Streptococcus Mutans Biofilm Formation Research Articles

Inhibition of Streptococcus mutans biofilm formation, extracellular polysaccharide production, and virulence by an oxazole derivative.

Dental caries, a biofilm-related oral disease, is a result of disruption of the microbial ecological balance in the oral environment. Streptococcus mutans, which is one of the primary cariogenic bacteria, produces glucosyltransferases (Gtfs) that synthesize extracellular polysaccharides (EPSs). The EPSs, especially water-insoluble glucans, contribute to the formation of dental plaque, biofilm stability, and structural integrity, by allowing bacteria to adhere to tooth surfaces and supplying the bacteria with protection against noxious stimuli and other environmental attacks. The identification of novel alternatives that selectively inhibit cariogenic organisms without suppressing oral microbial residents is required. The goal of the current study is to investigate the influence of an oxazole derivative on S. mutans biofilm formation and the development of dental caries in rats, given that oxazole and its derivatives often exhibit extensive and pharmacologically important biological activities. Our data shows that one particular oxazole derivative, named 5H6, inhibited the formation of S. mutans biofilms and prevented synthesis of extracellular polysaccharides by antagonizing Gtfs in vitro, without affecting the growth of the bacteria. In addition, topical applications with the inhibitor resulted in diminished incidence and severity of both smooth and sulcal surface caries in vivo with a lower percentage of S. mutans in the animals' dental plaque compared to the control group (P < 0.05). Our results showed that this oxazole derivative has the capacity to inhibit biofilm formation and cariogenicity of S. mutans.

Silver–polysaccharide antimicrobial nanocomposite coating for methacrylic surfaces reduces Streptococcus mutans biofilm formation in vitro

ObjectivesThe aim of this study was to determine the in vitro microbiological performances of a lactose-modified chitosan (Chitlac) coating inside which silver nanoparticles were embedded (Chitlac-nAg) for BisGMA/TEGDMA methacrylic specimens. MethodsDifferent concentrations of nAg inside Chitlac coating were tested (1mM, 2mM, 5mM). Specimen surface was analyzed by means of field-emission scanning electron microscopy (FEISEM) and energy-dispersive X-ray spectroscopy (EDS). A 48h monospecific Streptococcus mutans biofilm was developed over the specimen surfaces using a modified drip-flow bioreactor; adherent viable biomass was assessed by MTT test and biofilm was imaged by confocal laser-scanning microscopy (CLSM). ResultsThe presence of finely dispersed nanoparticles inside the Chitlac coating was confirmed by FEISEM and EDS analysis. All nanoparticles were embedded in the Chitlac coating layer. Chitlac-nAg coatings were able to significantly decrease biofilm formation depending on the nAg concentration, reaching a −80% viable biomass decrease when the 5mM nAg-Chitlac group was confronted to non-coated control specimens. CLSM analysis did not provide evidence of a contact-killing activity, however the antibacterial Chitlac-nAg coating was able to alter biofilm morphology preventing the development of mature biofilm structures. ConclusionsThe microbiological model applied in this study helped in assessing the antibacterial properties of a coating designed for methacrylate surfaces. Clinical significanceA microbiological model based on a bioreactor-grown biofilm is useful for preliminary in vitro tests of dental materials. In translational terms, an antibacterial nanocomposite coating based on Chitlac-nAg and designed to be applied to methacrylic surfaces may be a promising way to obtain dental materials able to actively prevent secondary caries.

High production of erythritol from Candida sorbosivorans SSE-24 and its inhibitory effect on biofilm formation of Streptococcus mutans

Amongst different isolates screened for erythritol production, isolate no. SSE-24 was found to be the best erythritol producer and identified as Candida sorbosivorans SSE-24. Statistical optimization was used to determine the optimum level of the significant variables for maximum erythritol production. The interactive effects of glucose, inoculum level and yeast extract were determined to be significant. The optimum medium composition for erythritol production was 160g/L glucose, 12g/L yeast extract, 10% inoculum level and 0.35g/L FeSO4⋅7H2O. The production of erythritol was successfully scaled up to a 30L level, where 60.20g/L of erythritol was produced, with a yield of 0.38g/g. The fermentation broth was purified by activated charcoal followed by vacuum concentration, ion exchange chromatography and crystallization. Purity of erythritol was further determined by NMR. Significant inhibitory effect of erythritol on growth (>78%) and biofilm formation (40.2%) of Streptococcus mutans enhances the importance of this study.

