Mesorhizobium helmanticense sp. nov., isolated from Lotus corniculatus nodules

Abstract

In this study, three strains belonging to the genus Mesorhizobium, CSLC115NT, CSLC19N and CSLC37N, isolated from Lotus corniculatus nodules in Spain, were characterized. Their 16S rRNA gene sequences were closely related to those of Mesorhizobium metallidurans STM 2683T, Mesorhizobium tianshanense A-1BST, Mesorhizobium tarimense CCBAU 83306T, Mesorhizobium gobiense CCBAU 83330T and Mesorhizobium caraganae CCBAU 11299T with similarity values higher than 99.7 %. The analysis of concatenated recA and glnII genes showed that the most closely related type strains were M. metallidurans STM 2683T, M. tianshanense A-1BST and M. tarimense CCBAU 83306T with 96, 95 and 94 % similarity values in the recA gene and 95, 94 and 94 % in the glnII gene, respectively. M. metallidurans LMG 24485T, M. tianshanense USDA 3592T and M. tarimense LMG 24338T showed means of 44, 41 and 42 % DNA-DNA relatedness, respectively, with respect to strain CSLC115NT. The major fatty acids were those from summed feature 8 (C18 : 1ω7c/C18 : 1ω6c), C16 : 0 and C18 : 1ω7c 11-methyl. The results of phenotypic characterization support that the L. corniculatus nodulating strains analysed in this work belong to a novel species of the genus Mesorhizobium for which the name Mesorhizobium helmanticense sp. nov. is proposed, and the type strain is CSLC115NT (= LMG 29734T=CECT 9168T).