PLANCTOMYCETES are a phylum of aquatic bacteria and are found in samples of brackish , and marine and fresh water . They reproduce by budding . In structure, the organisms of this group are ovoid and have a holdfast , at the tip of a thin cylindrical extension from the cell body called the stalk, at the nonreproductive end that helps them to attach to each other during budding.
* 1 Structure * 2 Molecular Signatures * 3 Life cycle * 4 Phylogeny * 5 Taxonomy * 6 See also * 7 References * 8 External links
For a long time bacteria belonging to this group were considered to lack peptidoglycan , (also called murein) in their cell walls , which is an important heteropolymer present in most bacterial cell walls that serves as a protective component. It was thought that instead their walls were made up of glycoprotein which is rich in glutamate . Recently, however, representatives of all three clades within the Planctomycetes were found to possess peptidoglycan containing cell walls.
Planctomycetes have a distinctive morphology with the appearance of membrane -bound internal compartments, often referred to as the paryphoplasm (ribosome-free space), pirellulosome (ribosome-containing space) and nucleoid (condensed nucleic acid region, in these species surrounded by a double membrane). Until the discovery of the Poribacteria , planctomycetes were the only bacteria known with these apparent internal compartments. Three-dimensional electron tomography reconstruction of a representative species, Gemmata obscuriglobus , has yielded varying interpretations of this observation. One 2013 study found the appearance of internal compartments to be due to a densely invaginated but continuous single membrane, concluding that only the two compartments typical of Gram-negative bacteria - the cytoplasm and periplasm - are present. However, the excess membrane triples the surface area of the cell relative to its volume, which may be related to Gemmata's sterol biosynthesis abilities. A 2014 study using similar methods reported confirmation of the earlier enclosed compartment hypothesis.
It has recently been shown that Gemmata obscuriglobus is able to take in large molecules via a process which in some ways resembles endocytosis , the process used by eukaryotic cells to engulf external items.
Although the Planctomycetes are renowned for their unusual cellular characteristics, their distinctness from all other bacteria is additionally supported by the shared presence of two conserved signature indels (CSIs). These CSIs demarcate the group from neighboring phyla within the PVC group . An additional CSI has been found that is shared by all Planctomycetes species, with the exception of Kuenenia stuttgartiensis , which is in line with the observation that K. stuttgartiensis forms a deep branch within the phylum.
A conserved signature indel has also been found to be shared by the entire PVC group , including Planctomycetes. Planctomycetes also harbours an important conserved signature protein that has been characterized to play an important housekeeping function that is exclusive to members belonging to the PVC clade.
The life cycle of many planctomycetes involves alternation between sessile cells and flagellated swarmer cells. The sessile cells bud to form the flagellated swarmer cells which swim for a while before settling down to attach and begin reproduction.
The phylogeny based on the work of the All-Species Living Tree Project .
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LSPN) and the National Center for Biotechnology Information (NCBI).
* Class PHYCISPHAERAE Fukunaga et al. 2010
* Order TEPIDISPHAERALES Kovaleva et al. 2015
* Family TEPIDISPHAERACEAE Kovaleva et al. 2015
* Genus Tepidisphaera Kovaleva et al. 2015
* Species Tepidisphaera mucosa Kovaleva et al. 2015
* Order PHYCISPHAERALES Fukunaga et al. 2010
* Family PHYCISPHAERACEAE Fukunaga et al. 2010
* Genus Algisphaera Yoon, Jang & Kasai 2014
* Species Algisphaera agarilytica Yoon, Jang & Kasai 2014
* Genus Phycisphaera Fukunaga et al. 2010
* Species Phycisphaera mikurensis Fukunaga et al. 2010
* Class PLANCTOMYCETACIA
* Species ?"Candidatus Nostocoida limicola III " ♠ Liu et al. 2001 * Species ?"Candidatus Nostocoida acidiphila " ♠ Kulichevskaya et al. 2012
* Order "BROCADIALES " Jetten et al. 2011
* Family "BROCADIACEAE " Jetten et al. 2011
* Genus "Candidatus Anammoxoglobus " Kartal et al. 2006
