How to break out bacteria on the plate

Paul N Hengen pnh at
Wed Jun 12 10:34:31 EST 1996

Bernard Murray (bernard at wrote:

> I'm now finding the method to detect a enzyme activity on agar plate.
> It is intracellular enzyme and its activity can show halo on the plate.
> If we can break out our bacteria on the agar plate as it is,
> we can find colonies that have the enzyme.
> Is there any method or reagent to break out bacteria on the plate?

: How about lifting colonies onto a membrane and then breaking the bacteria
: there?

Another idea is to start with an E. coli lysogenized with lambda(cI857ts)
grow colonies at 30C, then switch to 42C which will allow lysis of the
cells directly on the agar plate. As long as the phage does not interfere
with the enzyme assay, this seems very straight forward.

Something could simply turn the plate upside down over a beaker of
chloroform, or spray it on with an atomizer. I think this was done long ago
when petri dishes were made of glass. I don't know what will happen with
polycarbonate.  You might fog or melt the plates...could make for interesting
artwork :-)

* Paul N. Hengen, Ph.D.                           /--------------------------/*
* National Cancer Institute                       |Internet: pnh at |*
* Laboratory of Mathematical Biology              |   Phone: (301) 846-5581  |*
* Frederick Cancer Research and Development Center|     FAX: (301) 846-5598  |*
* Frederick, Maryland 21702-1201 USA              /--------------------------/*
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