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Gram negative rods in csf8/28/2023 ( March 2014) ( Learn how and when to remove this template message)īacteria are traditionally classified based on their Gram-staining response into the gram-positive and gram-negative bacteria. Please help improve it to make it understandable to non-experts, without removing the technical details. This section may be too technical for most readers to understand. However some authors, such as Cavalier-Smith still treat them as a monophyletic taxon (though not a clade his definition of monophyly requires a single common ancestor but does not require holophyly, the property that all descendants be encompassed by the taxon) and refer to the group as a subkingdom "Negibacteria". Since 1987, the monophyly of the gram-negative bacteria has been disproven with molecular studies. Historically, the kingdom Monera was divided into four divisions based on Gram staining: Firmacutes (+), Gracillicutes (−), Mollicutes (0) and Mendocutes (var.). Most, with few exceptions, do not form sporesĪlong with cell shape, Gram staining is a rapid diagnostic tool and once was used to group species at the subdivision of Bacteria.Some contain Braun's lipoprotein, which serves as a link between the outer membrane and the peptidoglycan chain by a covalent bond.Lipoproteins are attached to the polysaccharide backbone.Teichoic acids or lipoteichoic acids are absent.If present, flagella have four supporting rings instead of two.The S-layer is directly attached to the outer membrane rather than to the peptidoglycan. Between the outer membrane and the cytoplasmic membrane there is a space filled with a concentrated gel-like substance called periplasm.Porins exist in the outer membrane, which act like pores for particular molecules.Has outer membrane containing lipopolysaccharides (LPS, which consists of lipid A, core polysaccharide, and O antigen) in its outer leaflet and phospholipids in the inner leaflet.A thin peptidoglycan layer is present (this is much thicker in gram-positive bacteria).
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