oralpresentation
Description

Title: 0167 - DNase and Proteinase Trigger Growth of Streptococci Within Oral Biofilms

Authors:

Thomas Thurnheer (Presenter)
Center of Dental Medicine University of Zurich

Patricia Martin Perez, Center of Dental Medicine University of Zurich
Lamprini Karygianni, Center of Dental Medicine University of Zurich

Abstract:

Objectives: Biofilms consist of microorganisms living in a self-produced matrix of extracellular polymeric substances (EPS) that are mainly polysaccharides, proteins, nucleic acids and lipids. Previous experiments had shown that short expositions of growing biofilms to deoxyribonuclease I (DNase I) and proteinase K did not affect the total CFU in the Z├╝rich supragingival biofilm-model. The aim of this study was to investigate the impact of the presence of DNase I and/or proteinase K during the whole growth phase on in vitro biofilm formation and structure.

Methods: The standard six-species supragingival biofilm employed contained Actinomyces oris, Candida albicans, Fusobacterium nucleatum, Streptococcus mutans, Streptococcus oralis, and Veillonella dispar. Biofilms were grown anaerobically on hydroxyapatite discs in 24-well culture dishes. The growth medium contained 70% saliva and 30% FUM as well as DNase I and proteinase K (0.001mg or 0.002mg, each). After 64 h biofilms were either harvested and quantified by culture analysis or proceeded to staining using anti-DNA antibodies, streptavidin (Cy3), calcofluor, SYPRO Ruby and YoPro-1/Sytox or fluorescent in situ hybridization (FISH) followed by confocal laser scanning microscopy (CLSM).

Results: Neither DNase I nor proteinase K had an impact on total CFU when they were present during the whole growth phase of the biofilms compared to the control without enzymes. However, the combination of DNase I and proteinase K resulted in a significant increase by one or two log10 levels of the CFUs of S. mutans and S. oralis, respectively (p<0.001), whereas C. albicans and V. dispar showed lower CFUs (p<0.001) compared to the control. Overall, a significant increase in total CFU (p<0.001) could be observed.

Conclusions: The reduction of extracellular DNA and proteins by DNase I and proteinase K, respectively, not only affected the biofilm structures, it also favored growth of streptococci probably by reducing nutritional competition.

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE

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