Team:ZJU-China/Protocol
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- | + | <h3>1. Preparation of heat shock competent cells.</h3> | |
+ | <p>*The most important thing to remember is to keep the cell as cold as possible at all the time.</p> | ||
+ | <h4>Preparation:</h4> | ||
+ | <strong>Autoclave sterilization:</strong>Erlenmeyer flask;1L reagent bottles (for TFB);100ml centrifuge bottles (bottles and caps need to be sterilized separately);vacuum filter flask; 0.22nm filter membrane;80%glycerol; LB broth. | ||
+ | <h4>Procedure:</h4> | ||
+ | <ol> | ||
+ | <li> 1. Streak out E. coli (DH5α, DH10β, BL21, BW25113 and so on) onto LB plate. Cultivate it inversely.</li> | ||
+ | <li> 2. Growing overnight @37℃</li> | ||
+ | <li>3. Pick a single colony and inoculate overnight using 5mL LB Broth, shake it @37℃, 200r/min.</li> | ||
+ | <li>4. Inoculate 2ml overnight culture to 100ml LB broth, shake it @37℃, 200r/min until OD600=0.4 or so. (About 3.5 hours) | ||
+ | <p>* Remember to open spectrophotometer in advance and use LB as blank.</p></li> | ||
+ | <li>5. Chill the cell on ice for 15min.</li> | ||
+ | <li>6. Centrifuge the cells at 5000rpm for 10min @4℃. | ||
+ | <p>*Remember to balance the centrifuge bottles/tubes before centrifugation.</p></li> | ||
+ | <li>7. Discard the supernatant.</li> | ||
+ | <li>8. Resuspend the cells with 2ml TFB. Then fill it with TFB.</li> | ||
+ | <li>9. Centrifuge at 5000rpm for 10min @4℃.</li> | ||
+ | <li>10. Add some TFB buffer to resuspend the cell, and then fill the tube with TFB buffer.</li> | ||
+ | <li>11. Centrifuge at 5000rpm for 10min @4℃.</li> | ||
+ | <li>12. Discard the supernatant.</li> | ||
+ | <li>13. Resuspend the cell with 3ml TFB buffer, then add 700ul 80%glycerol to 15% of final concentration of glycerol.</li> | ||
+ | <li>14. Fill the 1.5ml EP tube with 50ul liquid. Quick-freeze in liquid nitrogen. Stock in -80℃.</li> | ||
+ | </ol> | ||
+ | Preparation of TFB: | ||
+ | Mother solution: CaCl2: 0.5M, MgCl2: 1M. | ||
+ | Final concentration 500ml | ||
+ | CaCl2 100mM 100ml | ||
+ | MgCl2 70mM 35ml | ||
+ | NaAc(add powder) 40mM 1.64g | ||
+ | Using acetic acid to adjust pH to 5.5, Filtrated, Stock @4℃ | ||
+ | |||
+ | 2. Heat shock transformation. | ||
+ | Preparation: | ||
+ | water bath 42℃, rotary shaker @37℃, 150rpm, ice, E. coli @-80℃. | ||
+ | Procedure: | ||
+ | 1. Thaw the competent cells or super competent cells on ice. About 10 minutes | ||
+ | 2. Add 1ul of plasmids (about 30ng) to cells and swirl it gently. | ||
+ | 5. Incubate the cells on ice for 30 minutes. | ||
+ | 6. Heat pulse the tube in a 42℃ water bath for 80~90 sec. | ||
+ | *The length of time of the heat pulse is critical for obtaining the highest efficiencies. | ||
+ | 7. Incubate the cells on ice for 2min. | ||
+ | 8. Add 1ml of LB medium to the tube. Then shake it @37℃ 150rpm for about 1h. | ||
+ | 9. Centrifuge the tube at <5000rpm for 2min, then discard the supernatant making the residue less than 50ul. | ||
+ | 11. Coat the plates containing specific antibiotics with the culture. | ||
+ | 12. Cultivate the plate inversely @37℃ for about 12h (12h~14h). | ||
+ | |||
</div> | </div> |
Revision as of 09:08, 17 October 2014
1. Preparation of heat shock competent cells.
*The most important thing to remember is to keep the cell as cold as possible at all the time.
Preparation:
Autoclave sterilization:Erlenmeyer flask;1L reagent bottles (for TFB);100ml centrifuge bottles (bottles and caps need to be sterilized separately);vacuum filter flask; 0.22nm filter membrane;80%glycerol; LB broth.Procedure:
- 1. Streak out E. coli (DH5α, DH10β, BL21, BW25113 and so on) onto LB plate. Cultivate it inversely.
- 2. Growing overnight @37℃
- 3. Pick a single colony and inoculate overnight using 5mL LB Broth, shake it @37℃, 200r/min.
- 4. Inoculate 2ml overnight culture to 100ml LB broth, shake it @37℃, 200r/min until OD600=0.4 or so. (About 3.5 hours)
* Remember to open spectrophotometer in advance and use LB as blank.
- 5. Chill the cell on ice for 15min.
- 6. Centrifuge the cells at 5000rpm for 10min @4℃.
*Remember to balance the centrifuge bottles/tubes before centrifugation.
- 7. Discard the supernatant.
- 8. Resuspend the cells with 2ml TFB. Then fill it with TFB.
- 9. Centrifuge at 5000rpm for 10min @4℃.
- 10. Add some TFB buffer to resuspend the cell, and then fill the tube with TFB buffer.
- 11. Centrifuge at 5000rpm for 10min @4℃.
- 12. Discard the supernatant.
- 13. Resuspend the cell with 3ml TFB buffer, then add 700ul 80%glycerol to 15% of final concentration of glycerol.
- 14. Fill the 1.5ml EP tube with 50ul liquid. Quick-freeze in liquid nitrogen. Stock in -80℃.