Inducing SOS response

Dr. Richard V. Goering rgoeri at
Fri Jan 14 19:22:55 EST 1994

If you try mitomycin C remember that it is light sensitive.  It can be 
incorporated into growth media (e.g., BHI, etc.) but must be added after 
autoclaving just as you would an antibiotic such as ampicillin.  For 
best results you'll have to determine the proper concentration (i.e., 
below the MIC) which will vary from strain to strain.  I would suggest 
somewhere between 0.2 to 1 ug/ml as a start.  If you decide to go the UV 
route it's really not a problem.  You can irradiate a bacterial 
suspension (just make sure it's in saline, not a lot of organics which 
will absorb UV) in a conventional plastic petri plate with the lid off 
for the short period of UV exposure they will require.

Good luck,
R. Goering

On Fri, 14 Jan 1994, Christopher Coward wrote:

> I want to induce the SOS response in E. coli to investigate mutants deficient
> in the exit from the SOS response (ie although they may repair any DNA
> damage, they do not resume cell division). Does anyone have any suggestions as
> to how to induce SOS for this purpose in a simple way. So far growth in the
> prescence of MMS (0.05%) has been suggested, I was also wondering about
> using mitomycin C, but have no idea what concentration would be appropriate
> to enable wt cells to grow, while the mutants don't. UV is another possibilty
> but trickier to do, needing UV - transparant plates and stuff.
> Cheers, Chris

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