The Role of Extracellular DNA from Monomicrobial and Polymicrobial Oral Biofilm

• Grant number: 17/07339-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: October 01, 2017
• End date: December 31, 2020
• Field of knowledge: Health Sciences - Dentistry - Periodontology
• Principal Investigator: Gabriel Padilla
• Grantee: Santiago Martín Lattar
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Biofilm associated polymicrobial infections, particularly those involving fungi and bacteria, are responsible for significant morbidity and tend to be challenging to treat. The microorganisms in biofilms live in a self-produced matrix of hydrated extracellular polymeric substances (EPS) that form their immediate environment, EPS are mainly polysaccharides, proteins, nucleic acids (eDNA) and lipids. Dental biofilm is an example of a multispecies biofilm and, bacteria live in harmony with the host, however, ecological shifts may occur within the microbial community and result in the two major oral diseases: dental caries and periodontal diseases. Polymicrobial infections are responsible for significant mortality and morbidity in adults and children. Candida albicans, Staphylococcus aureus, Streptococcus mutans and Porphyromonas gingivalis are respectively, considered opportunistic fungal and bacterial pathogens. Periodontopathogens present in oral cavity and cause periodontal disease. Cooperative interactions between oral streptococci and the pathogens play important roles in the development of dental biofilms in the oral cavity. Multispecies biofilm consisting of fungi, Gram positive and Gram negative bacteria, aerobes and anaerobes have been observed in vitro and in vivo biofilm model. The inner layer of oral biofilm confers bacterial resistance against nonspecific and specific host defenses during infection, and confers tolerance to various antimicrobials agents (biosurfactants and antibiotics), as well as environmental stress. The inner layer of biofilm contains eDNA which is a major structural component in the biofilm matrix. eDNA facilitates the microbial adhesion, antibiotic resistance and horizontal gene transfer between biofilm cells. This project was designed to develop in vitro polymicrobial and monomicrobial oral biofilm model, in order to study the eDNA role during microbial growth, genetics transformation and antibiotic resistance.