Otto Kandler Munchen, July 16, 1957
Botanisches Institut
Miinchen 48
Menzingerstr. 57

Dear Dr. Lederberg,’

Thank you very much for your letter, I am glae that the stable
Proteus-L strains are growing well in your lab and that you gat the same
resutjls with DAP-feeding. It is very interesting, that some of your coli
strains are already stabel and that some of them go back to the bacterial
stage with DAP. We would like very much to get some of these stabel xiz
coli-L-phase strains together with the corresponding bacterial phase,
because we were not successful in isolating any L-cultures from E.@oli.
We are now working on the isolation of the DAP-containing substance
from the unstable I-phase strains. This substance seems to be very similar
to the wall material of the bacterial form. “ve feel that only the stable
forms are really naked protoplasts and that the unstable forms still hawe
a membrane, but it might well be that it is not quite a normal one as regards
its stability. We agree with you that penicillin acts in some manner on the
property of the wall, but we are not sure if this is the primary andonly
effect. -

With best wishes for your further work,

Sincereley yours,

J freee