Identification and analysis of a clinically isolated strain of Halomonas based on whole-genome sequencing and comparative genomics

Objective: The aim of this study was to identify the species of a Halomonas strain isolated from a neonatal blood sample and to understand the potential pathogenicity and characteristic genes of the strain. Methods: The genomic DNA of strain 18071143 (identified as Halomonas by matrix-assisted laser desorption-ionization time of flight-mass spectrometry and the 16S ribosomal RNA (rRNA) gene sequence) was sequenced using Nanopore PromethION platforms. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) were calculated using the complete genome sequences of the strain. Comparative genomic analyses were performed on strain 18071143 and 3 strains of Halomonas (Halomonas stevensii S18214, Halomonas hamiltonii KCTC 22154, and Halomonas johnsoniae KCTC 22157) that were associated with human infections and had high genomic similarity to strain 18071143. Results: Phylogenetic, ANI, and dDDH similarity analyses based on genome sequence indicated that strain 18071143 belonged to the species H stevensii. Similarities exist between strain 18071143 and the other 3 Halomonas strains in terms of gene structure and protein function. Nonetheless, strain 18071143 has greater potential for DNA replication, recombination, repair, and horizontal transfer. Conclusion: Whole-genome sequencing holds great promise for accurate strain identification in clinical microbiology. In addition, the results of this study provide data for understanding Halomonas from the perspective of pathogenic bacteria.