Name: planctomycetes cell structure and life cycle
Uploaded: 2025-06-12T09:20:11.000Z
Duration: 1 min 26 s
Channel: JoVE

Planctomyceten werden in zwei Ordnungen eingeteilt – Planctomycetales und Brocadiales. Diese gramnegativen Bakterien weisen einzigartige Eigenschaften auf. Sie teilen sich durch Knospen. Einige haben Stiele oder Anhängsel, während andere rosettenartige Zellanordnungen bilden. Bestimmte Spezies besitzen eine S-Schicht in ihrer Zellhülle. Alle Planctomyceten weisen intrazelluläre Kompartimente auf, die eukaryotischen Organellen ähneln. Sie produzieren spezialisierte Strukturen, die als Pirellulosomen bekannt sind, bei denen es sich um membranumschlossene Kompartimente handelt, die das Nukleoid, die Ribosomen und andere zytoplasmatische Komponenten enthalten. Bei der Gattung Gemmata ist das Nukleoid weiter von Einstülpungen der Zellmembran umgeben, wodurch eine Struktur entsteht, die von einer echten Einheitsmembran umgeben ist. Die Gattung Isosphaera ist ein filamentöses, gleitendes Bakterium, das in heißen Quellen vorkommt. Ein weiteres bemerkenswertes Kompartiment, das Anammoxosom, findet sich in Mitgliedern der Ordnung Brocadiales, wie z. B. Brocadia anammoxidans. Das Anammoxosom erleichtert die anaerobe Oxidation von Ammoniak – eine Form der Chemolithoautotrophie. Das toxische Hydrazin-Zwischenprodukt dieser Reaktion ist in seiner einzigartigen Lipidmembran enthalten und schützt die zytoplasmatischen Komponenten.

bakterien phylum planctomycetes

Bacterial Phylum Planctomycetes 

Planctomyceten sind eine Gruppe morphologisch unterschiedlicher Bakterien, die haupts&#228;chlich in zwei Ordnungen eingeteilt werden: Planctomycetales und Brocadiales. Diese gramnegativen Bakterien weisen einzigartige Merkmale auf, darunter Zellteilung durch Knospung sowie Stiele oder Anh&#228;nge an ihren Zellen. Ihre Zellen treten h&#228;ufig in Rosettenanordnungen auf und sind au&#223;ergew&#246;hnlich aufgrund der S-Schicht in der Zellh&#252;lle, ein Merkmal, das bei Bakterien relativ selten vorkommt. Dar&#252;ber hinaus zeigen Planctomyceten oft intrazellul&#228;re Kompartimente, die eukaryotischen Organellen &#228;hneln.
W&#228;hrend sich Prokaryoten und Eukaryoten typischerweise deutlich in ihrer Zellstruktur unterscheiden, stellt die Kompartimentierung bei Planctomyceten diese Unterscheidung in Frage. Eukaryotische Zellen besitzen einen membranumh&#252;llten Zellkern, wohingegen die prokaryotische DNA in einem Nukleoid im Cytoplasma kompaktiert ist. Planctomyceten hingegen bilden spezialisierte Strukturen, sogenannte Pirellulosomen, nicht von einer Einheitsmembran, auch Doppelschichtmembran genannt, umgebene Kompartimente, die das Nukleoid, Ribosomen und andere zytoplasmatische Komponenten enthalten.
Der Lebenszyklus von Planctomyces verl&#228;uft &#252;ber Knospung. Bewegliche Schw&#228;rmerzellen haften an einer Oberfl&#228;che, entwickeln an der Anhaftungsstelle einen Stiel und produzieren an der gegen&#252;berliegenden Zellpolseite eine neue Zelle durch Knospung. Diese Tochterzelle entwickelt anschlie&#223;end ein Flagellum, l&#246;st sich von der Mutterzelle und beginnt einen neuen Zyklus. Physiologisch gesehen sind Planctomyces-Arten fakultativ aerob und k&#246;nnen entweder durch oxidative Zellatmung oder durch Fermentation von Zuckern wachsen. Sie bewohnen verschiedene aquatische Lebensr&#228;ume, einschlie&#223;lich S&#252;&#223;- und Meerwasser&#246;kosystemen. Die Gattung Isosphaera, ein Verwandter von Planctomyces, ist ein filament&#246;ses, gleitendes Bakterium, das in hei&#223;en Quellen vorkommt. Die Isolierung von Planctomyces und verwandten Arten erfordert in der Regel n&#228;hrstoffarme Medien.
In bestimmten Gattungen, wie Gemmata, wird das Nukleoid zus&#228;tzlich durch Einst&#252;lpungen der Zellmembran eingeschlossen, wodurch eine Struktur entsteht, die von einer Einheitsmembran, oder auch Doppelschichtmembran, umgeben ist. Trotz dieser strukturellen Komplexit&#228;t liegt die DNA weiterhin in einer kovalent geschlossenen, zirkul&#228;ren und superhelikalisierten Form vor, wie sie f&#252;r bakterielle Genome typisch ist.
Ein weiteres bemerkenswertes Kompartiment, das Anammoxosom, findet sich in Mitgliedern der Ordnung Brocadiales, wie Brocadia anammoxidans. Diese Struktur erm&#246;glicht die anaerobe Oxidation von Ammoniak und ist durch eine einzigartige Lipidmembran gesch&#252;tzt, die eine Sch&#228;digung durch toxische Zwischenprodukte dieses Stoffwechselprozesses verhindert.
Planctomyces ist eine der am umfassendsten untersuchten Gattungen innerhalb dieses Stammes. &#196;hnlich dem gestielten Bakterium Caulobacter weist Planctomyces einen Stiel auf, dessen Struktur sich jedoch durch seine Zusammensetzung aus ausschlie&#223;lich Protein unterscheidet &#8211; ohne Zellwand oder Cytoplasma. Der Stiel dient haupts&#228;chlich als Anheftungsmechanismus und ist schlanker als der prosthekale Stiel von Caulobacter.

