Agrobacterium (SEM image)
Scientific classification e
Domain: Bacteria
Phylum: Proteobacteria
Class: Alphaproteobacteria
Order: Rhizobiales
Kuykendall 2006

See text

  • Hyphomicrobiales Douglas 1957

The Rhizobiales 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 Bradyrhizobiaceae, Hyphomicrobiaceae, Phyllobacteriaceae, and Rhizobiaceae contain at least six 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).


Accepted families

Provisional families

These families have been proposed but not yet validly published according to the rules of the Bacteriological Code.

Genera incertae sedis

These genera belong to the Rhizobiales, but have not been assigned to a family.


The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature[10] and National Center for Biotechnology Information[11] and the phylogeny is based on whole-genome sequences.[12]


Brucella Meyer and Shaw 1920

Ochrobactrum Holmes et al. 1988


Bartonella Strong et al. 1915 (Approved Lists 1980) emend. Brenner et al. 1993


Mesorhizobium Jarvis et al. 1997

Hoeflea Peix et al. 2005

Chelativorans Doronina et al. 2010


Rhizobium Frank 1889 (Approved Lists 1980) emend. Young et al. 2001

Agrobacterium Conn 1942 (Approved Lists 1980) emend. Sawada et al. 1993

Sinorhizobium Chen et al. 1988 emend. De Lajudie et al. 1994

Ensifer Casida 1982

Candidatus Liberibacter corrig. Jagoueix et al. 1994

Candidatus Hodgkinia McCutcheon et al. 2009


Aurantimonas Denner et al. 2003 emend. Rathsack et al. 2011

Fulvimarina Cho and Giovannoni 2003 emend. Rathsack et al. 2011


Cucumibacter Hwang and Cho 2008

Maritalea Hwang et al. 2009

Pelagibacterium Xu et al. 2011


Amorphus Zeevi Ben Yosef et al. 2008

Pleomorphomonas Hwang et al. 2009[b]


Kaistia Im et al. 2005[c]


Bradyrhizobium Jordan 1982

Nitrobacter Winogradsky 1892

Rhodopseudomonas Czurda and Maresch 1937

Oligotropha Meyer et al. 1994

Afipia Brenner et al. 1992


Ancylobacter Raj 1983

Starkeya Kelly et al. 2000

Xanthobacter Wiegel et al. 1978

Azorhizobium Dreyfus et al. 1988


Methylobacterium Methylobacterium Patt et al. 1976 (Approved Lists 1980) emend. Green and Bousfield 1983

Microvirga Kanso and Patel 2003


Methylocapsa Dedysh et al. 2002

Methylocella Dedysh et al. 2000 emend. Dunfield et al. 2003

Beijerinckia Derx 1950

Methyloferula Vorobev et al. 2011


Methylosinus (ex Whittenbury et al. 1970) Bowman et al. 1993

Methylocystis (ex Whittenbury et al. 1970) Bowman et al. 1993 emend. Dedysh et al. 2007

Hyphomicrobiaceae pro parte

Hyphomicrobium Stutzer and Hartleb 1899


Rhodomicrobium Duchow and Douglas 1949 (Approved Lists 1980) emend. Imhoff et al. 1984


Parvibaculum Schleheck et al. 2004

Meganema Thomsen et al. 2006[e]

Sphingomonas Yabuuchi et al. 1990 emend. Yabuuchi et al. 1999 (outgroup)

Magnetospirillum Schleifer et al. 1992 (outgroup)

Natural genetic transformation

Natural genetic transformation has been reported in at least three Rhizobiales species: Agrobacterium tumefaciens,[13] Methylobacterium organophilum,[14] and Bradyrhizobium japonicum.[15] 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


  1. ^ Cucumibacter, Maritalea, and Pelagibacterium are currently included in Hyphomicrobiaceae.
  2. ^ Pleomorphomonas is currently included in Methylocystaceae.
  3. ^ Kaistia is currently included in Rhizobiaceae.
  4. ^ Rhodomicrobium is currently included in Hyphomicrobiaceae.
  5. ^ Meganema is currently included in Methylobacteriaceae.


