Hydrogen sulfide-producing bacteria in tongue biofilm and their relationship with oral malodour

H2S-producing bacteria in the tongue biofilm appear to cause low to intermediate levels of oral malodour in patients without periodontitis, and the predominant H2S-producing bacteria are mainly commensal species of the oral cavity, such as Veillonella and Actinomyces species. Furthermore, the numbers of both H2S-producing bacteria and total bacteria in the tongue biofilm were higher in the odour group, suggesting that for subjects with low to intermediate levels of malodour an increase in bacterial density in the tongue biofilm is associated with oral malodour.