Ensifer fredii is a nitrogen fixing bacterium.

Ensifer fredii exhibits a broad host-range and is able to nodulate both determinant hosts, such as soy, as well as indeterminate hosts including the pigeon pea.

[clarification needed] Because of their ease of host infection there is interest in their genetics and the symbiotic role in host infection and nodule formation.

[3] Ensifer fredii was first isolated from soybeans.

The type strain was isolated from a root nodule of Glycine max growing in Hunan Province, China, designated strain USDA 205 (= ATCC 35423 = PRC 205).