Novosphingobium rhizovicinum sp. nov. and Novosphingobium kalidii sp. nov., two novel species isolated from rhizosphere soil and a root of halophyte Kalidium cuspidatum.

Abstract

Two bacteria, designated strain M1R2S20^T and RD2P27^T, were isolated from rhizosphere soil and a root of Kalidium cuspidatum in Baotou, Inner Mongolia, China. Phylogenetic analyses based on the 16S rRNA gene sequences revealed that strains M1R2S20^T and RD2P27^T were tightly clustered and both shared the highest 16S rRNA gene similarities (98.6 and 98.5 %) to Novosphingobium fluoreni ACCC 19180^T and less than 97.8% similarities with all other current type strains. Values of the digital DNA-DNA hybridization (dDDH), the average nucleotide identity based on the blast method (ANIb) and the average amino acid identity (AAI) of the two strains and their closely related species were 32.2, 79.0, and 84.5%, which were lower than the threshold values (70% for dDDH, 95% for ANIb and 95% for AAI). The major fatty acids of strains M1R2S20^T and RD2P27^T were C_18 : 1  ω7c and summed feature 3 (C_16 : 1  ω6c and/or C_16 : 1  ω7c). The only quinone was ubiquinone-10. Spermidine was the predominant polyamine. The genomic DNA G+C contents for strain M1R2S20^T and RD2P27^T were 62.4 and 62.7%. The phenotypic, chemotaxonomic and phylogenetic results supported that strains M1R2S20^T and RD2P27^T could be identified as two novel species within the genus Novosphingobium, for which the name Novosphingobium rhizovicinum sp. nov. and Novosphingobium kalidii sp. nov. are proposed. The type strains are N. rhizovicinum M1R2S20^T (=CGMCC 1.62060^T=KCTC 8106^T) and N. kalidii RD2P27^T (=CGMCC 1.62131^T=KCTC 8107^T).