To the best of my recollection, I got "K-12" from Ed Tatum when I came to Yale in March 1946, and kept my own stock
of it. I have no record of re-clonings; but from a very early time I followed the possibility of minimizing recloning of a
stock culture. If an identifiable variant (colony morphology, etc.) were noticed it would be given a distinctive stock number.
I have no recollection that K-12 was ever lost or contaminated so as to call for a recall or reisolation. But without an exhaustive
search through my correspondence (a 10 year task) I can't be sure. You might do well to ask Larry Morse (Denver) if he
remembers anything in that line.
Do also keep in mind the first step mutants from K12:
58, 679 (Ed's auxotrophs)
W1485, 1872 lambda-sensitive
that are fairly ancient.
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Frits and Ida Orskov dropped by the other day. I asked them about Levin's "reisolation" of K-12. He pointed out
they were merely "zymotyped" and have not been sero-typed.
about the linkage chart.
PS can you spare another reprint of 1980. Micr Rev?