Bacteriophage receptor development and synthesis of O-specific side chains after addition of D-galactose to the uridine diphosphate-galactose-4-epimeraseless mutant Salmonella typhimurium LT2-M1.

The formation of complete cell wall core lipopolysaccharide (LPS) and O-antigenic side chains after addition of d-galactose to the uridine diphosphate-galactose-4-epimeraseless mutant, Salmonella typhimurium LT2-M1, has been studied by (i) determination of adsorption rates of smooth and rough specific bacteriophages, (ii) passive hemagglutination inhibition, and (iii) qualitative and quantitative determination of the polysaccharide composition and structure. A rapid synthesis of the complete core LPS and O side chains occurred in bacteria in the log phase and the early stationary phase. Phage C21, which attaches to unsubstituted Rc structures, was adsorbed by the bacteria for only 10 min after the addition of d-galactose. Unsubstituted Rc structures, however, could still be detected after 160 min by immunological and chemical assays. Attachment of the P22 phage, which requires O-specific side chains with more than one repeating unit for adsorption, was demonstrated 10 min after the addition of d-galactose. Attachment of the Felix O-1 phage, which requires a complete core, was observed between 20 and 80 min after the addition of d-galactose. The rough specific phages 6SR and Br2 did not adsorb to the bacteria at any time after the addition of d-galactose. By passive hemagglutination inhibition, the presence of O-specific structures could be demonstrated after 10 min. No antigenic activity of the Ra and Rb structures was observed in the LPS preparations isolated at any time after the addition of d-galactose. Methylation analysis of LPS preparations isolated at 10 and 160 min after the addition of d-galactose showed that the O-specific side chains contained an average of 11 and 15 repeating units, respectively. In the 10-min sample, every 25th "Rc structure" carried a side chain, compared to every 3rd residue in the 160-min sample.