Liu_2025_Front.Microbiol_16_1683098

INTRODUCTION: Two Gram-stain negative, facultatively anaerobic, rod-shaped, motile, and non-spore forming bacterial strains, 142053(T) and 142359(T), were isolated from sputum samples obtained from different patients. METHODS: Growth of strain 142053(T) and 142359(T) occurred at 8-42 degreesC (optimum 28-37 degreesC), pH 5.0-9.0 (optimum 6.0-8.0) and NaCl concentrations of 0-5% (w/v) (optimum 0-4%). Comparison of 16S rRNA gene sequences showed that strain 142053(T) and 142359(T) exhibited high similarity to Kluyvera intermedia NBRC 102594(T) (99.48%) and Kluyvera georgiana ATCC 51603(T) (98.68%), respectively. RESULTS: Phylogenomic tree of species from family Enterobacteriaceae revealed that strain 142053(T) and 142359(T) formed distinct branches within the Kluyvera clade. The digital DNA-DNA hybridization between 142053(T), 142359(T), and all type strains of Kluyvera species were >=39.5% and >=54.7%, respectively, and the corresponding average nucleotide identity were >=90.56% and >=93.85%, both below the species delineation threshold. The two strains differ phenotypically from other Kluyvera species by their lipase and arginine dihydrolase utilization and from each other by -arabitol utilization. The predominant fatty acids identified in both strains were C(16:0), summed feature 3 (C(16:1) omega7c/C(16:1) omega6c), summed feature 8 (C(18:1) omega7c) and C(17:0) cyclo. DISCUSSION: Based on the phenotypic, chemotaxonomic, phylogenetic and genomic evidence, strains 142053(T) and 142359(T) represent two novel species of the genus Kluyvera, for which the names Kluyvera huaxiensis sp. nov. and Kluyvera chengduensis sp. nov. are proposed, with type strains 142053(T) (= GDMCC 1.4845(T) = JCM 37413(T)) and 142359(T) (= GDMCC 1.5094(T) = JCM 37737(T)), respectively.