Lactobacillus transformation (Speer 2012)

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Overview

This is basically a modified version of the Mason (2005 protocol) for use with Lactobacillus plantarum and an Eppendorf 2510 electroporator.

Materials

• MRS media
• Glycine
• Milipore water
• 50mM EDTA solution
• 0.5M Sucrose, 10% glycerol solution

Procedure

1. Grow L. plantarum
   1. Inoculate 5ml MRS medium with L. plantarum freezer stock.
   2. Grow overnight at 30°C without shaking.
2. Make 100ml 2% glycine:
   1. Add 1g glycine to two flasks of 50ml MRS medium.
   2. Shake to dissolve.
3. Grow cells:
   1. Add 1ml overnight culture to each flask (1:50 dlution).
   2. Culture for ~3 hours at 37°C with shaking.
4. Wash 2x with ice-cold DI water:
   1. Centrifuge culture for 5min at 4000g
   2. Resuspend in 25ml ice-cold DI water.
   3. Repeat.
5. Treat with ice-cold EDTA:
   1. Centrifuge for 5min at 4000g
   2. Resuspend in 10ml 50mM EDTA.
   3. Incubate on ice for 5 minutes
6. Wash with ice-cold DI water:
   1. Centrifuge culture for 5min at 4000g
   2. Resuspend in 25ml ice-cold DI water.
7. Wash 2x with Electroporation Buffer:
   1. Centrifuge culture for 5min at 4000g
   2. Resuspend in 25ml ice-cold 0.5M Sucrose, 10% glycerol.
   3. Repeat.
8. Concentrate cells:
   1. Centrifuge culture for 5min at 4000g
   2. Resuspend in 0.8ml ice-cold 0.5M Sucrose, 10% glycerol.
9. Divide cells:
   1. Aliquot 90μL of cell concentrate into ~20 microcentrifuge tubes.
   2. Keep on ice until use (within the next two hours).
10. Add DNA:
    1. Add 10μL of plasmid DNA to the 90μL of cell concentrate.
    2. Keep on ice for 5 minutes.
    3. Put 1mm cuvettes on ice too.
11. Electroporate:
    1. Pipette the cell/DNA mixture into the cuvette
    2. Electrporate at 1200 volts
    3. Time constant should be ~5.0
12. Recovery:
    1. Immediately transfer the electroporated cells to 900μL of MRS medium.
    2. Incubate at 30°C for 2-3 hours.
13. Select:
    1. Plate on medium with the appropriate antibiotic
    2. Incubate at 30°C for two days.
    3. Pick colony

Notes

All questions, input and feedback are welcome!

References

There will be one here soon.

Contact

• mas853@psu.edu

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