Microstructure and Mechanical Properties of In Situ <i>Streptococcus mutans</i> Biofilms

Waters, Michael S.; Kundu, Santanu; Lin, Nancy J.; Lin‐Gibson, Sheng

doi:10.1021/am404344h

Cited by 25 publications

(15 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous work has determined the mechanical properties of biofilms through various methods. 21,22 The elastic modulus ( G ′) of S. epidermidis biofilms, found through mechanical rheometry, varies widely, from 1 Pa to 8 kPa, depending on factors such as growth conditions and analytical methods. 23–30 Under conditions that most resemble those in which S. epidermidis biofilms cause disease, Pavlovsky et al 31 determined that G′ is approximately 10 Pa.…”

Section: Introductionmentioning

confidence: 99%

Effects of Temperature on the Morphological, Polymeric, and Mechanical Properties ofStaphylococcus epidermidisBacterial Biofilms

et al. 2015

View full text Add to dashboard Cite

Changes in temperature were found to affect the morphology, cell viability, and mechanical properties of Staphylococcus epidermidis bacterial biofilms. S. epidermidis biofilms are commonly associated with hospital-acquired medical device infections. We observed the effect of heat treatment on three physical properties of the biofilms: the bacterial cell morphology and viability, the polymeric properties of the extracellular polymeric substance (EPS), and the rheological properties of the bulk biofilm. After application of a 1 h heat treatment at 45 °C, cell reproduction had ceased, and at 60 °C, cell viability was significantly reduced. Size exclusion chromatography was used to fractionate the extracellular polymeric substance (EPS) based on size. Chemical analysis of each fraction showed that the relative concentrations of the polysaccharide, protein, and DNA components of the EPS were unchanged by the heat treatment at 45 and 60 °C. The results suggest that the EPS molecular constituents are not significantly degraded by the temperature treatment. However, some aggregation on the scale of 100 nm was found by dynamic light scattering at 60 °C. Finally, relative to control biofilms maintained at 37 °C, we observed an order of magnitude reduction in the biofilm yield stress after 60 °C temperature treatment. No such difference was found for treatment at 45 °C. From these results, we conclude that the yield stress of bacterial biofilms is temperature-sensitive and that this sensitivity is correlated with cell viability. The observed significant decrease in yield stress with temperature suggests a means to weaken the mechanical integrity of S. epidermidis biofilms with applications in areas such as the treatment of biofilm-infected medical devices.

show abstract

Section: Introductionmentioning

confidence: 99%

Effects of Temperature on the Morphological, Polymeric, and Mechanical Properties ofStaphylococcus epidermidisBacterial Biofilms

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Previous work has indicated that the biophysical properties of S. mutans biofilms can be varied depending on the exopolysaccharide content, due to its viscoelastic characteristics similar to those of polymeric substances (Vinogradov et al 2004;Cense et al 2006;Waters et al 2014). The elastic (or storage) modulus of S. mutans biofilms was associated with the amount of exopolysaccharides (Waters et al 2014), while the tensile strength of the biofilms was predominantly determined by the tensile strength of the EPS matrix (Cense et al 2006). The present rheological data provide further support for the importance of exopolysaccharides in the viscoelastic properties and cohesiveness of the biofilm.…”

mentioning

confidence: 99%

Analysis of the mechanical stability and surface detachment of matureStreptococcus mutansbiofilms by applying a range of external shear forces

2014

View full text Add to dashboard Cite

Well-established biofilms formed by Streptococcus mutans via exopolysaccharide matrix synthesis are firmly attached to tooth surfaces. Enhanced understanding of the physical properties of mature biofilms may lead to improved approaches to detaching or disassembling these highly organized and adhesive structures. Here, the mechanical stability of S. mutans biofilms was investigated by determining their ability to withstand measured applications of shear stress using a custom-built device. The data show that the initial biofilm bulk (~ 50% biomass) was removed after exposure to 0.184 and 0.449 N m(-2) for 67 and 115 h old biofilms. However, removal of the remaining biofilm close to the surface was significantly reduced (vs initial bulk removal) even when shear forces were increased 10-fold. Treatment of biofilms with exopolysaccharide-digesting dextranase substantially compromised their mechanical stability and rigidity, resulting in bulk removal at a shear stress as low as 0.027 N m(-2) and > a two-fold reduction in the storage modulus (G'). The data reveal how incremental increases in shear stress cause distinctive patterns of biofilm detachment, while demonstrating that the exopolysaccharide matrix modulates the resistance of biofilms to mechanical clearance.

