Protocol Online logo
Top : Forum Archives: : General Lab Techniques

IPTG induction - (Oct/10/2006 )

hi everybody
i know that doubling time for E.coli is 20 minutes and i know the method of bacterial large scale purification but just one question suppose i started my induction of IPTG when the OD was 0.6-0.7 then left it for 2 hours , what is the expected OD then?
according to the doubling time it will be around 2.4 but i know that after induction bacteria convert most of its function to produce my protein rather than its own growth so is this right? and is it ok to find the OD after 2 hours from induction 1 or 1.2 ?


I have to admit I never check OD after induction, but theoritically you're right, the bacteria decrease the growth and concentrate on protein synthesis.
sometime the protein synthetised is toxic for the bacteria, and you see a decrease of the OD.
(that's why you should do a cinetic if your production is not good.)


I believe that is okay. As long as the OD doesn't start decreasing. I check the OD every hour.