carb in liquid cultures

[William J. Buikema]

In article <1993Aug11.120711.1 at agri.huji.ac.il> navot1 at agri.huji.ac.il writes:
>In the discussion about carbenicillin it was made pretty clear that for growth
>of colonies on petri dishes it results in less background of sattelites due to
>the inhibited breakdown of carb.
>Will it also work when growing bacteria in a liquid culture to saturation?
>(since the beta lactamase breaks down amp in a liquid culture sometimes
>allowing for non plasmid cells to totally take over the culture?)
>Sorry if this question was asked already but I seemed to have missed it)
>Thanx, Ilana

We have occasionally had problems with plasmid yields in E. coli carrying
an amp-resistant plasmid such as pUC19.  In most cases, these plasmids appear
unstable because they somehow inhibit growth, and with extended incubation
with beta-lactams plasmid-less cells overgrow the culture.  In most cases
we have found the use of carbenicillin and sulbactam (a beta-lactamase 
inhibitor) to be beneficial, especially in liquid culture.  This works both
for increasing plasmid yield of 'growth inhibiting' clones, and for maintaining
expression plasmids that may be somewhat leaky.  
	We get the sulbactam from Pfizer and use 5 ug/ml.

Bill


William J. Buikema              internet: wjb1 at midway.uchicago.edu
University of Chicago               or    w-buikema at uchicago.edu
Dept. of Molecular Genetics &       or    hetman at uchicago.edu 
    Cell Biology, CLSC 313
920 E. 58th St.
Chicago, IL  60637