Complete genome sequence of Streptococcus hominis isolated from subgingival biofilm

Streptococcus hominis is a recently described species within the genus Streptococcus, yet its genomic characteristics remain poorly understood, particularly in the context of the oral microbiome. Previously, only two complete genomes from non-oral sources were available. To address this gap, we sequenced and analyzed S. hominis strain KHUD_010, isolated from the subgingival biofilm of a healthy Korean adult.

Genomic DNA from KHUD_010 was extracted and confirmed as S. hominis by 16 S rRNA gene sequencing. Whole-genome sequencing using the PacBio Sequel II platform generated 135,974 HiFi reads (N50: 10,345 bp). De novo assembly with SMRT Link v11.0 produced a single circular chromosome of 1,883,665 bp with 39.04% GC content. Annotation via the NCBI Prokaryotic Genome Annotation Pipeline predicted 1,793 protein-coding genes, four rRNA operons (5 S, 16 S, 23 S), and 120 tRNAs. BUSCO analysis showed 99.1% completeness. Comparative genomics with NSJ-17 and UMB6992B revealed 1,416 core, 223 dispensable, and 398 strain-specific gene clusters. KHUD_010 harbored 18 unique gene clusters comprising 20 genes, mostly assigned to COG category L (replication, recombination, repair). This high-quality genome expands the genomic landscape of S. hominis and provides a valuable reference for future studies on oral microbiome diversity and host adaptation.