The current taxonomy of rhizobia [Updated 18th August
2007]
The species listed here are all of the most current
validly published names for the rhizobia, which currently
consist of 62 species found in 12 genera.
Rhizobia are nitrogen-fixing bacteria that form root
nodules on legume plants. Most of these bacterial species
are in the Rhizobiacae family in the alpha-proteobacteria
and are in either the Rhizobium,
Mesorhizobium, Ensifer, or
Bradyrhizobium genera. However recent research has
shown that there are many other rhizobial species in
addition to these. In some cases these new species have
arisen through lateral gene transfer of symbiotic
genes.
Taxonomy is a complicated and ever-changing discipline
of science, the list below is not "official" by any means,
and it is merely my compilation and interpretation of the
literature. An alternative
list is maintained by the "ICSP
Subcommittee on the taxonomy of Rhizobium and
Agrobacterium".
It is important to note that there are other
non-rhizobial species present in these
genera. For example in the Rhizobium genus, there
is Rhizobium radiobacter — formerly known as
Agrobacterium tumefaciens. However these species
are not listed here, as the 'Agrobacteria' do not form
nitrogen fixing symbiotic root nodules (unless they contain
a symbiotic plasmid – see Velazquez et. al. 2005). I
have another
page about these bacteria that could be confused with
'true' rhizobia.
To see all of the currently valid members of a genus,
including non-rhizobial species, click on the name of the
genus in the text after each title. This will take you to
the LPSN website.
This page was compiled from my own research; a paper by
J.G. Howieson and J. Brockwell presented at the 14th
Australian Nitrogen Fixation Conference, and the NCBI
and LPSN
websites.
This page is updated regularly. If you know of any
additions or corrections please email me.
If you wish you can cite this page as:
Weir, B. S. (2006) The current taxonomy of
rhizobia. New Zealand rhizobia website.
http://www.rhizobia.co.nz/taxonomy/rhizobia.html. Last
updated: 11th June, 2007.
Rhizobium
The genus Rhizobium
(Frank 1889) was the first named (from Latin meaning root
living), and for many years this was a 'catch all' genus
for all rhizobia. Some species were later moved in to new
genera based on phylogenetic analyses. It currently
consists of 16 species.
Rhizobium cellulosilyticum
|
new 28/3/07 (García-Fraile et. al.
2007) |
Rhizobium daejeonense
|
corrected 17/12/06 |
Rhizobium etli
|
|
| Rhizobium galegae |
|
| Rhizobium gallicum |
|
| Rhizobium giardinii |
|
| Rhizobium hainanense |
|
| Rhizobium huautlense |
|
Rhizobium indigoferae
|
|
Rhizobium leguminosarum
|
Type species |
Rhizobium loessense
|
formerly "Rhizobium huanglingense" |
Rhizobium lusitanum
|
|
| Rhizobium mongolense |
|
| Rhizobium multihospitium |
Han et. al. (2008) |
Rhizobium sullae
|
formerly "Rhizobium hedysari" |
| Rhizobium tropici |
|
| Rhizobium undicola |
formerly Allorhizobium undicola |
| Rhizobium yanglingense |
|
Older names such as Rhizobium phaseoli and
Rhizobium trifolii have been incorporated into the
species listed above at the biovar level.
Ensifer (formerly Sinorhizobium)
The Sinorhizobium
genus was described by Chen et al. in 1988.
However some recent studies show that
Sinorhizobium and the genus Ensifer
(Casida, 1982) belong to a single taxon. Ensifer
is the earlier heterotypic synonym (it was named first) and
thus takes priority (Young, 2003). This means that all
Sinorhizobium spp. must be renamed as
Ensifer spp. according to the Bacteriological
code. The taxonomy of this genus was verified in 2007 by
Martens et. al. Read
their paper for a more detailed explanation. The genus
currently consists of 15 species.
