Mycoplasma

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Mycoplasma
M. haemofelis IP2011.jpg
Mycoplasma haemofelis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Bacteria
Kingdom: Bacillati
Phylum: Mycoplasmatota
Class: Mollicutes
Order: Mycoplasmatales
Family: Mycoplasmataceae
Genus: Mycoplasma
J.Nowak 1929
Type species
Mycoplasma mycoides
(Borrel et al. 1910) Freundt 1955 (Approved Lists 1980)
Species

See text

Synonyms
  • " Asterococcus " Borrel et al. 1910 non Scherffel 1908 non Borkhsenius 1960
  • "Asteromyces" Wroblewski 1931 non Moreau & Moreau ex Hennebert 1962
  • "Borrelomyces" Turner 1935
  • "Bovimyces" Sabin 1941
  • HaemobartonellaTyzzer & Weinman 1939
  • " Pleuropneumonia " Tulasne & Brisou 1955
Mycoplasmosis
Specialty Infectious disease

Mycoplasma is a genus of bacteria that, like the other members of the class Mollicutes , lack a cell wall, and its peptidoglycan, around their cell membrane. [1] The absence of peptidoglycan makes them naturally resistant to antibiotics such as the beta-lactam antibiotics that target cell wall synthesis. They can be parasitic or saprotrophic. [2]

Contents

In casual speech, the name "mycoplasma" (plural mycoplasmas or mycoplasms) generally refers to all members of the class Mollicutes. In formal scientific classification, the designation Mycoplasma refers exclusively to the genus, a member of the Mycoplasmataceae, the only family in the order Mycoplasmatales (see "scientific classification"). In 2018, Mycoplasma was split with many clinically significant species moved to other genera in Mollicutes; see the page Mollicutes for an overview.

Etymology

The term "mycoplasma", from the Greek μύκης, mykes (fungus) and πλάσμα, plasma (formed), was first used by Albert Bernhard Frank in 1889 to describe an altered state of plant cell cytoplasm resulting from infiltration by fungus-like microorganisms. [3] [4] Julian Nowak later proposed the name mycoplasma for certain filamentous microorganisms imagined to have both cellular and acellular stages in their lifecycles, which could explain how they were visible with a microscope, but passed through filters impermeable to other bacteria. [5]

Later, the name for these mycoplasmas was pleuropneumonia-like organisms (PPLO), broadly referring to organisms similar in colonial morphology and filterability to the causative agent (a Mycoplasma species) of contagious bovine pleuropneumonia. [6] At present, all these organisms are classified as Mollicutes, and the term Mycoplasma solely refers to the genus.[ citation needed ]

Characteristics

Over 100 species were formerly included in the genus Mycoplasma, a member of the class Mollicutes. They are parasites or commensals of humans, animals, and plants. The genus Mycoplasma uses vertebrate and arthropod hosts. [7] Dietary nitrogen availability has been shown to alter codon bias and genome evolution in Mycoplasma and the plant parasites Phytoplasma . [8]

Mycoplasma species are among the smallest free-living organisms (about 0.2–0.3 μm in diameter). [9] [10] They have been found in the pleural cavities of cattle suffering from pleuropneumonia. These organisms are often called MLO (mycoplasma-like organisms) or, formerly, PPLO (pleuropneumonia-like organisms). [6]

Important characteristics

  1. Cell wall is absent and plasma membrane forms the outer boundary of the cell.
  2. Due to the absence of cell walls these organisms can change their shape and leads to pleomorphism.
  3. Lack of nucleus and other membrane-bound organelles.
  4. Genetic material is a single DNA duplex and is naked.
  5. Ribosomes are 70S type.
  6. Possess a replicating disc at one end which assists replication process and also the separation of the genetic materials.
  7. Heterotrophic nutrition. Some live as saprophytes but the majority are parasites of plants and animals. The parasitic nature is due to the inability of mycoplasmal bacteria to synthesise the required growth factor.

