- Planctomycetes
Taxobox
color = lightgrey
name = "Planctomycetes"
image_caption =
domain = Bacteria
phylum = Planctomycetes
classis = Planctomycetia
ordo = Planctomycetales
ordo_authority = Schlesner & Stackebrandt, 1987
familia = Planctomycetaceae
familia_authority = Schlesner & Stackebrandt, 1987
subdivision_ranks = Genera
subdivision = "Gemmata "
"Isosphera "
"Pirellula "
"Planctomyces "
"candidatus Brocadia"
"candidatus Kuenenia"
"candidatus Scalindua"
"candidatus Anammoxoglobus"Planctomycetes are a
phylum of aquaticbacteria and are found in field samples of brackish, and marine and freshwater samples. They reproduce bybudding . In structure, the organisms of this group are ovoid and have aholdfast , called the stalk, at the nonreproductive end that helps them to attach to each other during budding.Cavalier-Smith has postulated that the Planctomycetes are within the cladePlanctobacteria in the larger cladeGracilicutes .tructure
The
organism s belonging to this group lack murein in theircell wall . Murein is an importantheteropolymer present in mostbacteria l cell walls that serves as a protective component in the cell wallskeleton . Instead their walls are made up ofglycoprotein rich inglutamate . Planctomycetes have internal structures that are more complex than would be typically expected inprokaryotes . While they don't have a nucleus in the eukaryotic sense, thenuclear material can sometimes be enclosed in a double membrane. In addition to thisnucleoid , there are two other membrane-separated compartments; the pirellulosome or riboplasm, which contains theribosome and relatedproteins , and the ribosome-free paryphoplasm (Glockner, 2003).Genome
RNA sequencing shows that the planctomycetes are distantly related to the otherbacteria . Their closest relations appear to be theVerrucomicrobia andChlamydiae . Hou S., Makarova K.S., Saw J.H., Senin P., Ly B.V., Zhou Z., Ren Y., Wang J., Galperin M.Y., Omelchenko M.V., Wolf Y.I., Yutin N., Koonin E.V., Stott M.B., Mountain B.W., Crowe M.A., Smirnova A.V., Dunfield P.F., Feng L., Wang L., Alam M. 2008 Complete genome sequence of the extremely acidophilic methanotroph isolate V4, "Methylacidiphilum infernorum", a representative of the bacterial phylum "Verrucomicrobia". Biol. Direct. 3(1):26. ] A number of essential pathways are not organised as operons, which is unusual for bacteria (Glöckner, 2003). A number of genes have been found (through sequence comparisons) that are similar to genes found in eukaryotes. One such example is a gene sequence (in "Gemmata obscuriglobus") that was found to have significant homology to theintegrin alpha-V, a protein that is important in transmembrane signal transduction in eukaryotes (Jenkins "et al.", 2002).Life cycle
The life cycle 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.References
*
*External links
* [http://planctomycetes.en.xanax-prescription.be/]
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