February 4, 1977

Dr. Frank Youn

Department of Microbiology

University of Rochester School of Medicine
Rochester, New York 14642

Dear Frank,

I was very glad to see Microbiology 76, which just arrived on my desk,
and appears to be an extremely useful conspectus about the present situation
in Bacillus subtilis. Of course there are many things that have happened even
since the collection of those papers but that is only for the better.

I was particularly glad that you undertook to review the earlier history
of the development of biochemical genetics in subtilis. But I was disappointed
that you overlooked the initial report by B@rkholder and Giles (American
Journal of Botany, 34:345-348) 1947 which was the original source of most of
the biochemical mutants that were done in thd early work on the organism.
Charles Yanofsky came to Yale, I believe,,in the next year, and certainly
picked up his strains from Bérkholder and Giles including for the purposes
you mentioned of further studies on tryptophan metabolism. The use of subtilis
for getting biochemical mutants was to be sure a "me too" kind of thing and
was very much under the encouragement of Tatum's previous work.

What you have no way to know is a story that I have to tell on myself:
namely that in early 1947 I trééd crossing some of these strains, did get a
few prototropha but could not be sure they were not reversions stimulated
by cross-feeding of the 2 parental strains and did not pursue the matter any
further! I had plenty to do with crossing in those days but would certainly
have been excited enough to be able to get into a transforming system. But the

only thing I wanted to pass on to you for the reeord was the Bérkholder
Giles reference.

Sincerely yours,

Joshua Lederberg
Professor of Genetics

JL/rr