Ensifer abri
|
D |
Ensifer americanum
|
|
| Ensifer arboris |
|
| Ensifer fredii |
formerly Rhizobium fredii, Type
species |
| Ensifer indiaense |
D |
| Ensifer kostiense |
|
| Ensifer kummerowiae |
|
| Ensifer medicae |
|
| Ensifer meliloti |
formerly Rhizobium meliloti |
| Ensifer mexicanus |
new 19-2-07 (Lloret et. al. 2007) |
| 'Sinorhizobium morelense' |
E |
Ensifer adhaerens
|
A |
Ensifer saheli
|
B |
Ensifer terangae
|
C |
| Ensifer xinjiangense |
|
A - This name is a earlier heterotypic
synonym of Sinorhizobium morelense (see Young,
2003)
B - This species is also known as
Sinorhizobium sahelense (why?)
C - This species is incorrectly known as
Sinorhizobium teranga
D - Although these species have been
published (Ogasawara, et. al. 2003), they have not
yet been included in the "Validation List" of the
International Journal of Systematic and Evolutionary
Microbiology.
E - This species is distinct from
Ensifer adhaerens but cannot yet be named
Ensifer. See Martens et. al. 2007 for details.
References
A general excellent resource is:
List of Bacterial names with Standing in Nomenclature
(LBSN). (2004) Available http://www.bacterio.cict.fr/
For the full list of references for each strain, please
check my PhD
thesis, Table 1.1, page 3. New References added since
the publication of my thesis will be listed
below:
Valverde, Angel, Igual, Jose M., Peix,
Alvaro, Cervantes, Emilio, Velazquez, Encarna.
Rhizobium lusitanum sp. nov. a bacterium that
nodulates Phaseolus vulgaris. Int J Syst Evol
Microbiol 2006 56: 2631-2637. Abstract
Chen, Wen-Ming,
James, Euan K., Coenye, Tom, Chou, Jui-Hsing, Barrios,
Edmundo, de Faria, Sergio M., Elliott, Geoffrey N., Sheu,
Shih-Yi, Sprent, Janet I., Vandamme, Peter.
Burkholderia mimosarum sp. nov., isolated from
root nodules of Mimosa spp. from Taiwan and South
America. Int J Syst Evol Microbiol 2006 56:
1847-1851. Abstract
Lloret L,
Ormeno-Orrillo E, Rincon R, Martinez-Romero J,
Rogel-Hernandez MA, Martinez-Romero E. (2007)
Ensifer mexicanus sp. nov. a new species
nodulating Acacia angustissima (Mill.) Kuntze in
Mexico. Syst Appl Microbiol. Abstract
Martens,
Miet, Delaere, Manuel, Coopman, Renata, De Vos, Paul,
Gillis, Monique, Willems, Anne. Multilocus
sequence analysis of Ensifer and related taxa Int
J Syst Evol Microbiol 2007 57: 489-503. Abstract
Garcia-Fraile, Paula, Rivas, Raul, Willems,
Anne, Peix, Alvaro, Martens, Miet, Martinez-Molina,
Eustoquio, Mateos, Pedro F., Velazquez, Encarna.
Rhizobium cellulosilyticum sp. nov., isolated from
sawdust of Populus alba Int J Syst Evol Microbiol 2007 57:
844-848. Abstract
Zurdo-Pineiro, Jose Luis, Rivas, Raul,
Trujillo, Martha E., Vizcaino, Nieves, Carrasco, Jose
Antonio, Chamber, Manuel, Palomares, Antonio, Mateos, Pedro
F., Martinez-Molina, Eustoquio, Velazquez,
Encarna. Ochrobactrum cytisi sp. nov.,
isolated from nodules of Cytisus scoparius in Spain Int J
Syst Evol Microbiol 2007 57: 784-788. Abstract
Wang, Feng Qin,
Wang, En Tao, Liu, Jie, Chen, Qiang, Sui, Xin Hua, Chen,
Wen Feng, Chen, Wen Xin. Mesorhizobium
albiziae sp. nov., a novel bacterium that nodulates
Albizia kalkora in a subtropical region of China.
Int J Syst Evol Microbiol 2007 57: 1192-1199
Abstract
Han, Tian Xu, Wang, En Tao, Wu, Li Juan, Chen, Wen Feng, Gu, Jin Gang, Gu, Chun Tao, Tian, Chang Fu, Chen, Wen Xin.
Rhizobium multihospitium sp. nov., isolated from multiple legume species native of Xinjiang, China
Int J Syst Evol Microbiol 2008 58: 1693-1699
Abstract
