Competence-stimulating peptide-dependent localized cell death and extracellular DNA production in Streptococcus mutans biofilms.

Competence-stimulating peptide-dependent localized cell death and extracellular DNA production in Streptococcus mutans biofilms. Appl Environ Microbiol. 2020 Sep 18;: Authors: Nagasawa R, Yamamoto T, Utada AS, Nomura N, Obana N Abstract Extracellular DNA (eDNA) is a biofilm component that contributes to the formation and structural stability of biofilms. Streptococcus mutans, a major cariogenic bacterium, induces eDNA-dependent biofilm formation under specific conditions. Since cell death can result in the release and accumulation of DNA, the dead cells in biofilms are a source of eDNA. However, it remains unknown how eDNA is released from dead cells and is localized within S. mutans biofilms. We focused on cell death induced by the extracellular signaling peptide, competence-stimulating peptide (CSP). We demonstrate that nucleic acid release into the extracellular environment occurs in a subpopulation of dead cells. eDNA production induced by CSP was highly dependent on the lytF gene, which encodes an autolysin. Although lytF expression was induced bimodally by CSP, lytF-expressing cells further divided into surviving cells and eDNA-producing dead cells. Moreover, we found that lytF-expressing cells were abundant near the bottom of the biofilm, even when all cells in the biofilm received the CSP signal. Dead cells and eDNA were also abundantly present near the bottom of the biofilm. The number of lytF-expressing cells in biofilms wa...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research