Department of Genetics
University of Wisconsin
Madison 6, Wisconsin, U.S.

Novemher B? 1951.

Dr. R. Th. Scholtens,

Rijks Instituut voor de Volksgezondheid
Sterrenbos 1

Utrecht. Holland

Dear Dr. Scholtens:

I have read your letter of November 8 with great interest. As it happens,
I have been deeply concerned with the problem of recombination in Salmonella
since 1947. Only this year, my student, Mr. Zinder has completed a study of
genetic interactions in Salmonella typhimurium as a Ph.D. thesis.

We were surprised to find that recombination in Salponella is very different
from Escherichia coli. In fact, it rather closely resembles the so-called
"transformation" of pneumococcus (@wiffith, Avery et al.).

As to phage types, we have worked extensively with Lilleengen's set of
typhimurium. Much as you have published, we find that most of the phage reactions
depend on the state of lysogenicity, so that a genetic analysis would not be
so fruitful. This does not seem to be so in S. typhi however (at least for
the Vi types). Mr. Zinder and another student are just beginning to study these
from a genetic viewpoint.

At the present time, Mr. Zinder is finishing his experiments and writing
his dissertation. There are so many details to discuss that I think it might be
better to wait until this 1s written ahd published. When you have read all the
details of this work, I will be glad to hear from you if you wish to apply them
further. We have no mutants in S. paratyphi B; my previous experience with the
nutrition of these strains (Archives Biochem.313:287-290, 1948) was not encouraging.

A preliminary abstract of our work is enclosed.

Thank you for the reprints recently sent to me. I shall look forward to
a continuing exchange of reprints and other information.

Yours sincerely,

Joshua Lederberg
Associate Professor of Genetics