慢生根瘤菌科（学名：Bradyrhizobiaceae）是细菌的一个科，其下包括有十个属。 它们包括与植物相关的细菌，例如慢生根瘤菌属（Bradyrhizobium）就是一种生长于豆科植物根部的根瘤菌，有固氮作用。亦有其他与动物相关的细菌，例如过往我们以为会引起的猫抓热的Afipia felis。 余下的物种有自由生活的，例如：红假单胞菌属(Rhodopseudomonas)的紫细菌，存在于海水与泥土里。光从属异营生物Rhodopseudomonas palustris也属于本科物种，其DX-1品种能够在不产生氢气而产生电流，可作为新一代的生物发电材质。 存在于空气中慢生根瘤菌科的细菌Afipia，以二甲基砜为其碳来源。

The Bradyrhizobiaceae are a family of bacteria, with ten genera. They include plant-associated bacteria such as Bradyrhizobium, a genus of rhizobia associated with some legumes. It also contains animal-associated bacteria such as Afipia felis, formerly thought to cause cat scratch disease. Others are free-living, such as Rhodopseudomonas, a purple bacterium found in marine water and soils. The strain Rhodopseudomonas palustris DX-1 can generate an electric current with no hydrogen production, a trait being explored in the development of the microbial fuel cell. The genus Afipia has also been found in the atmosphere, where it uses methylsulfonylmethane as a carbon source.