Nicotine promotes Streptococcus mutans extracellular polysaccharide synthesis, cell aggregation and overall lactate dehydrogenase activity

Several epidemiology studies have reported a positive relationship between smoking and dental caries. Nicotine, an alkaloid component of tobacco, has been demonstrated to stimulate biofilm formation and metabolic activity of Streptococcus mutans, one of the most important pathogens of dental caries. The first aim of the present study was to explore the possible mechanisms leading to increased biofilm by nicotine treatment from three aspects, extracellular polysaccharides (EPS) synthesis, glucosyltransferase (Gtf) synthesis and glucan-binding protein (Gbp) synthesis at the mRNA and protein levels. The second aim was to investigate how nicotine affects S. mutans virulence, particular in lactate dehydrogenase (LDH) activity. Confocal laser scanning microscopy results demonstrated that both biofilm bacterial cell numbers and EPS were increased by nicotine. Gtf and GbpA protein expression of S. mutans planktonic cells were upregulated while GbpB protein expression of biofilm cells were downregulated by nicotine. The mRNA expression trends of those genes were mostly consistent with results on protein level but not statistically significant, and gtfD and gbpD of biofilm cells were inhibited. Nicotine was not directly involved in S. mutans LDH activity. However, since it increases the total number of bacterial cells in biofilm, the overall LDH activity of S. mutans biofilm is increased. In conclusion, nicotine stimulates S. mutans planktonic cell Gtf and Gbp expression. This leads to more planktonic cells attaching to the dental biofilm. Increased cell numbers within biofilm results in higher overall LDH activity. This contributes to caries development in smokers.

Effect of brief cetylpyridinium chloride treatments during early and mature cariogenic biofilm formation.

The aim of this study was to investigate the antibiofilm activity of brief cetylpyridinium chloride (CPC) treatments during early and mature Streptococcus mutans biofilm formation. Streptococcus mutans biofilms were formed on saliva-coated hydroxyapatite disks. The biofilms were treated with CPC twice daily (1min/treatment) from 0 to 50h or from 48 to 98h. Acidogenicity, dry weight, viability, and water-insoluble extracellular polysaccharides of the biofilms were analyzed. Confocal laser scanning microscopy (CLSM) images were obtained to confirm the antibiofilm activity during mature biofilm formation and to evaluate the relationship between treatment time and the antibiofilm activity. CPC showed complete antibiofilm activity during early biofilm formation at 0.025% to 0.1%. During mature biofilm formation, CPC inhibited dry weight, viability, and acidogenicity at 0.075% and 0.1%. CLSM images showed an increase in dead cells at 0.075% and 0.1% CPC. The antibiofilm activity during mature biofilm formation increased as the concentration of CPC increased. Images from the CLSM study also showed that antibiofilm activity increased as treatment time increased. Our findings suggest that brief CPC treatments have strong anti-S.mutans biofilm activity. The antibiofilm activity was dependent on the stage of biofilm formation, CPC concentration, and treatment time.

ClpP affects biofilm formation of Streptococcus mutans differently in the presence of cariogenic carbohydrates through regulating gtfBC and ftf.

The abilities to form biofilms on teeth surface and to metabolize a wide range of carbohydrates are key virulence attributes of Streptococcus mutans. ClpP has been proved to play an important role in biofilm development in streptococci. Here we demonstrated that ClpP was involved in biofilm formation of S. mutans. ClpP inactivation resulted in enhanced biofilm formation or initial cell adherence in broth supplemented with sucrose, while reduced in broth supplemented with glucose or fructose. Our results also indicated that the enhanced capacities of biofilm formation and initial cell adherence were achieved through regulating the expression of a number of extracellular sucrose-metabolizing enzymes, such as glucosyltransferases (GTFB and GTFC) at early-exponential growth phase and fructosyltransferase at late-exponential growth phase in the presence of sucrose.

