Lactobacilli and human dental caries: more than mechanical retention

Lactobacilli have been considered as major contributors to human dental caries for over a century. Recent in vitro model studies have shown that when compared to Streptococcus mutans, a keystone pathogen of human dental caries, the ability of lactobacilli to form biofilms is poor, although differences exist between the different major species. Further studies using molecular and bioinformatics approaches provide evidence that multiple mechanisms, including adhesin- receptor mediated physical contact with S. mutans, facilitate the adherence and establishment of lactobacilli on the tooth surface. There is also evidence that under conditions like continuous sugar consumption, weak acids and other antimicrobials such as bacteriocins from lactobacilli can become detrimental to the microbial community, especially those in the proximity. Details on the underlying mechanisms of how different Lactobacillus sp. establish and persist in the highly complex microbiota on the tooth surface await further investigation.

Automated summary

Lactobacilli have been long considered as major contributors to dental caries, but their ability to form biofilms is relatively poor compared to the key pathogen Streptococcus mutans. However, multiple mechanisms, including physical contact through adhesin-receptor mediated interaction, enable the adherence and establishment of lactobacilli on the tooth surface. Moreover, weak acids and bacteriocins produced by lactobacilli can be detrimental to the microbial community, especially when there is continuous sugar consumption. Further investigation is needed to fully understand the underlying mechanisms of how different Lactobacillus species establish and persist in the complex microbiota on the tooth surface.