Terrihabitans rhizophilus sp. nov., isolated from the rhizosphere soil of plant in temperate semi-arid steppe

Abstract

A bacterial strain PJ23^T was isolated from the rhizosphere soil of Elymus dahuricus Turcz. sampled from a temperate semi-arid steppe in the northern of Inner Mongolia Autonomous Region, China. The strain is Gram-stain-negative, aerobic, light-pink, short rod-shaped, and non-spore-forming. Cell growth could be observed at 4–29℃ (optimal at 24℃), pH 6.0–8.6 (optimal at 8.0) and in the presence of 0–5.0% (w/v) NaCl (optimal at 2.5%). The major cellular fatty acids of strain PJ23^T were Summed feature 8 (C_{18:1 ω6c} and/or C_{18:1 ω7c}) (39.42%) and C_16:0 (9.60%). The polar lipids were phosphatidylcholine, two unidentified glycolipids, one unidentified aminophospholipid, and two other unidentified polar lipids. The major respiratory quinone was ubiquinone-10. Phylogeny analysis based on 16S rRNA gene sequences retrieved from the genomes showed that, the strain was closely related to the species Terrihabitans soli IZ6^T and Flaviflagellibacter deserti SYSU D60017^T, with the sequence similarities of 96.79% and 96.15%, respectively. The G + C content was 65.23 mol% calculated on draft genome sequencing. Between the strains PJ23^T and Terrihabitans soli IZ6^T, the average nucleotide identity (ANI), amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH) was 73.39%,71.12% and 15.7%, these values were lower than the proposed and generally accepted species boundaries of ANI, AAI and dDDH, respectively. Based on phenotypic, chemotaxonomic, and phylogenetic characteristics, strain PJ23^T represents a novel species of Terrihabitans, for which the name Terrihabitans rhizophilus sp. nov. is proposed. The type strain is PJ23^T (= KCTC 92977 ^T = CGMCC 1.61577 ^T).