Evidence for shorter average O-polysaccharide chainlength in the lipopolysaccharide of a bacteriophage Felix 01-sensitive variant of Salmonella anatum A1.

Prolonged culturing in the laboratory has resulted in the formation of a stable derivative of the smooth Group E bacterial strain, Salmonella anatum A1, that is sensitive to both the R-core-specific bacteriophage Felix 01 and O-polysaccharide-specific bacteriophage epsilon 15. The variant strain, designated S. anatum A1-1, exhibits a normal number of irreversible binding sites for epsilon 15 but the relative quality and/or accessibility of those sites appears to be diminished. Infectious epsilon 15 phage particles are released more rapidly from S. anatum A1-1 than from its parent under acidic pH conditions known to interfere with the phage DNA ejection step. The purified lipopolysaccharide (LPS) of S. anatum A1-1 exhibits a reduced rhamnose/heptose ratio in chemical assays. Fractionation of this LPS on SDS-urea-polyacrylamide gels followed by silver staining reveals a narrower range of O-polysaccharide chain lengths relative to that of the parent (0 to 20 vs. 0 to 40 repeating units, respectively).