Combined DNase and Proteinase Treatment Interferes with Composition and Structural Integrity of Multispecies Oral Biofilms

Modification of oral biofilms adhering to dental hard tissues could lead to new treatment approaches in cariology and periodontology. In this study the impact of DNase I and/or proteinase K on the formation of a simulated supragingival biofilm was investigated in vitro. Six-species biofilms were grown anaerobically in the presence of DNase I and proteinase K. After 64 h biofilms were either harvested and quantified by culture analysis or proceeded to staining followed by confocal laser scanning microscopy. Microbial cells were stained using DNA-dyes or fluorescent in situ hybridization. Exopolysaccharides, eDNA and exoproteins were stained with Calcofluor, anti-DNA-antibody, and SyproTM Ruby, respectively. Overall, results showed that neither DNase I nor proteinase K had an impact on total colony-forming units (CFUs) compared to the control without enzymes. However, DNase I significantly suppressed the growth of Actinomyces oris, Fusobacterium nucleatum, Streptococcus mutans, Streptococcus oralis and Candida albicans. Proteinase K treatment induced significant increase in S. mutans and S. oralis CFUs (p < 0.001), whereas C. albicans and V. dispar showed lower CFUs compared to the control. Interestingly, confocal images visualized the biofilm degradation caused by DNase I and proteinase K. Thus, enzymatic treatment should be combined with conventional antimicrobial agents aiming at both bactericidal effectiveness and biofilm dispersal.

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Single DNase or Proteinase Treatment Induces Change in Composition and Structural Integrity of Multispecies Oral Biofilms

Antibiotics ◽

10.3390/antibiotics10040400 ◽

2021 ◽

Vol 10 (4) ◽

pp. 400

Author(s):

Lamprini Karygianni ◽

Pune N. Paqué ◽

Thomas Attin ◽

Thomas Thurnheer

Keyword(s):

Laser Scanning ◽

Structural Integrity ◽

Dnase I ◽

Laser Scanning Microscopy ◽

Proteinase K ◽

Confocal Laser ◽

Significance Level ◽

Biofilm Thickness ◽

Biofilm Control ◽

Oral Biofilms

Biofilm virulence is mainly based on its bacterial cell surrounding biofilm matrix, which contains a scaffold of exopolysaccharides, carbohydrates, proteins, lipids, and nucleic acids. Targeting these nucleid acids or proteins could enable an efficient biofilm control. Therefore, the study aimed to test the effect of deoxyribonuclease I (DNase I) and proteinase K on oral biofilms. Six-species biofilms (Streptococcus mutans, Streptococcus oralis, Actinomyces oris, Fusobacterium nucleatum, Veillonella dispar, and Candida albicans) were exposed to DNase I (0.001 mg/mL, 0.002 mg/mL) or proteinase K (0.05 mg/mL, 0.1 mg/mL) for 1 h during biofilm formation. After 64 h, biofilms were harvested, quantified by culture analysis and visualized by image analysis using CLSM (confocal laser scanning microscopy). Statistical analysis was performed by ANOVA, followed by the Tukey test at a 5% significance level. The biofilm treatment with proteinase K induced a significant increase of Logs10 counts in S. mutans and a decrease in C. albicans, while biofilm thickness was reduced from 28.5 μm (control) to 9.07 μm (0.05 mg/mL) and 7.4 μm (0.1 mg/mL). Treatment with DNase I had no effect on the total bacterial growth within the biofilm. Targeting proteins of biofilms by proteinase K are promising adjunctive tool for biofilm control.

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Effects of antimicrobial agents on oral biofilms in a saliva-conditioned flowcell

Biofilms ◽

10.1017/s1479050503001017 ◽

2004 ◽

Vol 1 (1) ◽

pp. 5-12 ◽

Cited By ~ 15

Author(s):

J. S. Foster ◽

P. C. Pan ◽

P. E. Kolenbrander

Keyword(s):

