Electron Microscopical Study of Neisseria Meningitidis Releasing Various Amounts of Free Endotoxin

Abstract

A study was made of the ultrastructure of 4 strains of N. meningitidis which liberate varying amounts of free endotoxin in a chemically-defined, protein-free medium. The 2 strains which did not release detectable or only sparse amounts of free, filtrable endotoxin were rather uniform in cell size. Their cells appeared to be intact and showed a low tendency to aggregate. Cells of these strains showed only sporadic loose, trilaminar membranes and blebs, and free membranous structures were sparse in the medium. The endotoxin releasing strains liberated a high yield of free structures from the outer cell wall into the medium. These structures may represent the lipopolysaccharide (LPS).