The Action of Bacteriophages on Rod—Cells and Penicillin-—
Induced Large Bodies of Proteus mirabilis.

H. Bohme and U. Taubeneck

Institut ftir Kulturpflanzenforschung, Gatersleben and Institut
fiir Mikrobiologie und experimentelle Iherapie, Jena
der Deutscheg Akademie der Wissenschaften zu Berlin.

of Hux

In liquid culture medium with high concentrations of penicil-
lin Proteus mirabilis develops spherical large bodies which

are able to return to the normal rod—like form after artificial
removal of the antibiotic. In connection with studies on phage-
resistance of P.mirabilis the reaction of normal rod—cells and
large bodies to the action of bacteriophages has been compared.
Lysis of rod-cells grown in an antibiotic-free medium begins

21 minutes after initiation of adsorption of phages with a
multiplicity of 5; lysis is completed after 30~40 minutes. The
behavior of a culture of penicillin-induced large bodies (6 to
8 hours old) after adsorption of phages with the same multipli-
city is exactly like that of the culture of rod-—cells. The la—
tent period lasts 21 minutes too. Microscopic control showed
that the large bodies were lysed completely. It is easy to
isolate phage-resistant mutants of P.mirabilis by cultivation
of the sensitive strain on solid media together with an excess
of phages. Penicillin-induced large bodies of a phage-resistant
mutant preserve phage-resistance, no lysis happens. The ex-
periments were carried out with 2 unrelated strains of P.mi-
rabilis and their phage-resistant mutants. the results were
identical with both strains. The sensitivity to phages of

large bodies induced from phage~sensitive rod-cells leads to
the conclusion that the receptors necessary for adsorption of
phages remain intact after transformation of rod-cells into
large bodies. This is a difference between large bodies of
Proteus and protoplasts produced from E. coli and B.megaterium
which generally are not able to adsorb phages (for exceptions
see Lederberg and Claire, Frazer and Mahler). The resistance

to streptomycin of large bodies of Proteus and protoplasts of
E. coli also seems to be different. According to Leder-

berg and Claire penicillin-induced protoplasts of a strepto-
mycin-resistant mutant of E.coli were inhibited by a strepto~
mycin concentration of 20 Ag/ml. In our experiments the peni-
cillin-induced large bodies of P.mirabilis behaved in liquid
media with 400 u penicillin per ml plus 40 u streptomycin
per ml in the same manner as in this medium without strepto—
mycin; that means they were not inhibited. On solid media
with serum, penicillin and streptomycin the streptomycin—
resistant mutant forms I-—colonies as on the same medium
without streptomycin.