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Two bacterial strains, designated LH3₁3ᵀ and NS4₇, were isolated from urban wastewater samples collected in Shenzhen, China. Cells were aerobic, Gram-stain-negative, oxidase-negative, catalase-positive, non-motile and short rods to coccobacilli. Phylogenetic analysis based on 16S rRNA gene sequences placed the two strains within the genus Acinetobacter, showing the highest sequence similarity to ‘Acinetobacter seohaensis’ SW-100 (98. 44–98. 39%). Among the validly published species, the closest relatives were Acinetobacter indicus and Acinetobacter baumannii, with sequence similarities of 97. 5–97. 4% and 96. 5–96. 3%, respectively, values below the generally accepted species demarcation threshold. Whole-genome sequencing and comparative genomic analyses further supported the novelty of the strains. The average nucleotide identity (ANI) values between strains LH3₁3ᵀ and NS4₇ and their closest related species, Acinetobacter towneri DSM 14962ᵀ, were 92. 5–92. 6%, and the corresponding digital DNA–DNA hybridization (dDDH) values were 50. 2–50. 6%, both clearly below the species delineation thresholds. In contrast, ANI and dDDH values between LH3₁3ᵀ and NS4₇ were 97. 6 and 82. 7%, respectively, indicating that they belong to the same species. Core-genome phylogenomic analysis based on 81 bacterial core genes confirmed that the 2 strains formed a distinct and well-supported clade within the genus Acinetobacter. Phenotypic, physiological and chemotaxonomic characteristics further differentiated strains LH3₁3ᵀ and NS4₇ from their closest phylogenetic relatives. Based on the combined evidence from phylogenetic, genomic, phenotypic and chemotaxonomic analyses, strains LH3₁3ᵀ and NS4₇ represent a novel species of the genus Acinetobacter, for which the name Acinetobacter pengchengensis sp. nov. is proposed. The type strain is LH3₁3ᵀ (=JCM 37796ᵀ=GDMCC 1. 4974ᵀ).
Yang et al. (Wed,) studied this question.