Laser Scanning ◽

Antimicrobial Agents ◽

Cetylpyridinium Chloride ◽

Oral Bacteria ◽

Laser Scanning Microscopy ◽

Cellular Damage ◽

Confocal Laser ◽

Oral Biofilms

Oral bacteria form mixed-species biofilms known as dental plaque. Growth of these complex microbial communities is often controlled with the use of antimicrobial mouthrinses. Novel laboratory methods for testing the efficacy of antimicrobials in situ are necessary to complement current clinical testing protocols. In this study, we examined the effects of antimicrobial agents on a streptococcal biofilm grown in a saliva-conditioned flowcell. The flowcell coupled with confocal laser scanning microscopy enabled examination of growing oral biofilms in situ without disruption of the microbial community. Biofilms composed of Streptococcus gordonii DL1 were grown in an in vitro flowcell and treated with several commercially available antimicrobial mouthrinses containing essential oils, triclosan, cetylpyridinium chloride/domiphen or chlorhexidine. The results of this study revealed varying abilities of the antimicrobial agents to cause cellular damage on the growing biofilm in situ. This study therefore demonstrated the usefulness of the flowcell in the rapid assessment of antimicrobial efficacy.

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Confocal and SEM imaging to demonstrate food pathogen- biofilm biocontrol by pyocyanin from Pseudomonas aeruginosa BTRY1

International Journal of Bioassays ◽

10.21746/ijbio.2017.01.007 ◽

2016 ◽

Vol 6 (01) ◽

pp. 5218

Author(s):

Laxmi Mohandas ◽

Anju T. R. ◽

Sarita G. Bhat*

Keyword(s):

Pseudomonas Aeruginosa ◽

Biofilm Formation ◽

Laser Scanning ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Antibiofilm Activity ◽

Opportunistic Pathogens ◽

Redox Active ◽

Sem Imaging ◽

The Impact

An assortment of redox-active phenazine compounds like pyocyanin with their characteristic blue-green colour are synthesized by Pseudomonas aeruginosa, Gram-negative opportunistic pathogens, which are also considered one of the most commercially valuable microorganisms. In this study, pyocyanin from Pseudomonas aeruginosa BTRY1 from food sample was assessed for its antibiofilm activity by micro titer plate assay against strong biofilm producers belonging to the genera Bacillus, Staphylococcus, Brevibacterium and Micrococcus. Pyocyanin inhibited biofilm activity in very minute concentrations. This was also confirmed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). Both SEM and CLSM helped to visualize the biocontrol of biofilm formation by eight pathogens. The imaging and quantification by CLSM also established the impact of pyocyanin on biofilm-biocontrol mainly in the food industry.

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Morphological and biochemical changes inPseudomonas fluorescensbiofilms induced by sub-inhibitory exposure to antimicrobial agents

Canadian Journal of Microbiology ◽

10.1139/w08-109 ◽

2009 ◽

Vol 55 (2) ◽

pp. 163-178 ◽

Cited By ~ 31

Author(s):

James J. Dynes ◽

John R. Lawrence ◽

Darren R. Korber ◽

George D.W. Swerhone ◽

Gary G. Leppard ◽

...

Keyword(s):

Antimicrobial Agent ◽

Pseudomonas Fluorescens ◽

Benzalkonium Chloride ◽

Laser Scanning ◽

Antimicrobial Agents ◽

Membrane Integrity ◽

Biochemical Changes ◽

Laser Scanning Microscopy ◽

Spectral Signature ◽

Confocal Laser

Confocal laser scanning microscopy (CLSM) and scanning transmission X-ray microscopy (STXM) were used to examine the morphological and biochemical changes in Pseudomonas fluorescens biofilms grown in the presence of subinhibitory concentrations of 4 antimicrobial agents: triclosan, benzalkonium chloride, chlorhexidine dihydrochloride, and trisodium phosphate. CLSM analyses using the stains SYTO9 and propidium iodide indicated that the antimicrobial agents affected cell membrane integrity and cellular density to differing degrees. However, fluorescein diacetate assays and plate counts demonstrated that the cells remained metabolically active. Fluorescent lectin binding assays showed that changes in the arrangement and composition of the exopolymer matrix of the biofilms also occurred and that these changes depended on the antimicrobial agent. Detailed single cell analyses using STXM provided evidence that the cell morphology, and the spatial distribution and relative amounts of protein, lipids and polysaccharides in the biofilms and within the cells were different for each antimicrobial. The distribution of chlorhexidine in the biofilm, determined from its distinct spectral signature, was localized mainly inside the bacterial cells. Each antimicrobial agent elicited a unique response; P. fluorescens cells and biofilms changed their morphology and architecture, as well as the distribution and abundance of biomacromolecules, in particular the exopolymer matrix. Pseudomonas fluorescens also exhibited adaptation to benzalkonium chloride at 10 µg/mL. Our observations point to the importance of changes in the quantity and chemistry of the exopolymeric matrix in the response to antimicrobial agents and suggest their importance as targets for control.

