E.coli strain

Chris Boyd chrisb at hgu.mrc.ac.uk
Wed Nov 20 05:27:25 EST 1996


Dave Smith (davesmith at bioch.tamu.edu) wrote:
: Thomas Broschard <Thomas.Broschard at esbs.u-strasbg.fr> wrote:

: >Does anyone have the E. coli K12 strain KK2186.  This strain is 
: >genetically identical to JM103 except that it is nonlysogenic for 
: >bacteriophage P1.  The strain has originally been described by Berman 
: >and Zagursky in a paper in Gene (1984) 27: 183-191 and is mentioned in 
: >Jeffrey Millers's Handbook 'A short course in bacterial genetics'.  
: >Please let me know at the e.mail address janel at esbs.u-strasbg.fr.
: >Thank you in advance.  Regine Janel


: We discovered JM103 was a P1 lysogen about five years ago--everyone
: has to reinvent a wheel sometime in their life.
: We cured the strain and now call it JM103Y.  If you are interested in
: it, let me know and I'll see if we can send it your way.

I can't understand why anyone would choose to use JM103 as a cloning
host these days, whether cured of its P1 or not, primarily because it's
recA+ and rk+ mk+. This means it's poor for cloning heterologous DNA
(which is liable to EcoK restriction) and poor at maintaining repeated
sequences (recombination proficient). You could use JM109, which is
very similar to JM103 (-P1) except that it is recA- and rk-.

However, for maximal transformation efficiencies, I would recommend
DH11S for M13 work and DH10B otherwise. Both are available from
GibcoBRL (no connection, other than a rather peevish niggle about them
not replying to strain requests from me).

Best wishes,
--
Chris Boyd                       | from, | MRC Human Genetics Unit
chrisb at hgu.mrc.ac.uk             |  not  |  Western General Hospital
http://www.hgu.mrc.ac.uk/~chrisb |   for |   Edinburgh EH4 2XU, SCOTLAND



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