show abstract

“…These structural changes may affect the stability of the biofilms treated with αMG and facilitate mechanical clearance of biofilms. The mechanical stability of biofilms appears to be dependent on the exopolysaccharide content, as EPS binds the cells together while strengthening their cohesiveness [15] , [47] – [50] . Furthermore, glucans enhance S. mutans adhesive strength, while the development of multi-microcolony aggregates via EPS-cell adhesions provides structural integrity to S. mutans biofilms [16] , [18] .…”

Section: Resultsmentioning

confidence: 99%

α-Mangostin Disrupts the Development of Streptococcus mutans Biofilms and Facilitates Its Mechanical Removal

et al. 2014

View full text Add to dashboard Cite

α-Mangostin (αMG) has been reported to be an effective antimicrobial agent against planktonic cells of Streptococcus mutans, a biofilm-forming and acid-producing cariogenic organism. However, its anti-biofilm activity remains to be determined. We examined whether αMG, a xanthone purified from Garcinia mangostana L grown in Vietnam, disrupts the development, acidogenicity, and/or the mechanical stability of S. mutans biofilms. Treatment regimens simulating those experienced clinically (twice-daily, 60 s exposure each) were used to assess the bioactivity of αMG using a saliva-coated hydroxyapatite (sHA) biofilm model. Topical applications of early-formed biofilms with αMG (150 µM) effectively reduced further biomass accumulation and disrupted the 3D architecture of S. mutans biofilms. Biofilms treated with αMG had lower amounts of extracellular insoluble and intracellular iodophilic polysaccharides (30–45%) than those treated with vehicle control (P<0.05), while the number of viable bacterial counts was unaffected. Furthermore, αMG treatments significantly compromised the mechanical stability of the biofilm, facilitating its removal from the sHA surface when subjected to a constant shear stress of 0.809 N/m2 (>3-fold biofilm detachment from sHA vs. vehicle-treated biofilms; P<0.05). Moreover, acid production by S. mutans biofilms was disrupted following αMG treatments (vs. vehicle-control, P<0.05). The activity of enzymes associated with glucan synthesis, acid production, and acid tolerance (glucosyltransferases B and C, phosphotransferase-PTS system, and F1F0-ATPase) were significantly inhibited by αMG. The expression of manL, encoding a key component of the mannose PTS, and gtfB were slightly repressed by αMG treatment (P<0.05), while the expression of atpD (encoding F-ATPase) and gtfC genes was unaffected. Hence, this study reveals that brief exposures to αMG can disrupt the development and structural integrity of S. mutans biofilms, at least in part via inhibition of key enzymatic systems associated with exopolysaccharide synthesis and acidogenicity. αMG could be an effective anti-virulence additive for the control and/or removal of cariogenic biofilms.

show abstract

Microstructure and Mechanical Properties of In Situ Streptococcus mutans Biofilms

Cited by 25 publications

References 23 publications

Effects of Temperature on the Morphological, Polymeric, and Mechanical Properties ofStaphylococcus epidermidisBacterial Biofilms

Effects of Temperature on the Morphological, Polymeric, and Mechanical Properties ofStaphylococcus epidermidisBacterial Biofilms

Analysis of the mechanical stability and surface detachment of matureStreptococcus mutansbiofilms by applying a range of external shear forces

α-Mangostin Disrupts the Development of Streptococcus mutans Biofilms and Facilitates Its Mechanical Removal

Contact Info

Product

Resources

About