Cell and colony morphology

Due to the lack of a rigid cell wall, Mycoplasma species (like all Mollicutes) can contort into a broad range of shapes, from round to oblong. They are pleomorphic and therefore cannot be identified as rods, cocci or spirochetes. [11]

Colony morphology of Mycoplasma on Hayflick agar Mycoplasma Howe Bovine Mastitis 2022.jpg
Colony morphology of Mycoplasma on Hayflick agar

Colonies show the typical "fried egg" appearance (about 0.5 mm in diameter). [10]

Reproduction

In 1954, using phase-contrast microscopy, continual observations of live cells have shown that Mycoplasma species ("mycoplasmas", formerly called pleuropneumonia-like organisms, PPLO, now classified as Mollicutes) and L-form bacteria (previously also called L-phase bacteria) do not proliferate by binary fission, but by a uni- or multi-polar budding mechanism. Microphotograph series of growing microcultures of different strains of PPLOs, L-form bacteria and, as a control, a Micrococcus species (dividing by binary fission) have been presented. [10] Additionally, electron microscopic studies have been performed. [12]

Taxonomy

History of taxonomy

Before 1980, Mycoplasma species (often commonly called "mycoplasmas", now classified as Mollicutes ) were sometimes considered stable L-form bacteria or even viruses, but phylogenetic analysis has identified them as bacteria that have lost their cell walls in the course of evolution. [13]

The medical and agricultural importance of members of the genus Mycoplasma and related genera have led to the extensive cataloging of many of these organisms by culture, serology, and small sub-unit rRNA gene and whole-genome sequencing. A recent focus in the sub-discipline of molecular phylogenetics has both clarified and confused certain aspects of the organization of the class Mollicutes. [14]

Taxonomists once[ when? ] classified Mycoplasma and relatives in the phylum Firmicutes, consisting of low G+C Gram-positive bacteria such as Clostridium , Lactobacillus , and Streptococcus ; but modern polyphasic analyses situate them in the phylum Tenericutes. [15]

By the 1990s, it had become readily apparent that this approach was problematic: the type species, M. mycoides , along with other significant mycoplasma species like M. capricolum, is evolutionarily more closely related to the genus Spiroplasma in the order Entomoplasmatales than to the other members of the genus Mycoplasma. As a result, if the group was to be rearranged to match phylogeny, a number of medically important species (e.g. M. pneumoniae, M. genitalium) would have to be put in a different genus, causing widespread confusion in medical and agricultural communities. The genus was discussed multiple times by the International Committee on Systematic Bacteriology's (ICSB) subcommittee on Mollicutes between 1992 and 2011, to no effect. [16]

Regardless of taxonomy, by 2007 it was solidly known that Molicutes could be divided into four nontaxonomic lineages. [17] [18]

As of 2018

In 2018, Gupta et al. re-circumscribed the genus Mycoplasma around M. mycoides. A total of 78 species were removed from Mycoplasma, creating five new genera and a number of higher taxonomic levels. Under this new scheme, a new family Mycoplasmoidaceae was created to correspond to the "pneumoniae" group, with M. pneumoniae and related species transferred to a new genus Mycoplasmoides. Another new family Metamycoplasmataceae was created to correspond to the "hominis" group. Both families belong to a new order Mycoplasmoitales, distinct from the Mycoplasmatales of Mycoplasma. [18] The taxonomy was accepted by the ICSB with validation list 184 in 2018 and became the correct name. Both List of Prokaryotic names with Standing in Nomenclature (LPSN) [16] and National Center for Biotechnology Information (NCBI) now use the new nomenclature. [19]

Gupta's proposed taxonomy, as expected, moved the medically important "pneumoniae" group out of Mycoplasma into its own genus. As a result, a number of mycoplasmologists petitioned to the ICSB to reject the name in 2019. They argue that although Gupta's phylogenetic methods were likely solid, the proposed name changes are too sweeping to be practically adopted, citing some principles of the Code such as "name stability". [20] Gupta and Oren wrote a rebuttal in 2020, further detailing the pre-existing taxonomic problems. [21] [22] In 2022, the ICSP's Judicial Opinion 122 ruled in favor of the name changes proposed by Gupta, meaning they remain valid under the Prokaryotic Code [23] (and for the purpose of the LPSN, they remain the "correct names"). [22] However, the older names also remain valid; their use remains acceptable under the Code. [23]

Gupta et al. 2019 performed some uncontroversial sorting of the order Mycoplasmatales. [24]

Phylogenies of Mycoplasmasensu stricto/sensu Gupta
16S rRNA based LTP_10_2024 [25] [26] [27] 120 marker proteins based GTDB 09-RS220 [28] [29] [30]
Mycoplasma s.s.