Effect of Air-Polishing on Titanium Surfaces, Biofilm Removal, and Biocompatibility: A Pilot Study.

Purpose. The aims of this in vitro study were to evaluate morphological changes induced by glycine powder air-polishing on titanium surfaces, biofilm removal, and biocompatibility. Material and Methods. Titanium grade IV discs were allocated into two groups: (1) discs without biofilm and (2) discs for Streptococcus mutans biofilm formation. Discs in each group were further subdivided into (a) no treatment and (b) air-polishing treatment with glycine powder. Discs were characterized by scanning electron microscopy (SEM), electron-dispersive spectroscopy (EDS), and confocal microscopy. Bacterial biofilms were quantified using a crystal violet dye-binding assay. Biocompatibility was evaluated by measuring the coverage and viability of L929 fibroblast cells cultured on the discs. Results. Air-polishing increased the roughness of treated discs (P < 0.05). EDS analysis did not show significant differences in the chemical composition of treated and nontreated discs. The amount of residual biofilm on treated discs was 8.6-fold lower than untreated controls (P < 0.05). Coverage of treated discs by fibroblasts was half that of untreated discs (P < 0.05) although both groups had the same cell viability. Conclusions. Air-polishing removed a significant amount of biofilm from titanium surfaces. The “polishing” was accompanied by increased surface roughness, but there were no changes in chemical and elemental compositions, nor the biocompatibility.

Action of silver nanoparticles towards biological systems: cytotoxicity evaluation using hen's egg test and inhibition of Streptococcus mutans biofilm formation

This study aimed to evaluate the cytotoxicity and bactericidal properties of four silver nanoparticle (AgNP) colloids and their ability to inhibit Streptococcus mutans biofilm formation on dental enamel. The cytotoxicity of AgNPs was evaluated based on signs of vascular change on the chorioallantoic membrane using the hen's egg test (HET-CAM). Bactericidal properties and inhibition of S. mutans biofilm formation were determined using a parallel-flow cell system and a dichromatic fluorescent stain. The percentage of viable cells was calculated from regression data generated from a viability standard. AgNP colloids proved to be non-irritating, as they were unable to promote vasoconstriction, haemorrhage or coagulation. AgNP colloids inhibited S. mutans biofilm formation on dental enamel, and cell viability measured by fluorescence was 0% for samples S1, S2, S3 and S4 and 36.5% for the positive control (diluted 30% silver diamine fluoride). AgNPs are new products with a low production cost because they have a lower concentration of silver, with low toxicity and an effective bactericidal effect against a cariogenic oral bacterium. Moreover, they do not promote colour change in dental enamel, which is an aesthetic advantage compared with traditional silver products.

Inhibitory effects of green tea polyphenol epigallocatechin gallate (EGCG) on exopolysaccharide production by Streptococcus mutans under microfluidic conditions

Plaque-forming microorganisms produce insoluble exopolysaccharide (EPS), which allows the microorganisms to attach strongly to the tooth surface. Then, they start forming biofilm, which is responsible for plaque formation. The green tea polyphenol epigallocatechin gallate (EGCG) is known to inhibit biofilm formation of oral bacteria. However, its inhibitory effects on biofilm formation between the teeth have not been well studied due to the lack of devices that mimic the space between the teeth. In this study, we used a microfluidic device packed with glass beads (250–300 µm in diameter) to mimic the small cavities between the teeth in order to test the inhibitory effects of EGCG on the biofilm formation of Streptococcus mutans, one of the plaque-forming microorganisms. EPS production by S. mutans was more effectively inhibited by EGCG in the microfluidic device, compared to on agar plates, suggesting that it is more effective against biofilm formation by S. mutans cells under flow conditions than under non-flow conditions, such as conditions achieved by agar plates. These results suggest that our microfluidic device may be highly useful for studying the actual effects of antimicrobial compounds against plaqueforming microorganisms.

