Grammnegatiivset

Grammnegatiivset, also known as Gram-negative bacteria, are a group of bacteria that lack a thick peptidoglycan layer in their cell walls, which is a characteristic feature of Gram-positive bacteria. This absence of peptidoglycan allows Gram-negative bacteria to retain the crystal violet stain used in the Gram stain procedure, resulting in a pink or red appearance under the microscope. The cell walls of Gram-negative bacteria are typically composed of a thin peptidoglycan layer, an outer membrane, and an outer layer of lipopolysaccharides (LPS) and lipoproteins.

The outer membrane of Gram-negative bacteria is a phospholipid bilayer that contains porins, which are protein channels that allow the passage of small molecules and ions. This membrane is impermeable to many antibiotics, making Gram-negative bacteria more resistant to certain antimicrobial treatments compared to Gram-positive bacteria. The outer layer of LPS and lipoproteins provides additional protection and contributes to the virulence of some Gram-negative pathogens.

Examples of Gram-negative bacteria include Escherichia coli, Salmonella, Pseudomonas aeruginosa, and Klebsiella pneumoniae. These bacteria can cause a wide range of infections, from urinary tract infections to severe systemic infections such as sepsis. The study of Gram-negative bacteria is important in the fields of microbiology, immunology, and infectious disease research.