Dear Jacob,
In my hands, different strains of E. coli appear to behave differently
- I found BL21(DE3) needing harder centrifugation than JM109(DE3) to
get a good pellet. And BL21 lysing partially when doing osmotic shock
extraction of a periplasmically expressed protein - while XL1Blue
behaved well.
Although - thinking about the other comment - perhaps I had an
infection with a phage to which BL21 was sensitive but the others not?
Mark
Quoting Jacob Keller <j-kell...@md.northwestern.edu>:
Dear crystallographers,
I recently expressed some new constructs, and found after my usual
expression protocol that the cell pellets were not compacted at the
bottom corner of the bottles us usual, but were instead smeared as a
film on the side, and further, were somewhat clumpy, like clots, and
with a smaller pellet in the usual location. The centrifugation was
exactly as usual. I noticed that there was also a bit more foam in the
medium than usual, but I am not convinced that this was the issue,
although it might be a symptom. My suspicion is that the constructs are
lethal and cause cell lysis, but I am not sure. Has anybody seen this
phenomenon before, and gotten to the bottom of it?
Jacob Keller
*******************************************
Jacob Pearson Keller
Northwestern University
Medical Scientist Training Program
Dallos Laboratory
F. Searle 1-240
2240 Campus Drive
Evanston IL 60208
lab: 847.491.2438
cel: 773.608.9185
email: j-kell...@northwestern.edu
*******************************************
