e. coli lysis

[Mark Bowen]

I am looking for a gentle but effective method to lyse small volumes
(~1mL) of E. coli culture for LacZ activity assays.  I've tried using
SDS/chloroform as well as toluene as per Miller 1972, but find these to
be somewhat variable.  I know of many other bug-busting  methods, but
was wondering if people had experience getting reproducible lysis
without affecting LacZ activity.

thanks for any assistance