Sinorhizobium/Ensifer is a genus of nitrogen-fixing

Nitrogen fixation

Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...

 bacteria (rhizobia

Rhizobia

Rhizobia are soil bacteria that fix nitrogen after becoming established inside root nodules of legumes . Rhizobia require a plant host; they cannot independently fix nitrogen...

), two of which (Sinorhizobium meliloti

Sinorhizobium meliloti

Sinorhizobium meliloti is a Gram-negative nitrogen-fixing bacterium . It forms a symbiotic relationship with legumes from the genera Medicago, Melilotus and Trigonella, including the model legume Medicago truncatula. This symbiosis results in a new plant organ termed a root nodule. The S...

and Sinorhizobium medicae) have been sequenced.

Etymology

Sinorhizobium is a combination of Medieval Latin

Medieval Latin

Medieval Latin was the form of Latin used in the Middle Ages, primarily as a medium of scholarly exchange and as the liturgical language of the medieval Roman Catholic Church, but also as a language of science, literature, law, and administration. Despite the clerical origin of many of its authors,...

 sino, -a (which means "China"), Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 rhizo, -a (which means "root"), and New Latin

New Latin

The term New Latin, or Neo-Latin, is used to describe the Latin language used in original works created between c. 1500 and c. 1900. Among other uses, Latin during this period was employed in scholarly and scientific publications...

 bios (which means "life"). Thus the full name means "a bacterium living in a root in China".

Ensifer is from the New Latin

New Latin

The term New Latin, or Neo-Latin, is used to describe the Latin language used in original works created between c. 1500 and c. 1900. Among other uses, Latin during this period was employed in scholarly and scientific publications...

 term ensifer, which means "sword-bearing" or "sword-bearer".

Proper Name

The name Ensifer was published in 1982 and the name Sinorhizobium was published in 1988. By the rules of the Bacteriological Code (1990 Revision) of the International Committee on Systematics of Prokaryotes (ICSP), the older name (Ensifer) has 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 Sinorhizobium fredii—though there is some dissent).