Bradyrhizobium nivariense sp. nov., predominant species nodulating Cytisus supranubius in the high mountain ecosystem of Tenerife (Canary Islands)

Bradyrhizobial strains nodulate the native legume <i>Cytisus supranubius</i> (<i>Genisteae</i>) in its natural habitat: the high-mountain ecosystem of Tenerife (Canary Islands), where nitrogen fixation is an essential activity in its N-poor soils. Three of these strains, SSUT18^T, SSUT77 and SSUT112, are representative of a major phylotype within the genus <i>Bradyrhizobium,</i> and the phylogenetic analysis of their 16S rRNA gene sequences showed that <i>Bradyrhizobium canariense</i> is their closest relative. Nevertheless, the multilocus sequence analysis and the genome analysis distinguished these strains from the type strain of <i>B. canariense</i> and from the remaining species of the genus <i>Bradyrhizobium</i>. The calculated Average Nucleotide Identity (blast) (ANIb) and digital DNA-DNA hybridization values between the genomes of the strains from the new species and <i>B. canariense</i> were also lower than the threshold values proposed for species differentiation. These data, together with differences observed in chemotaxonomic and phenotypic characteristics, support the classification of the strains SSUT18^T, SSUT77 and SSUT112 into a new species of <i>Bradyrhizobium</i>, for which we propose the name <i>Bradyrhizobium nivariense</i> sp. nov. (type strain SSUT18^T=CECT 30998^T=LMG 33353^T).