Gram-negative
bacteria stain pink with the gram stain procedure. The Gram-negative cell
wall is composed of a thin, inner layer of peptidoglycan and an outer
membrane consisting of molecules of phospholipids, lipopolysaccharides
(LPS), lipoproteins and sutface proteins. The
outer membrane of Neisseria has shorter lipooligosaccharides
(LOS) instead of lipopolysaccharides.