Note on Absorption of Phage by Heat-Killed Bacilli

Abstract

Investigations on the Salmonella were carried out employing the method recently described by us 1 for studying the specificity of absorption, particularly from polyvalent phages, by heat-killed bacilli. In principle the method depends on the fact that the absorption of phage by heat-killed bacilli is largely irreversible and consequently the residual phage may be studied both qualitatively and quantitatively without removing the absorbing organisms.

In general, it was possible with this procedure to differentiate some of the following groups, for instance, the suipestifer group which absorbed specifically the homologous phage and also the suipestifer fraction 1 of the polyvalent anti-paratyphosus A phage. However, some of the suipestifer strains, particularly those of the European type, were characterized by a capacity to absorb actively also other fractions, for example, the paratyphosus B fraction of the polyvalent anti-paratyphosus A phage when B. aertrycke (of the paratyphosus B group) was used to test for residual phage. (Table I.) This same type of suipestifer absorbed the anti-paratyphosus B phage to a moderate degree, but less intensely than the paratyphosus B group of organisms, while other suipestifer strains showed no absorption.∗

The paratyphosus A group of organisms and also some of the European suipestifers employed were the most active absorbers of the anti-paratyphosus A phage when the homologous strain was the test organism. The distinction between these could be made readily since the paratyphosus A strains failed to absorb actively the anti-suipestifer phage.

In contrast to the ease with which differences within the suipestifers could be demonstrated, was the failure to distinguish the typhosus-enteritidis group from the aertrycke-paratyphosus B group, since in the several combinations of phages and test organisms available, both groups absorbed equally well. (Presumably this observation is in harmony with the findings recorded by Furth and Landsteiner, 2 that some anti-sera of the 2 groups gave weak to moderate precipitin reactions also with the heterologous extract.)