%0 Journal Article %A Washio, Jumpei %A Sato, Takuichi %A Koseki, Takeyoshi %A Takahashi, Nobuhiro %T Hydrogen sulfide-producing bacteria in tongue biofilm and their relationship with oral malodour %D 2005 %J Journal of Medical Microbiology, %V 54 %N 9 %P 889-895 %@ 1473-5644 %R https://doi.org/10.1099/jmm.0.46118-0 %I Microbiology Society, %X 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 °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. %U https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.46118-0