Isolation and Characterization of the Lipopolysaccharide of Thiocapsa roseopersicina

The lipopolysaccharide from Thiocapsa roseopersicina was isolated by phenol/water, being found in the water phase. It is cleaved into a polysaccharide moiety (degraded polysaccharide) and lipid A by hydrolysis with 10% acetic acid (100°C, 3h). d-Mannose, l-rhamnose, 3-amino-3,6-dideoxy-d-galactose and d-glucose are the major constituents of the degraded polysaccharide. 2-O-Methyl-l-rhamnose, 3-O-methyl-d-mannose, d-galactose, glucosamine and quinovosamine are minor constituents. d-Glycero-d-manno-heptose (tentatively identified) and 3-deoxy-d-manno-octulosonic acid were detected in only small amounts. Conspicuously, lipid A from T. roseopersicina contains a neutral sugar, d-mannose, in addition to d-glucosamine, as had been observed with lipid A from Chromatium vinosum D. Major fatty acids are β-hydroxymyristic and lauric acids. Only trace amounts of phosphorus were found indicating this lipid A to be free of phosphate. The lipopolysaccharide of T. roseopersicina represents the O-antigen of the strain. It reacts with antisera prepared against living or heat-killed cells in passive hemagglutination.