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Analysis of the role of ssa_0094 gene in biofilm formation by Streptococcus sanguinis

Grant number: 17/23183-4
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): February 01, 2018
Effective date (End): July 31, 2021
Field of knowledge:Health Sciences - Dentistry
Principal researcher:Renata de Oliveira Mattos Graner
Grantee:Isabela Camargo
Home Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil


Streptococcus sanguinis is a major commensal species which initiates colonization of teeth surfaces and is capable to inhibit the cariogenic species Streptococcus mutans. The molecular mechanisms involved in biofilm formation by S. sanguinis are however poorly understood. DNA is a major component of the extracellular matrix of biofilms formed by S. sanguinis. There is evidence that S. sanguinis releases genomic DNA in an autolytic-independent way, through a tightly regulated process that involves activation of murein hydrolases during bacterial growth. Our research group showed that DNA release by S. sanguinis is induced by the two-component regulatory system VicRK. We also established that VicRK induces the expression of genes as yet uncharacterized, which encode putative murein hydrolases. These include ssa_0094, which is significantly up-regulated during biofilm formation. The aim of this study is to investigate the role of ssa_0094 in DNA-dependent biofilm formation by S. sanguinis. To that purpose, ssa_0094 will be deleted in the S. sanguinis reference strain SK36, by homologous recombination with a mutated allele in which ssa_0094 will be replaced by an erythromycin resistance gene. The isogenic mutant will be then compared to parent strain regarding its planktonic growth in BHI, biofilm formation on polystyrene plates and release of genomic DNA, which will be quantified in culture supernatants by quantitative PCR with primers for 16SrRNA gene. A complemented mutant with an episomal copy of ssa_0094 will be also used as a control. Our hypothesis is that deletion of ssa_0094 will compromise DNA release by S. sanguinis and in turn, the bacterial capacity to form biofilm. Therefore, the results of this project might contribute for the identification of functions involved in release of genomic DNA and biofilm formation in S. sanguinis. (AU)

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