Analyses of the influence of spxB, gtfP and IgA in biofilm formation by Streptococcus sanguinis

• Grant number: 18/21978-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2019
• End date: January 31, 2020
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Renata de Oliveira Mattos Graner
• Grantee: Johnny Naoki Soares
• Host Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil

Abstract

Streptococcus sanguinis is a major comensal species of streptococci, which initiates tooth colonization and which modulates the maturation of dental biofilms. However, the molecular mechanisms involved in its capacity to form biofilms are poorly understood. As a pioneer species of dental surfaces, S. sanguinis needs to bind to the acquired dental pellicle (AP) and to produce exopolymers that form the biofilm extracellular matrix. The aim of this project is to investigate the effects of deletion of genes iga, spxB and gtfP, which are potentially involved in S. sanguinis interaction with AP and/or in the production of extracellular matrix components [extracellular DNA (eDNA) and glucans synthesized from sucrose], on biofilm formation. To that purpose, different in vitro models will be applied to compare the biofilms formed by parent strain SK36 with the respective isogenic mutants of iga, spxB and gtfP in complex medium or chemically defined medium with or without sucrose, in the presence of human saliva. The initial stages of biofilm formation will be analyzed by scanning electron microscopy of biofilms formed on glass slides, previously treated with human saliva, during 4h. The biomass of biofilms formed during 18 h in microtiter plates, and stained with crystal violet, will be also compared between strains. The biomass and tridimensional structure of biofilms formed under the same conditions during 4, 18 and 24h will be analyzed using confocal microscopy. The results of this project might provide information about the gene functions involved in the processes of biofilm initiation and maturation by S. sanguinis, an important modulatory species of dental biofilms.