Ensifer Alkalisoli Sp Nov Isolated From Root Nodules Of Sesbania Cannabina Grown In Saline-Alkaline Soils

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 gin/I. 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 SO2(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 omega 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%.