Isolate Genomic DNA from E coli

Protocol 1

Centrifuge 3mL of an overnight culture grown in LB to pellet cells.
Resuspend in 0.75mL 1% NaCl. Centrifuge.
Resuspend pellet in 0.75mL TES (10mM Tris-HCl, 10mM EDTA, pH 8.0, 2% SDS)
Incubate at 75oC for 15 minutes. Vortex.
Add 1ml phenol:chloroform (3:1 v/r). Centrifuge.
Pipet off the aqueous layer (top) into a fresh tube.
Add 1mL chloroform. Centrifuge.
Pipet off the aqueous layer (top) into a fresh tube.
Add 100μL 3M NaOAc (pH 5.2) & 1mL isopropanol.
Invert tube & centrifuge.
Add 500μL absolute ethanol & spool out DNA into fresh tube.
Resuspend DNA (spooled) in 150 uL TE (10mM Tris-HCl, 2mM EDTA, pH 8.0) with 1μL 50ug/mL RNase.

Protocol 2

grow culture in your favorite medium
Mix samples directly with ice cold Killing Buffer in ratio 1:1 and put on ice (samples should be processed as fast as possible)
Spin down cells 3 min max. speed at 4°C and discard supernatant
resuspend in 300 μL TE and add 40 μL 10% SDS and 3 μL 0.5 M EDTA
incubate 5 min at 65°C
add 750 μL isopropanol and mix
spin at max. speed for 5 min at room temperature and discard supernatant
resuspend pellet in 500 μL TE and add 2 μL RNase A (25 mg/ml)
incubate for 30 min at 65°C
add 2 μL proteinase K (25 mg/ml) and incubate at 37°C for 15 min
phenol extract (2x phenol & 2x chlorophorm)
precipitate over night with 1 ml ethanol and 40 μL 3M Na-Acetate
spin down DNA at 4°C for 15 min, wash in 70% ethanol and resuspend pellet in 50 μL dH2O