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Rhizobium

{{Short description|Genus of nitrogen-fixing bacteria}}

{{About|the bacterial genus|the generic term that includes species in other genera|Rhizobia}}

{{Automatic taxobox

| image = Rhizobium tropici strain BR816 on TY agar.JPG

| image_caption = Rhizobium tropici on an agar plate (Tryptone — Yeast extract agar).

| taxon = Rhizobium

| authority = Frank 1889 (Approved Lists 1980){{cite journal |last1=Frank |first1=B. |title= Über die Pilzsymbiose der Leguminosen |journal= Berichte der Deutschen Botanischen Gesellschaft |year= 1889 | volume = 7 | pages=332–346}}{{cite journal |last1=Skerman |first1=VB |last2=McGowan |first2=V |last3=Sneath |first3=PH |title=Approved lists of bacterial names |journal=International Journal of Systematic Bacteriology |year=1980 |volume=30 |pages=225–420 |doi=10.1099/00207713-30-1-225 |doi-access=free }}

| type_species = Rhizobium leguminosarum

| type_species_authority = (Frank 1879) Frank 1889 (Approved Lists 1980)

| subdivision_ranks = Species

| subdivision = See text

}}

Rhizobium is a genus of Gram-negative soil bacteria that fix nitrogen. Rhizobium species form an endosymbiotic nitrogen-fixing association with roots of (primarily) legumes and other flowering plants.

The bacteria colonize plant cells to form root nodules, where they convert atmospheric nitrogen into ammonia using the enzyme nitrogenase. The ammonia is shared with the host plant in the form of organic nitrogenous compounds such as glutamine or ureides.{{Cite journal |last1=Thilakarathna |first1=Malinda S. |last2=Raizada |first2=Manish N. |date=2018-01-01 |title=Visualizing Glutamine Accumulation in Root Systems Involved in the Legume–Rhizobia Symbiosis by Placement on Agar Embedded with Companion Biosensor Cells |url=https://apsjournals.apsnet.org/doi/10.1094/PBIOMES-07-18-0031-TA |journal=Phytobiomes Journal |volume=2 |issue=3 |pages=117–128 |doi=10.1094/PBIOMES-07-18-0031-TA|doi-access=free }}{{cn|reason=Claim of direct glutamine exchange appears to generalize from a single study and is a questionable assertion. More evidence is needed.|date=May 2025}} The plant, in turn, provides the bacteria with organic compounds made by photosynthesis. This mutually beneficial relationship is true of all of the rhizobia, of which the genus Rhizobium is a typical example.{{cite journal |last1=Sawada |first1=Hiroyuki |last2=Kuykendall |first2=L. David |last3=Young |first3=John M. |date=June 2003 |title=Changing concepts in the systematics of bacterial nitrogen-fixing legume symbionts |journal=The Journal of General and Applied Microbiology |volume=49 |issue=3 |pages=155–79 |doi=10.2323/jgam.49.155 |pmid=12949698 |doi-access=free}} Rhizobium is also capable of solubilizing phosphate.{{cite journal |last1=Sridevi |first1=M |last2=Mallaiah |first2=KV |date=March 2009 |title=Phosphate solubilization by Rhizobium strains |url= |journal=Indian Journal of Microbiology |volume=49 |issue=1 |pages=98–102 |doi=10.1007/s12088-009-0005-1 |pmc=3450048 |pmid=23100757}}

History

Martinus Beijerinck was the first to isolate and cultivate a microorganism from the nodules of legumes in 1888.{{Cite journal |last=Beijerinck |first=Martinus W. |date=1888 |title=Die Bacteriender Papilionaceenknöllchen |journal=Bot. Ztg. |volume=46}} He named it Bacillus radicicola, which is now placed in Bergey's Manual of Determinative Bacteriology under the genus Rhizobium.{{cn|date=March 2025}}

Research

Rhizobium forms a symbiotic relationship with certain plants, such as legumes, fixing nitrogen from the air into ammonia, which acts as a natural fertilizer for the plants. The Agricultural Research Service is conducting research involving the genetic mapping of various rhizobial species with their respective symbiotic plant species, like alfalfa or soybean. The goal of this research is to increase the plants' productivity without using fertilizers.{{cite web|url=https://agresearchmag.ars.usda.gov/2010/jan/microbe|title=Marvelous Microbe Collections Accelerate Discoveries To Protect People, Plants—and More!|work=Agricultural Research|date=January 2010|publisher=United States Department of Agriculture|access-date=10 August 2018}}