M. putrefaciensTully et al. 1974

M. cottewiiDa Massa et al. 1994

M. yeatsiiDa Massa et al. 1994

M. capri(Edward 1953) Hudson, Cottew & Adler 1967 non El Nasri 1966

M. mycoides (Borrel et al. 1910) Freundt 1955

M. capricolum Tully et al. 1974

M. capricolum capripneumoniaeLeach, Erno & MacOwan 1993

M. leachiiManso-Silván et al. 2009

Mycoplasma s.s.

M. putrefaciens

M. cottewii

M. yeatsii

M. feriruminatorisFischer et al. 2015 [31]

M. capri

M. mycoides

M. capricolum

M. leachii

Unassigned species

The GTDB and LTP phylogeny above does not include a number of names published under this genus that are either correct or pro-correct according to the LPSN. These species likely belong to a different genus under the standards of the 2018 reorganization, but has not been moved because a new combination has not been proposed, or because the new combination has not been made valid publication, or because the taxonomic opinion of the LPSN/LoRN refuses to use the new name as the correct name. The classification of LTP and GTDB is used here to assign a probable target genus.

Many new species have been proposed in Mycoplasma while disregarding the 2018 reorganization; see LPSN for a list. These will be included here and sorted by lineage eventually.

Hemotrophic mycoplasmas: This category includes species that should be moved to Eperythrozoon under the Gupta reorganization.

  • "Ca. M. aoti" Barker et al. 2011
  • "Ca. M. erythrocervae" Watanabe et al. 2010
  • "Ca. M. haematobrackenitadaridae" Becker et al. 2025
  • "Ca. M. haematocervi" corrig. Watanabe et al. 2010
  • "Ca. M. haematodidelphidis" corrig. Messick et al. 2002
  • "Ca. M. haematohominis" corrig. Millán et al. 2015
  • "Ca. M. haematohydrochoeri" corrig. Vieira et al. 2021
  • "Ca. M. haematomacacae" corrig. Maggi et al. 2013
  • "Ca. M. haematominiopteri" corrig. Millán et al. 2015
  • "Ca. M. haematomolossi" Becker et al. 2025
  • "M. haematomyotis" Volokhov et al. 2023
  • "Ca. M. haematonasuae" corrig. Collere et al. 2021
  • "Ca. M. haematoparvum" Sykes et al. 2005
  • "M. haematophyllostomi" Volokhov et al. 2023
  • "Ca. M. haematoselmanitadaridae" Becker et al. 2025
  • "Ca. M. haematosphigguri" corrig. Valente et al. 2021
  • "Ca. M. haematotapirus" Mongruel et al. 2022
  • "Ca. M. haematoterrestris" Mongruel et al. 2022
  • "Ca. M. haematotraderitadaridae" Becker et al. 2025
  • "Ca. M. haematovis" corrig. Hornok et al. 2009
  • "Ca. M. haemobovis" Meli et al. 2010
  • "Ca. M. haemomeles" Harasawa, Orusa & Giangaspero 2014
  • "Ca. M. haemomuris" (Mayer 1921) Neimark et al. 2002
  • "Ca. M. haemoparvum" Kenny et al. 2004
  • "Ca. M. hemominiopterus" Millán et al. 2015

Nested in Mycoplasmoides :

  • "M. bradburyae" Ramírez et al. 2023– in GTDB

Nested in Mycoplasmopsis :

  • M. hafeziiZiegler et al. 2019– in LTP, close to Mycoplsmopsis alligatoris
  • M. phocimorsusSkafte-Holm et al. 2023– in LTP, close to "Mycoplasmopsis elephantis"

