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==Microbiology== === Morphology === [[File:Model of the Mycobacterial Cell Envelope.png|thumb|upright=1.5|Model of the ''Mycobacterium spp.'' cell envelope with 3-D protein structures]] Mycobacteria are [[aerobic organism|aerobic]] with 0.2-0.6 ΞΌm wide and 1.0-10 ΞΌm long [[Bacillus (shape)|rod shapes]]. They are generally [[Non-motile bacteria|non-motile]], except for the species ''[[Mycobacterium marinum]]'', which has been shown to be motile within [[macrophage]]s.<ref>{{cite journal | vauthors = Stamm LM, Morisaki JH, Gao LY, Jeng RL, McDonald KL, Roth R, Takeshita S, Heuser J, Welch MD, Brown EJ | display-authors = 6 | title = Mycobacterium marinum escapes from phagosomes and is propelled by actin-based motility | journal = The Journal of Experimental Medicine | volume = 198 | issue = 9 | pages = 1361β1368 | date = November 2003 | pmid = 14597736 | pmc = 2194249 | doi = 10.1084/jem.20031072 }}</ref> Mycobacteria possess [[Bacterial capsule|capsules]] and most do not form [[endospores]]. ''M. marinum'' and perhaps ''M. bovis'' have been shown to [[spore|sporulate]];<ref>{{cite journal | vauthors = Ghosh J, Larsson P, Singh B, Pettersson BM, Islam NM, Sarkar SN, Dasgupta S, Kirsebom LA | display-authors = 6 | title = Sporulation in mycobacteria | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 106 | issue = 26 | pages = 10781β10786 | date = June 2009 | pmid = 19541637 | pmc = 2705590 | doi = 10.1073/pnas.0904104106 | doi-access = free | bibcode = 2009PNAS..10610781G }}</ref> however, this has been contested by further research.<ref>{{cite journal | vauthors = Traag BA, Driks A, Stragier P, Bitter W, Broussard G, Hatfull G, Chu F, Adams KN, Ramakrishnan L, Losick R | display-authors = 6 | title = Do mycobacteria produce endospores? | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 107 | issue = 2 | pages = 878β881 | date = January 2010 | pmid = 20080769 | pmc = 2818926 | doi = 10.1073/pnas.0911299107 | doi-access = free | bibcode = 2010PNAS..107..878T }}</ref> The distinguishing characteristic of all ''Mycobacterium'' species is a thick, [[hydrophobic]], and [[mycolic acid]]-rich cell wall made of [[peptidoglycan]] and [[arabinogalactan]], with these unique components offering targets for new tuberculosis drugs.<ref name= BhamidiS>{{cite book | vauthors = Bhamidi S|year=2009|chapter=Mycobacterial Cell Wall Arabinogalactan|title=Bacterial Polysaccharides: Current Innovations and Future Trends|publisher=Caister Academic Press|isbn= 978-1-904455-45-5}}</ref> === Physiology === Many ''Mycobacterium'' species readily grow with minimal nutrients, using [[ammonia]] and/or [[amino acid]]s as nitrogen sources and [[glycerol]] as a carbon source in the presence of mineral salts. Temperatures for optimal growth vary between species and media conditions, ranging from 25 to 45 Β°C.<ref name="Forbes_2018"/> Most ''Mycobacterium'' species, including most clinically relevant species, can be cultured in [[blood agar]].<ref>{{cite journal | vauthors = Lagier JC, Edouard S, Pagnier I, Mediannikov O, Drancourt M, Raoult D | title = Current and past strategies for bacterial culture in clinical microbiology | journal = Clinical Microbiology Reviews | volume = 28 | issue = 1 | pages = 208β236 | date = January 2015 | pmid = 25567228 | pmc = 4284306 | doi = 10.1128/CMR.00110-14 }}</ref> However, some species grow very slowly due to extremely long reproductive cycles, such as ''[[M. leprae]]'' requiring 12 days per division cycle compared to 20 minutes for some ''E. coli'' strains.