[Q] Sonication times for E. coli?

Dr. Duncan Clark duncan at genesys.demon.co.uk
Wed Jul 24 04:30:53 EST 1996


In article <mantei-2407960715570001 at retrograde.ethz.ch>, Ned Mantei
<mantei at neuro.biol.ethz.ch> writes
>In article <4t4316$793 at decaxp.HARVARD.EDU>, timur at beagle.colorado.edu wrote:
>
>> Hello.  How long should one sonicate E. coli cells for in order to
>> break down most cells
>
>1) Sonicate until the suspension has a "dirty dishwater" look, instead of
>looking sort of "creamy".
>2) Take 100 ul aliquots at various times, including before you start.
>Centrifuge 1 min. in Eppendorf centrifuge. As cells break the pellet gets
>smaller.

A lot depends on the sonicator power, cell density and the volume you
are trying to sonicate. I remember years ago seeing a paper suggesting
that the release of nucleic acids is monitored ie OD260 as an indication
of breakage. I also remember a paper on purification of EcoR I from a
super-over-expressing clone where they found the best yield was by
sonicating a very dilute suspension of cells - much more so than one
would normally have used. 

Duncan 

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My mind's made up. Don't confuse me with the facts!
Duncan Clark
GeneSys Ltd.



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