* Species "Candidatus Anammoxoglobus propionicus " Kartal et al. 2006
* Genus "Candidatus Brocadia " Jetten et al. 2001
* Species "Candidatus B. anammoxidans " Jetten et al. 2001 * Species "Candidatus B. brasiliensis " Araujo et al. 2011 * Species "Candidatus B. caroliniensis " * Species "Candidatus B. fulgida " Kartal et al. 2004 * Species "Candidatus B. sinica " Hu et al. 2010
* Genus "Candidatus Jettenia " Quan et al. 2008
* Species "Candidatus Jettenia asiatica " Quan et al. 2008 * Species "Candidatus Jettenia caeni " Ali et al. 2015 * Species "Candidatus Jettenia moscovienalis " Nikolaev et al. 2015
* Genus "Candidatus Kuenenia " Schmid et al. 2000
* Species "Candidatus Kuenenia stuttgartiensis " Schmid et al. 2000
* Genus "Candidatus Scalindua " Schmid et al. 2003
* Species "Candidatus S. arabica " Woebken et al. 2008 * Species "Candidatus S. marina " Van de Vossenberg et al. 2007 * Species "Candidatus S. profunda " Van De Vossenberg et al. 2008 * Species "Candidatus S. richardsii " Fuchsman et al. 2012 * Species "Candidatus S. wagneri " Schmid et al. 2003 * Species "Candidatus S. sorokinii " Kuypers et al. 2003 * Species Candidatus S. brodae Schmid et al. 2003
* Order PLANCTOMYCETALES Schlesner & Stackebrandt 1987 emend. Ward 2011
* Family PLANCTOMYCETACEAE Schlesner & Stackebrandt 1987 emend. Scheuner et al. 2014
* Genus "Bythopirellula " ♠ Storesund & Ovreas 2013
* Species "Bythopirellula goksoyri " ♠ Storesund & Ovreas 2013
* Genus "Candidatus Anammoximicrobium " ♠ Khramenkov et al. 2013
* Species "Candidatus Anammoximicrobium moscowii " ♠ Khramenkov et al. 2013
* Genus Aquisphaera Bondoso et al. 2011
* Species Aquisphaera giovannonii Bondoso et al. 2011
* Genus Blastopirellula Schlesner et al. 2004
* Species B. cremea Lee et al. 2013 * Species B. marina (Schlesner 1987) Schlesner et al. 2004
* Genus Gemmata Franzmann and Skerman 1985
* Species Gemmata obscuriglobus Franzmann & Skerman 1985
* Genus Gimesia Scheuner et al. 2015
* Species Gimesia maris Scheuner et al. 2015
* Genus Paludisphaera Kulichevskaya et al. 2015
* Species Paludisphaera borealis Kulichevskaya et al. 2015
* Genus Pirellula Schlesner & Hirsch 1987 emend. Schlesner et al. 2004
* Species Pirellula staleyi Schlesner & Hirsch 1987
* Genus Planctomicrobium Kulichevskaya et al. 2015
* Species Planctomicrobium piriforme Kulichevskaya et al. 2015
* Genus Planctomyces Gimesi 1924
* Species P. bekefii ♪ Gimesi 1924 (type sp.) * Species P. guttaeformis ♪ (ex Hortobágyi 1965) Starr and Schmidt 1984 * Species P. stranskae ♪ (ex Wawrik 1952) Starr and Schmidt 1984
* Genus Planctopirus Scheuner et al. 2015
* Species Planctopirus limnophila corrig. (Hirsch -webkit-column-width: 30em; column-width: 30em; list-style-type: decimal;">
* ^ Jeske, O., Schueler, M., Schumann, P., Schneider, A., Boedeker, C., Jogler, M., Bollschweiler, D., Rohde, M., Mayer, C., Engelhardt, H., Spring, S. & Jogler, C. (2015). " Planctomycetes do possess a peptidoglycan cell wall". Nature Communications. 6: 7116. PMC 4432640 . PMID 25964217 . doi :10.1038/ncomms8116 . CS1 maint: Uses authors parameter (link ) * ^ van Teeseling, M.C.F., Mesman, R.J., Kuru, E., Espaillat, A., Cava, F., Brun, Y.V., VanNieuwenhze, M.S., Kartal, B & van Niftrik, L. (2015). " Anammox Planctomycetes have a peptidoglycan cell wall". Nature Communications. 6: 6878. PMC 4432595 . PMID 25962786 . doi :10.1038/ncomms7878 . CS1 maint: Uses authors parameter (link ) * ^ Lindsay, M. R.; Webb, R. I.; Strous, M; Jetten, M. S.; Butler, M. K.; Forde, R. J.; Fuerst, J. A. (2001). "Cell compartmentalisation in planctomycetes: Novel types of structural organisation for the bacterial cell". Archives of microbiology. 175 (6): 413–29. PMID 11491082 . doi :10.1007/s002030100280 . * ^ Glöckner, F. O.; Kube, M; Bauer, M; Teeling, H; Lombardot, T; Ludwig, W; Gade, D; Beck, A; Borzym, K; Heitmann, K; Rabus, R; Schlesner, H; Amann, R; Reinhardt, R (2003). "Complete genome sequence of the marine planctomycete Pirellula sp. Strain 1" . Proceedings of the National Academy of Sciences. 100 (14): 8298–303. PMC 166223 . PMID 12835416 . doi :10.1073/pnas.1431443100 . * ^ Fieseler, L; Horn, M; Wagner, M; Hentschel, U (June 2004). "Discovery of the novel candidate phylum "Poribacteria" in marine sponges." . Applied and Environmental Microbiology. 70 (6): 3724–32. PMC 427773 . PMID 15184179 . doi :10.1128/aem.70.6.3724-3732.2004 .
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