Reporting two novel Kluyvera species, Kluyvera huaxiensis and Kluyvera chengduensis, isolated from human sputa

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 °C (optimum 28–37 °C), 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 ᴅ-arabitol utilization. The predominant fatty acids identified in both strains were C 16:0 , summed feature 3 (C 16:1 ω7c /C 16:1 ω6c ), summed feature 8 (C 18:1 ω7c ) 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.