Team:British Columbia/Notebook/Protocols/ElectrocompCells

From 2014.igem.org

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<h1>Electrocompetent Cell Production</h1>
<h1>Electrocompetent Cell Production</h1>
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<h2>Day 1</h2>
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<h3>Day 1</h3>
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<li>Grow plate overnight at 37&deg;C.</li>
<li>Grow plate overnight at 37&deg;C.</li>
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<h2>Day 2</h2>
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<h3>Day 2</h3>
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<h2>Day 3</h2>
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<h3>Day 3</h3>
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<li>Inoculate 1 L of LB media with 10 mL starter culture and grow in a 37&deg;C shaker. Measure the OD<sub>600</sub> every hour, then every 15 - 20 minutes when the OD gets above 0.2.</li>
<li>Inoculate 1 L of LB media with 10 mL starter culture and grow in a 37&deg;C shaker. Measure the OD<sub>600</sub> every hour, then every 15 - 20 minutes when the OD gets above 0.2.</li>
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<br>
<li>When the OD<sub>600</sub> reaches 0.35 - 0.4, immediately put the cells on ice. Chill the culture for 20 - 30 minutes, swirling occasionally to ensure even cooling.  
<li>When the OD<sub>600</sub> reaches 0.35 - 0.4, immediately put the cells on ice. Chill the culture for 20 - 30 minutes, swirling occasionally to ensure even cooling.  
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<br>
<br>
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Place centrifuge bottles on ice at this time:
Place centrifuge bottles on ice at this time:
<ul>
<ul>
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<br>
<li>It is important not to let the OD get any higher than 0.4. It usually takes about 3 hours to reach an OD of 0.35 when using a 10 mL starter culture.</li>
<li>It is important not to let the OD get any higher than 0.4. It usually takes about 3 hours to reach an OD of 0.35 when using a 10 mL starter culture.</li>
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<br>
<li>It is also very important to keep the cells at 4&deg;C for the remainder of the procedure. The cells, and any bottles or solutions that they come into contact with, must be pre-chilled to 4&deg;C.</li>
<li>It is also very important to keep the cells at 4&deg;C for the remainder of the procedure. The cells, and any bottles or solutions that they come into contact with, must be pre-chilled to 4&deg;C.</li>
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<li>(SPIN #1) Split the 1 L culture into four parts by pouring about 250 mL into ice-cold centrifuge bottles. Harvest the cells by centrifugation at 1000<i>g</i> (~2400 rpm in the Beckman JA-10 rotor) for 20 minutes at 4&deg;C.</li>
<li>(SPIN #1) Split the 1 L culture into four parts by pouring about 250 mL into ice-cold centrifuge bottles. Harvest the cells by centrifugation at 1000<i>g</i> (~2400 rpm in the Beckman JA-10 rotor) for 20 minutes at 4&deg;C.</li>
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<br>
<li>Decant the supernatant and resuspend each pellet in 200 mL of ice-cold ddH<sub>2</sub>O.</li>
<li>Decant the supernatant and resuspend each pellet in 200 mL of ice-cold ddH<sub>2</sub>O.</li>
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<br>
<li>(SPIN #2) Harvest the cells by centrifugation at 1000<i>g</i> (~2400 rpm in the Beckman JA-10 rotor) for 20 minutes at 4&deg;C.</li>
<li>(SPIN #2) Harvest the cells by centrifugation at 1000<i>g</i> (~2400 rpm in the Beckman JA-10 rotor) for 20 minutes at 4&deg;C.</li>
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<br>
<li>Decant the supernatant and resuspend each pellet in 100 mL of ice-cold ddH<sub>2</sub>O.</li>
<li>Decant the supernatant and resuspend each pellet in 100 mL of ice-cold ddH<sub>2</sub>O.</li>
 +
<br>
<li>(SPIN #3)Combine resuspensions into 2 centrifuge bottles (so each contains about 200 mL of cell suspension). Harvest the cells by centrifugation at 1000<i>g</i> (~2400 rpm in the Beckman JA-10 rotor) for 20 minutes at 4&deg;C. At this step, rinse two 50 mL conical tubes with ddH<sub>2</sub>O and chill on ice.</li>
<li>(SPIN #3)Combine resuspensions into 2 centrifuge bottles (so each contains about 200 mL of cell suspension). Harvest the cells by centrifugation at 1000<i>g</i> (~2400 rpm in the Beckman JA-10 rotor) for 20 minutes at 4&deg;C. At this step, rinse two 50 mL conical tubes with ddH<sub>2</sub>O and chill on ice.</li>
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<br>
<li>Decant the supernatant and resuspend each pellet in 40 mL of ice-cold 10% glycerol. Transfer each suspension to a 50 mL conical tube.</li>
<li>Decant the supernatant and resuspend each pellet in 40 mL of ice-cold 10% glycerol. Transfer each suspension to a 50 mL conical tube.</li>
 +
<br>
<li>Harvest the cells by centrifugation at 1000<i>g</i> (~2100 rpm in the Beckman GH-3.8 rotor) for 20 minutes at 4&deg;C. Start putting 1.5 mL microfuge tubes on ice if not already chilled.</li>
<li>Harvest the cells by centrifugation at 1000<i>g</i> (~2100 rpm in the Beckman GH-3.8 rotor) for 20 minutes at 4&deg;C. Start putting 1.5 mL microfuge tubes on ice if not already chilled.</li>
 +
<br>
<li>Carefully aspirate the supernatant with a sterile Pasteur pipette (pellets lose adherence in 10% glycerol). Resuspend each pellet in 1 mL of ice-cold 10% glycerol by gently swirling. The final OD<sub>600</sub> of the resuspended cells should be ~ 200 - 250.</li>
<li>Carefully aspirate the supernatant with a sterile Pasteur pipette (pellets lose adherence in 10% glycerol). Resuspend each pellet in 1 mL of ice-cold 10% glycerol by gently swirling. The final OD<sub>600</sub> of the resuspended cells should be ~ 200 - 250.</li>
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<br>
<li>Aliquot into sterile 1.5 mL microfuge tubes and snap freeze with liquid nitrogen. Store frozen cells in the -80&deg;C freezer.</li>
<li>Aliquot into sterile 1.5 mL microfuge tubes and snap freeze with liquid nitrogen. Store frozen cells in the -80&deg;C freezer.</li>
</ol>
</ol>

