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Five strains of Gram-stain-negative, rod-shaped bacteria were isolated from Carmichaelia and Montigena root nodules. Based on 16S rRNA gene phylogeny, they were shown to belong to the genus Mesorhizobium, and to be most closely related to Mesorhizobium jarvisii ATCC 33669 T (100-99.6 % sequence similarity), Mesorhizobium huakuii IAM 14158 T (99.9-99.6 %), Mesorhizobium japonicum MAFF303099 T (99.8-99.6 %) and Mesorhizobium erdmanii USDA 3471 T (99.8-99.5 %). Additionally, the strains formed distinct groups based on housekeeping gene analysis and were most closely related to M. jarvisii ATCC 33669 T (89.6-89.5 and 97.6-97.3 % sequence similarity for glnII and recA, respectively), M. erdmanii USDA 3471 T (94.3-94.0 and 94.9-94.1 %), M. japonicum MAFF303099 T (90.0-89.9 and 96.7-96.2 %) and M. huakuii IAM 14158 T (89.9-90.0 and 95.4-94.9 %). Chemotaxonomic data supported the assignment of the strains to the genus Mesorhizobium and DNA-DNA hybridizations, average nucleotide identity analysis, matrix-assisted laser desorption ionization time-of-flight MS analysis, physiological and biochemical tests differentiated them genotypically and phenotypically from their nearest neighbouring species. Therefore, these strains are considered to represent a novel species, for which the name Mesorhizobium carmichaelinearum sp. nov. is proposed. The type strain is ICMP 18942 T (=MonP1N1 T =LMG 28414 T ).

Forty eight rhizobial isolates from New Zealand (NZ) native Sophora spp. growing in natural ecosystems were characterised. Thirty eight isolates across five groups showed greatest similarity to Mesorhizobium ciceri LMG 14989(T) with respect to their 16S rRNA and concatenated recA, glnll and rpoB sequences. Seven isolates had a 16S rRNA sequence identical to M. amorphae ATCC 19665(T) but showed greatest similarity to M. septentrionale LMG 23930(T) on their concatenated recA, glnll and rpoB sequences. All isolates grouped closely together for their nifH, nodA and nodC sequences, clearly separate from all other rhizobia in the GenBank database. None of the type strains closest to the Sophora isolates based on 16S rRNA sequence similarity nodulated Sophora microphylla but they all nodulated their original host. Twenty one Sophora isolates selected from the different 16S rRNA groupings produced N2-fixing nodules on three Sophora spp. but none nodulated any host of the type strains for the related species. DNA hybridisations indicated that these isolates belong to novel Mesorhizobium spp. that nodulate NZ native Sophora species., (Copyright © 2014 Elsevier GmbH. All rights reserved.)