Dr. Clifford W. Nesseltine

Northern Utilination Resezsch Branch
United Stetes becaurtment of Agric lture
Peoria Falls, [Illinois

Dear Dr. Hessoltinet .

fam -riting you at the instance of Dr. Robert Pittenger at Eli Lilly & Co.
This fall we ere planning to resume some exnerinents on the genetics of
actinonycetes. JI had carried out a fo) experiments with Streptonyces |
griseus a couple of years ago, but what I could do was limited by the conmon
failing that on contimed transfer the cultures tended to lose their capacity
to sporulztee Tho sporulation is essentis] for the manipulations of genetic
work.

Iam writing to you in hopes th t you may be able to offer some recommenda-
tions or, even better, some cultures with more desirable properties. These
would be in the order of importancet (2) vigorous sporul:tion which persitsta
as far as possible on rereated transfer, (2) vigorous, rapid growth on syn~
thetic media preferably at higher temperatures urowx! 37 degrees if possible,
and (3), least. important, Cistinctive plementation. If you can recommend

any po Mticulur isolutes to these »urposes, I would appreciate your counsel.

This work is scheculed to be contimed by Dr. 5. G. Bradley who will be coming
here this fall on a postedostoral fellaishin. At the present time he is at
the Department of Biology at Northvestew University, Evenston, Dlinola. Une
til next September if you could forvurd any promising cultures directly to
him, he could get right to them. Meamnile he 1s attewting to make his own
4solations of cultures thet would be appropricte, and any tins in this direce
tion would also be avprecieted.

Dr. wAttenger also supolied me with some formulas for media which would en-
courage continued sporut tion. If you have any ret concoctions of your own,
they would also te apprecisted.

Yours sincerely, |

Joshua Lederberg
/n Assoc. Professor of Genetics