Pseudomonas nitrititolerans sp. nov., a nitrite-tolerant denitrifying bacterium isolated from a nitrification/denitrification bioreactor

Abstract

A nitrite-tolerant denitrifying bacterium, strain GL14^T, was isolated from the nitrification/denitrification bioreactor in our laboratory. Strain GL14^T was Gram-stain-negative, rod-shaped, non-spore-forming, facultatively anaerobic and motile by means of a single polar flagellum. Phylogenetic analyses based on 16S rRNA gene sequences indicated that it was assigned to the genus Pseudomonas with highest 16S rRNA gene sequence similarity (98.77 %) to Pseudomonas xanthomarina DSM 18231^T and Pseudomonassongnenensis NEAU-ST5-5^T, followed by Pseudomonasstutzeri ATCC 17588^T (98.42 %), Pseudomonaskunmingensis HL22-2^T (98.29 %) and Pseudomonaszhaodongensis NEAU-ST5-21^T (98.22 %). Phylogenetic analysis based on both concatenated sequences of the 16S rRNA gene and two housekeeping genes (gyrB and rpoD) and genome sequences further clarified the intrageneric phylogenetic position of strain GL14^T. The DNA G+C content of GL14^T was 63.1 mol%. The results of digital DNA-DNA hybridization (highest 24.2 % of DNA-DNA relatedness) based on the Genome-to-Genome Distance Calculator and average nucleotide identity analyses (highest 80.23 %) confirmed that the strain was distinctly delineated from known species of the genus Pseudomonas. The major fatty acids were summed feature 8 (C18 : 1ω7c/C18 : 1ω6c), C16 : 0, summed feature 3 (C16 : 1ω7c/C16 : 1ω6c), C17 : 0cyclo and C12 : 0. The respiratory quinone was ubiquinone Q-9. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. Based on the phylogenetic, genomic, phenotypic and chemotaxonomic analyses, it was concluded that strain GL14^T represents a novel species of the genus Pseudomonas, for which the name Pseudomonas nitrititolerans sp. nov. is proposed. The type strain is GL14^T (=CGMCC 1.13874^T=NBRC 113853^T).

Keywords: 16S rRNA; Pseudomonas nitrititolerans; genome; nitrite tolerance; novel species.