December 4, 1953

Dr. L, A. Favret
Fhytotechnical Institute
Castelar

Argentine Republic

Dear Dr. Favret:

I have your letter of the 23rd of November referring to your interest in work
with biochemical mutants of Escherichia coli. I will be happy to cooperate with you
in any way that I can but your letter did not make it clear precisely what you desired.

I have not, myself, had any interest or experience in the matter of mutants of
& Gold concerned with nitrate reduction nor am I acquainted with any other invest-
igator who has studied this question in this organism. I trust you are familiar with
the work of MaecELroy on this matter which made use of certain mutants of Neurospora.
I am therefore unable to supply any mtants of & $Ol4 which would be of immediate
or direct value to you.

If, however, it would be important to you to have various rutritional rmtants
of &. coli, strain k-12, as a foundation for your own work in developing nitrate
defective mutants I will be very happy to send you the basic stocks. Please let
me know your wishes in this regard.

Tam not well enough acquainted with your colleagues in Argentina to be able
perhaps to give you an adequate reference. It might be of some advantage to you,
however, to consult with Dr. Jose Reissig who is now at the Fundacion Campomar <t
Buenos Aires in Leloir's Laboratory as he has had considerable experience with
biochemical mutants of Neurospora.

I trust that you are also acquainted with the work of Pollock anc his
colleagues in London on the adaptive nitratase of certain coliform bacteria.

Yours sincerely,

Joshua Lederberg
Associate Professor of Genetics

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