Journal of Microbial & Biochemical Technology

Abstract

Relationship between Bacterial Floras in Saliva and Tongue Coating and Volatile Sulfur Compounds in Oral Air

Kouichirou Shin, Izumi Aoyama, Koji Yamauchi, Fumiaki Abe and Ken Yaegaki

Volatile sulfur compounds produced by oral bacteria are known to be responsible for oral malodor. In this study, 20 volunteers without periodontitis were divided into malodor (n=10, H2S>1.5 ng/10 ml air or CH3SH>0.5 ng/10 ml air) and control (n=10) groups, based on a gas chromatography analysis of concentrations of volatile sulfur compounds in their mouth air. The total number of bacteria in whole saliva and tongue coating samples was analyzed by quantitative PCR, and the relative abundance of bacterial species was determined by targeted pyrosequencing of DNA encoding the V5-6 hypervariable region of 16S rRNA. The total number of bacteria in tongue coating suspensions analyzed by quantitative PCR was significantly higher in the malodor group compared to the control group. Total reads of 15,581 and 298,079 were yielded by pyrosequencing of saliva and tongue coating samples, respectively. These sequences were assigned to taxons by BLAST searches against reference sequences of the Human Oral Microbiome Database based on ≥ 97% homology. Percentages of Peptostreptococcus stomatis and Capnocytophaga sputigena in saliva, as well as Clostridiales sp. oral taxon 85 and P. stomatis in tongue coating, were significantly higher in the malodor group. In contrast, the percentage of saliva samples with Porphyromonas endodontalis was significantly lower in the malodor group. Estimated numbers of Lachnospiraceae sp. oral taxon 82, Eubacterium infirmum, P. stomatis, Veillonella parvula, Fusobacterium periodonticum, Prevotella sp. oral taxon 474, Mogibacterium diversum, Solobacterium moorei, and Haemophilus parainfluenzae in tongue coating samples were significantly higher the in malodor group. These results indicate that the bacterial load of several commensal species in tongue coating correlates with the concentration of volatile sulfur compounds in mouth air.