Help wanted: Glucose conc. in minimal media.

John Tomaszewski tomasz at u.washington.edu
Fri Dec 8 18:44:57 EST 1995

Hi all,
	I'm expressing a small protein in E.coli. using a MOPS minimal 
media (outlined in J. of Bacteriology, Sept. 1974, p.736-747) with good 
results (~30g wet cell paste/10L).  The protein is being used for NMR 
studies and I'm using this media for 15N labelling.  Thus far I've been 
using a glucose conc. of 0.2% or 2g/L (the recipe called for 3.6g/L but 
the 2g/L seemed to be a fairly std. value and has  worked fine).  What 
I'd like to consider is 13C labelling as well but for 10L, 20g of 13C 
glucose is price prohibitive.  (I realize there are alternatives to 
glucose but I don't really have the means or time to try them all out.)

	What I want to ask is:
If I give the bugs more time, can I safely reduce the [glucose] to reduce 
the cost and still manage approx. the same final yield?  The above paper 
reports a theoretical cell yield of 10% if the [glucose] is reduced by 
1/10, although the growth rate is reported to remain about the same.  Is 
this borne out in practice?  I don't have much experience with this.


**  **  ** ** * **            DEPARTMENT OF CHEMISTRY             **
**  **  ** ** * **        tomasz at helix.chem.washington.edu        **
**   *****  *****                JOHN TOMASZEWSKI                 ** 

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