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Latest revision as of 06:58, 19 October 2016
Rubidium Chloride Competent Cells
Introduction
Making competence cells with RbCl. Reference: http://openwetware.org/wiki/RbCl_competent_cell#RF1
Materials
- sterilized 250 mL centrifuge bottles
- sterilized 1.5 mL microfuge tubes (at least 50)
- sterilized 100 mL LB in 250 mL flask
- filter sterilized 50 mL chilled RF1 (33 mL would be used)
- 0.605 g Rubidium Chloride (100 mM RbCl)
- 0.495 g Manganese(II) chloride tetrahydrate (50 mM)
- 0.147 g Potassium acetate (30 mM)
- 0.074 g Calcium chloride dihydrate (10 mM)
- 7.5 g or 6 mL Glycerol (15% m/v)
- filter sterilized 50 mL chilled RF2 (4 mL would be used)
- 0.105 g MOPS (10 mM)
- 0.06 g Rubidium Chloride (10 mM)
- 0.55 g Calcium chloride dihydrate (75 mM)
- 7.5 g or 6 mL Glycerol (15% m/v)
Procedure
- Making RF1 Solution
- RF1 Solution (50 ml)
- 0.605 g Rubidium Chloride (100 mM RbCl)
- 0.495 g Manganese(II) chloride tetrahydrate (50 mM)
- 0.147 g Potassium acetate (30 mM)
- 0.074 g Calcium chloride dihydrate (10 mM)
- 7.5 g or 6 mL Glycerol (15% m/v)
- Adjust final pH to 5.8 using 0.2 M acetic acid (maybe 400 μL for 33 mL). Filter-sterilize.
- Glacial acetic acid: 1.049 g·cm-3 / 60.05 g·mol-1 = 17.47 M
- Making RF2 Solution
- RF2 Solution (50 ml)
- 0.105 g MOPS (10 mM)
- 0.06 g Rubidium Chloride (10 mM)
- 0.55 g Calcium chloride dihydrate (75 mM)
- 7.5 g or 6 mL Glycerol (15% m/v)
- Adjust final pH to 6.8 using 1 M NaOH (maybe 200 μL for 30 mL). Filter-sterilize.
- Day 1
- Streak DH5α from frozen glycerol stock on the LB plate.
- Incubate at 37 °C, over night.
- Prepare sterilized LB.
- Day 2
- Pick up a single colony from the LB plate.
- Inoculate to 3 mL sterilized LB.
- Incubate at 37 °C, over night.
- Put RF1, RF2, centrifuge tube and eppendorf tubes into the 4 °C refrigerator.
- Day 3
- Put RF1, RF2, centrifuge tube and eppendorf tubes on ice.
- Inoculate 1ml of over night culture to 100 mL of LB in flask.
- Monitor OD600 from initial until 0.2 to 0.6. [0.4 - 0.55 optimum]
- Transfer culture to centrifuge bottle and chill on ice 10 -15 min.
- Pellet cells by centrifugation at 2700 g (4200 rpm in an F14 6x250y rotor) for 10 min at 4 °C.
- Decant liquid and stand the bottle in an inverted position for < 1 min.
- resuspend in 1/3 original volume (33 mL) chilled RF1 buffer gently (NO VORTEX).
- Optimally, resuspend using a 25 mL disposable pipet (RbCl will permanently stain glass pipets).
- Continue mixing until cells are evenly resuspended and no clumps are visible.
- Incubate cells/RF1 on ice for 15 min.
- Pellet cells by centrifugation at 580 g (1950 rpm in an F14 6x250y rotor) for 15 min at 4 °C.
- Decant liquid and gently resuspend in 1/25 original volume (4 mL) chilled RF2 buffer.
- Incubate cells/RF2 on ice for 15 min.
- Get eppendor tubes and box ready.
- Aliquot 100 ul each into chilled 1.5 mL eppendorf tubes and freeze on dry ice (or ice).
- Store at -80 °C.
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