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Learn how to prepare an overnight culture of E. coli and avoid issues like mixed cell growth and decreased mFP production. Follow this procedure for successful bacterial growth and protein expression in your lab experiments.
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Possible Problems • When there is a mixed culture of red and white (nonexpressing) cells, the white cells will grow faster than those that are using their resources producing red fluorescent protein (mFP) = less mFP produced for purification. • Some transformed cells stop expressing rpf fairly early.
Materials • Sterile 125 mL flasks of LB/amp broth. • Vented cap to ensure adequate aeration during overnight shaking • Mini shaker table • Frozen cells transformed with pARA-R • Tube of sterile arabinose (500mg/mL)
Procedure Morning, Day before Lab 6 • Aseptically, add 500 uL of transformed cells into each flask of LB/amp broth • Secure vented cap (do not wet the membrane) • Shake and incubate (35o C) for 2–3 hours • Following the 2–3 hours, add the appropriate volume of arabinose to each flask so the final concentration of arabinose is 5mg/100mL • Continue to shake overnight