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The effect of the dispersion of microfibrillated cellulose on the mechanical properties of melt-compounded polypropylene–polyethylene copolymer

Cellulose ◽

10.1007/s10570-019-02756-8 ◽

2019 ◽

Vol 26 (18) ◽

pp. 9645-9659 ◽

Cited By ~ 9

Author(s):

Caterina Palange ◽

Marcus A. Johns ◽

David J. Scurr ◽

Jonathan S. Phipps ◽

Stephen J. Eichhorn

Keyword(s):

Tannic Acid ◽

Laser Scanning ◽

Secondary Ion Mass Spectrometry ◽

High Surface ◽

Microfibrillated Cellulose ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Cellulose Content ◽

Reinforced Composites ◽

The Impact

Abstract Microfibrillated cellulose (MFC) is a highly expanded, high surface area networked form of cellulose-based reinforcement. Due to the poor compatibility of cellulose with most common apolar thermoplastic matrices, the production of cellulose-reinforced composites in industry is currently limited to polar materials. In this study, a facile water-based chemistry, based on the reaction of MFC with tannic acid and subsequent functionalisation with an alkyl amine, is used to render the surface of the MFC fibrils hydrophobic and enhance the dispersion of the cellulose-based filler into an apolar thermoplastic matrix. The level of dispersion of the compatibilized MFC reinforced composites was evaluated using Time of Flight Secondary Ion Mass Spectrometry and multi-channel Spectral Confocal Laser Scanning Microscopy. The agglomeration of cellulosic filler within the composites was reduced by functionalising the surface of the MFC fibrils with tannic acid and octadecylamine. The resulting composites exhibited an increase in modulus at a high cellulose content. Despite the dispersion of a large portion of the functionalised filler, the presence of some remaining aggregates affected the impact properties of the composites produced.

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Effect of Etching Procedures on the Adhesion of Biofilm-Coated Dentin

Materials ◽

10.3390/ma13122762 ◽

2020 ◽

Vol 13 (12) ◽

pp. 2762

Author(s):

Bo-Kyung Jeon ◽

Chang-Ha Lee ◽

A Reum Kim ◽

Seung Hyun Han ◽

Hyun-Jung Kim ◽

...

Keyword(s):

Bond Strength ◽

Biofilm Formation ◽

Laser Scanning ◽

Failure Modes ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Acid Etching ◽

Dentin Surface ◽

Biofilm Removal ◽

Oral Biofilms

Oral biofilms coat all surfaces in the oral cavity including the exposed dentin surface. This study aimed to investigate biofilm removal by acid etching procedures and the effects of the residual biofilm on dentin surfaces on composite–dentin adhesion. Dentin discs were assigned to five groups: no biofilm formation (C); biofilm formation and no surface treatment (BF); biofilm formation and acid etching (BF-E); biofilm formation and acid etching followed by chlorhexidine soaking (BF-EC); and biofilm formation and rubbing with pumice, followed by acid etching (BF-RE). Biofilms were formed on saliva-precoated dentin discs by soaking the discs in Streptococcus mutans (S. mutans) suspension. Biofilm removal from the dentin surface was evaluated quantitatively and qualitatively by confocal laser scanning microscopy and scanning electron microscopy, respectively. To compare the bond strength of the biofilm-coated dentin discs with the surface treatments, specimens were assigned to four groups: no biofilm formation and acid etching (C-E); BF-E; BF-EC; and BF-RE. Assessments of the micro-shear bond strength and subsequent failure modes were performed. BF-E and BF-EC did not remove the biofilm, whereas BF-RE partially removed the biofilm attached to the dentin (p < 0.05). The bond strength of BF-RE was significantly higher than those of BF-E and BF-EC, but lower than that of C-E (p < 0.05). In conclusion, mechanical biofilm removal is recommended before etching procedures to enhance adhesion to the biofilm-coated dentin.

