Higher-Level Taxonomy & Evolution Codexery

Gram-positive bacteria

Bacteria with thick peptidoglycan retaining crystal violet stain.

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Gram-positive bacteria are defined by a thick peptidoglycan layer that retains the crystal violet stain in the Gram staining procedure.[1][2] They are bound by a single lipid membrane and lack the outer membrane found in gram-negative bacteria.[2] The term "monoderm bacteria" has been proposed for cells with a single cell membrane.[2]

Key facts and history

The Gram stain was named after Hans Christian Gram, and the adjectives "Gram-positive" and "Gram-negative" may be capitalized or lowercased depending on the style guide used.[3] Historically, the kingdom Monera was divided into four divisions based primarily on Gram staining, with Bacillota being the positive-staining division.[4] Carl Woese's 16S ribosomal RNA studies challenged the monophyly of gram-positive bacteria and led to the recognition of twelve bacterial phyla.[4][5] Two of those phyla were gram-positive: the high G+C Actinobacteria and the low G+C Firmicutes.[5]

Only some gram-positive species have a capsule, and only some are flagellates, with flagella having just two basal body rings.[6] Six gram-positive genera are typically pathogenic in humans, including the cocci Streptococcus and Staphylococcus and the rod-shaped Bacillus and Clostridium.[7] Because gram-positive bacteria lack an outer membrane, they are more susceptible to antibiotics like penicillin that target cell wall construction.[8] Teichoic acids, including lipoteichoic acids that help secure the peptidoglycan layer, are a distinctive feature of gram-positive bacterial cell walls.[6]

In methicillin-resistant Staphylococcus aureus (MRSA), a gram-positive bacterium, resistance to beta-lactam antibiotics occurs because the drug is unable to properly attach to the bacterial enzymes responsible for cell wall assembly.[9]

What the research sources say

The Open Library record for "Clinical Microbiology Made Ridiculously Simple" lists its publication by MedMaster Inc. in February 2007.[10] The Open Library record for "Brock biology of microorganisms" lists its publication by Pearson Prentice Hall in 2006.[11] Basic Biology states that bacteria are ancient, single-celled organisms found everywhere on Earth.[1] Basic Biology notes that differences in cell wall structure separate bacteria into gram-positive and gram-negative groups.[1]

According to Basic Biology, gram-positive bacteria possess a substantial peptidoglycan layer in their cell wall, whereas gram-negative bacteria lack such a thick layer.[1]

References

  1. Basic Biology, "Bacteria", 18 March 2016. facts only, no text reused. basicbiology.net
  2. Wikipedia, "Gram-positive bacteria" (CC BY-SA 4.0), which cites: Gupta, "Protein phylogenies and signature sequences: A reappraisal of evolutionary relationships among archaebacteria, eubacteria and eukaryotes", Microbiology and Molecular Biology Reviews, 1998, p. 1435–1491; Gupta, "What are archaebacteria: life's third domain or monoderm prokaryotes related to Gram-positive bacteria? A new proposal for the classification of prokaryotic organisms", Molecular Microbiology, 1998, p. 695–707 (original not read by us) en.wikipedia.org
  3. Wikipedia, "Gram-positive bacteria" (CC BY-SA 4.0), which cites: "Emerging Infectious Diseases Journal Style Guide", CDC.gov (we also read that source) en.wikipedia.org
  4. Wikipedia, "Gram-positive bacteria" (CC BY-SA 4.0), which cites: Gibbons, "Proposals Concerning the Higher Taxa of Bacteria", International Journal of Systematic and Evolutionary Microbiology, 1978, p. 1–6; Woese, "Bacterial evolution", Microbiological Reviews, 1987, p. 221–271 (original not read by us) en.wikipedia.org
  5. Wikipedia, "Gram-positive bacteria" (CC BY-SA 4.0), which cites: Woese, "Bacterial evolution", Microbiological Reviews, 1987, p. 221–271 (original not read by us) en.wikipedia.org
  6. Wikipedia, "Gram-positive bacteria" (CC BY-SA 4.0), which cites: Brown, "Wall Teichoic Acids of Gram-Positive Bacteria", Annual Review of Microbiology, 2013-09-08, p. 313–336 (original not read by us) en.wikipedia.org
  7. Wikipedia, "Gram-positive bacteria" (CC BY-SA 4.0), which cites: Gladwin, "Clinical Microbiology Made Ridiculously Simple", MedMaster, 2007, p. 4–5; Sahebnasagh, "Detection of methicillin-resistant Staphylococcus aureus strains from clinical samples in Tehran by detection of the mecA and nuc genes", 4–7 September 2011 (we also read that source) en.wikipedia.org
  8. Wikipedia, "Gram-positive bacteria" (CC BY-SA 4.0), which cites: Basic Biology, "Bacteria", 18 March 2016 (we also read that source) en.wikipedia.org
  9. Wikipedia, "Gram-positive bacteria" (CC BY-SA 4.0), which cites: MacDonald, "Avery's Neonatology: Pathophysiology and Management of the Newborn", Wolters Kluwer, 2015; Lau, "Catabacter hongkongensis gen. nov., sp. nov., Isolated from Blood Cultures of Patients from Hong Kong and Canada", Journal of Clinical Microbiology, 22 November 2006, p. 395–401; CDC, "Methicillin-resistant Staphylococcus aureus (MRSA) Basics", Methicillin-resistant Staphylococcus aureus (MRSA), 2025-06-26 (we also read that source) en.wikipedia.org
  10. Open Library record, ISBN 9780940780811 ("Clinical Microbiology Made Ridiculously Simple (Medmaster)"). CC0 (metadata); book content not read. openlibrary.org
  11. Open Library record, ISBN 9780131443297 ("Brock biology of microorganisms"). CC0 (metadata); book content not read. openlibrary.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-positive 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.

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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.

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