# Mechanisms underlying spatial interaction in the oral microbiota

> **NIH NIH R01** · UNIVERSITY OF RHODE ISLAND · 2020 · $406,647

## Abstract

ABSTRACT
Human oral plaque is a polymicrobial community whose composition varies during health and disease.
Recent advances in technology have yielded new information on the identity and abundance of
constituent species during these conditions yet do not allow predictions of direct interactions between
specific organisms. The biogeography of reproducible structures within supragingival plaque has been
characterized through advanced microscopy methods suggesting key organisms that may help arrange
plaque structure. Species-species co-proximity within these ordered structures is suggestive of
metabolite mediated interactions between them. Our global hypothesis is that adjacent species in healthy
plaque biofilms have specific metabolic and physical interactions that shape both the physical and
compositional structure of this community. To identify mechanistic interactions between adjacent
species, we must determine which species exist together in vivo. Preliminary data indicates that the
highly abundant Corynebacterium matruchotii and Haemophilus parainfluenzae bacterial species exist
directly adjacent to several Streptococcus spp. suggesting they must be able to tolerate pH and oxidative
stress produced by oral streptococci. Direct imaging further suggests that some species bind directly to
each other or mutually to a host intermediate such as salivary protein. The physical means of attachment
for C. matruchotii and H. parainfluenzae to Streptococcus spp. are unknown. This proposal will
determine which Streptococcus species interact with C. matruchotii and H. parainfluenzae via
microscopy (Aim 1). It will also determine if C. matruchotii and H. parainfluenzae participate in cross-
feeding interactions with streptococcal produced metabolites and will identify mechanisms that either
bacterium uses to tolerate pH and oxidative stress through transcriptome analyses, mutant library
assays, and quantitative metabolite measurements (Aim 2). Lastly, our proposal will determine physical
factors produced by bacteria that are responsible for co-adhesion between different species. These will
be identified by direct and random mutagenesis of C. matruchotii and H. parainfluenzae and tested in
combination with known interacting Streptococcus species. The goal of this proposal is to identify
interacting species in healthy supragingival plaque and characterize mechanistic interactions between
them, revealing how they may contribute to plaque structure and composition. Our rationale is that we
will identify mechanisms that promote interactions between highly abundant organisms in healthy plaque
and identify candidate species and their associated interactions for use in probiotic or prophylactic
interventions to manage oral plaque communities to prevent opportunistic infection.

## Key facts

- **NIH application ID:** 9974507
- **Project number:** 5R01DE027958-02
- **Recipient organization:** UNIVERSITY OF RHODE ISLAND
- **Principal Investigator:** Matthew Ramsey
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $406,647
- **Award type:** 5
- **Project period:** 2019-07-08 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9974507

## Citation

> US National Institutes of Health, RePORTER application 9974507, Mechanisms underlying spatial interaction in the oral microbiota (5R01DE027958-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9974507. Licensed CC0.

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