Latest revision as of 02:41, 18 October 2014

2014 UBC iGEM

Electrocompetent Cell Production

Day 1


  1. Streak out frozen glycerol stock of bacterial cells (Top 10, DH5α, etc.) onto an LB plate without antibiotics.
  2. Grow plate overnight at 37°C.

Day 2


  1. Autoclave:
    1. 2 L of ddH2O
    2. 100 mL of 10% v/v glycerol (molecular biology grade)
    3. 1 L of LB (or preferred media)
    4. 4 centrifuge bottles and caps
    5. few microfuge tubes
  2. Chill overnight at 4°C:
    1. ddH2O
    2. 10% glycerol.
    3. centrifuge rotor.
  3. Prepare starter culture of cells.
    1. Select a single colony of E. coli from fresh LB plate and inoculate a 10 mL starter culture of LB (or preferred media).
    2. Grow culture at 37°C in shaker overnight.
    3. Possible media substitutes include SOB, 2xYT, etc.
    4. All glassware should be detergent-free, as trace detergent residue reduces competency.

Day 3


  1. Inoculate 1 L of LB media with 10 mL starter culture and grow in a 37°C shaker. Measure the OD600 every hour, then every 15 - 20 minutes when the OD gets above 0.2.

  2. When the OD600 reaches 0.35 - 0.4, immediately put the cells on ice. Chill the culture for 20 - 30 minutes, swirling occasionally to ensure even cooling.

    Place centrifuge bottles on ice at this time:

    • It is important not to let the OD get any higher than 0.4. It usually takes about 3 hours to reach an OD of 0.35 when using a 10 mL starter culture.

    • It is also very important to keep the cells at 4°C for the remainder of the procedure. The cells, and any bottles or solutions that they come into contact with, must be pre-chilled to 4°C.

  3. (SPIN #1) Split the 1 L culture into four parts by pouring about 250 mL into ice-cold centrifuge bottles. Harvest the cells by centrifugation at 1000g (~2400 rpm in the Beckman JA-10 rotor) for 20 minutes at 4°C.

  4. Decant the supernatant and resuspend each pellet in 200 mL of ice-cold ddH2O.

  5. (SPIN #2) Harvest the cells by centrifugation at 1000g (~2400 rpm in the Beckman JA-10 rotor) for 20 minutes at 4°C.

  6. Decant the supernatant and resuspend each pellet in 100 mL of ice-cold ddH2O.

  7. (SPIN #3)Combine resuspensions into 2 centrifuge bottles (so each contains about 200 mL of cell suspension). Harvest the cells by centrifugation at 1000g (~2400 rpm in the Beckman JA-10 rotor) for 20 minutes at 4°C. At this step, rinse two 50 mL conical tubes with ddH2O and chill on ice.

  8. Decant the supernatant and resuspend each pellet in 40 mL of ice-cold 10% glycerol. Transfer each suspension to a 50 mL conical tube.

  9. Harvest the cells by centrifugation at 1000g (~2100 rpm in the Beckman GH-3.8 rotor) for 20 minutes at 4°C. Start putting 1.5 mL microfuge tubes on ice if not already chilled.

  10. Carefully aspirate the supernatant with a sterile Pasteur pipette (pellets lose adherence in 10% glycerol). Resuspend each pellet in 1 mL of ice-cold 10% glycerol by gently swirling. The final OD600 of the resuspended cells should be ~ 200 - 250.

  11. Aliquot into sterile 1.5 mL microfuge tubes and snap freeze with liquid nitrogen. Store frozen cells in the -80°C freezer.