Unbreakable bugs!!!

[Philippe Lefebvre]

Hi everybody
We have a strange problem here: for two weeks, we have been unable to obtain a good 
and efficient lysis of E. coli strains (for protein extraction purposes).  We are 
usin Tris Glucose buffer, to which we are adding lysozyme.  Lysis occurs within 
minutes, usually... We have tried new lyzozyme, pure water, freshly transformed 
bugs, checked pH...  still no lysis.  Does anyone ever encountered such a problem?

Thanks for your help
Dr Phil Good