Ostober 25, 1949.

Dr. P. R. Fdvards ,

Public Health Service
Comnunicable Disease Center,
Laboratory Division,
Chamblee, Georgia.

Dear Dr. Edwards:

About three years ago, I received from Mr. Borman at the Connecticut
State Labs. a cultura labelled " S. coli il, 458", which he told m at
the time was received from you. In the course of our current studies of
the Salmonella group, locking for genetic recombination us in E. coli
Kel2, we have acoumlcated sone evidence that components of this strain
will undergo recombination with each other.

As received, this culture tured out to be a mixture. hen streaked out
on EdB-lactoge agar, about equal numbers of Lac+ and Lac=- were seen. The
Lac+ component required histidine for growth on syntustic mediums the
Lac= had no growth factor reyuirements. Biochemical mtations have since
been inguced in each of these stocks, by ultraviolet frradistion and selec-
tion with penicillin, and these substruins then tested for recombination,
It woulc be laportant for us to be sure that bothsthe Lace and the Lae+
were variants of an originally pure 5. coli 1. “ould you be able to teat
these cultures serologically fcr this ddentity? The favor would be greatly
appreciated. Dr. %. Braun told me that the AMS is having ereat trouble
with the stability of the Vi antigen in this culture, and womdered whether
our observation could have anything to do with it, but I don't see how,

I am sending slants of the two cultures under separzte cover.

If recombination here can be verified, we shall probably undertake to
do some serological work, although the organism coce not ceem too promising
for our purposes. According to the textbooks, the diagnostic formla 4a
XXXT; =; 1,5 [Vi]. Have you ever noticed any form variation in the somatic
antagen, or have you had occasion to determine whether an alternate phase
can be obtained with the aid of 1,5 antiserum?

coli 1 is not the only Salmonella that may have a recombination mechanisa;
some very promising results were obtained with certain typhimrium cultures,
But iysogenic bacteriophages turned up which confused our resukts very
considerably, mainly by killing off many of the recombination cells. I
am strongly impressed with the role that lysogenic phages may play in
Salmonella variation, especially in mixed flora, since it turns out that
most or all Salmonella cultures are infectedcwith one or more latent
phaggs. In addition to the favor already requested, I would also
appreciate receiving your chrrent stock of F. coli 1 for comparison,
Thanks very much for your previous, and I hope, future, assistance.

Sincerely,

Joshua Lederberg
Assistant Professor of G

mnadd...