Partition of Salmonella typhimurium in a Two-Polymer Aqueous Phase System in Relation to Liability to Phagocytosis

Abstract

Analysis of the partition in a two-polymer phase system of Salmonella typhimurium R mutants with different susceptibility to phagocytosis distinguished between the mutants. Close to 80% of the R mutants least resistant to phagocytosis accumulated in the dextran-rich phase, whereas more phagocytosis-resistant mutants showed higher affinity for the interface and the polyethylene glycol-rich top phase. By growing the uridine diphosphate (pyro)-gal-4-epimeraseless mutant LT2-M1 in the presence of d -galactose for different periods of time, two well-defined peaks were obtained in counter-current distribution analysis with an aqueous two-polymer phase system revealing a heterogeneous population in the culture. One peak was located at a site characteristic of R bacteria, the other at the site of S bacteria. As growth proceeded, more bacteria transferred from the R-type to the S-type peak. Within each peak, a gradual increase in resistance to phagocytosis by rabbit polymorphonuclear cells occurred with increasing length of growth in d -galactose.