Ensifer (often referred to in literature by its synonym Sinorhizobium) is a genus of nitrogen-fixing bacteria (rhizobia), three of which ( Ensifer meliloti,
Etymology
The generic epithet
Ensifer derives from the
Latin noun
ensifer, "sword-bearer".
The synonym
Sinorhizobium is a combination of
Medieval Latin noun
sino ("China"), the
Ancient Greek noun
rhiza ("root"), and the
Ancient Greek noun
bium ("life"). Thus, the Neo-Latin generic epithet of the synonym
Sinorhizobium means "a
Rhizobium isolated from China", in turn referring to the related genus
Rhizobium ("root-associated life form").
Proper name
The name
Ensifer was published in 1982 and the name
Sinorhizobium was published in 1988 thus the latter is regarded as a later synonym and by the rules of the Bacteriological Code (1990 Revision) of the International Committee on Systematics of Prokaryotes (ICSP), the older name (
Ensifer) takes priority.
In response to a request that the single extant species of
Ensifer (
Ensifer adhaerens) be moved to
Sinorhizobium, a special ICSP subcommittee was formed to evaluate the request. It was ultimately ruled that
Ensifer retained priority and that all
Sinorhizobium species be transferred to the genus
Ensifer.
However, both terms continue to be used in published scientific literature, with
Sinorhizobium being the more common.
Deprecated species
Two species have been described which have since been reclassified into existing species:
Sinorhizobium morelense (now
Ensifer adhaerens)
and
Sinorhizobium xinjiangense (now
Ensifer fredii—though some dissent exists
).
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN).
The following phylogeny is based on whole-genome analysis.
This phylogeny is based on a constrained analysis of the 16S ribosomal RNA.
