Rickettsiales

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Rickettsiales
Rickettsia rickettsii within a cell of a tick

Rickettsia rickettsii within a cell of a tick

Systematics
Classification : Creature
Domain : Bacteria (bacteria)
Department : Proteobacteria
Class : Alphaproteobacteria
Order : Rickettsiales
Scientific name
Rickettsiales
Gieszczykiewicz 1939
Familys

The Rickettsiales form an order of small bacteria within the Alphaproteobacteria . Most species in this group are obligate intracellularly, they can only survive as endosymbionts within foreign cells. Rickettsiales are difficult to grow in the laboratory. Many genera, such as Rickettsia , contain pathogens .

The genome of the species Rickettsia prowazekii has been fully sequenced and shows similarity to mitochondrial DNA , which is of interest for the endosymbiotic theory . Metagenomic analyzes published in 2018 suggest, however, that the ancestor of the mitochondrion is not a rickettsial.

Pathogenic genera and pests (selection)

Rickettsiaceae family

Anaplasmataceae family

Holosporaceae family

  • A bacterium that has not yet been identified in detail, but based on 16S rRNA analyzes, probably belongs to this family, causes necrotizing hepatopancreatitis (NHP) in shrimp. The species is therefore often referred to as the NHP bacterium (NHPB). In shrimp farms , the spread of this species can cause major economic damage.

Systematics

The systematics of this order has undergone major changes in recent years due to 16S rRNA analyzes . The Bartonellaceae family , which was previously incorporated into this order, was placed in a different order, Rhizobiales . But many changes have also been made within families. Among other things, the division of the Rickettsiaceae into three tribes was abandoned.

Families of this order and unclear positions:

Genera with an unclear or controversial position within this order:

  • Caedibacter
  • Odyssella
  • Midichloria
  • Hepatincola
  • Nicolleia
  • Pelagibacter

Older, classic system

An older classification, which is still often found in the literature:

Rickettsiaceae: (This family is divided into three groups ( tribe ))

  • Tribe Rickettsieae with the genera: Rickettsia , Rochalimaea , Coxiella
  • Tribus Ehrlicheae with the genera: Ehrlichia , Cowdria , Neorickettsia
  • Tribe Wolbachieae with the genera: Wolbachia , Rickettsiella

Bartonellaceae:

Anaplasmataceae:

  • Genera: Anaplasma , Aegyptianella , Haemobartonella and Eperythrozoon

swell

  1. ↑ J. Martijn, J. Vosseberg, L. Guy, P. Offre, TJ Ettema: Deep mitochondrial origin outside the sampled alphaproteobacteria. In: Nature . Volume 557, Number 7703, May 2018, pp. 101-105, doi : 10.1038 / s41586-018-0059-5 , PMID 29695865
  2. ↑ Dumler (JS), Barbet (AF), Bekker (CPJ), Dasch (GA), Palmer (GH), Ray (SC), Rikihisa (Y.) and Rurangirwa (FR): Reorganization of genera in the families Rickettsiaceae and Anaplasmataceae in the order Rickettsiales: unification of some species of Ehrlichia with Anaplasma, Cowdria with Ehrlichia and Ehrlichia with Neorickettsia, description of six new species combinations and designation of Ehrlichia equi and 'HGE agent' as subjective synonyms of Ehrlichia phagocytophila. Int. J. Syst. Evol. Microbiol. 2001, 51, 2145-2165
  3. ↑ Systematics according to the National Center for Biotechnology Information (NCBI) (status: February 2007)
  4. ↑ Here to: Franz Nienhaus: Viruses, Mycoplasma and Rickettsia . (UTB for science; 1361) Ulmer, Stuttgart 1985 ISBN 3-8001-2536-6

literature

  • Köhler, Werner (Ed.) Medical Microbiology , 8th edition, Munich / Jena 2001 ISBN 978-3-437-41640-8
  • Martin Dworkin, Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer, Erko Stackebrandt (Eds.) The Prokaryotes, A Handbook of the Biology of Bacteria . 7 volumes, 3rd edition, Springer-Verlag, New York et al. O., 2006, ISBN 0-387-30740-0 . Vol. 5: Proteobacteria: Alpha and Beta Subclasses ISBN 0-387-25495-1

Web links

Commons : Rickettsiales  - collection of images, videos and audio files