Bakterien Phylum Planctomycetes

Planctomyceten sind eine Gruppe morphologisch unterschiedlicher Bakterien, die haupts&#228;chlich in zwei Ordnungen eingeteilt werden: Planctomycetales ...

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planctomycetes cell structure and life cycle

Planctomycetes are a group of gram-negative bacteria known for unusual cell structures and a distinctive life cycle. They are mainly placed in two orders, Planctomycetales and Brocadiales. Many cells show stalks or other appendages and often appear in rosette groups.

A key feature of these bacteria is their cell envelope. Planctomycetes have an S-layer, a surface layer that is relatively uncommon in bacteria. They also divide by budding, which is different from the simple cell split seen in many other bacteria.

Planctomycetes are also known for internal compartments that resemble parts of eukaryotic cells. Eukaryotes have a membrane-bound nucleus, while prokaryotes usually keep DNA in a nucleoid in the cytoplasm. In Planctomycetes, special compartments called pirellulosomes contain the nucleoid, ribosomes, and other cytoplasmic material.

The life cycle of Planctomyces begins with a motile swarmer cell attaching to a surface. A stalk forms at the attachment site, and a new cell then develops at the opposite pole by budding. The daughter cell grows a flagellum, leaves the mother cell, and starts the cycle again. Planctomyces species are facultative aerobes, so they can grow by respiration or by fermenting sugars, and they live in freshwater and marine environments. Low-nutrient media are usually needed to isolate Planctomyces and its relatives.

Some related bacteria show even more unusual structures. Isosphaera is a filamentous, gliding bacterium found in hot springs. In Gemmata, the nucleoid is further surrounded by membrane invaginations, so it has a true unit membrane around it. Even so, the DNA remains a covalently closed, circular, and supercoiled bacterial genome.

Members of Brocadiales include Brocadia anammoxidans, which has an anammoxosome. This compartment supports anaerobic oxidation of ammonia and is protected by a special lipid membrane that helps block toxic intermediates made during the process. Planctomyces is one of the best-studied genera in the phylum. It has a stalk like Caulobacter, but the Planctomyces stalk is made of protein only and does not contain cell wall or cytoplasm. Its main role is attachment, and it is thinner than the prosthecal stalk of Caulobacter.

Planctomycetes Cell Structure and Life Cycle

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key terms and concepts

Explore Planctomycetes cell structure, budding division, stalks, and unique compartments like pirellulosomes and anammoxosomes in this high school biology video.

Planctomycetes Cell Structure and Life Cycle | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

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Planctomycetes Cell Structure and Life Cycle

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