Association between oral bacterial species and halitosis: findings from a study of a community-based Japanese population

Halitosis is known to be associated with oral bacteria; however, its specific relationship with particular bacterial species within the oral microbiota remains uncertain. Our objective was to identify oral bacterial species associated with volatile sulfur compound (VSC) production that contribute to halitosis in a community-based Japanese population. This study included 1018 participants. Tongue plaque samples were collected and the oral microbiome was analyzed via 16S rDNA amplicon sequencing. Participants with VSC levels greater than 250 ppb were categorized as having oral malodor. Linear discriminant analysis effect size was used to compare bacterial compositions between participants with and without halitosis. In this study, we identified 37 bacterial genera in tongue plaque samples. Significant differences in bacterial composition were found between the malodor and control groups.<i>Porphyromonas, Fusobacterium</i>, and<i>Solobacterium</i>were more abundant in the malodor group, whereas<i>Streptococcus</i>and<i>Rothia</i>were more prevalent in the control group. Multiple regression analysis further revealed that<i>Porphyromonas</i>and<i>Solobacterium</i>abundances were positively correlated with oral malodor. We found that halitosis in this Japanese population is associated primarily with pathogenic periodontal bacteria (members of the red and orange complexes) and<i>Solobacterium moorei</i>. The bacterial community composition of individuals with halitosis differs significantly from that of healthy individuals, emphasizing the role of specific bacterial species in oral malodor development. These findings increase our understanding of the microbial basis of halitosis and suggest that targeting<i>Solobacterium</i>, along with treating periodontal disease, may be effective in combating halitosis.