LB media chemical composition

Scott Coutts scott.coutts at
Thu Feb 12 21:08:03 EST 2004

Oops, I hit the 'send' button too quickly on the other post and forgot 
to add a few things...

> What is the chemical composition of LB media?  The product sheets
> generally list the "ingredients" as tryptone and yeast extract, and some
> list the composition in terms of amino acids and electrolytes.  But it
> appears that given its messy origins this LB should be quite a bit more
> rich with metabolites.  

You only get the list of amino acids and electrolytes because, 
generally, that's all we care about for non-fastidious organisms.

> For example does LB contain nitrogenous bases or
> nucleotides?  What carbohydrates are known to be present?

The nucleotide products may be present in the yeast extract, but they 
are not added in any other form. Most of the nitrogen requirements of 
the organisms are satisfied by the amino acids in the trypton.

To find out what carbohydrates are present, you'll have to look for th 
echemical analysis of the yeast extract and tryptone. There are no 
extra, particular carbohydrates added. Remember that the bacteria that 
grow on LB are quite capable of syntesising their own metabolites.

By the way, you'll probably find analysis sheets from Oxoid's website, 
so you can look up the yeast extract and tryptone.

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