do e.coli cells get ruptured during high spin - (May/25/2010 )

hi all

I have a very silly doubt but i like to share ya. Do E.coli cells-dh5alpha cells get ruptured when we centrifuge them at rpm> 12000rpm?
If not then why do we spin the cells while preparing for competent cell at a lower rpm 5000rpm?

Thanks in advance.

in general rpm is not a meaningful notation for centrifugation steps since the centrifugal force is dependent on the radius of the rotor. Therefore it is always better to use rcf or g instead of rpm (it is seen throughout a lot of papers but rpm is invalid).

So if you mean 12000 rcf ...normally a short spin should not reduce the viability of E. coli cells significantly ...but we also use 5000 rcf for the preparation of competent cells.
I think its more a matter of the procedure u use ...if you wash the cells repeatedly with ice cold water the cells become very fragile therefore it is recommended to treat them as gentle as possible to preserve their viability.

Regards,
p