Precipitable Substances Prepared from Bacilli of the Salmonella Group.

Abstract

Extending previous work, 1 soluble specific substances were prepared from a number of types of the Salmonella group which yield large amounts of reducing sugar on hydrolysis, and are resistant to tryptic and peptic digestion and to the action of alkaline hypochlorite solution. The group reactions of these substances correspond in a general way to those of the so-called stable agglutinogens 2 regardless of the method in which the extracts were prepared. (Digestion of the autoclaved bacilli with trypsin, or extraction of the alcohol treated bacilli by heating with saline solution, or dissolving the microbes with alkaline hypochlorite solution.) This parallelism was also seen when the specificity was tested by means of immune sera absorbed with heterologous bacilli of the Salmonella group.

One striking exception to this was observed with the soluble substance of B. paratyphosus B and Stanley. The sera for these types when absorbed with bacilli of the strains Reading or Abortus Equi no longer precipitated the homologous soluble specific substance, although they still agglutinated the homologous bacilli, a reaction in which factor I (White) is involved. It was found that this loss was due to a high sensitivity to alkali of the precipitable substance as originally extracted by saline solution. On the contrary, the other reactions mentioned persisted even after boiling the preparation for several hours with normal sodium hydroxide, whereas hydrolysis with normal hydrochloric acid for a few minutes resulted in liberation of reducing sugar and the destruction of the serological properties. The reactions for factor I were not altered by digesting the substance with pepsin or trypsin at a pH which in itself was not injurious.