Gram-negative Bacteria - Characteristics

Characteristics

The following characteristics are displayed for Gram-negative bacteria:

1. Cytoplasmic membrane
2. Thin peptidoglycan layer (which is much thicker in Gram-positive bacteria)
3. Outer membrane containing lipopolysaccharide (LPS, which consists of lipid A, core polysaccharide, and O antigen) in its outer leaflet and phospholipids in the inner leaflet
4. Porins exist in the outer membrane, which act like pores for particular molecules
5. There is a space between the layers of peptidoglycan and the secondary cell membrane called the periplasmic space
6. The S-layer is directly attached to the outer membrane, rather than the peptidoglycan
7. If present, flagella have four supporting rings instead of two
8. No teichoic acids or lipoteichoic acids are present
9. Lipoproteins are attached to the polysaccharide backbone.
10. Most of them contain Braun's lipoprotein, which serves as a link between the outer membrane and the peptidoglycan chain by a covalent bond
11. Most do not sporulate (Coxiella burnetii, which produces spore-like structures, is a notable exception)