Currently, i cultured a recombinant protein in E. coli BL21 with a variation in agitation speed. And in my result it showed that an increase in specific growth rate does not correspond to an increase in protein yield. Is it normal for this to happen?
Dear Labitta Tsuraya Widagdo
which kind of media are you using? Is your expression based on a inducibile or constitutive promoter?
Even if higher oxigenation is generally fauvourable for E.coli growth, viability and therefore may also improve protein productivity, biomass and protein expression are not ever proportional.
In the past i have done some some trials with pet24 GFP in BL21 DE3 using 2 different media;
enpressoB:
see minute 4'40'' of the following video:
https://www.blogger.com/video.g?token=AD6v5dwU8Sl-43BfVTSeIRFBcQiWXAeg80Ud5UCxiXqUj4AFUO7p1BOHHmV4NiV0MY32A41mTgUH2-nyouDVBhcVFOuGc1lJ5_1WgP3RrsvakB6iJHCW_JOnrD8kIeiUSimWYahOs-OP
YGR:
see minute 5' of the following video:
https://www.blogger.com/video.g?token=AD6v5dzLWqhoYwVoIC07Aj1G4RRYNxwM3Ndyk09KE3rmvGIdgfhR6WOBAH6TE0sDThwNquI9hZ9u7vKUDdMsusqQ3IcouXA53Y37DqhPmlYX4e9_Jnz5YS-87K68gQcCTjBMvNE4MlI
good luck
Manuele
Hi, this review may be of interest to you:
Article Beyond de-foaming: The effects of antifoams on bioprocess productivity
If I understand your question correctly, they describe similar combination of effects (like more growth, but similar protein production and vice versa). So yes, it is possible.
Hi Labitta Tsuraya Widagdo
yes, it's possible, and it's pretty easy to understand what happens, if you just remember that you're actually talking about two different, uncorrelated things: growth rate and protein yield.
A higher growth rate means a larger amount of bacteria, which means a fast protein translation rates as well.
However, a fast protein translation rate doesn't necessarily mean a high protein yield, specially if the protein is fragile and/or difficult to fold.
A high protein translation rate can lead to misfolded protein that goes directly to inclusion bodies.
And fragile protein at high concentration may lead to aggregation and precipitation processes, again leading to proteins into inclusion bodies.
Best
Yves
All other people have answered well for your question.
What I want to add is that actually for a lot of protein expression once you start the induction process (usually by adding appropriate amounts of IPTG), you may need to lower both the agitation speed and temperature for better expression of soluble target protein. I usually use 160 -180 rpm with room temperature (20 - 22 C) for overnight induction (18 -24 hours), and can get decent results. Hope this will help.
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