Rhizobium qitaiense sp. nov. and Mycoplana qihuense sp. nov. isolated from chickpea nodules

Abstract

Abstract Two symbiotic nitrogen-fixing bacteria (TRM95796Tand TRM96650T) isolated from effective root nodules of chickpeas were characterised to clarify their taxonomic status using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences, single-copy genes and core-proteome average amino acid identity (cpAAI) indicated that strain TRM95796T was grouped as a separate clade closely related to Rhizobium setariae KVB221T(97.23%), and strain TRM96650T was closely related to Mycoplana. azooxidifex Po 20/26T (97.5%). The results of both the analyses of the concatenated recA atpD and glnII genes and whose genomes revealed that strains TRM95796T was related to two clusters formed by the type strains of the closely related species belonging to Rhizobium, in congruence with the 16S rRNA gene phylogeny. Strain TRM96650T was related to two clusters formed by the type strains of the closely related species belonging to Mycoplana. The OrthoANI values between TRM95796T, and the type strains of the available Rhizobium species were 75.9% for R. setariae KVB221T, 75.8% for R. alvei TNR-22T, which were below the threshold of 95–96% for delineation of bacterial species. The OrthoANI values between TRM96647T, and the type strains of the available Mycoplana species were 90.8% for Mycoplana azooxidifex Po 20/26T, and 82.4% for M. subbaraonis JC85T, which were below the threshold of 95–96% for delineation of bacterial species. The dDDH values of the three novel species with the most closely related species were 18.3–42.8%. Based on the genomic, phenotypic and phylogenetic analyses, strains TRM95796T and TRM96650T are suggested to represent two new species of the genus Rhizobium and Mycoplana, whose names are proposed as Rhizobium qitaiense sp. nov., Mycoplana qihuense sp. nov. The type strains are TRM95796T (= GDMCC 1.3495T = JCM 35985T) and TRM96650T (= GDMCC 1.34953T = JCM35987T), respectively.