 μl of TE and vortexed. An 8 µl of lysozyme at the
concentration of 50 mg/ml was added and the solution was incubated at 37 °C for 30 min. A volume
of 4 µl of proteinase K at the concentration of 20 mg/ml and 20 µl of 10% SDS were added in the tube,
gently mixed, and incubated at 56 °C for 1 h. A volume of 70 µl of 5 M NaCl and 55 μl of 10% CTAB
(10% CTAB/0.7M NaCl) were added and the mixture was incubated at 56 °C for 10 min. The samples
were cooled down at room temperature. The DNA extraction with phenol/chloroform/isoamyl alcohol
(25:25:1) according to standard procedure was performed twice. The DNA was precipitated by adding
an equal volume of 96% ethanol at room temperature for 10 min followed by centrifugation at 12,000 x g
for 5 min. The supernatant was discarded and the DNA pellet was washed twice with 75% ethanol. The
DNA pellet was dried and dissolved in 100 μl of TE buffer.