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Turkish Journal of Biology

Abstract

Background/aim: The cross-kingdom biofilm structure formed by Candida tropicalis and Streptococcus mutans may increase caries formation. The aim of this study was to evaluate the in vitro effect of the exogenous tyrosol on single- and dual-species biofilms as well as planktonic cultures formed by C. tropicalis and S. mutans. Materials and methods: The antimicrobial efficacy of tyrosol was evaluated through broth microdilution, colony-forming unit (CFU) enumeration, and XTT reduction tests to assess cell viability and metabolic activity. Transmission electron microscopy (TEM) was used to examine ultrastructural changes in planktonic cells. Biofilm dynamics were visualized via scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The in vitro cytotoxicity of tyrosol was evaluated using NIH/3T3 fibroblast cells. Results: XTT results showed that the biofilm-reducing effect of amphotericin B (AMB) on single C. tropicalis biofilm at the minimum inhibitory concentration (MIC) and 2× MIC was significantly higher than that of control (47% and 48%, respectively) (p < 0.05). Tyrosol also had a metabolic activity-reducing effect on single C. tropicalis biofilm, but this effect was not statistically significant (39% at 2× MIC and 42% at MIC). Tyrosol and ampicillin (AMP) had no significant reducing effect on single S. mutans biofilm cells (p > 0.05). However, AMP resistance increased in dual culture. CFU enumeration, TEM, SEM, and CLSM data supported these findings. The effect of tyrosol on NIH/3T3 fibroblast cells was suppressive at low concentrations (1–4 mg/mL) and enhancing at high concentrations (4.5–20 mg/mL). Conclusion: This study investigated the antimicrobial and antibiofilm properties of tyrosol against C. tropicalis and S. mutans, individually and in combination. The results showed that tyrosol inhibited growth and biofilm formation, particularly in dual-species biofilms. Although S. mutans had greater resistance, overall microbial viability was reduced. Despite some observed increase in AMP resistance, tyrosol was selectively cytotoxic, indicating its promise as a natural therapeutic agent pending further research.

Author ORCID Identifier

ZARIFEH ADAMPOUR: 0000-0001-6505-4999

BETÜL YILMAZ ÖZTÜRK: 0000-0002-1817-8240

BÜKAY YENİCE GÜRSU: 0000-0002-6822-3484

İLKNUR DAĞ: 0000-0002-7352-8653

DOI

10.55730/1300-0152.2779

Keywords

Dual biofilm, Streptococcus mutans, Candida tropicalis, tyrosol, antimicrobial resistance

First Page

770

Last Page

789

Publisher

The Scientific and Technological Research Council of Türkiye (TÜBİTAK)

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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