<ref>{{cite journal | vauthors = Shepard CC, Mcrae DH | title = Mycobacterium leprae in Mice: Minimal Infectious Dose, Relationship Between Staining Quality and Infectivity, and Effect of Cortisone | journal = Journal of Bacteriology | volume = 89 | issue = 2 | pages = 365β372 | date = February 1965 | pmid = 14255702 | pmc = 305516 | doi = 10.1128/jb.89.2.365-372.1965 }}</ref> === Ecology === Whereas ''Mycobacterium tuberculosis'' and ''M. leprae'' are pathogenic, most mycobacteria do not cause disease unless they enter skin lesions of those with pulmonary and/or immune dysfunction, despite being widespread across aquatic and terrestrial environments. Through [[biofilm]] formation, cell wall resistance to [[chlorine]], and association with [[amoeba]]s, mycobacteria can survive a variety of environmental stressors. The agar media used for most [[water testing]] does not support the growth of mycobacteria, allowing it to go undetected in municipal and hospital systems.<ref>{{cite journal | vauthors = Vaerewijck MJ, Huys G, Palomino JC, Swings J, Portaels F | title = Mycobacteria in drinking water distribution systems: ecology and significance for human health | journal = FEMS Microbiology Reviews | volume = 29 | issue = 5 | pages = 911β934 | date = November 2005 | pmid = 16219512 | doi = 10.1016/j.femsre.2005.02.001 | doi-access = free }}</ref> === Genomics === Hundreds of ''Mycobacterium'' genomes have been completely sequenced.<ref>{{Cite web |title=JGI GOLD {{!}} Projects |url=https://gold.jgi.doe.gov/projects?Project.Is+Public=Yes&Organism.Organism+Name=Mycobacterium&Organism.Organism+Name=Mycobacterium&Project.Project+Status=Complete+and+Published&Project.Is+Public=Yes&Project.Project+Status=Complete+and+Published |access-date=2023-05-13 |website=gold.jgi.doe.gov}}</ref> The genome sizes of mycobacteria range from relatively small ones (e.g. in ''M. leprae'') to quite large ones, such as that as ''[[Mycobacterium vulneris|M. vulneris]],'' encoding 6,653 proteins, larger than the ~6000 proteins of [[Eukaryote|eukaryotic]] [[Saccharomyces cerevisiae|yeast]].<ref>{{cite journal |vauthors=Croce O, Robert C, Raoult D, Drancourt M |date=May 2014 |title=Draft Genome Sequence of Mycobacterium vulneris DSM 45247T |journal=Genome Announcements |volume=2 |issue=3 |doi=10.1128/genomeA.00370-14 |pmc=4014686 |pmid=24812218}}</ref> {| class="wikitable" |+Protein-Coding Genomic Information !Organism !Number of Protein Coding Genes |- |''M. intracellulare'' |5,289<ref>{{Cite web |title=UniProt |url=https://www.uniprot.org/proteomes/UP000595205 |access-date=2023-05-07 |website=www.uniprot.org}}</ref> |- |[[Mycobacterium colombiense|''M. colombiense'']] |5,084<ref>{{Cite web |title=UniProt |url=https://www.uniprot.org/proteomes/UP000250915 |access-date=2023-05-07 |website=www.uniprot.org}}</ref> |- |''M. leprae'' |1,603<ref name="uniprot_UP000000806">{{Cite web |title=UniProt |url=https://www.uniprot.org/proteomes/UP000000806 |access-date=2023-05-07 |website=www.uniprot.org}}</ref> |- |''M. tuberculosis'' |3,995<ref name="uniprot_UP000000806"/> |- |''M. smegmatis'' |6,602<ref>{{Cite web |title=UniProt |url=https://www.uniprot.org/proteomes/UP000000757 |access-date=2023-05-07 |website=www.uniprot.org}}</ref> |- |''M. chelonae'' |4,948<ref>{{Cite web |title=UniProt |url=https://www.uniprot.org/proteomes/UP000317728 |access-date=2023-05-07 |website=www.uniprot.org}}</ref> |}
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