Leifsonia araucanica sp. nov., isolated from nodules of Lupinus luteus and reclassification of Leifsonia naganoensis as a later heterotypic synonym of Leifsonia aquatica.

Abstract

A Gram-positive, non-spore-forming, rod-shaped actinobacterium, designated strain Le1T, was isolated from root nodules of Lupinus luteus cultivated in volcanic soils of southern Chile. Phylogenetic analysis based on the 16S rRNA gene placed strain Le1ᵀ within the genus Leifsonia, showing the highest sequence similarity to Leifsonia lichenia and related species. However, genome-based analyses supported clear taxonomic separation. The draft genome of strain Le1ᵀ is 4.03 Mb, with a DNA G+C content of 69.26 mol%. Average nucleotide identity and digital DNA-DNA hybridization values between strain Le1ᵀ and its closest relatives ranged from 88.5 to 80.8% and 32.8 to 21.3%, respectively, below the accepted species delineation thresholds. Phylogenomic reconstruction based on 92 conserved core genes confirmed that strain Le1ᵀ forms a distinct and well-supported lineage within the genus. The predominant cellular fatty acids of strain Le1ᵀ are anteiso-C15 : 0, anteiso-C17 : 0, iso-C16 : 0 and C16 : 0. Phenotypic characteristics differentiate strain Le1ᵀ from its closest phylogenetic relatives. On the basis of polyphasic taxonomic evidence, strain Le1ᵀ represents a novel species of the genus Leifsonia, for which the name Leifsonia araucanica sp. nov. is proposed. The type strain is Le1ᵀ (=RGM 3741ᵀ=LMG 34089ᵀ). In addition, genome-based comparisons indicate that Leifsonia naganoensis Suzuki et al. 2000 should be regarded as a later heterotypic synonym of Leifsonia aquatica (ex Leifson 1962) Evtushenko et al. 2000.