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Mosaic-CLSM Assessment of Bacterial Spatial Distribution in Cosmetic Matrices According to Matrix Viscosity and Bacterial Hydrophobicity

Cosmetics ◽

10.3390/cosmetics7020032 ◽

2020 ◽

Vol 7 (2) ◽

pp. 32

Author(s):

Samia Almoughrabie ◽

Chrisse Ngari ◽

Romain Briandet ◽

Valérie Poulet ◽

Florence Dubois-Brissonnet

Keyword(s):

Spatial Distribution ◽

Laser Scanning ◽

Rapid Assessment ◽

Challenge Test ◽

Surface Hydrophobicity ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Bacterial Surface ◽

Bacterial Hydrophobicity ◽

The Impact

The reliability of the challenge test depends, among other parameters, on the spatial distribution of microorganisms in the matrix. The present study aims to quickly identify factors that are susceptible to impair a uniform distribution of inoculated bacteria in cosmetic matrices in this context. We used mosaic confocal laser scanning microscopy (M-CLSM) to obtain rapid assessment of the impact of the composition and viscosity of cosmetic matrices on S. aureus spatial distribution. Several models of cosmetic matrices were formulated with different concentrations of two thickeners and were inoculated with three S. aureus strains having different levels of hydrophobicity. The spatial distribution of S. aureus in each matrix was evaluated according to the frequency distribution of the fluorescence values of at least 1350 CLSM images. We showed that, whatever the thickener used, an increasingly concentration of thickener results in increasingly bacterial clustered distribution. Moreover, higher bacterial hydrophobicity also resulted in a more clustered spatial distribution. In conclusion, CLSM-based method allows a rapid characterization of bacterial spatial distribution in complex emulsified systems. Both matrix viscosity and bacterial surface hydrophobicity affect the bacterial spatial distribution which can have an impact on the reliability of bacterial enumeration during challenge test.

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Bacterial colonization of enamel in situ investigated using fluorescence in situ hybridization

Journal of Medical Microbiology ◽

10.1099/jmm.0.011213-0 ◽

2009 ◽

Vol 58 (10) ◽

pp. 1359-1366 ◽

Cited By ~ 48

Author(s):

Ali Al-Ahmad ◽

Marie Follo ◽

Ann-Carina Selzer ◽

Elmar Hellwig ◽

Matthias Hannig ◽

...

Keyword(s):

Biofilm Formation ◽

Laser Scanning ◽

Bacterial Colonization ◽

Bacterial Species ◽

Fusobacterium Nucleatum ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Actinomyces Naeslundii ◽

Oral Biofilms

Oral biofilms are one of the greatest challenges in dental research. The present study aimed to investigate initial bacterial colonization of enamel surfaces in situ using fluorescence in situ hybridization (FISH) over a 12 h period. For this purpose, bovine enamel slabs were fixed on buccal sites of individual splints worn by six subjects for 2, 6 and 12 h to allow biofilm formation. Specimens were processed for FISH and evaluated with confocal laser-scanning microscopy, using probes for eubacteria, Streptococcus species, Veillonella species, Fusobacterium nucleatum and Actinomyces naeslundii. The number of adherent bacteria increased with time and all tested bacterial species were detected in the biofilm formed in situ. The general percentage composition of the eubacteria did not change over the investigated period, but the number of streptococci, the most frequently detected species, increased significantly with time (2 h: 17.7±13.8 %; 6 h: 20.0±16.6 %; 12 h: 24.7±16.1 %). However, ≤1 % of the surface was covered with bacteria after 12 h of biofilm formation in situ. In conclusion, FISH is an appropriate method for quantifying initial biofilm formation in situ, and the proportion of streptococci increases during the first 12 h of bacterial adherence.

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A Novel Hybrid Peptide Composed of LfcinB6 and KR-12-a4 With Enhanced Antimicrobial, Anti-Inflammatory and Anti-Biofilm Activities

10.21203/rs.3.rs-1109468/v1 ◽

2021 ◽

Author(s):

Chelladurai Ajish ◽

Sungtae Yang ◽

S. Dinesh Kumar ◽

Eun Young Kim ◽

Hye Jung Min ◽

...