Effects of antimicrobial peptide L-K6, a temporin-1CEb analog on oral pathogen growth, Streptococcus mutans biofilm formation, and anti-inflammatory activity.

Dental caries and periodontitis are common bacterial mouth infections. As a potentially attractive substitute for conventional antibiotics, antimicrobial peptides have been widely tested and used for controlling bacterial infections. In this study, we tested the efficacy of the peptides from the skin secretions of Rana chensinensis for killing several major cariogenic and periodontic pathogens as well as Candida albicans. L-K6, a temporin-1CEb analog, exhibited high antimicrobial activity against the tested oral pathogens and was able to inhibit Streptococcus mutans biofilm formation and reduce 1-day-old S. mutans biofilms with a minimum biofilm inhibitory concentration and reducing concentration of 3.13 and 6.25 μM, respectively. The results of confocal laser scanning microscopy demonstrated that the peptide significantly reduced cell viability within oral biofilms. Furthermore, as little as 5 μM L-K6 significantly inhibited lipopolysaccharide (LPS)- and interleukin-1β-induced productions of interleukin-8 and tumor necrosis factor-α from THP-1 monocytic cells. This anti-inflammatory activity is associated with the binding of L-K6 to LPS and neutralizing LPS-induced proinflammatory responses in THP-1 cells, as well as dissociating LPS aggregates. Our results suggest that L-K6 may have potential clinical applications in treating dental caries by killing S. mutans within dental plaque and acting as anti-inflammatory agents in infected tissues.

Hydrophilicity of dentin bonding systems influences in vitro Streptococcus mutans biofilm formation

ObjectiveTo evaluate in vitro Streptococcus mutans (S. mutans) biofilm formation on the surface of five light-curing experimental dental bonding systems (DBS) with increasing hydrophilicity. The null hypothesis tested was that resin chemical composition and hydrophilicity does not affect S. mutans biofilm formation. MethodsFive light-curing versions of experimental resin blends with increasing hydrophilicity were investigated (R1, R2, R3, R4 and R5). R1 and R2 contained ethoxylated BisGMA/TEGDMA or BisGMA/TEGDMA, respectively, and were very hydrophobic, were representative of pit-and-fissure bonding agents. R3 was representative of a typical two-step etch-and-rinse adhesive, while R4 and R5 were very hydrophilic resins analogous to self-etching adhesives. Twenty-eight disks were prepared for each resin blend. After a 24h-incubation at 37°C, a multilayer monospecific biofilm of S. mutans was obtained on the surface of each disk. The adherent biomass was determined using the MTT assay and evaluated morphologically with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). ResultsR2 and R3 surfaces showed the highest biofilm formation while R1 and R4 showed a similar intermediate biofilm formation. R5 was more hydrophilic and acidic and was significantly less colonized than all the other resins. A significant quadratic relationship between biofilm formation and hydrophilicity of the resin blends was found. CLSM and SEM evaluation confirmed MTT assay results. ConclusionsThe null hypothesis was rejected since S. mutans biofilm formation was influenced by hydrophilicity, surface acidity and chemical composition of the experimental resins. Further studies using a bioreactor are needed to confirm the results and clarify the role of the single factors.

The effect of five probiotic lactobacilli strains on the growth and biofilm formation of Streptococcus mutans.