Synonimized before 2018 reorganization:

Not in LTP/GTDB, some of which have a 16S in GenBank that can be used to assign the genus:

  • "Ca. M. corallicola" Neulinger et al. 2009–Mycoplsmopsis (among species mentioned in Gupta et al. (2018), "Mycoplsmopsis iguanae" was the highest 16S BLAST hit)
  • "Ca. M. coregoni" corrig. Rasmussen et al. 2021
  • "Ca. M. didelphidis" corrig. Pontarolo et al. 2021
  • "M. insons" May et al. 2007
  • "Ca. M. kahanei" Neimark et al. 2002
  • "M. monodon" Ghadersohi & Owens 1998
  • "M. pneumophila" Lyerova et al. 2008
  • "Ca. M. ravipulmonis" Neimark, Mitchelmore & Leach 1998
  • "Ca. M. salmoniarum" corrig. Rasmussen et al. 2021
  • "M. sphenisci" Frasca et al. 2005
  • "M. timone" Greub & Raoult 2001
  • "Ca. M. tructae" Sanchez et al. 2020
  • "Ca. M. turicense" corrig. Willi et al. 2006
  • "M. volis" Dillehay et al. 1995
  • "M. vulturii" Oaks et al. 2004

Synthetic mycoplasma genome

A chemically synthesized genome of a mycoplasmal cell based entirely on synthetic DNA which can self-replicate has been referred to as Mycoplasma laboratorium . [32] It is therefore a model for a minimal genome, that is, a genome that is reduced to mostly essential genes.

