Ministére de I'Instruction publique

UNIVERSITE DE LIEGE

Microbiologie et Hygiéne

 

Prof. P. Fredericq

 

Liége, le February 26, 1958,

1, rue des Bonnes-Villes

Prof.J, LEDERBERG
Dept.of Genetics
University of Wisconsin
MADISON 6 (Wisconsin)

Dear Professor Lederberg,

I am sending by the same mail 2 strains of Salmo-
nella producing colicin I, Sa.118 is a S,bareilly isolated
from a chicken and S.211 is a S,typhi murium isolated from man,
Some colicinogenic properties may be transfered from coli to
Salmonella but I have not yet triedy the reverse, While in
the States I want to study the transfer by transduction bet-
ween strains of Salmonella.

Steriligation by chloroform is accomplished by
putting 0.5 to 1 ml of chloroform in the lid and keeping the
petri disk closed during + hour or more; the dish is then kept
open for $ hour or more to evaporate what still remains, A
second layer of about 4 ml of melted agar to whieh has been
added 0.1 ml of a young broth culture of the indicator is then
poured on tope The chloroform sterilization is efficient to
kill all surface bacteria and to prevent their dissemination
in the second layer,but some living cells may still be found
in the depth of the colonies, The chloroform handling does
not require,special chamber but of course it has to be done
not to near a burning flame,

I am looking forward to seeing you soon,

Yours sincerely,

Prof.P,FREDERICQ,