Rhizobial isolates in active layer samples of permafrost soil of Spitsbergen, Arctic

Twenty-nine strains were isolated from two samples of the permafrost active layer Spitsbergen archipelago. The estimated number bacteria ranged 4.0⋅104 to 1.7⋅107 CFU∙g-1. As a result sequencing 16S rRNA (rrs) genes, isolates assigned 13 genera belonging phyla Actinobacteria, Proteobacteria (classes α, β, and γ), Bacteroidetes, Firmicutes. Six belonged rhizobial genus Mesorhizobium (order Rhizobiales). A plant nodulation assay with seedlings legume plants Astragalus norvegicus, A. frigidus, subpolaris Oxytropis sordida, originated Khibiny (Murmansk region, Russia) inoculated isolates, showed inability these form nodules on roots. Symbiotic (sym) genes nodC nodD not detected in either.