Revision as of 23:41, 13 July 2012 by Gutiloluis (Talk | contribs)



Bacterial DNA extraction protocol

  1. Shaking culture overnight.
  2. Centrifuge twice at 10,700 rpm in 1.5 mL tube 2 or 3 minutes. On the same tube centrifuge all the cultures and remove the supernatant.
  3. Wash the pellet twice with 1 mL NaCl 1 M and Resuspend.
  4. Centrifuge 2 minutes at 10,700 rpm and remove the supernatant.
  5. Resuspend the pellet on 567 μL TE (10 mM Tris-HCl pH 8; 1 mM EDTA pH 8).
  6. Add 3 μL proteinase K (20 mg/mL) and 30 μL SDS (10%). Resuspend gently.
  7. Incubate 2 hours 30 minutes at 37°C.
  8. Add 100 μL NaCl 5 M and 80 μL of the mix NaCl-CTAB (NaCl 0.7 M and CTAB 10%). Preheat the mix to solve it.
  9. Incubate 10 minutes at 65°C.
  10. Add 600 μL phenol.
  11. Gently shake manually for 10 minutes.
  12. Centrifuge 10 minutes at 10,700 rpm.
  13. Transfer the upper aqueous phase to a new tube and add an equal volume of chloroform-alcohol isoamyl (24:1).Gently mix by vortex.
  14. Centrifuge 5 minutes at 10,700 rpm.
  15. Transfer the upper aqueous phase to a new tube.
  16. Add 0.6 V of isopropyl alcohol and incubate at least 15 minutes at -80°C or overnight at -20°C.
  17. Centrifuge 20 minutes at 10,700 rpm. Remove supernatant.
  18. Wash the pellet with 1 mL ethanol 70% (2 or 3 times).
  19. Centrifuge 15 minutes at 10,700 rpm. Remove supernatant with pipette.
  20. Dry the pellet under vacuum for 20 minutes.
  21. Resuspend the pellet on 30 μL TE or H2O.
  22. Add 2 μL RNAse and incubate 2 hours 30 minutes at 37°C.
  23. Store the tubes at -20°C.



Electro-competent cells of E. coli DH5α are electroporated at 1.25 mV, immediately we add SOC medium to the bacteria and we incubated on a shaker at 37°C for one hour, then, we culture cells in a solid medium containing the antibiotic of selection.

Primer Design

PCR - Pfu DNA polimerase

One reaction.

Reactives Volume(μL)
H2O 17.95
Buffer 2
MgSO4 1.6
dNTP's 0.4
Primer Fw 0.4
Primer Rv 0.4
Taq 0.06
Pfu 0.19
Total 25

PCR - Taq DNA polimerase

One reaction.

Reactives Volume(μL)
H2O 6.15
Buffer 1
MgCl2 0.5
dNTP's 0.25
Primer Fw 0.5
Primer Rv 0.5
Taq 0.1
Total 10

If needed add 1 μL of DMSO per reaction, and adjust the amount of H2O to a final volume of 10 μL.

PCR - Colony

Based on the protocol used with Taq polimerase, add 1 μL more of H2O and take a few cells from the strain pricking it with a toothpick and mixing them with the other PCR reactives instead of using purified DNA.

PCR - Boiling

We make a lysate of the cells and add 1 μL of that lysate instead of purified DNA using the Taq polimerase protocol. To obtain the lysate, scrape the strain and resuspend the cells taken on 50 μL of H2O, then, put at 95°C for 10 minutes.