rhizobium rhizobium 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. this article is about the bacterial genus. for the generic term that includes species in other genera, see rhizobia. rhizobium rhizobium tropici on an agar plate scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: hyphomicrobiales family: rhizobiaceae genus: rhizobiumfrank 1889 (approved lists 1980) type species rhizobium leguminosarum(frank 1879) frank 1889 (approved lists 1980) species see text 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. 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. rhizobium is also capable of solubilizing phosphate. history martinus beijerinck was the first to isolate and cultivate a microorganism from the nodules of legumes in 1888. he named it bacillus radicicola, which is now placed in bergey's manual of determinative bacteriology under the genus rhizobium....................... 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. current research is being conducted by agricultural research service microbiologists to discover a way to use rhizobium’s biological nitrogen fixation. this research involves 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. in molecular biology, rhizobium has also 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. 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. species the genus rhizobium comprises the following species: rhizobium acidisoli román-ponce et al. 2016 rhizobium aegyptiacum shamseldin et al. 2016 rhizobium aethiopicum aserse et al. 2017 rhizobium alamii berge et al. 2009 "rhizobium album" hang et al. 2019 "rhizobium albus" li et al. 2017 rhizobium altiplani baraúna et al. 2016 rhizobium alvei sheu et al. 2015 rhizobium anhuiense zhang et al. 2015 rhizobium aquaticum máthé et al. 2019 "rhizobium arachis" wang et al. 2001 rhizobium arenae zhang et al. 2017 rhizobium arsenicireducens mohapatra et al. 2020 rhizobium azooxidifex behrendt et al. 2016 rhizobium bangladeshense rashid et al. 2015 rhizobium binae rashid et al. 2015 rhizobium calliandrae rincón-rosales et al. 2013 rhizobium capsici lin et al. 2015 rhizobium cauense liu et al. 2015 rhizobium cellulosilyticum garcía-fraile et al. 2007 rhizobium changzhiense zhang et al. 2021 rhizobium chutanense huo et al. 2019 "rhizobium cremeum" yang et al. 2022 "rhizobium croatiense" rajnovic et al. 2022 "rhizobium deserti" liu et al. 2020 rhizobium dioscoreae ouyabe et al. 2020 rhizobium ecuadorense ribeiro et al. 2015 rhizobium endophyticum lópez-lópez et al. 2010 rhizobium esperanzae cordeiro et al. 2017 rhizobium etli segovia et al. 1993 rhizobium favelukesii torres tejerizo et al. 2016 "rhizobium flavescens" su et al. 2021 rhizobium freirei dall'agnol et al. 2013 rhizobium gallicum amarger et al. 1997 rhizobium gei shi et al. 2016 "rhizobium glycinendophyticum" wang et al. 2020 rhizobium grahamii lópez-lópez et al. 2011 rhizobium hainanense chen et al. 1997 rhizobium halophytocola bibi et al. 2012 "rhizobium halotolerans" diange and lee 2013 "rhizobium hedysari" casella et al. 1986 "rhizobium hedysari" xu et al. 2017 "rhizobium hedysarum" casella et al. 1984 rhizobium helianthi wei et al. 2015 rhizobium hidalgonense yan et al. 2020 "rhizobium indicum" rahi et al. 2020 rhizobium indigoferae wei et al. 2002 rhizobium jaguaris rincón-rosales et al. 2013 "rhizobium kunmingense" shen et al. 2010 rhizobium laguerreae saïdi et al. 2014 rhizobium leguminosarum (frank 1879) frank 1889 (approved lists 1980) rhizobium lemnae kittiwongwattana & thawai 2014 rhizobium lentis rashid et al. 2015 rhizobium leucaenae ribeiro et al. 2011 rhizobium lusitanum valverde et al. 2006 "candidatus rhizobium massiliense" greub et al. 2004. rhizobium mayense rincón-rosales et al. 2013 rhizobium mesoamericanum lópez-lópez et al. 2011 rhizobium mesosinicum lin et al. 2009 rhizobium metallidurans grison et al. 2015 rhizobium miluonense gu et al. 2008 rhizobium mongolense van berkum et al. 1998 rhizobium multihospitium han et al. 2008 rhizobium oryzicola zhang et al. 2015 "rhizobium oryzihabitans" zhao et al. 2020 rhizobium pakistanense corrig. khalid et al. 2015 "rhizobium panacihumi" kang et al. 2019 rhizobium paranaense dall'agnol et al. 2014 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 rhizobium populi rozahon et al. 2014 "rhizobium populisoli" shen et al. 2021 rhizobium puerariae boonsnongcheep et al. 2016 "rhizobium qilianshanense" xu et al. 2013 "rhizobium quercicola" wang et al. 2022 "rhizobium redzepovicii" rajnovic et al. 2022 rhizobium rhizogenes (riker et al. 1930) young et al. 2001 "rhizobium rhizolycopersici" thin et al. 2021 rhizobium rhizoryzae zhang et al. 2014 rhizobium ruizarguesonis jorrin et al. 2020 rhizobium smilacinae zhang et al. 2014 rhizobium soli yoon et al. 2010 rhizobium sophorae jiao et al. 2014 rhizobium sophoriradicis jiao et al. 2014 rhizobium straminoryzae lin et al. 2014 rhizobium sullae squartini et al. 2002 "rhizobium terrae" ruan et al. 2020 rhizobium tibeticum hou et al. 2009 rhizobium tropici martínez-romero et al. 1991 rhizobium tubonense zhang et al. 2011 rhizobium tumorigenes kuzmanović et al. 2019 rhizobium vallis wang et al. 2011 rhizobium viscosum (gasdorf et al. 1965) flores-félix et al. 2017 rhizobium wenxiniae gao et al. 2017 rhizobium yanglingense tan et al. 2001 rhizobium zeae celador-lera et al. 2017 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. rhizobium rhizobium tubonense rhizobium rhizogenes rhizobium jaguaris rhizobium leucaenae rhizobium lusitanum rhizobium miluonense rhizobium freirei rhizobium tropici rhizobium hainanense rhizobium multihospitium rhizobium altiplani rhizobium grahamii rhizobium favelukesii rhizobium tibeticum rhizobium loessense rhizobium mongolense rhizobium leguminosarum rhizobium laguerreae rhizobium aethiopicum rhizobium esperanzae rhizobium etli outgroups allorhizobium ciceribacter agrobacterium pseudorhizobium neorhizobium notes this species belongs in pararhizobium, but hasn't been formally transferred, yet. these species belong in neorhizobium, but haven't been formally transferred, yet. this species belongs in peteryoungia, but hasn't been formally transferred, yet.