See also

References

  1. ↑ Ryan KJ, Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 409–12. ISBN   978-0-8385-8529-0.
  2. ↑ Larsen B, Hwang J (2010). "Mycoplasma, Ureaplasma, and Adverse Pregnancy Outcomes: A Fresh Look". Infectious Diseases in Obstetrics and Gynecology. 2010: 1–7. doi: 10.1155/2010/521921 . ISSN   1064-7449. PMC   2913664 . PMID   20706675.
  3. ↑ Frank B (1889). "Ueber der Pilzsymbiose der Leguminosen" [On fungal symbioses of legumes]. Berichte der Deutschen Botanischen Gesellschaft (in German). 7: 332–346. From p. 335: "Die durch die Infection entstandene veränderte Art des Plasmas in den Rindenzellen will ich, da sie offenbar durch die Vermischmung mit einem pilzartigen Wesen entstanden ist, als Mycoplasma bezeichnen." [I want to designate as "mycoplasma" the altered type of plasma in the cortex cells which arose by infection, since it [i.e., the altered type of plasma] obviously arose by mixing with a fungal organism.]
  4. ↑ Krass CJ, Gardner MW (January 1973). "Etymology of the Term Mycoplasma". Int. J. Syst. Evol. Microbiol. 23 (1): 62–64. doi: 10.1099/00207713-23-1-62 .
  5. ↑ Browning G, Citti C, eds. (2014). Mollicutes Molecular Biology and Pathogenesis (1st ed.). Caister Academic Press. pp. 1–14. ISBN   978-1-908230-30-0.
  6. 1 2 Edward DG, Freundt EA (February 1956). "The classification and nomenclature of organisms of the pleuropneumonia group" (PDF). J. Gen. Microbiol. 14 (1): 197–207. doi: 10.1099/00221287-14-1-197 . PMID   13306904.
  7. ↑ Maggi RG, Compton SM, Trull CL, Mascarelli PE, Mozayeni BR, Breitschwerdt EB (1 October 2013). "Infection with Hemotropic Mycoplasma Species in Patients with or without Extensive Arthropod or Animal Contact". Journal of Clinical Microbiology. 51 (10): 3237–3241. doi:10.1128/JCM.01125-13. PMC   3811635 . PMID   23863574.– discusses two species, both of which are more adequately put in Eperythrozoon post-2018.
  8. ↑ Seward E, Kelly S (2016). "Dietary nitrogen alters codon bias and genome composition in parasitic microorganisms". Genome Biology. 17 (226): 3–15. doi: 10.1186/s13059-016-1087-9 . PMC   5109750 . PMID   27842572.
  9. ↑ "Mycoplasma". The Lecturio Medical Concept Library. Retrieved 8 July 2021.
  10. 1 2 3 Kandler G, Kandler O (1954). "Untersuchungen über die Morphologie und die Vermehrung der pleuropneumonie-ähnlichen Organismen und der L-Phase der Bakterien. I. Lichtmikroskopische Untersuchungen" [Studies on morphology and multiplication of pleuropneumonia-like organisms and on bacterial L-phase, I. Light microscopy (now mycoplasmas and L-form bacteria)](PDF). Archiv für Mikrobiologie (in German). 21 (2). (Article in English available): 178–201. Bibcode:1954ArMic..21..178K. doi:10.1007/BF01816378. PMID   14350641. S2CID   21257985.
  11. ↑ Gladwin M, Trattler W, Mahan CS (2014). Clinical Microbiology made ridiculously simple. Miami, Fl: MedMaster, Inc. p. 156. ISBN   978-1-935660-15-6.
  12. ↑ Kandler G, Kandler O, Huber O (1954). "Untersuchungen über die Morphologie und die Vermehrung der pleuropneumonie-ähnlichen Organismen und der L-Phase der Bakterien. II. Elektronenmikroskopische Untersuchungen" [Studies on morphology and multiplication of pleuropneumonia-like organisms and on bacterial L-phase, II. Electron microscopy (now mycoplasmas and L-form bacteria)](PDF). Archiv für Mikrobiologie (in German). 21 (2). (Article in English available): 202–216. Bibcode:1954ArMic..21..202K. doi:10.1007/BF01816379. PMID   14350642. S2CID   45546531.
  13. ↑ Woese CR, Maniloff J, Zablen L (1980). "Phylogenetic analysis of the mycoplasmas" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 77 (1): 494–498. Bibcode:1980PNAS...77..494W. doi: 10.1073/pnas.77.1.494 . PMID   692864.
  14. ↑ Johansson K-E, Pettersson B (2002). "Taxonomy of Mollicutes". Molecular Biology and Pathogenicity of Mycoplasmas (Razin S, Herrmann R, eds.). New York: Kluwer Academic/Plenum. pp. 1–30. ISBN   0-306-47287-2.
  15. ↑ Brown DR (2011). "Phylum XVI. Tenericutes Murray 1984a, 356VP". Bergey's Manual of Systematic Bacteriology, Second Edition, Vol. 4, (Krieg NR, Staley JT, Brown DR, et al., eds.). New York: Springer. pp. 567–568. ISBN   978-0-387-95042-6.
