Bradyrhizobium japonicum USDA 110是广泛应用的大豆高效根瘤菌菌株，但由于它与Bradyrhizobium japonicum的模式株USDA6T并不一样，不是同样的种，因此，它的分类地位一直处于模糊状态。近来，巴西科学家Mariangela Hungria课题组将USDA 110及相关菌株进行了分类学研究，确定USDA 110为不同于已知种的新种，将其命名为：高效固氮慢生根瘤菌(Bradyrhizobium diazoefficiens)，或者：高效固氮大豆慢生根瘤菌。

论文见：http://ijs.sgmjournals.org/content/early/2013/03/13/ijs.0.049130-0.short

以下是摘要：

Bradyrhizobium japonicum was described from soybean root-nodule bacterial isolates. Since its description, several studies have revealed heterogeneities among rhizobia assigned to this species. Strains assigned to B. japonicum Group Ia have been isolated in several countries, and many of them are outstanding soybean symbionts used in inoculants worldwide, but they have also been isolated from other legume hosts. Here we summarize published studies indicating that Group Ia strains are different from B. japonicum type strain USDA 6T and its closely related strains, and present new morpho-physiological, genotypic and genomic evidences to support their reclassification into a novel species for which the name Bradyrhizobium diazoefficiens sp. nov. is proposed. The type strain of the novel species is the well-studied USDA 110T strain (=IAM 13628, =CCRC 13528, =NRRL B-4361, =IFO 14792, =TAL 102T, =BCRC 13528, =JCM 10833, =TISTR 339T, =SEMIA 5032T, =3I1B110, =ACCC 15034, =CCT 4249, =NBRC 14792, =NRRL B-4450, =R-12974, CNPSo 46T).