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AMERICAN CYANAMID COMPANY
IS37 WEST MAIN STREET

STAMFORD, CONN.

TELEPHONE
STAMFORD 4-614]

 

August 20, 1946

Mr. Joshua Lederberg

Yale University

Osborn Botanical Laboratory
New Haven, Connecticut

Dear Lederberg:

We are sending under separate cover cultures of
two lysineless mutant strains of E. coli, 66-489 and 15L-171,
and a methionine requiring culture (18-15L-171) derived from the
latter as described in my letter of August 1. The culture of
66-489 was taken from a stock culture of the original single
colony isolate while 15L-171 has been carried through five, se-
rial, single colony isolations from A.C.-agar. The culture of
18-15L-171 was taken after the second transfer in the basal me-
dium plue methionine from a single colony culture of colony #18
isolated fram a plate of 15L-171 in basal-agar supplemented with
methionine and thiamine.

We have attempted to make differential plate.
‘counts with a single colony culture of 15L-171 on supplemented

basal-agar but the colonies vary considerably in size. Approxi- ly sine
mately as many colonies grow in the basal agar (at 48-72 hours)

as in the basal agar plus methionine or thiamine, although the
majority of such colonies fail to grow at a normal rate when in-

oculated into the basal medium and appear to be similar to 18- u
15L-171. Most of the subsurface colonies have a rough appearance (lysine) * ,
due to numerous satellite colonies. We have not studied strain

66-489 in a similar manner but have noted that it gave light

growth in the basal medium plus a combination of thirty-six

growth factors without lysine and without reversion. We have

not tested the two strains for syntrophism but hope to do so

shortly.

We have not studied strain 18-15L-171 in great >
detail but it appears capable of growth also with homocystine, Hacmient 2:
cystine plus lysine, and delayed growth with thiamine which is
accompanied by the ability to grow normally with lysine. Cystine
inhibits the growth on methionine.

We do not intend to carry these studies further
and shall probably only state in one of our papers that such
Mr. Joshua Lederberg -2- August 20, 1946

spontaneous changes in growth requirements have been observed.
If you are interested in more detailed information on these or
similar strains you might stop in sometime on your way through
Stamford. You may be interested in using some of the other
mutant strains aleo for genetic studies. Several others show
some relation between methionine and lysine, including a strain
with a partial block which grows with either pantothenate or
methionine plue lysine. :

We shall be interested in hearing of the results
of your genetic studies. They are likely to have some bearing
on the use of the mutant strains in studies of bacterial metab-
olism.

With best regards,

Sincerely,
AMERICAN CYANAMID COMPANY

Oh ag

RRR:ab Raymond R. Roepke