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From 2012.igem.org

Procedure

1. Prepare a Erlenmeyer flask with 50mL of LB-medium and keep it at 37°C
2. Pick E.coli BL21 from a plate and grow them over night in a 10 mL LB culture containing 50mg/L Kanamycin at 37°C
3. Inoculate the large flask with 1 mL of the overnight culture and grow at 37°C for 2.5h until the OD600 reaches approx. 0.6
4. Induce with 1.25 mM IPTG (0.25 mL of a 250 mM stock)
5. Incubate at 37°C for 4 h
6. Centrifuge the cells in 50ml greiner tubes at 4700 rpm for 18 minutes
7. Decant the supernatant and resuspend the pellets in ± 10 mL washing buffer each
8. Centrifuge again at 4700 rpm for 18 minutes
9. Decant the supernatant and centrifuge for another minute
10. Pipette any liquid to clear the tube of supernatant
11. (possible to freeze the cells to -20°C at this point)