  16. 1 2 A.C. Parte, et al. "Mycoplasma". List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved 9 September 2022.
  17. ↑ Oshima K, Nishida H (September 2007). "Phylogenetic relationships among mycoplasmas based on the whole genomic information". J. Mol. Evol. 65 (3): 249–58. Bibcode:2007JMolE..65..249O. doi:10.1007/s00239-007-9010-3. PMID   17687503.
  18. 1 2 Gupta R, Sawnani S, Adeolu M, Alnajar S, Oren A (2018). "Phylogenetic framework for the phylum Tenericutes based on genome sequence data: proposal for the creation of a new order Mycoplasmoidales ord. nov., containing two new families Mycoplasmoidaceae fam. nov. and Metamycoplasmataceae fam. nov. harbouring Eperythrozoon, Ureaplasma and five novel genera". Antonie van Leeuwenhoek. 111 (9): 1583–1630. doi:10.1007/s10482-018-1047-3. PMID   29556819. S2CID   254226604.
  19. ↑ Sayers, et al. "Mycoplasma". National Center for Biotechnology Information (NCBI) taxonomy database. Retrieved 9 September 2022.
  20. ↑ Balish M, Bertaccini A, Blanchard A, Brown D, Browning G, Chalker V, Frey J, Gasparich G, Hoelzle L, Knight T, Knox C, Chih-Horng K, Manso-Silván L, May M, Pollack J, Ramírez A, Spergser J, Taylor-Robinson D, Volokhov D, Zhao Y (2019). "Recommended rejection of the names Malacoplasma gen. nov., Mesomycoplasma gen. nov., Metamycoplasma gen. nov., Metamycoplasmataceae fam. nov., Mycoplasmoidaceae fam. nov., Mycoplasmoidales ord. nov., Mycoplasmoides gen. nov., Mycoplasmopsis gen. nov. [Gupta, Sawnani, Adeolu, Alnajar and Oren 2018] and all proposed species comb. nov. placed therein". International Journal of Systematic and Evolutionary Microbiology. 69 (11): 3650–3653. doi: 10.1099/ijsem.0.003632 . hdl: 11585/720151 . PMID   31385780.
  21. ↑ Gupta RS, Oren A (1 February 2020). "Necessity and rationale for the proposed name changes in the classification of Mollicutes species. Reply to: 'Recommended rejection of the names Malacoplasma gen. nov., Mesomycoplasma gen. nov., Metamycoplasma gen. nov., Metamycoplasmataceae fam. nov., Mycoplasmoidaceae fam. nov., Mycoplasmoidales ord. nov., Mycoplasmoides gen. nov., Mycoplasmopsis gen. nov. [Gupta, Sawnani, Adeolu, Alnajar and Oren 2018] and all proposed species comb. nov. placed therein', by M. Balish et al. (Int J Syst Evol Microbiol, 2019;69:3650–3653)". International Journal of Systematic and Evolutionary Microbiology. 70 (2): 1431–1438. doi: 10.1099/ijsem.0.003869 . PMID   31971499.
  22. 1 2 "Genus: Mycoplasmoides". lpsn.dsmz.de.; see also LPSN FAQ on correct name
  23. 1 2 Arahal DR, Busse HJ, Bull CT, Christensen H, Chuvochina M, Dedysh SN, Fournier PE, Konstantinidis KT, Parker CT, Rossello-Mora R, Ventosa A, Göker M (10 August 2022). "Judicial Opinions 112–122". International Journal of Systematic and Evolutionary Microbiology. 72 (8). doi:10.1099/ijsem.0.005481. PMID   35947640.
  24. ↑ Gupta RS, Son J, Oren A (April 2019). "A phylogenomic and molecular markers based taxonomic framework for members of the order Entomoplasmatales: proposal for an emended order Mycoplasmatales containing the family Spiroplasmataceae and emended family Mycoplasmataceae comprising six genera". Antonie van Leeuwenhoek. 112 (4): 561–588. doi:10.1007/s10482-018-1188-4. PMID   30392177.
  25. ↑ "The LTP" . Retrieved 10 December 2024.
  26. ↑ "LTP_all tree in newick format" . Retrieved 10 December 2024.
  27. ↑ "LTP_10_2024 Release Notes" (PDF). Retrieved 10 December 2024.
  28. ↑ "GTDB release 09-RS220". Genome Taxonomy Database . Retrieved 10 May 2024.
  29. ↑ "bac120_r220.sp_labels". Genome Taxonomy Database . Retrieved 10 May 2024.
  30. ↑ "Taxon History". Genome Taxonomy Database . Retrieved 10 May 2024.
  31. ↑ LPSN lpsn.dsmz.de
  32. ↑ Gibson DG, Glass JI, Lartigue C, Noskov VN, Chuang RY, Algire MA, Benders GA, Montague MG, Ma L, Moodie MM, Merryman C, Vashee S, Krishnakumar R, Assad-Garcia N, Andrews-Pfannkoch C, Denisova EA, Young L, Qi ZQ, Segall-Shapiro TH, Calvey CH, Parmar PP, Hutchison CA, Smith HO, Venter JC (July 2010). "Creation of a bacterial cell controlled by a chemically synthesized genome". Science. 329 (5987): 52–6. Bibcode:2010Sci...329...52G. doi: 10.1126/science.1190719 . PMID   20488990.
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