( RUTGERS . THE STATE UNIVERSITY

\ .
INSTITUTE OF MICROBIOLOGY S ept ember l 6 Jd 9 57 NEW BRUNSWICK, NEW JERSEY

Dr. Joshua Lederberg

c/o Rubbo

Bacteriology Department

Melbourne University

Carlton N3, Vic., Australia ‘

Dear Josh:

I found your note of August 22 after my return from California, where
a rather dull Stanford meeting was spiced by the rumor of your moving to
Berkeley. (However, I also heard statements to the contrary from sonneborn
and Levinthal). As far as the illustrations are concerned, we shall be glad to
receive the prints after your return to Madison in November. Incidentally, I
expect to be in Madison on November 20 and 21 if present plans and Joe Wilson's
funds persist. .

Among a number of slightly interesting breaks in our varied enterprises
here is one that might be of particular interest to you: One of my graduate
students, Jacob Michael, has ascertained in studies with Shigella dysenteriae and
E. coli strains that there is an inverse correlation between penicillin resistance
and resistance to bactericidal factors of normal human serum. This relationship
was first detected by measuring penicillin resistance of strains selected for
differences in serum resistance, and was confirmed by demonstrating that step-
wise mutational increases in penicillin resistance are associated with correspond-
ing decreases in serum resistance. (However, other serum-resistant mutants
which do not show this relationship also have been observed.) To test the
assumption that this may be the result of overproduction of cell wall components
in penicillin- resistant mutants (to compensate for interference, which at the same
time would offer more sites for interaction with serum bactericidins), the serum
resistance of cells following pre-growth in the presence or absence of non-inhibit-
ory concentrations of penicillin was tested. In accord with the above assumption,
penicillin- grown cells proved more resistant to serum than their related controls
pre-grown in plain broth. However, there was an interesting zone effect: pre-
growth in 0.5 or 5 units protected against serum, pre-growth in l or 2 units did
not (the actual units of course differ depending upon the strain employed). Also,
the bactericidal effects of normal serum disappeared in the presence of 20%
sucrose; cells thus treated and transferred into H,0 survived 100% whereas
penicillin + sucrose-treated cells lyse after transfer to H20.

 

Barbara and J, minus the children, had an interesting time in California
for 3 weeks, even though we confirmed that revisiting old-familiar places, after
an interval of several years, can be a disappointing experience.
Dr. Joshua Lederberg -2- September 16, 1957

With best regards to Esther and you,

Sincerely,

Ue)

Werner Braun

WB:DP