Chemical and ultrastructural comparison of endotoxins extracted from Salmonella minnesota wild type and R mutants.

Endotoxic lipopolysaccharide and glycolipids ( RGl ) extracted from Salmonella minnesota wild type and R mutant cells ( chemotypes Ra, Rb, Rc, Rd1, and Rd2 ), respectively, with hot phenol-water (PW) and phenol-chloroform-petroleum ether (PCP) were analyzed chemically and electron microscopically. All RGl extracted with PW ( RGl -PW) contained excess amounts of phosphate, O-ester linked fatty acids and neutral sugars, while all RGl extracted with PCP ( RGl -PCP) contained excess amounts of free amino groups and fatty acids, in addition to the RGl constituents. Polyamine (cadaverine), phosphoethanolamine, and an unidentified amino compound were contained in RGl -PCP as free amino groups. When stained with uranyl formate, the ultrastructure of RGl -PW showed a spherical form (onion-like form), whereas the micrographs of RGl -PCP showed a filamentous structure, regardless of strain differences. On the other hand, the micrographs of RGl -PW represented spherical and doughnut-shaped forms, and the micrographs of RGl -PCP showed filamentous or stick forms, when stained with uranyl acetate. Thus, it is suggested that the ultrastructures of RGl were dominated by the solvent systems used for extraction, and not by the strains used here.