Direct interactions with commensal streptococci modify intercellular communication behaviors of Streptococcus mutans

Abstract

The formation of dental caries is a complex process that ultimately leads to damage of the tooth enamel from acids produced by microbes in attached biofilms. The bacterial interactions occurring within these biofilms between cariogenic bacteria, such as the mutans streptococci, and health-associated commensal streptococci, are thought to be critical determinants of health and disease. To better understand these interactions, a Streptococcus mutans reporter strain that actively monitors cell–cell communication via peptide signaling was cocultured with different commensal streptococci. Signaling by S. mutans, normally highly active in monoculture, was completely inhibited by several species of commensals, but only when the bacteria were in direct contact with S. mutans. We identified a novel gene expression pattern that occurred in S. mutans when cultured directly with these commensals. Finally, mutant derivatives of commensals lacking previously shown antagonistic gene products displayed wild-type levels of signal inhibition in cocultures. Collectively, these results reveal a novel pathway(s) in multiple health-associated commensal streptococci that blocks peptide signaling and induces a common contact-dependent pattern of differential gene expression in S. mutans. Understanding the molecular basis for this inhibition will assist in the rational design of new risk assessments, diagnostics, and treatments for the most pervasive oral infectious diseases.

Zinc import mediated by AdcABC is critical for colonization of the dental biofilm by Streptococcus mutans in an animal model

“…In addition to the host‐driven mechanisms of metal sequestration, bacteria in polymicrobial biofilms such as dental plaque must also compete with the other oral residents for nutrients. Interestingly, a recent study showed that transcription of the S. mutans adcA and adcB genes was induced (about six‐ and threefold, respectively) when S. mutans was co‐cultured with Streptococcus A12, a health‐associated peroxigenic oral streptococcus (Kaspar et al., 2020). It should be noted that, in principle, peroxigenic streptococci are better equipped to scavenge zinc than S. mutans due to the concerted effort of AdcAII and Pht proteins in addition to the AdcABC system.…”

“…mutans adcA and adcB genes was induced (about six-and threefold, respectively) when S. mutans was co-cultured with Streptococcus A12, a health-associated peroxigenic oral streptococcus (Kaspar et al, 2020). It should be noted that, in principle, peroxigenic streptococci are better equipped to scavenge zinc than S. mutans due to the concerted effort of AdcAII and Pht proteins in addition to the AdcABC system.…”

Zinc Import Mediated by AdcABC is Critical for Colonization of the Dental Biofilm byStreptococcus mutansin an Animal Model

“…In addition to the host-driven mechanisms of metal sequestration, bacteria in polymicrobial biofilms such as dental plaque must also compete with the other oral residents for nutrients. Interestingly, a recent study showed that transcription of the S. mutans adcA and adcB genes was induced (about 6-and 3-fold, respectively) when S. mutans was co-cultured with Streptococcus A12, a health-associated peroxigenic oral streptococci (Kaspar, Lee, Richard, Walker, & Burne, 2020). It should be noted that, in principle, peroxigenic streptococci are better equipped to scavenge zinc than S. mutans due to the concerted effort of AdcAII and Pht proteins in addition to the AdcABC system.…”

Spatial Correlations and Distribution of Competence Gene Expression in Biofilms of Streptococcus mutans

“…Finally we note that the oral biofilm is a complex multispecies community in which S. mutans must compete with a number of commensal species ( Bowen et al, 2018 ). These interactions can lead to highly localized inhibitory effects on competence behavior ( Kaspar et al, 2020 ). Therefore, although the present work shows that the physical properties of the single-species biofilm do not themselves impose heterogeneity in competence behavior, localized interactions with commensal species may quite possibly impose spatial heterogeneity onto competence.…”