This study aimed to confirm the species identity and characterize two Selenomonas sputigena strains (KCOM 1787 and KCOM 2046) isolated from the oral cavities of Korean individuals using genomic and chemotaxonomic approaches. Whole-genome sequencing was performed with PacBio RSII and Illumina platforms. Species-level classification was assessed using 16S rDNA similarity, average nucleotide identity (OrthoANI), and genome-togenome distance calculation (GGDC). Chemotaxonomic analysis included cellular fatty acid profiling using gas chromatography and polar lipid analysis using two-dimensional thin-layer chromatography. The two strains showed 16S rDNA similarities of 98.85% and 99.53% with the S. sputigena type strain ATCC 35185T. OrthoANI values exceeded the species threshold (95.34% and 95.69%), whereas GGDC values were below the conventional cutoff (61.6% and 63.7%). Despite the low GGDC values, classification as S. sputigena was supported by the combined evidence of high 16S similarity, OrthoANI values above the species demarcation threshold, and minimal differences in genomic GC content (< 1 mol%). Chemotaxonomic analysis revealed that the major fatty acids were C14:0 DMA and C16:1 cis -7, while the polar lipids included phosphatidylethanolamine and several unidentified aminolipids. Although GGDC values were below the 70% species threshold, the high OrthoANI values, 16S rDNA similarity, and genomic GC content supported the classification of KCOM 1787 and KCOM 2046 as S. sputigena. These strains may serve as valuable resources for future studies on intraspecies variation and the pathogenesis of oral Selenomonas species.

Introduction
Materials and Methods
    1. Bacteria and bacterial culture
    2. Phylogenetic analysis based on 16S rDNAnucleotide sequences
    3. Genome sequencing and bacterial speciesdetermination
    4. Morphological characterization
    5. Biochemical characterization
    6. Bacterial fatty acid composition analysis
    7. Polar lipid analysis
Results
    1. 16S rDNA sequence homology and phylogeneticanalysis
    2. Bacterial species identification throughwhole-genome sequencing
    3. Morphological characterization
    4. Analysis of biochemical characterization, bacterialfatty acid composition and polar lipids
Discussion
Funding
Conflicts of Interest
Supplementary Data
References

• Yun Kyong Lim(Department of Oral Biochemistry, College of Dentistry, Chosun University, Gwangju 61452, Republic of Korea, Oral Bacterial Pathogen Resource Specialized Bank and Korean Collection for Oral Microbiology, Chosun University, Gwangju 61452, Republic of Korea)
• Soon-Nang Park(Department of Oral Biochemistry, College of Dentistry, Chosun University, Gwangju 61452, Republic of Korea, Oral Bacterial Pathogen Resource Specialized Bank and Korean Collection for Oral Microbiology, Chosun University, Gwangju 61452, Republic of Korea)
• Joong-Ki Kook(Department of Oral Biochemistry, College of Dentistry, Chosun University, Gwangju 61452, Republic of Korea, Oral Bacterial Pathogen Resource Specialized Bank and Korean Collection for Oral Microbiology, Chosun University, Gwangju 61452, Republic of Korea) Corresponding author