Two novel Enterobacter species, Enterobacter chinensis sp. nov. and Enterobacter rongchengensis sp. nov., recovered from clinical samples carrying multiple virulence factors.

Two Enterobacter strains 170198 T and 170250 T were isolated from clinical blood samples from distinct patients in a hospital in Chengdu, China, in 2022. These isolates were subjected to whole-genome sequencing. A phylogenomic tree based on 2,096 concatenated core genes showed that the two strains were clustered within the genus Enterobacter . The average nucleotide identity (ANI) and in silico DNA-DNA hybridization ( is DDH) values between each of the two strains and type strains of all currently known Enterobacter species were determined. The two strains belonged to two novel species as the highest ANI and is DDH values with type strains of all currently known Enterobacter species below the cutoff for species demarcation (96% for ANI and 70% for is DDH). Then the physiological and biochemical studies demonstrated that biochemical features and the profile of whole fatty acids of strains 170198 T and 170250 T were largely consistent with those known Enterobacter species. Nevertheless, the two novel species can be differentiated from all other Enterobacter species by certain biochemical characteristics. In conclusion, 170198 T and 170250 T represent two novel species of the genus Enterobacter , for which we propose Enterobacter chinensis sp. nov. and Enterobacter rongchengensis sp. nov., as the species names. The type strains of Enterobacter chinensis sp. nov., and Enterobacter rongchengensis sp. nov. are 170198 T (=GDMCC 1.3549 T =JCM 35826 T ) and 170250 T (=GDMCC 1.3670 T =JCM 36189 T ), respectively. The two novel species have clinical significance with the ability to cause bloodstream infections.IMPORTANCE Enterobacter is a group of bacteria comprising several common opportunistic pathogens and has a complicated taxonomy. Here, we reported two novel Enterobacter species. We demonstrated that the two novel species can be differentiated from other Enterobacter species by certain phenotypic characteristics and therefore provide information for designing tests for identification. We also showed that strains of the two novel species are able to cause human bloodstream infections and carry multiple virulence factors and therefore are of clinical significance. We highlight that the virulence of Enterobacter is less studied and warrants further exploration. We believe that the findings here are valuable for enhancing the appreciation toward Enterobacter , an important pathogen.