Abstract
Endodontic persistent infections are often mediated by bacterial biofilms. This mode of bacterial growth is characterized by the presence of a matrix mainly composed of extracellular polymeric substances (EPSs) that protect the encased microorganisms. To establish better control and disinfection protocols, elucidation of the main components of biofilm matrices present in endodontic infections is required. The aim of the present study was to characterize the principal components ofE. faecalis,A. naeslundii, and dual-species biofilm matrices by means of Raman spectroscopy and confocal scanning laser microscopy (CSLM) techniques. The total biomass of biofilms was quantified via crystal violet assays, and the monospecies biofilms showed higher biomass than the dual-species biofilms. Raman spectroscopy and confocal laser scanning microscopy were used to identify the biochemical composition and structure of the biofilm matrices. Spectra originating from the biofilms of two endodontic pathogens show the presence of carbohydrates, proteins, fatty acids, and nucleic acids in all samples; however, variation in the levels of expression of these biomolecules allows spectroscopic differentiation of the biofilms using principal component analysis. This study is the first attempt to identify the composition of monospecies and dual-species biofilms of endodontic origin. Our data provides an important approach to the understanding of molecular dynamics of endodontic infections.
Highlights
Microbiota diversity of persistent endodontic infections is very limited, and Gram-positive facultative bacteria are commonly isolated [1, 2]
Bacterial biofilms are surface-associated communities that produce a variety of macromolecules. ese so-called extracellular polymeric substances (EPSs), such as polysaccharides, proteins, fatty acids, and extracellular DNA [9], provide the structural and functional integrity of the biofilm matrix and are involved in communication processes, genetic transfer, nutrition, and the interaction of the bacteria with their environment [10, 11]. e production and type of EPS is influenced by different factors such as bacterial species, environmental conditions, nutrient Journal of Spectroscopy availability, adhesion surface, etc. [12]. ese factors are the origin of high diversity and multiple types of biofilms, and this heterogeneity is the main cause of the pathogenesis of many chronic and life-threatening infections [13]
In the field of endodontics, a previous study used Raman spectroscopy to analyse the chemical compositions of E. faecalis biofilms in different physiological states in which the matrix components differed according to the growth phase [20]. is study provided important information about monospecies biofilm composition; root canal infections are clearly mediated by monospecies, dualspecies, or multispecies biofilms [8, 12, 21], and it is necessary to investigate monospecies and dual species of different relevant root canal bacteria, especially those involved in persistent periapical pathosis
Summary
Microbiota diversity of persistent endodontic infections is very limited, and Gram-positive facultative bacteria are commonly isolated [1, 2]. Is study provided important information about monospecies biofilm composition; root canal infections are clearly mediated by monospecies, dualspecies, or multispecies biofilms [8, 12, 21], and it is necessary to investigate monospecies and dual species of different relevant root canal bacteria, especially those involved in persistent periapical pathosis. Data resulting from such studies could represent a valuable contribution to the establishment of a new understanding and the determination of strategies to prevent and eradicate biofilms from the root canal system. The present study was designed to combine Raman spectroscopy and confocal laser scanning microscopy techniques to obtain biochemical composition from monospecies and dual-species endodontic biofilms
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