To compare the effects of five probiotic lactobacilli strains on the growth and biofilm formation of Streptococcus mutans (MS). Five probiotic lactobacilli bacteria (LB), Lactobacillus casei Shirota, Lactobacillus casei LC01, Lactobacillus plantarum ST-III, Lactobacillus paracasei Lpc-37, and Lactobacillus rhamnosus HN001, were used as test strains effecting on the Streptococci strain S. mutans UA159 in this study. The effect of LB strains and their supernatants on the viability of the MS was evaluated. Then, the effect of LB strains on the growth of MS biofilm formation was observed by fluorescence microscope. All of the LB strains inhibited the growth of MS at concentrations of 1 × 10(8) and 3 × 10(8) CFU ml(-1) (P < 0.05). Untreated (without pH adjustment and ultrafiltration) LB supernatants from all of the LB strains inhibited the growth of MS (P < 0.05) as well. After pH adjustment and ultrafiltration (treated), only supernatants from L. casei Shirota and L. rhamnosus HN001 inhibited the growth of MS (P < 0.05). MS biofilm formation was also inhibited by all untreated supernatants and by the treated supernatants of L. casei Shirota and L. rhamnosus HN001 (P < 0.05). All five probiotic lactobacilli strains inhibited the growth and biofilm formation of MS, likely through the production of an acid environment, bacteriocin-like poly peptides, or both, and the effects on MS were dependent on the LB strains used.

Inhibition of biofilm formation by conformationally constrained indole-based analogues of the marine alkaloid oroidin

Herein, we describe indole-based analogues of oroidin as a novel class of 2-aminoimidazole-based inhibitors of methicillin-resistant Staphylococcus aureus biofilm formation and, to the best of our knowledge, the first reported 2-aminoimidazole-based inhibitors of Streptococcus mutans biofilm formation. This study highlighted the indole moiety as a dibromopyrrole mimetic for obtaining inhibitors of S. aureus and S. mutans biofilm formation. The most potent compound in the series, 5-(trifluoromethoxy)indole-based analogue 4b (MBIC50=20μM), emerged as a promising hit for further optimisation of novel inhibitors of S. aureus and S. mutans biofilms.

Subinhibitory concentrations of triclosan promote Streptococcus mutans biofilm formation and adherence to oral epithelial cells.

Triclosan is a general membrane-active agent with a broad-spectrum antimicrobial activity that is commonly used in oral care products. In this study, we investigated the effect of sub-minimum inhibitory concentrations (MICs) of triclosan on the capacity of the cariogenic bacterium Streptococcus mutans to form biofilm and adhere to oral epithelial cells. As quantified by crystal violet staining, biofilm formation by two reference strains of S. mutans was dose-dependently promoted, in the range of 2.2- to 6.2-fold, by 1/2 and 1/4 MIC of triclosan. Observations by scanning electron microscopy revealed the presence of a dense biofilm attached to the polystyrene surface. Growth of S. mutans in the presence of triclosan at sub-MICs also increased its capacity to adhere to a monolayer of gingival epithelial cells. The expression of several genes involved in adherence and biofilm formation in S. mutans was investigated by quantitative RT-PCR. It was found that sub-MICs of triclosan significantly increased the expression of comD, gtfC, and luxS, and to a lesser extent of gtfB and atlA genes. These findings stress the importance of maintaining effective bactericidal concentrations of therapeutic triclosan since sub-MICs may promote colonization of the oral cavity by S. mutans.

Anti-microbial efficacy of Allium sativum against Streptococcus mutans biofilm formation on orthodontic mini-implants

Introduction: The aim of this study was to examine the effect of Allium sativum (garlic) extract on the biofilm formation by Streptococcus mutans on the surface of orthodontic mini-implants. Materials and Methods: Three brands (Dentos, Forestadent and Hubit) of titanium mini-implants were used as samples, which were divided into four groups each containing S. mutans along with four different concentrations of garlic extract-0 mg/ml, 16 mg/ml, 32 mg/ml, 64 mg/ml and 1 mini-implant from each of the three brands. The amount of viable S. mutans bacteria, as well as its biofilm formation on the surface of mini-implants was determined quantitatively as well as qualitatively using microbial viability assay, electron dispersive X-ray spectroscopy and scanning electron microscopy analysis. ANOVA test was done. Results: 32 mg/ml and 64 mg/ml concentration of garlic extract showed a considerable antimicrobial efficacy against S. mutans and effectively prevented the biofilm formation by S. mutans on the surfaces of all the mini-implants with 32 mg/ml being the lowest effective concentration of garlic extract to prevent S. mutans biofilm formation and 64 mg/ml being the most potent concentration. Conclusion: Garlic extract can be a promising alternative to other chemical agents used in mouthwashes to prevent bacterial biofilm formation on the surface of orthodontic mini-implants and can thus help in the reduction of mini-implant failure due to biofilm formation. It has a potential to serve as a herbal substitute to chlorhexidine, which has been shown to exhibit several side-effects during long-term use.

