I am studying the expression and toxicity of a GFP construct using pBAD24 on E.coli BW25113. First I used LB as a medium, but due to heterogeneous expression between cells I decided to use M9+tryptone and glycerol as carbon source (with better results).
But I still getting low expression levels, even using 0.2% arabinose and different induction times.
i tried the pET28, but getting very high levels using 1mM IPTG.
It is possible to improve the expression without changing the vector?
You could try increasing the concentration of arabinose to 1%. Also tryptone is a digest of casein indicating that you could have some level of contamination with lactose (this might be a little difficult to test), and lactose can repress expression of arabinose metabolism (see ref below). You might want to switch to complete minimal media instead of tryptone supplemented media.
Article Regulation of metabolism in Escherichia coli during growth o...
Are you using L-arabinose or L/D-arabinose? The ara system is chiral sensitive...
If you think lactose remnants are a problem try vegetable based peptone or tryptone
I am using L-arabinose. I will try different concentration and other supplements.
Thank you for the answers
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