Role and Pathogenicity of Actinomyces oris in Oral Biofilm Formation and Its Association with Short-chain Fatty Acids

Abstract

Actinomyces oris, one of the initial colonizers, attaches to tooth surfaces and forms biofilms via the fimbriae expressed on its surface. Many oral bacteria produce short-chain fatty acids (SCFAs) as metabolites during growth. These SCFAs have been detected in human saliva and dental plaque. SCFAs have been shown to promote biofilm formation and the initial attachment and colonization of Actinomyces naeslundii. However, the relationship between SCFAs and A. oris has not been clarified. In this study, we investigated the effects of SCFAs on A. oris biofilm formation and initial attachment and colonization, including the relationship between SCFAs and the fimbriae of A. oris. The results showed that butyric acid and propionic acid promoted FimA-dependent biofilm formation by A. oris. Furthermore, a mixture of acetic acid, butyric acid, and propionic acid, which are SCFAs produced in dental plaque, promoted the initial attachment and colonization of A. oris via FimA-dependent and FimA-independent mechanisms. Furthermore, the results suggested that non-ionized acids were involved in this phenomenon.