Two novel bacterial isolates were cultured from the rhizosphere of Cardamine hupingshanesis growing in Enshi, Hubei, China. Both strains are capable of reducing selenite to elemental selenium. Strain R3-92 T exhibited a high 16S rRNA gene sequence similarity (99.0%) to Sphingopyxis panaciterrae Gsoil 124 T , whilst strain R2-26 T showed a 16S rRNA gene sequence similarity of 99.5% to Paeniglutamicibacter kerguelensis KNG15 T . The phylogenetic analysis, based on whole-genome sequences and 92 core genes, positioned strain R3-92 T in the same cluster as Sphingopyxis witflariensis DSM 14551 T , and strain R2-26 T in the same cluster as P. kerguelensis DSM 15797 T . The genomes of strains R3-92 T and R2-26 T were 4.8 and 4.2 Mbp in size with DNA G+C contents of 63.6 mol% and 66.5 mol%, respectively. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values for both strains, compared to their closest relatives, were below the species delineation threshold. Strain R3-92 T grew at 4–37 ℃, pH 5–9 and 0–4% (w/v) NaCl concentration, and its main fatty acids were summed feature 8 (C 18 : 1 ω 7 c and/or C 18 : 1 ω 6 c , 35.1%) and summed feature 3 (iso-C 15 : 0 2-OH and/or C 16 : 1 ω 7 c , 28.4%). Strain R2-26 T grew at 4–37 ℃, pH 6–9 and 0–8% (w/v) NaCl concentration, and its main fatty acids were anteiso-C 15 : 0 (62.2%) and anteiso-C 17 : 0 (14.1%). The combination of ANI results, dDDH results and phenotypic characteristics of strains R3-92 T and R2-26 T distinguishes them from their closely related strains. Based on the polyphasic analyses, strains R3-92 T and R2-26 T represent novel species of the genera Sphingopyxis and Paeniglutamicibacter , respectively, for which the names Sphingopyxis selenitireducens sp. nov. (type strain R3-92 T =GDMCC 1.4372 T =JCM 37246 T ) and Paeniglutamicibacter selenitireducens sp. nov. (type strain R2-26 T =GDMCC 1.4369 T =JCM 37299 T ) are proposed.
Liu et al. (Wed,) studied this question.