February 12, 1947.
Dear Dr. Woodruff:

As you may recall from thessymposium at Cold Spring Harbor last
summer, I have been working here in Prof. Tatum's laboratory on the
Bpparent recombination of genetic factors in Escherichia coli. A
brief reprint summarizing some of our conclusions is enclosed: In
this work, the study of such factors as resistance to bacteriphage
has been partkoularly fruitful, sugeesting that other resistance
characters might be equally useful. Ye are particularly anxious to stuay
the inheritance of resistance to antibiotics.

The range of antibiotics applicable to #scherichia coli is of course
not as extensive as if we were dealing with a gram-+ organism. We are
using streptomycin now, and would like toe try other antibiotics, resis-
tance to which is independent of that to streptomycin. I have particularly
in mind streptothricin. I should appreciate it very greatly indeed
if you could let me know how I might obtain reasonable quantities of
this agent (2-400,000 E. coli. inh. units), or even better, if you coulda
yourself supply me with same. While purified material would be preferable,
it need not be of the same degree of purification as would be demanded
for chemical studies. If you should have in mind any other agents which
might be suitable, or any other suggestions, I would like to hear from
you about them.

Yours sincerely,

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-' Joshua Lederberg.

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