No expression in liquid media?!

Walfrieda Schroeter walfrieda.schroeter at
Sun Oct 21 09:11:48 EST 2001

Yoram Gerchman wrote:
> Greetings netters
> We are trying to express a fluorescence protein in E. coli. We cloned it
> into the pBad system (Invitrogen) and got nice expression on agar plates
> (although slow- the fluorescence appear only after a few days). When we
> try to expression (e.g. fluorescence) in cells grown in liquid media we
> see nothing We tried varying the arabinose concentration etc but nothing
> worked. Any ideas?
> Thanks Yoram
> ---------------------------------------------------------
> "Support bacteria, it's the only culture some people have."
> Anonymous
> ---

We had the same or related problem with expression proteins in E.coli
sometimes. Colonies grew on solid medium, but the same bacteria were
unable to grow in liquid medium. There was nothing we could do about it,
and, unfortunately, we never found out the reason. The ad hoc
explanation that the protein is somehow toxic for the bacteria seems to
be inadequate, as the colonies grew well...

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