Biofilm Adhesion Research Articles

Chlorogenic Acid: A Promising Strategy for Milk Preservation by Inhibiting Staphylococcus aureus Growth and Biofilm Formation

Chlorogenic acid (CGA), a polyhydroxy phenolic acid, has been extensively studied for its antimicrobial properties. Staphylococcus aureus (S. aureus) threatens food safety by forming biofilms. This study aimed to investigate the mechanism of CGA against S. aureus and its biofilm. The anti-bacterial activity of CGA was assessed using crystal violet staining, TEM, SEM, a CLSM, and using metabolomics and molecular docking to elucidate the mechanism. The results indicated that the minimum inhibitory concentration of CGA against S. aureus was 2.5 mg/mL. CGA disrupts the integrity of bacterial cell membranes, leading to increased hydrophobicity, morphological changes, scattering, and reduced spreading. This disruption decreases biofilm adhesion and bacterial count. Metabolomics and molecular docking analyses revealed that CGA down-regulates key amino acids. It forms hydrogen bonds with penicillin-binding protein 4 (PBP4), Amidase, glutamate synthetase B, and glutamate synthetase A. By inhibiting amino acid metabolism, CGA prevents biofilm formation. CGA interacts with amino acids such as aspartic acid, glutamine, and glutamate through hydroxyl (-OH) and carbonyl (-C=O) groups. This interaction reduces cell viability and biofilm cohesion. The novel findings of this study, particularly the extension of the shelf life of pasteurized milk by inhibiting S. aureus growth, highlight the potential of CGA as a promising anti-biofilm strategy and preservative in the dairy industry.

Antibiofilm activity of exopolysaccharide-mediated ZnO nanoparticle against Pseudomonas aeruginosa biofilm.

Exopolysaccharides (EPSs) are the group of biological macromolecules those play a potent role in protecting the bacteria from any sorts of stress. They exhibit multifunctional roles in natural and bioactive product science hence exhibits various types of medical and biochemical applications. EPS ensures the storage of nutrients, produce antigens to create defense mechanism during infection, and is also responsible for the formation of biofilm and cell adhesion. Green synthesis of ZnO nanoparticle mediated by EPS from Lactobacillus sp. which is a type of lactic acid bacteria (LAB) is a novel approach for its application in the food industry as it exhibits antimicrobial and antibiofilm potential. In this study, Lactobacillus sp. was cultivated in Lactobacillus broth media (LBM) and glucose mineral salt media (GMSM) to identify the best suitable media that would provide maximum amount of EPS, and it was observed that the two media exhibited maximum yield of 0.8g/L and 0.6g/L respectively after 48-h incubation. SEM, EDS, and XRD were used for characterizing the green synthesized ZnONPs from the EPS and was observed that the NPs were synthesized. 62.6% and 67.6% ZnONPs were observed in LBM-ZnONP and GMSM-ZnONP respectively from XRD analysis. UV spectroscopic detection showed corresponding peak of the nanoparticle formed at 349nm which confirmed the production of ZnO NPs. Scanning electron microscopic (SEM) images and Fourier transform infrared spectroscopy (FT-IR) established the average size, shape, and composition of the nanoparticles. The peaks of the FT-IR also revealed the presence of the C = H and N-H stretching (1 H). It was also observed that the average size of LBM ZnONPs were 60.578nm whereas GMSM ZnONPs were 53.09nm. Viability studies exhibited that the NPs brought considerable reduction of the sessile cells of P. aeuginosa. It was further observed that the cells treated with NPs did not show revival. The NPs were able to inhibit the quorum sensing (QS) mechanism of Pseudomonas aeruginosa thereby preventing the development of virulence. Out of the two NPs, it was observed that GMSM ZnONPs showed better efficacy in comparison to LBM ZnONPs. Thus, the study concludes that EPS-mediated NPs can be used effectively in the process of treating the biofilm.

The effect of antibacterial peptide ε-Polylysine against Pseudomonas aeruginosa biofilm in marine environment

Natural antibacterial agents with antimicrobial properties have a broad potential to prevent bacterial from forming biofilms adhesion in marine environments. ε-Polylysine (E-PL) consist of homomeric polymer with 25–30 lysine residues with stability, nontoxicity, and biodegradability. ε-Polylysine is a natural cationic antibacterial peptide that can resist microbial forming biofilm adhesion. The current study investigated the action of E-PL against Pseudomonas aeruginosa biofilm isolated from a marine environment. Crystal violet staining was used to examine the effects of E-PL on the formation and destruction of mature biofilms. Scanning Electron and fluorescence microscopy revealed that E-PL treatment damaged the biofilm structure and affected the secretion of extracellular polymers. The CCK8 colorimetric assay showed that E-PL also decreased the metabolic activity and motility of biofilm bacteria. QPCR and transcriptome analysis revealed that E-PL affected biofilm formation and transcriptional regulation by downregulating genes involved in flagellar synthesis (flgE, PA4651, pilW), chemotaxis transduction (PA1251, PA4951, PA4788), biofilm biosynthesis (pelC, pelD, pslK, plsM), transcriptional regulation (PA3973, PA3508, PA0268), phenazine biosynthesis (phzM, phzH, phzS), and electron transfer (PA5401, PA5400, PA3492). This study used multiple methods to identify the mechanism of E-PL action against biofilm, informing the design of novel biofilm treatment methods.

