Gram-negative bacteria
Bacteria with a thin cell wall and outer membrane, often antibiotic-resistant.
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They do not retain the crystal violet stain used in Gram staining.[1] Every habitat on Earth that sustains life contains these bacteria.[1]
Quick Facts
- Classification
- Diderm bacteria (two membranes)
- Defining feature
- Thin peptidoglycan layer between inner and outer membranes
- Outer membrane composition
- Lipopolysaccharides (LPS) in outer leaflet, phospholipids in inner leaflet
- Medically relevant pathogens
- Escherichia coli
- Pseudomonas aeruginosa
- Yersinia pestis
- Neisseria gonorrhoeae
- Antibiotic resistance factor
- Outer membrane barrier against penicillin
- detergents
- lysozyme
- Toxin component
- Lipid A of LPS can trigger septic shock
Facts from the source article.
Key facts and history
Since 1987, molecular studies have disproven the monophyly of gram-negative bacteria.[2] Gram-negative bacteria are also known as diderm bacteria because they have two membranes.[3] The outer membrane acts as a protective barrier against many antibiotics, including penicillin.[4] At one time, bacterial species were categorized at the subdivision level using the Gram staining technique.[2]
The kingdom Monera was historically split into four divisions according to Gram staining results.[2] Two major groupings plus some intermediate forms make up the current classification of gram-negative bacteria.[5] The kingdom Pseudomonadati contains the conventional LPS-diderm group, which all descend from a common ancestor.[5] An outer membrane and a cell wall composed of mycolic acid are features of the order Mycobacteriales.[5]
When immune cells lyse bacteria, the lipid A part of lipopolysaccharide can provoke a poisonous response.[4] Septic shock, characterized by low blood pressure and respiratory failure, can result from this response.[4]
References
- Wikipedia, "Gram-negative bacteria" (CC BY-SA 4.0), which cites: "Medical Microbiology", University of Texas Medical Branch at Galveston, 1996; Silhavy, "The Bacterial Cell Envelope", Cold Spring Harbor Perspectives in Biology, 2010-05-01 (original not read by us) en.wikipedia.org
- Wikipedia, "Gram-negative bacteria" (CC BY-SA 4.0), which cites: Gibbons, "Proposals Concerning the Higher Taxa of Bacteria", International Journal of Systematic Bacteriology, 1978, p. 1–6; Woese CR, "Bacterial evolution", Microbiol. Rev., June 1987, p. 221–71 (original not read by us) en.wikipedia.org
- Wikipedia, "Gram-negative bacteria" (CC BY-SA 4.0), which cites: Gupta, "Protein phylogenies and signature sequences: A reappraisal of evolutionary relationships among archaebacteria, eubacteria, and eukaryotes", Microbiol. Mol. Biol. Rev., December 1998, p. 1435–91; Gupta RS, "The natural evolutionary relationships among prokaryotes", Crit. Rev. Microbiol., 2000, p. 111–31; "Secretion and subcellular localizations of bacterial proteins: a semantic awareness issue", Trends Microbiol., April 2009, p. 139–45; Sutcliffe IC, "A phylum level perspective on bacterial cell envelope architecture", Tre en.wikipedia.org
- Wikipedia, "Gram-negative bacteria" (CC BY-SA 4.0), which cites: Pelletier, "Medical Microbiology", University of Texas Medical Branch at Galveston, 1996 (we also read that source) en.wikipedia.org
- Wikipedia, "Gram-negative bacteria" (CC BY-SA 4.0), which cites: Göker, "Valid publication of names of two domains and seven kingdoms of prokaryotes", International Journal of Systematic and Evolutionary Microbiology, 22 January 2024; Gupta, "Commentary: Genome-Based Taxonomic Classification of the Phylum Actinobacteria", Frontiers in Microbiology, 22 February 2019, p. 206 (original not read by us) en.wikipedia.org
Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Gram-negative bacteria (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.
More in Higher-Level Taxonomy & Evolution
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Gram-negative bacteria (CC BY-SA 4.0).
- Word definitions: the , each quoted from its Wikipedia article.
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