In molecular biology, Rhizobium has been identified as a contaminant of DNA extraction kit reagents and ultrapure water systems, which may lead to its erroneous appearance in microbiota or metagenomic datasets.{{cite journal |last1=Salter |first1=Susannah J. |last2=Cox |first2=Michael J. |last3=Turek |first3=Elena M. |last4=Calus |first4=Szymon T. |last5=Cookson |first5=William O. |last6=Moffatt |first6=Miriam F. |last7=Turner |first7=Paul |last8=Parkhill |first8=Julian |last9=Loman |first9=Nicholas J. |last10=Walker |first10=Alan W. |display-authors=6 |title=Reagent and laboratory contamination can critically impact sequence-based microbiome analyses |journal=BMC Biology |volume=12 |page=87 |date=November 2014 |pmid=25387460 |doi=10.1186/s12915-014-0087-z |pmc=4228153 |biorxiv=10.1101/007187 |doi-access=free |issn=1741-7007}} The presence of nitrogen-fixing bacteria as contaminants may be due to the use of nitrogen gas in ultra-pure water production to inhibit microbial growth in storage tanks.{{cite journal |last1=Kulakov |first1=Leonid A. |last2=McAlister |first2=Morven B. |last3=Ogden |first3=Kimberly L. |last4=Larkin |first4=Michael J. |last5=O'Hanlon |first5=John F. | title = Analysis of bacteria contaminating ultrapure water in industrial systems |journal =Applied and Environmental Microbiology |language=en |volume=68 |issue=4 |pages=1548–1555 |date=April 2002 |pmid=11916667 |pmc=123900 |doi =10.1128/AEM.68.4.1548-1555.2002}}

Species

The genus Rhizobium comprises the following species:-{{cite web |last1=Euzéby |first1=JP |last2=Parte |first2=AC |url=https://lpsn.dsmz.de/family/rhizobiaceae |title=Rhizobiaceae |access-date=September 16, 2022 |publisher=List of Prokaryotic names with Standing in Nomenclature (LPSN)}}

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  • Rhizobium pakistanense corrig. Khalid et al. 2015{{#tag:ref | These species belong in Neorhizobium, but haven't been formally transferred, yet. | group = Note | name = Neorhizobium}}

  • Rhizobium phaseoli Dangeard 1926 (Approved Lists 1980)
  • "Rhizobium phenanthrenilyticum" Wen et al. 2011
  • Rhizobium pisi Ramírez-Bahena et al. 2008
  • "Rhizobium pongamiae" Kesari et al. 2013{{cite journal |last1=Kesari |first1=Vigya |last2=Ramesh |first2=Aadi Moolam |last3=Rangan |first3=Latha |title=Rhizobium pongamiae sp. nov. from root nodules of Pongamia pinnata |journal=BioMed Research International |volume=2013 |page=165198 |year=2013 |pmid=24078904 |pmc=3783817 |doi=10.1155/2013/165198 |doi-access=free }}
  • Rhizobium populi Rozahon et al. 2014
  • "Rhizobium populisoli" Shen et al. 2021

  • "Rhizobium qilianshanense" Xu et al. 2013{{cite journal |last1=Xu |first1=Lin |last2=Zhang |first2=Yong |last3=Deng |first3=Zheng Shan |last4=Zhao |first4=Liang |last5=Wei |first5=Xiu Li |last6=Wei |first6=Ge Hong |title=Rhizobium qilianshanense sp. nov., a novel species isolated from root nodule of Oxytropis ochrocephala Bunge in China |journal=Antonie van Leeuwenhoek |volume=103 |issue=3 |pages=559–65 |date=March 2013 |pmid=23142858 |doi=10.1007/s10482-012-9840-x |s2cid=18660422}}
  • "Rhizobium quercicola" Wang et al. 2022

