Agrobacterium salinitolerans sp nov., a saline-alkaline-tolerant bacterium isolated from root nodule of Sesbania cannabina

Two Gram-staining-negative, aerobic bacteria (YIC 5082(T) and YIC4104) isolated from root nodules of Sesbania cannabina grown in a high-salt and alkaline environment were identified as a group in the genus Agrobacterium because they shared 100 and 99.7% sequence similarities of 16S rRNA and recA+ atpD genes, respectively. These two strains showed 99.2/100% and 93.9/95.4% 16S rRNA and recA+ atpD gene sequence similarities to Agrobacterium radiobacter LMG140 T and Agrobacterium. pusense NRCPB10 T, respectively. The average nucleotide identities (ANI) of genome sequences were 89.95% or lower between YIC 5082 T and the species of the genus Agrobacterium examined. Moreover, these two test strains formed a unique nifH lineage deeply separated from other rhizobia. Although the nodC gene was not detected in YIC 5082(T) and YIC4104, they could form effective root nodules on S. cannabina plants. The main cellular fatty acids in YIC 5082(T) were summed feature 8 (C-18 : 1 omega 7c/C-18 : 1 omega 6c), C-19 : 0 omega 8c, summed feature 2 (C-12 : 0 aldehyde/unknown equivalent chain length 10.9525) and C16 : 0. The DNA G+C content of YIC 5082 T was 59.3 mol%. The failure to utilize D-sorbitol as a carbon source distinguished YIC 5082(T) from the type strains of related species. YIC 5082 T could grow in presence of 5.0% (w/v) NaCl and at a pH of up to 10.0. Based on results regarding the genetic and phenotypic properties of YIC 5082(T) and YIC4104 the name Agrobacterium salinitolerans sp. nov. is proposed and YIC 5082 T (= HAMBI 3646 T = LMG 29287(T)) is designed as the type strain.