Halitosis is mainly caused by the action of oral microbes. The purpose of this study was to investigate the differences in salivary microbes and metabolites between subjects with and without
halitosis. Of the 52 participants, 22 were classified into the
halitosis group by the volatile
sulfur compound analysis on breath samples. The
16S rRNA gene amplicon sequencing and metabolomics approaches were used to investigate the difference in microbes and metabolites in saliva of the control and
halitosis groups. The profiles of microbiota and metabolites were relatively different between the
halitosis and control groups. The relative abundances of Prevotella, Alloprevotella, and Megasphaera were significantly higher in the
halitosis group. In contrast, the relative abundances of Streptococcus, Rothia, and Haemophilus were considerably higher in the control group. The levels of
5-aminovaleric acid and
n-acetylornithine were significantly higher in the
halitosis group. The correlation between identified metabolites and microbiota reveals that Alloprevotella and Prevotella might be related to the
cadaverine and
putrescine pathways that cause
halitosis. This study could provide insight into the mechanisms of
halitosis.