Hydrogen sulfide-producing bacteria in tongue biofilm and their relationship with oral malodour.
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 (126 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.
Washio
Jumpei
J
Division of Preventive Dentistry1, and Division of Oral Ecology and Biochemistry2, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
Sato
Takuichi
T
Division of Preventive Dentistry1, and Division of Oral Ecology and Biochemistry2, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
Koseki
Takeyoshi
T
Division of Preventive Dentistry1, and Division of Oral Ecology and Biochemistry2, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
Takahashi
Nobuhiro
N
Division of Preventive Dentistry1, and Division of Oral Ecology and Biochemistry2, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
D000328:Adult; D018441:Biofilms / Q000254:growth & development*; D004269:DNA, Bacterial / Q000032:analysis; D005260:Female; D006090:Gram-Negative Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D006094:Gram-Positive Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D006209:Halitosis / Q000382:microbiology*; D006801:Humans; D006862:Hydrogen Sulfide / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014059:Tongue / Q000382:microbiology*
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D006862:Hydrogen Sulfide