Mesorhizobium sanjuanii sp. nov. isolated from nodules of Lotus tenuis in saline-alkaline lowlands of Flooding Pampa, Argentina

SANNAZZARO, ANALÍA I.; TORRES TEJERIZO, GONZALO; FONTANA, MA. FLORENCIA; CUMPA VELÁZQUEZ, LIZ; HANSEN, LARS; PISTORIO, MARIANO; ESTRELLA, MARIA JULIA

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY.

SOC GENERAL MICROBIOLOGY

Lugar: London; Año: 2018

1466-5026

Two rhizobial strains, BSA 136T and BSA 150, related to the genus Mesorhizobium were isolated from root nodules of Lotus tenuis grown in saline-alkaline lowlands soils from Argentina. These strains showed different Rep-PCR fingerprinting patterns but shared more than 99% sequence similarity for both 16S rRNA and recA genes. Despite the symbiotic nodC gene sequences of our strains being related to the canonical Lotus biovar species comprising M. loti and M. japonicum, the 16S rRNA and recA phylogenetic markers suggest that their taxonomical identity is closely related to M. helmanticense, M. metallidurans, M. thianshanense, M. gobiense and M. tarimense. Multilocus sequence analysis performed with seven housekeeping genes confirmed that BSA 136T belongs to a separate clade within the genus Mesorhizobium. The comparisons for in silico DNA-DNA hybridization and Average Nucletide Identity indexes between the genomes of BSA 136T and most related Mesorhizobium species were below the threshold for species delineation. Phenotypic and chemotaxonomic features differentiated BSA 136T from closest related species. On the basis of our results, BSA 136T and BSA 150 can be considered to represent a novel species of the genus Mesorhizobium, for which the name Mesorhizobium sanjuanii sp. nov. is hereby proposed. The type strain of this species is BSA 136T (= CECT 9305T = LMG 30600T), which draft-genome sequence is available.