  • Rhizobium vallis Wang et al. 2011{{cite journal |last1=Wang |first1=Fang |last2=Wang |first2=En Tao |last3=Wu |first3=Li Juan |last4=Sui |first4=Xin Hua |last5=Li |first5=Ying Li |last6=Chen |first6=Wen Xin |title=Rhizobium vallis sp. nov., isolated from nodules of three leguminous species |journal=International Journal of Systematic and Evolutionary Microbiology |volume=61 |issue=11 |pages=2582–2588 |date=November 2011 |pmid=21131504 |doi=10.1099/ijs.0.026484-0 |doi-access=free}}

  • Rhizobium wenxiniae Gao et al. 2017{{#tag:ref | These species belong in Neorhizobium, but haven't been formally transferred, yet. | group = Note | name = Neorhizobium}}

  • Rhizobium yanglingense Tan et al. 2001{{cite journal |last1=Silva |first1=Claudia |last2=Vinuesa |first2=Pablo |last3=Eguiarte |first3=Luis E |last4=Souza |first4=Valeria |last5=Martínez-Romero |first5=Esperanza |title=Evolutionary genetics and biogeographic structure of Rhizobium gallicum sensu lato, a widely distributed bacterial symbiont of diverse legumes |journal=Molecular Ecology |volume=14 |issue=13 |pages=4033–50 |date=November 2005 |pmid=16262857 |doi=10.1111/j.1365-294X.2005.02721.x |s2cid=16668742 }}

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Species in "parentheses" have been described, but not validated according to the Bacteriological Code.

Phylogeny

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN). The phylogeny is based on whole-genome analysis.{{cite journal |last1=Hördt |first1=Anton |last2=López |first2=Marina García |last3=Meier-Kolthoff |first3=Jan P. |last4=Schleuning |first4=Marcel |last5=Weinhold |first5=Lisa-Maria |last6=Tindall |first6=Brian J. |last7=Gronow |first7=Sabine |last8=Kyrpides |first8=Nikos C. |last9=Woyke |first9=Tanja |last10=Göker |first10=Markus |title=Analysis of 1,000+ Type-Strain Genomes Substantially Improves Taxonomic Classification of Alphaproteobacteria |journal=Frontiers in Microbiology |date=7 April 2020 |volume=11 |page=468 |doi=10.3389/fmicb.2020.00468|pmid=32373076 |pmc=7179689 |doi-access=free }}

{{Clade

|1={{clade

|label1=Rhizobium

|1={{clade

|1={{clade

|1=Rhizobium tubonense

|2={{clade

|1=Rhizobium rhizogenes

|2={{clade

|1={{clade

|1=Rhizobium jaguaris

|2=Rhizobium leucaenae

}}

|2={{clade

|1=Rhizobium lusitanum

|2={{clade

|1={{clade

|1=Rhizobium miluonense

|2=Rhizobium freirei

}}

|2={{clade

|1=Rhizobium tropici

|2={{clade

|1=Rhizobium hainanense

|2=Rhizobium multihospitium

}}

}}

}}

}}

}}

}}

}}

|2={{clade

|1={{clade

|1={{clade

|1=Rhizobium altiplani

|2=Rhizobium grahamii

}}

|2={{clade

|1=Rhizobium favelukesii

|2=Rhizobium tibeticum

}}

}}

|2={{clade

|1={{clade

|1=Rhizobium loessense

|2=Rhizobium mongolense

}}

|2={{clade

|1={{clade

|1=Rhizobium leguminosarum

|2=Rhizobium laguerreae

}}

|2={{clade

|1=Rhizobium aethiopicum

|2={{clade

|1=Rhizobium esperanzae

|2=Rhizobium etli

}}

}}

}}

}}

}}

}}

|label2=outgroups

|2={{clade

|1={{clade

|1=Allorhizobium

|2=Ciceribacter

}}

|2={{clade

|1=Agrobacterium

|2={{clade

|1=Pseudorhizobium

|2=Neorhizobium

}}

}}

}}

}}

}}

Notes

{{Reflist|group=Note}}

References

{{Reflist}}

External links

  • [https://www.jic.ac.uk/research-impact/nitrogen-fixation/ Current research on nitrogen fixation by rhizobia] at the Norwich Research Park
  • [https://www.youtube.com/watch?v=3LlUk4EbxY8 Video and commentary on root nodules and Rhizobium in White Clover]

{{Taxonbar|from=Q830142}}

{{Authority control}}

Category:Rhizobiaceae

Category:Bacteria genera