LB contains glucose?

[Cornelius Krasel]

hbkg at hitel.kol.co.kr wrote:
> Glucose is known to repress lac promoter expression.
> LB media (1% tryptone, 0.5% yeast extract, 1% NaCl) is largely
> used for media for overproducing cloned gene products.
> gene expression under the regulation of lac promoter is repressed by
> glucose in the media.
> I am curious how much glucose exists in LB.

The only possible source of glucose could be the yeast extract, but
I don't think it contains appreciable amounts. At the place where I
learned my microbiology people would add a bit of glucose to the LB
if they wanted to make their lac-based promoters more tighter.

--Cornelius.

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/* Cornelius Krasel, U Wuerzburg, Dept. of Pharmacology, Versbacher Str. 9 */
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