Ensifer alkalisoli sp. nov. isolated from root nodules of Sesbania cannabina grown in saline–alkaline soils

Abstract

A group of Sesbania cannabina rhizobia belonging to four recA genotypes of a novel group was further characterized in comparison with the related Ensifer species. They showed 98.2 to 99.9 % similarities among themselves and 92.9 to 93.3 % similarities with the most related strain Ensifer sojae CCBAU 05684 T in multilocus sequence analysis of recA, atpD and glnII. The genome average nucleotide identity values between representative strain YIC4027 T and the type strains of its closely related species were 81.6 to 88.9 %. Identical symbiotic gene (nodA, nodC and nifH) sequences highly similar with those in other Sesbania-nodulating strains (Rhizobium sp. SIN-1, Neorhizobium huautlense S02 T , Ensifer saheli ORS609 T and Rhizobium sp. IRBG74) were detected. The representative strain YIC4027 T could form effective nodules on its original host Sesbania cannabina, but not on Sophora flavescens, Trifolium repens, Glycine max, Glycyrrhiza uralensis, Phaseolus vulgaris or Medicago sativa. The use of lactulose as sole carbon source, possession of C 13 : 0 2-OH, C 13 : 1 at 12-13, C 15 : 1 iso !9c, C 17 : 0 anteiso and C 18 : 0 iso and absence of C 14 : 0 anteiso, C 15 : 0 anteiso and C 18 : 0 3-OH in fatty acids distinguished the strain YIC4027 T from the type strains of its closely related species. Based on all the analyses mentioned above, we propose a novel species Ensifer alkalisoli sp. nov. and designate YIC4027 T (=HAMBI 3655 T =LMG 29286 T ) as the type strain. The genome size of YIC4027 T is 5.97 Mbp, comprising 5588 predicted genes, and the DNA G+C content is 62.2 mol%.

Taxonomy of Rhizobiaceae revisited: proposal of a new framework for genus delimitation

“…The description is as provided by Li et al . 2016 [57]. S. alkalisoli can be differentiated from other species of the genus Sinorhizobium based on OGRI calculations (ANI and isDDH).…”

The genome of Ensifer alkalisoli YIC4027 provides insights for host specificity and environmental adaptations

“…E. alkalisoli YIC4027 was proposed as a new species of Ensifer in our previous study [6]. To examine the relationship between YIC4027 and other rhizobia, we selected 11 completely sequenced genomes of representative rhizobial strains and constructed a phylogenetic tree based on their core genome.…”

“…E. alkalisoli YIC4027 is a motile rhizobium that efficiently fixes nitrogen in nodules of its host plant S. cannabina [6]. The complete genome sequence of YIC4027 provides the basis for a deeper understanding of molecular mechanisms underlying host specificity and environmental adaptations.…”

“…This led us to propose a new species, E. alkalisoli , with YIC4027 as a type strain. E. alkalisoli is closely related to E. fredii and E. sojae [6]. E. alkalisoli YIC4027 displays symbiotic nitrogen fixation ability, salt tolerance (up to 4% NaCl) and alkaline tolerance (pH 6–10) [6].…”

“…E. alkalisoli is closely related to E. fredii and E. sojae [6]. E. alkalisoli YIC4027 displays symbiotic nitrogen fixation ability, salt tolerance (up to 4% NaCl) and alkaline tolerance (pH 6–10) [6]. YIC4027 can enter a nodule symbiosis, but its host range is limited and S. cannabina is so far the only known host plant of YIC4027.…”