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533956 
Journal Article 
Hydrogen sulfide-producing bacteria in tongue biofilm and their relationship with oral malodour 
Washio, J; Sato, T; Koseki, T; Takahashi, N 
2005 
Yes 
Journal of Medical Microbiology
ISSN: 0022-2615
EISSN: 1473-5644 
54 
9 
889-895 
English 
The aims of this study were to identify hydrogen sulfide (H2S)-producing bacteria among tongue biofilm microflora and to investigate the relationship between bacterial flora and H2S levels in mouth air. Oral malodour levels in 10 subjects (age 21-56 years) were assessed by gas chromatography, and Breathtron and organoleptic scores. Based on these assessments, subjects were divided into two groups: an odour group and a no/low odour group. Tongue coatings were sampled and spread onto Fastidious Anaerobe Agar plates containing 0(.)05 % cysteine, 0(.)12 % glutathione and 0(.)02 % lead acetate, and were then incubated anaerobically at 37 degrees C for 2 weeks. Bacteria forming black or grey colonies were selected as H2S-producing phenotypes. The numbers of total bacteria (P < 0.005) and H2S-producing bacteria (P < 0.05) in the odour group were significantly larger than those in the no/low odour group. Bacteria forming black or grey colonies (1126 isolates from the odour group; 242 isolates from the no/low odour group) were subcultured, confirmed as producing H2S and identified according to 16S rRNA gene sequencing. Species of Veillonella (38.1 % in odour group; 46.3 % in no/low odour group), Actinomyces (25.4 %; 17.7 %) and Prevotella (10.3 %; 7.8 %) were the predominant H2S-producing bacteria in both the odour and no/low odour groups. These results suggest that an increase in the number of H2S-producing bacteria in the tongue biofilm is responsible for oral malodour, although the bacterial composition of tongue biofilm was similar between the two groups. 
volatile sulfur-compounds; mouth air; halitosis; children; microorganisms; individuals; bacteroides; organisms; surfaces