Chemical and Ultrastructural Comparison of Endotoxins Extracted fromSalmonella minnesotaWild Type and R Mutants

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Abstract
Endotoxic lipopolysaccharide and glycolipids (RGI) extracted from S. 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 by EM. All RGl extracted with PW (RGl-PW) contained excess amounts of phosphate, O-ester linked fatty acids and neutral sugars; 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). The micrographs of RGl-PCP showed a filamentous structure, regardless of strain differences. The micrographs of RGl-PW represented spherical and doughnut-shaped forms, and the micrographs of RGI-PCP showed filamentous or stick forms, when stained with uranyl acetate. Thus, the ultrastructures of RGl were evidently dominated by the solvent systems used for extraction, and not by the strains used here.