In vitro biofilm formation on experimental composites containing calcium-phosphate nanoparticles

Purpose: The aim of this study was to evaluate the influence of experimental RBCs filledwith TEGDMA-functionalized DCPDnanoparticles (DCPD-NP) on in vitro Streptococcusmutans (S. mutans) biofilm formation. The microbiological performances of the tested materials were compared with their surface properties. The null hypotheses were that (i) the presence of DCPD-NP would not reduce biofilm development on the experimental RBC surfaces when compared to control experimental RBCwithout DCPD-NP; (ii) functionalization of DCPD-NP would not affect RBC microbiological behaviour when compared to non-functionalized DCPD-NP. Methods andmaterials:Specimenswere prepared from the following materials: (A) RBC filled with 20vol.% functionalized DCPD nanoparticles (CaHPO4·2H2O); (B) RBC filled with 20vol.% non-functionalized (“bare”) DCPD nanoparticles; (C) RBC filled with 20vol.% silica; (D) Neat resin (unfilled). A standardized amount of RBC was placed into a custom-made steel mould and light-cured for 40 s at 1200mW/cm2 light intensity. All specimens were subjected to a standardized polishing protocol. Subsequently, surface roughness (SR, profilometry), surface free energy (SFE, sessile drop method) and surface chemical composition (energy-dispersive X-ray spectroscopy, EDX) were determined. A modified drip-flow reactor (MDFR) was used to obtain a monospecific S. mutans biofilm on the surfaces of the specimens. Adherent, viable biomasswas evaluated after 48h using the MTT assay. Data were statistically analyzed using one-way ANOVA and Student–Newman–Keuls post-hoc test setting the level of significance (a) to 0.05. Results: Results are displayed in Table 1. The null hypothesis (i) cannot be rejected since biofilm formation on both DCPD-NP filled RBCs was not significantly different to that of the silica-filled RBC. The null hypothesis (ii) can be rejected since DCPD-NP functionalization caused a significant reduction in biofilm formation. Neat resin specimens showed the lowest biofilm formation. Even if SR data may partly explain the microbiological results, no clear correlations between surface characteristics and biofilm formation results could be identified. Conclusion: Within the experimental conditions applied, DCPD-NP functionalization influences RBCs microbiological performances, even if DCPD-NP addition to RBCs does not seem to show a relevant antibacterial activity.

An in vitro and in vivo Comparison of the Effect of Stevia rebaudiana Extracts on Different Caries-Related Variables: A Randomized Controlled Trial Pilot Study

The effect of Stevia extracts on in vitro Streptococcus mutans biofilm formation and in vivo plaque pH was evaluated in this paper. Three 10% solutions containing stevioside, rebaudioside A or sucrose were prepared. MTT assay was used to evaluate microbiological counts in vitro. Twenty volunteers rinsed for 1 min with each solutions, and plaque pH was measured at 7 time points after each rinse. Higher in vitro S. mutans biofilm formation was observed in sucrose solution (p < 0.01). After 5, 10, 15 and 30 min, the sucrose in vivo rinse produced a statistically significantly lower pH value compared to the Stevia extracts (F = 99.45, p < 0.01).Stevia extracts can be considered nonacidogenic.

