My protein is expressed at 20C for 18h with 0.1mM IPTG
Anyone can suggest optimal OD for induction?
Hi Giggsy,
I'm assuming that you are looking at an incomplete method that you want to follow. Given the other parameters it looks like there's been some optimisation already and that they are probably the best to use.
So what OD? It is probable that an OD600 of 0.6 would be best. It would be easy to run a quick test to check in case a higher OD600 (e.g. 1.0 & 1.6) is better if you want to be certain.
-Richard
Hi there,
There is no golden rule but most of the proteins are actually expressed at higher level during early exponential growth phase.
I tend to agree with Richard. OD 0.4 to 0.6 is optimal prior to commencing induction. I also concur with the second commentator that a higher OD can culminate in higher levels of denatured insoluble protein ( inclusion bodies) as opposed to native soluble protein of utility
The determination of the optimal combination of IPTG concentration and time point of IPTG addition is an often encountered optimization objective. A corresponding method is also known as "induction profiling" and can be efficently done in microbioreactor systems. In case you want to know more, you can check open-access literature: Huber et al. 2009 Microb Cell Fact 8:42, Rohe et al. 2012 Microb Cell Fact 11:144 and Wandrey et al. 2016 Microb Cell Fact 15:63.
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