Paludibacterium denitrificans sp. nov., a Novel Denitrifying Bacterium Isolated from Activated Sludge.

A Gram-reaction-negative, facultatively aerobic, motile, non-spore-forming, rod-shaped, and denitrifying bacterium, designated dN18-1, was isolated from activated sludge, Republic of Korea. This bacterium was investigated via a polyphasic approach to reveal its taxonomic position. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain dN18-1 belongs to the genus Paludibacterium and is most closely related to P. purpuratum KCTC 42852 (96.2% sequence similarity), P. yongneupense KACC 11601 (96.1%), and P. paludis BCRC 80514 (95.2%). The average nucleotide identity values and digital DNA-DNA hybridization values calculated between strain dN18-1 and the closely related strains were 72.5-73.1% and 19.0-19.6%. The genome comprises of 3,347,996 bp with a G + C content of 57.3 mol%. Strain dN18-1 possesses ubiquinone Q-8 as a predominant respiratory quinone, and summed feature 3 (C ω6c and/or C ω7c), summed feature 8 (C ω6c/C ω7c), C and C, as its major fatty acids (>5%). The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and four unidentified aminophospholipids. The results of ANI calculation, digital DNA-DNA hybridization, physiological and biochemical tests allowed phenotypic differentiation of strain dN18-1 from rephrase other genus Paludibacterium species with validly published names. Therefore, this isolate represents a novel species, for which the name Paludibacterium denitrificans sp. nov. (type strain dN18-1 = KACC 19537 = CGMCC 1.16961) is proposed.