SMU.746-SMU.747, a Putative Membrane Permease Complex, Is Involved in Aciduricity, Acidogenesis, and Biofilm Formation in Streptococcus mutans

Dental caries induced by Streptococcus mutans is one of the most prevalent chronic infectious diseases worldwide. The pathogenicity of S. mutans relies on the bacterium's ability to colonize tooth surfaces and survive a strongly acidic environment. We performed an ISS1 transposon mutagenesis to screen for acid-sensitive mutants of S. mutans and identified an SMU.746-SMU.747 gene cluster that is needed for aciduricity. SMU.746 and SMU.747 appear to be organized in an operon and encode a putative membrane-associated permease. SMU.746- and SMU.747-deficient mutants showed a reduced ability to grow in acidified medium. However, the short-term or long-term acid survival capacity and F1F0 ATPase activity remained unaffected in the mutants. Furthermore, deletion of both genes did not change cell membrane permeability and the oxidative and heat stress responses. Growth was severely affected even with slight acidification of the defined medium (pH 6.5). The ability of the mutant strain to acidify the defined medium during growth in the presence of glucose and sucrose was significantly reduced, although the glycolysis rate was only slightly affected. Surprisingly, deletion of the SMU.746-SMU.747 genes triggered increased biofilm formation in low-pH medium. The observed effects were more striking in a chemically defined medium. We speculate that the SMU.746-SMU.747 complex is responsible for amino acid transport, and we discuss its possible role in colonization and survival in the oral environment.

A comprehensive study into the impact of a chitosan mouthwash upon oral microorganism's biofilm formation in vitro

Modern dentistry emphasizes the importance of dental plaque control to improve oral health. To that end the development of oral care formulations has been geared toward the incorporation of antiplaque agents that may play a crucial role in oral health maintenance. In later years the research into antiplaque agents has led to the discovery of compounds with significant capability to affect biofilm formation. Among these compounds was chitosan, a polysaccharide which showed great ability to interfere with Streptococcus mutans biofilm formation. As such the aim of this work was to incorporate chitosan into a mouthwash matrix and assess its effect upon biofilm formation of oral microorganisms. This assessment was performed via study of the impact the mouthwash upon microbial adherence, biofilm formation and mature biofilms. Additionally, the action of the chitosan mouthwash was compared with two commercially available mouthwashes. The results here obtained show that only the chitosan containing mouthwash was capable of interfering with all microorganisms’ adherence, biofilm formation and mature biofilms while at the same time showing vastly superior activity than both commercial mouthwashes assayed. As such a chitosan mouthwash shows great potential as a natural and efficient alternative to traditional mouthwashes.

Chemical composition and biological activity of Gaultheria procumbens L. essential oil

The aim of this study was to examine chemical composition and biological activity of Gaultheria procumbens L. essential oil (EO) against food spoilage and oral microorganisms. The components of EO were identified by GC–MS. Antimicrobial activity was determined against food spoilage (five bacteria and six fungal species) and oral microorganisms (eight bacteria and thirty two fungal species) by microdilution and microplate biofilm assay, antioxidant activity was tested using the persistent free radical 2,2-diphenyl-1-picryl hydrazyl (DPPH), while antiradical activity was examined by fluorescence spectroscopy and electron paramagnetic resonance spectroscopy (EPR). GC–MS.analysis showed that methyl salicylate (96.90%) was the main component of the oil. Essential oil inhibited the growth of all microorganisms tested, i.e. food and oral bacteria and fungi, respectively (MIC 0.18–3.00mg/ml and MBC 1.25–4.00mg/ml; MIC 0.73–5.00mg/ml and MFC 2.92–26.67mg/ml); The oil effectively inhibited the biofilm formation of oral Streptococcus mutans and Candida albicans as well (MIC 25.00 MBC 50.00mg/ml; MIC 12.50, MFC 50.00mg/ml). In addition, oil exhibited a dose-dependent DPPH-radical-scavenging activity with IC50 value of 30.61mg/ml. The specific fluorescence probe 2-[6-(4′-amino)phenoxy-3H-xanten-3-on-9-yl] benzoic acid (APF) and the the spin trap 5-(Diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO), capable for simultaneous detection of different free radical specie were used in antiradical activity of the oil measurements. Oil showed a moderate antiradical activity, reducing quantity of produced hydroxyl radicals to about 20% of initial value. This study succeeds in creating directly comparable and quantitative data for the oil unsufficiently examined so far.