  1. ^ Parker, Charles Thomas; Garrity, George M (1 January 2003). Parker, Charles Thomas; Garrity, George M (eds.). "Taxonomic Abstract for the families". The NamesforLife Abstracts. doi:10.1601/tx.30673.
  2. ^ a b c d e f g h The SILVA database, release 132. Accessed on 5/18/2018. See
  3. ^ a b Beck, D. A. C.; McTaggart, T. L.; Setboonsarng, U.; Vorobev, A.; Goodwin, L.; Shapiro, N.; Woyke, T.; Kalyuzhnaya, M. G.; Lidstrom, M. E.; Chistoserdova, L. (2015). "Multiphyletic origins of methylotrophy in Alphaproteobacteria, exemplified by comparative genomics of Lake Washington isolates". Environmental Microbiology. 17 (3): 547–54. doi:10.1111/1462-2920.12736. PMID 25683159.
  4. ^ Bao Z, Sato Y, Fujimura R, Ohta H. (2014). "Alsobacter metallidurans gen. nov., sp. nov., a thallium-tolerant soil bacterium in the order Rhizobiales". Int. J. Syst. Evol. Microbiol. 64 (Pt 3): 775–780. doi:10.1099/ijs.0.054783-0. PMID 24221990.CS1 maint: uses authors parameter (link)
  5. ^ Zeevi ben Yosef D, ben-Dov E, Kushmaro A. (2008). "Amorphus coralli gen. nov., sp. nov., a marine bacterium isolated from coral mucus, belonging to the order Rhizobiales". Int. J. Syst. Evol. Microbiol. 58 (12): 2704–2709. doi:10.1099/ijs.0.65462-0. PMID 19060044.CS1 maint: uses authors parameter (link)
  6. ^ a b Yee B, Oertli GE, Fuerst JA, Staley JT. (2010). "Reclassification of the polyphyletic genus Prosthecomicrobium to form two novel genera, Vasilyevaea gen. nov. and Bauldia gen. nov. with four new combinations: Vasilyevaea enhydra comb. nov., Vasilyevaea mishustinii comb. nov., Bauldia consociata comb. nov. and Bauldia litoralis comb. nov". Int. J. Syst. Evol. Microbiol. 60 (Pt 12): 2960–2966. doi:10.1099/ijs.0.018234-0. PMC 3052453. PMID 20118292.CS1 maint: uses authors parameter (link)
  7. ^ Poroshina MN, Trotsenko YA, Doronina NV. (2015). "Methylobrevis pamukkalensis gen. nov., sp. nov., a halotolerant restricted facultative methylotroph isolated from saline water". Int. J. Syst. Evol. Microbiol. 65 (4): 1321–1327. doi:10.1099/ijs.0.000105. PMID 25667389.CS1 maint: uses authors parameter (link)
  8. ^ Takeuchi M, Katayama T, Yamagishi T, Hanada S, Tamaki H, Kamagata Y, Oshima K, Hattori M, Marumo K, Nedachi M, Maeda H, Suwa Y, Sakata S. (2014). "Methyloceanibacter caenitepidi gen. nov., sp. nov., a facultatively methylotrophic bacterium isolated from marine sediments near a hydrothermal vent". Int. J. Syst. Evol. Microbiol. 64 (Pt 2): 462–468. doi:10.1099/ijs.0.053397-0. PMID 24096357.CS1 maint: uses authors parameter (link)
  9. ^ Doronina NV, Poroshina MN, Kaparullina EN, Ezhov VA, Trotsenko YA. (2013). "Methyloligella halotolerans gen. nov., sp. nov. and Methyloligella solikamskensis sp. nov., two non-pigmented halotolerant obligately methylotrophic bacteria isolated from the Ural saline environments". Syst. Appl. Microbiol. 36 (3): 148–154. doi:10.1016/j.syapm.2012.12.001. PMID 23351489.CS1 maint: uses authors parameter (link)
  10. ^ J.P. Euzéby. "Proteobacteria (scroll down for Rhizobiales)". List of Prokaryotic names with Standing in Nomenclature. Archived from the original on 2013-01-27. Retrieved 2012-05-02.
  11. ^ "Rhizobiales". National Center for Biotechnology Information. Retrieved 2012-05-02.
  12. ^ Collapsed from the tree built by PATRIC Archived 2016-03-15 at the Wayback Machine. Access date: 2012-05-02.
  13. ^ Demanèche S, Kay E, Gourbière F, Simonet P (2001). "Natural transformation of Pseudomonas fluorescens and Agrobacterium tumefaciens in soil". Appl. Environ. Microbiol. 67 (6): 2617–21. doi:10.1128/AEM.67.6.2617-2621.2001. PMC 92915. PMID 11375171.
  14. ^ O'Connor M, Wopat A, Hanson RS (1977). "Genetic transformation in Methylobacterium organophilum". J. Gen. Microbiol. 98 (1): 265–72. doi:10.1099/00221287-98-1-265. PMID 401866.
  15. ^ Raina JL, Modi VV (1972). "Deoxyribonucleate binding and transformation in Rhizobium japonicum". J. Bacteriol. 111 (2): 356–60. doi:10.1128/JB.111.2.356-360.1972. PMC 251290. PMID 4538250.

Further reading