UNIVERSITY of ILLINOIS

COLLEGE of AGRICULTURE

AGRICULTURAL EXPERIMENT STATION
URBANA, ILLINOIS

DEPARTMENT

of HorticuLTurE April l2, 1955

Dr. Joshua Lederberg
Department of Genetics
University of Wisconsin
College of Agriculture
Madison, Wisconsin

Dear Dr. Lederberg:

Enclosed is a reprint of "The Physiology
of the Actinomycetes". I am delighted that you have under~
taken the study of the genetics of this group of organisms.
We had contemplated doing this for a few years now, but
always “backed off" because we never felt competant to carry
through such a program.

For the past few years we have been
studying the biosynthesis of chloramphenicol, a metabolic
product of Streptomyces venezuelae. As part of this investi-
gation, we have studied the production of U.V. and X-ray
mutants. Many mutants appear with X-ray irradiation. Most
frequent are those for pigment production, early fragmentation
of the mycelium, loss of sporulation and colony size. In
addition, some mutants lose their autotrophic (except for
carbon) metabolism. A few mutants which we have tested pro
duce a great deal of acids, which we are identifying. We
are now attempting to find the growth-promoting factor
which is absent in the mutants that have lost their ability
to grow on chemically defined media.

The mutants which no longer produce a
melanin-type pigment but retain their mycelial habit also
are very striking.

Some of these cultures mignt furnish
excellent material for genetic studies. If you are interested
in some of these cultures, we would be glad to cooperate with

you.
Sincerely yours,
Sy SRA
David Gottlied ©
Professor, Plant Pathology
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