Mesorhizobium calcicola sp. nov., Mesorhizobium waitakense sp. nov., Mesorhizobium sophorae sp. nov., Mesorhizobium newzealandense sp. nov. and Mesorhizobium kowhaii sp. nov. isolated from Sophora root nodules.

Abstract

In total, 31 strains of Gram-stain-negative, rod-shaped bacteria were isolated from Sophora root nodules and authenticated as rhizobia on this host. Based on 16S rRNA gene phylogeny, they were shown to belong to the genus Mesorhizobium, with the representative strains ICMP 19560T, ICMP 19523T, ICMP 19535T, ICMP 19545T and ICMP 19512T being related most closely to Mesorhizobium sangaii SCAU7T (99.9-99.6 % similarity), Mesorhizobium cantuariense ICMP 19515T (99.7-99.6 %) and Mesorhizobium ciceri UMP-CA7T (99.7-99.5 %). Additionally, the novel strains formed distinct groups based on housekeeping gene sequence analysis and were closely related to Mesorhizobium waimense ICMP 19557T (93.5-94.9, 92.5-95.6 and 94.2-96.0 %), M. cantuariense ICMP 19515T (93.1-97.7, 93.5-95.4 and 94.8-96.8 %) and M. ciceri UMP-CA7T (93.2-97.2, 94.6-96.8 and 95.5-97.3 %) for glnII, recA and rpoB, respectively. Chemotaxonomic data supported the assignment of the strains to the genus Mesorhizobium, and DNA-DNA hybridizations, matrix-assisted laser desorption/ionization time-of-flight MS analysis, enterobacterial repetitive intergenic consensus PCR, physiological and biochemical tests allowed the genotypic and phenotypic differentiation from their nearest neighbouring species. Therefore, these strains represent five novel species for which the names Mesorhizobium calcicola sp. nov. (type strain ICMP 19560T = LMG 28224T = HAMBI 3609T), Mesorhizobium waitakense sp. nov. (type strain ICMP 19523T = LMG 28227T = HAMBI 3605T), Mesorhizobium sophorae sp. nov. (type strain ICMP 19535T = LMG 28223T = HAMBI 3606T), Mesorhizobium newzealandense sp. nov. (type strain ICMP 19545T = LMG 28226T = HAMBI 3607T) and Mesorhizobium kowhaii sp. nov. (type strain ICMP 19512T = LMG 28222T = HAMBI 3603T) are proposed.