# Exploring the role of C. albicans oxidative stress pathways in S. mutans reactive oxygen species tolerance

> **NIH NIH F30** · UNIVERSITY OF FLORIDA · 2024 · $47,959

## Abstract

Abstract
Dental caries is the most prevalent chronic infectious disease, affecting an estimated 2.5 billion people
worldwide. Streptococcus mutans is an important pathogen in dental caries due to its ability to acidify the oral
pH, inhibiting the growth of health-associated non-aciduric bacteria and narrowing the diversity of the oral
microbiota. Candida albicans has emerged as a synergistic partner to S. mutans in dental caries, with the two
organisms being co-isolated from early childhood, root, and dentinal caries. Dual-species S. mutans-C.
albicans biofilms demonstrate enhanced matrix formation, cariogenicity, and stress tolerance including
chlorhexidine and hydrogen peroxide. Hydrogen peroxide has a more than century-long history of oral use for
its anti-microbial effect. Many oral hygiene products including mouthwashes and toothpastes incorporate
hydrogen peroxide. While hydrogen peroxide has shown to be efficacious as an adjunct in treating
periodontitis, its anti-caries effect is less studied. Interestingly, S. mutans is relatively susceptible to oxidative
stress in comparison to health-associated oral streptococci. However, the enhanced oxidative stress tolerance
of S. mutans in co-culture with C. albicans may reduce hydrogen peroxide's effectiveness as an anti-caries
agent. C. albicans encodes a robust set of oxidative stress tolerance genes. Notably, these include 6
superoxide dismutase (SOD) enzymes (3 of which are extracellular) and a catalase enzyme, which detoxify
superoxide to hydrogen peroxide and hydrogen peroxide to water, respectively. S. mutans encodes only a
single SOD enzyme. Our working hypothesis is that C. albicans oxidative stress tolerance enzymes, catalase
and extracellular SODs, enhance S. mutans oxidative stress tolerance in S. mutans-C. albicans biofilms. The
goals of this application are to elucidate the mechanism of C. albicans protection of S. mutans oxidative stress
tolerance in vitro and in vivo. To accomplish these goals the PI will utilize biofilm, survival, interruption, and
confocal microscopy assays (Aim 1) and rat caries model (Aim 2) to determine the roles of C. albicans catalase
and extracellular SOD enzymes on S. mutans oxidative stress tolerance and subsequent cariogenicity
Knowledge gained from this study will provide a novel target for disruption of S. mutans-C. albicans synergism
and the highly cariogenic biofilms these organisms produce. Additionally, the comprehensive training plan
provided will further the PI's development to a well-rounded dental researcher through formal coursework,
opportunities to learn new techniques, mentor students, improve scientific presenting and writing skills,
balancing dental practice and research, and networking with other dentists and scientists at conferences.

## Key facts

- **NIH application ID:** 10996678
- **Project number:** 1F30DE034286-01
- **Recipient organization:** UNIVERSITY OF FLORIDA
- **Principal Investigator:** Callahan Kashmira Katrak
- **Activity code:** F30 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $47,959
- **Award type:** 1
- **Project period:** 2024-08-16 → 2026-08-15

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10996678

## Citation

> US National Institutes of Health, RePORTER application 10996678, Exploring the role of C. albicans oxidative stress pathways in S. mutans reactive oxygen species tolerance (1F30DE034286-01). Retrieved via MORVS 2026-10-26 from https://api.morvs.ai/grant/nih/10996678. Licensed CC0.

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