Azospirillum Endophyticum sp. nov., an Endophyte of Paris Polyphylla Smith var. Yunnanensis.

Abstract

A Gram-negative, facultative anaerobic bacterial strain, designated YIM B02556T, was isolated from the root of Paris polyphylla Smith var. yunnanensis collected from Yunnan Province, southwest China. By using a polyphasic approach, its taxonomic position was investigated. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YIM B02556T belonged to the genus Azospirillum and the 16S rRNA gene sequence similarity values of strain YIM B02556T to the type strains of members of this genus ranged from 94.9 to 98.3%. Overall genome relatedness index (OGRI) analysis estimated based on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) between YIM B02556T and other Azospirillum species type strains were <90.8% and <37.8%, lower than the limit of species circumscription. Cells of the strain were characterized as oxidase- and catalase-positive, with motility provided by flagella. The growth conditions of the strain were found to occur at 20-40°C (optimum, 35°C), and pH 6.0-9.5 (optimum, pH 7.5). Strain YIM B02556T can tolerate 2% NaCl concentration. Strain YIM B02556T contained Q-10 as the major ubiquinone. The major fatty acids were C18:1 ω7c and summed feature three (C16:1 ω7c and/or C16:1 ω6c). The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. Based on polyphasic analysis, strain YIM B02556T could be differentiated genotypically and phenotypically from recognized species of the genus Azospirillum. Therefore, the isolate represents a novel species, for which the name Azospirillum endophyticum is proposed. The type strain is YIM B02556T (=JCM 34631T=CGMCC 1.18654T).