Change in LB recipe?

Michael Szardenings msz at bio.embnet.se
Mon Oct 9 10:42:03 EST 1995


In article <mikef-0610951624580001 at mikesmac.mjr.com>, mikef at mjr.com (Mike
Finney) wrote:

> In article <Pine.SOL.3.91.951005183525.17428A-100000 at howard>, Rafael
> Maldonado <rafael at howard.genetics.utah.edu> wrote:
> 
> >On 5 Oct 1995, Dale Yuzuki's Work Account wrote:
> >> 
> >> Recently someone in our lab noticed that the premixed LB broth powder from
> >> Difco contained 0.5 g/L NaCl instead of the 5.0 g/L formerly (also found
> >> in Current Protocols and Sambrook). Maniatis' recipe had 10 g/L.
> >
> >Don't be confused. Check "Experiments in Molecular Genetics", J.H. 
> >Miller (1972) CSHL Press, and you will see the difference: 
> >
> >Luria-Bertani Medium (LB)
> >        NaCl    5 g/l  (10g/l in 1992 edition
> >Luria Broth (also LB)
> >        NaCl   0.5 g/l
> 
(lines deleted) 
> Does
> anyone know if these different formulations ever make a practical
> difference?  Offhand, I suspect that PEG precipitations might be affected.
> 

There seem to be more effects than just this. The supercoiling of plasmids
has been shown to be influenced by the medium and in its turn the
expression in different media. Some strains have also more or less strong
turgor and too low salt may have effects on the stability of bacterial
pellets during centrifugation etc. At least the expression part I have
seen myself. In that case it was up to 50% more heterologous protein when
1% NaCl were used instead of 0.5%.
But in general: The variations in these 'LB'-recipes that I have seen
regarding the tryptone (0.5-1.2%) and yeast extract (0.5-1.6%) contents
may have more impact on the behaviour of E.coli strains. Still all general
protocols seem to work in all of these different labs, so its in most
cases only a more or less happy microorganism.
   
                  Skål     
                           Michael
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