Keyword(s):

Antimicrobial Activity ◽

Laser Scanning ◽

Antimicrobial Agents ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Bacterial Cells ◽

Bacterial Strains ◽

Hybrid Peptide ◽

Cell Selectivity ◽

Anti Inflammatory

Abstract Hybridizing two known antimicrobial peptides (AMPs) is a simple and effective strategy for designing antimicrobial agents with enhanced cell selectivity against bacterial cells. Here, we generated a hybrid peptide Lf-KR in which LfcinB6 and KR-12-a4 were linked with a Pro hinge to obtain a novel AMP with potent antimicrobial, anti-inflammatory, and anti-biofilm activities. Lf-KR exerted superior cell selectivity for bacterial cells over sheep red blood cells. Lf-KR showed broad-spectrum antimicrobial activities (MIC: 4–8 mM) against tested 12 bacterial strains and retained its antimicrobial activity in the presence of salts at physiological concentrations. Membrane depolarization and dye leakage assays showed that the enhanced antimicrobial activity of Lf-KR was due to increased permeabilization and depolarization of microbial membranes. Lf-KR significantly inhibited the expression and production of pro-inflammatory cytokines (NO and TNF-a) in LPS-stimulated mouse macrophage RAW264.7 cells. In addition, Lf-KR showed a powerful eradication effect on preformed multidrug-resistant Pseudomonas aeruginosa (MDRPA) biofilms. We confirmed using confocal laser scanning microscopy that a large portion of the preformed MDRPA biofilm structure was perturbed by the addition of Lf-KR. Collectively, our results suggest that Lf-KR can be an antimicrobial, anti-inflammatory, and anti-biofilm candidate as a pharmaceutical agent.

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Suppression of Xanthomonas oryzae pv. oryzae biofilm formation by Acacia mangium methanol leaf extract

Brazilian Journal of Biology ◽

10.1590/1519-6984.206124 ◽

2020 ◽

Author(s):

S. N. Sarah Shafiei ◽

K. Ahmad ◽

N. F. M. Ikhsan ◽

S. I. Ismail ◽

K. Sijam

Keyword(s):

Biofilm Formation ◽

Laser Scanning ◽

Leaf Extract ◽

Antimicrobial Agents ◽

Acacia Mangium ◽

Positive Control ◽

Laser Scanning Microscopy ◽

Xanthomonas Oryzae ◽

Confocal Laser ◽

Biofilm Inhibition

Abstract Xanthomonas oryzae pv. oryzae (Xoo), a pathogen responsible for rice bacterial leaf blight, produces biofilm to protect viable Xoo cells from antimicrobial agents. A study was conducted to determine the potency of Acacia mangium methanol (AMMH) leaf extract as a Xoo biofilm inhibitor. Four concentrations (3.13, 6.25, 9.38, and 12.5 mg/mL) of AMMH leaf extract were tested for their ability to inhibit Xoo biofilm formation on a 96-well microtiter plate. The results showed that the negative controls had the highest O.D. values from other treatments, indicating the intense formation of biofilm. This was followed by the positive control (Streptomycin sulfate, 0.2 mg/mL) and AMMH leaf extract at concentration 3.13 mg/mL, which showed no significant differences in their O.D. values (1.96 and 1.57, respectively). All other treatments at concentrations of 6.25, 9.38, and 12.5 mg/mL showed no significant differences in their O.D. values (0.91, 0.79, and 0.53, respectively). For inhibition percentages, treatment with concentration 12.5 mg/mL gave the highest result (81.25%) followed by treatment at concentrations 6.25 and 9.38 mg/mL that showed no significant differences in their inhibition percentage (67.75% and 72.23%, respectively). Concentration 3.13 mg/mL resulted in 44.49% of biofilm inhibition and the positive control resulted in 30.75% of biofilm inhibition. Confocal laser scanning microscopy (CLSM) analysis of Xoo biofilm inhibition and breakdown showed the presence of non-viable Xoo cells and changes in aggregation size due to increase in AMMH leaf extract concentration. Control slides showed the absence of Xoo dead cells.

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