1. Centrifuge 1.5 ml culture (13000 rpm x 1 min.).
2. Decant supernatant, leaving 50-100 μl together with the bacterial pellet.
3. Vortex to resuspend cells completely.
4. Add 300 μl of TENS. Make sure it goes straight into the tube and mix thoroughly with the bacteria. Vortex if needed.
5. Add 150 μl of 3M NaOAc pH 5.2 and mix by inversion ~6 times.
6. Centrifuge 13000 rpm x 3 min.7. Pour supernatant into a new tube. Add 1 ml of EtOH at -20ºC. Mix by inversion.
8. Centrifuge 13000 rpm x 3 min. Discard supernatant.
9. Rinse pellet with 70% EtOH. Centrifuge 13000 rpm x 1 min. Discard supernatant.
10. Centrifuge 13000 rpm x 10 seconds. Remove as much as you can using a pipette.
11. Leave tubes opened in a 37ºC chamber for 2-3 min.
12. Resusped in 20 μl of TE + RNaseA (10μg/ml working concentration).
13. Incubate 15-20 min. at 37ºC and store at -20ºC.
• TENS solution: 10 mM Tris-HCl pH 8, 1 mM EDTA, 0.1 M NaOH, 0.5% SDS.