Rhizobiales

The ''Hyphomicrobiales'' are an order of Gram-negative Alphaproteobacteria.

The rhizobia, which fix nitrogen and are symbiotic with plant roots, appear in several different families. The four families ''Nitrobacteraceae'', ''Hyphomicrobiaceae'', '' Phyllobacteriaceae'', and ''Rhizobiaceae'' contain at least several genera of nitrogen-fixing, legume-nodulating, microsymbiotic bacteria. Examples are the genera ''Bradyrhizobium'' and ''Rhizobium''. Species of the ''Methylocystaceae'' are methanotrophs; they use methanol (CH₃OH) or methane (CH₄) as their sole energy and carbon sources. Other important genera are the human pathogens ''Bartonella'' and ''Brucella'', as well as ''Agrobacterium'' (useful in genetic engineering).

Taxonomy

Accepted families

* ''Aestuariivirgaceae'' Li ''et al''. 2019
* '' Afifellaceae'' Hördt ''et al''. 2020
* ''Ahrensiaceae'' Hördt ''et al''. 2020
* ''Alsobacteraceae'' Sun ''et al''. 2018
* ''Amorphaceae'' Hördt ''et al''. 2020
* ''Ancalomicrobiaceae'' Dahal ''et al''. 2018
* ''Aurantimonadaceae'' Hördt ''et al''. 2020
* ''Bartonellaceae'' Gieszczykiewicz 1939 (Approved Lists 1980)
* ''Beijerinckiaceae'' Garrity ''et al''. 2006
* ''Blastochloridaceae'' Hördt ''et al''. 2020
* '' Boseaceae'' Hördt ''et al''. 2020

* '' Breoghaniaceae'' Hördt ''et al''. 2020
* ''Brucellaceae'' Breed ''et al''. 1957 (Approved Lists 1980)
* '' Chelatococcaceae'' Dedysh ''et al''. 2016
* ''Cohaesibacteraceae'' Hwang and Cho 2008
* ''Devosiaceae'' Hördt ''et al''. 2020
* ''Hyphomicrobiaceae'' Babudieri 1950 (Approved Lists 1980)
* '' Kaistiaceae'' Hördt ''et al''. 2020
* '' Lichenibacteriaceae'' Pankratov ''et al''. 2020
* '' Lichenihabitantaceae'' Noh ''et al''. 2019

* ''Methylobacteriaceae'' Garrity ''et al''. 2006
* ''Methylocystaceae'' Bowman 2006
* ''Nitrobacteraceae'' corrig. Buchanan 1917 (Approved Lists 1980)

* '' Notoacmeibacteraceae'' Huang ''et al''. 2017
* ''Parvibaculaceae'' Hördt ''et al''. 2020
* '' Phreatobacteraceae'' Hördt ''et al''. 2020
* '' Phyllobacteriaceae'' Mergaert and Swings 2006
* '' Pleomorphomonadaceae'' Hördt ''et al''. 2020
* '' Pseudoxanthobacteraceae'' Hördt ''et al''. 2020
* '' Rhabdaerophilaceae'' Ming ''et al''. 2020
* ''Rhizobiaceae'' Conn 1938 (Approved Lists 1980)
* '' Rhodobiaceae'' Garrity ''et al''. 2006
* '' Roseiarcaceae'' Kulichevskaya ''et al''. 2014
* ''Salinarimonadaceae'' Cole ''et al''. 2018
* ''Segnochrobactraceae'' Akter ''et al''. 2020
* '' Stappiaceae'' Hördt ''et al''. 2020
* '' Tepidamorphaceae'' Hördt ''et al''. 2020
* ''Xanthobacteraceae'' Lee ''et al''. 2005

Unassigned Genera

The following genus has not been assigned to a family:
* '' Flaviflagellibacter'' Dong ''et al''. 2019

Provisional Taxa

These taxa have been published, but have not been validated according to the Bacteriological Code:
* "''Nordella''" La Scola ''et al''. 2004
* "''Propylenellaceae''" Liu ''et al''. 2021
** "''Propylenella''" Liu ''et al''. 2021
*** "''Propylenella binzhouense''" Liu ''et al''. 2021
* "''Thermopetrobacter''" Sislak 2013

Phylogeny

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature and the phylogeny is based on whole-genome sequences.

Natural genetic transformation

Natural genetic transformation has been reported in at least four ''Hyphomicrobiales'' species: ''Agrobacterium tumefaciens'', '' Methylobacterium organophilum'', '' Ensifer adhaerens'', and ''Bradyrhizobium japonicum''. Natural genetic transformation is a sexual process involving DNA transfer from one bacterial cell to another through the intervening medium, and the integration of the donor sequence into the recipient genome by homologous recombination.

See also

* Lar1

Notes

References

Further reading

*
*
*
*
*

{{Authority control

Bacteria orders
Soil biology