Mesorhizobium zhangyense sp. nov., isolated from wild Thermopsis lanceolate in northwestern China

A Gram-stain-negative strain, 23-3-2T, was isolated from a nodule of Thermopsis lanceolate grown in Northwest China. Phylogenetic analysis of 16S rRNA gene sequence showed that the strain was closely related to Mesorhizobium camelthorni CCNWXJ 40-4T and M. alhagi CCNWXJ 12-2T having 98.0 and 97.9% similarities, respectively. Phylogenetic analysis based on the protein-coding genes atpD and glnA showed lower similarity with the same closely related species (94.5 and 89.9%, respectively), which suggest that 23-3-2T strain represents a distinctly delineated genospecies of the genus Mesorhizobium. The 23-3-2T strain grew at 20–37 °C temperature (optimum 28 °C) and 5.0–9.0 pH range (optimum pH 7.0). The cells contained Q-10 as the sole respiratory quinone and 18:1ω7c (24.56%) as the major cellular fatty acid. The DNA relatedness between the strain 23-3-2T and the two reference strains was 39–44%. Based on the phenotypic, chemotaxonomic and phylogenetic properties, strain 23-3-2T represents a novel species of the genus Mesorhizobium, for which the name Mesorhizobium zhangyense sp. nov. is proposed. The type strain is 23-3-2T (= CGMCC 1.15528T = NBRC 112337T). The respective DPD Taxon Number is TA00147.