Ensifer meliloti

Ensifer meliloti (formerly Rhizobium meliloti and Sinorhizobium meliloti) are an aerobic, Gram-negative, and diazotrophic species of bacteria. E. meliloti are motile and possess a cluster of peritrichous flagella. E. meliloti fix atmospheric nitrogen into ammonia for their legume hosts, such as alfalfa. E. meliloti forms a symbiotic relationship with legumes from the genera Medicago, Melilotus and Trigonella, including the model legume Medicago truncatula. This symbiosis promotes the development of a plant organ, termed a root nodule. Because soil often contains a limited amount of nitrogen for plant use, the symbiotic relationship between E. meliloti and their legume hosts has agricultural applications. These techniques reduce the need for inorganic nitrogenous fertilizers.