Effectiveness of coatings in reducing biofilm adhesion on arch wires: A systematic review

To evaluate the Effectiveness of coatings in reducing biofilm adhesion on arch wire. A literature search was performed on PubMed, Medline, Google Scholar, and Science Direct to examine studies that compared the uncoated group of arch wires to those with nano coatings and assessed the anti-adherent property. After extracting the data from each study, two risk of bias assessment tools were employed and tabulated data was obtained. 8 Studies met the requirements for inclusion. For majority of the included articles, the risk of bias assessment indicated a low to moderate risk. The antibacterial properties of various nanoparticle coatings were examined and evaluated.Regardless of patient compliance, a proper application of each type of coated arch-wire can help prevent white spot lesions and reduce bacterial aggregation around orthodontic attachments. Majority of the studies that made up this systematic review have a risk of bias grade of "fair." A meta-analysis was not feasible because of heterogeneity in the different coating techniques used to test the antibacterial property.

Illuminating microbial mat assembly: Cyanobacteria and Chloroflexota cooperate to structure light-responsive biofilms.

Microbial mats are stratified communities often dominated by unicellular and filamentous phototrophs within an exopolymer matrix. It is challenging to quantify the dynamic responses of community members in situ as they experience steep gradients and rapid fluctuations of light. To address this, we developed a binary consortium using two representative isolates from hot spring mats: the unicellular oxygenic phototrophic cyanobacterium Synechococcus OS-B' (Syn OS-B') and the filamentous anoxygenic phototroph Chloroflexus MS-CIW-1 (Chfl MS-1). We quantified the motility of individual cells and entire colonies and demonstrated that Chfl MS-1 formed bundles of filaments that moved in all directions with no directional bias to light. Syn OS-B' was slightly less motile but exhibited positive phototaxis. This binary consortium displayed cooperative behavior by moving further than either species alone and formed ordered arrays where both species aligned with the light source. No cooperative motility was observed when a non-motile pilB mutant of Syn OS-B' was used instead of Syn OS-B'. The binary consortium also produced more adherent biofilm than individual species, consistent with the close interspecies association revealed by electron microscopy. We propose that cyanobacteria and Chloroflexota cooperate in forming natural microbial mats, by colonizing new niches and building robust biofilms.

Optogenetic patterning generates multi-strain biofilms with spatially distributed antibiotic resistance

Spatial organization of microbes in biofilms enables crucial community function such as division of labor. However, quantitative understanding of such emergent community properties remains limited due to a scarcity of tools for patterning heterogeneous biofilms. Here we develop a synthetic optogenetic toolkit ‘Multipattern Biofilm Lithography’ for rational engineering and orthogonal patterning of multi-strain biofilms, inspired by successive adhesion and phenotypic differentiation in natural biofilms. We apply this toolkit to profile the growth dynamics of heterogeneous biofilm communities, and observe the emergence of spatially modulated commensal relationships due to shared antibiotic protection against the beta-lactam ampicillin. Supported by biophysical modeling, these results yield in-vivo measurements of key parameters, e.g., molecular beta-lactamase production per cell and length scale of antibiotic zone of protection. Our toolbox and associated findings provide quantitative insights into the spatial organization and distributed antibiotic protection within biofilms, with direct implications for future biofilm research and engineering.

Insight into the effect of natural aging of polystyrene microplastics on the sorption of legacy and emerging per- and polyfluorinated alkyl substances in seawater

Microplastics (MPs) are abundant in aquatic environments and due to their small size, surface properties, and strong hydrophobicity, they can easily sorb chemicals, thus potentially acting as pollutant carriers. To date, most studies investigating the sorption of chemicals on MPs have principally focused on virgin MPs. However, MPs in the environment undergo aging effects, which changes their physical-chemical properties and aptitude to interact with chemicals, such as per- and polyfluorinated alkyl substances (PFAS) referred to as “forever chemicals”. In this study, we compared the sorption behavior of nine PFAS, exhibiting different physical-chemical properties, on virgin and naturally aged polystyrene microplastic (PS-MPs) to explore to what extent the environmental aging affects the sorption behavior of the PS-MPs for different legacy and emerging PFAS in seawater. Differences in the morphology and surface properties of aged PS-MPs were examined by infrared spectroscopy, surface area analysis, scanning electron microscopy, and X-ray diffraction. Results revealed that compared to virgin PS-MPs, aged PS-MPs exhibited morphological changes (e.g. cavities, pits, and rough surfaces) with biofilm development and signs of oxidation on the MPs surface. PFAS sorption on PS-MPs was enhanced for the aged PS-MPs compared to virgin PS-MPs with Kd values ranging from 327 L kg−1 for PFOA to 3247 L kg−1 for PFOS in aged PS-MPs. The difference in sorption capacity was mainly attributed to the physical-chemical changes and the adhered biofilm observed in aged PS-MPs. Results also showed that virgin PS-MPs adsorb PFAS mainly through steric hindrance, while the aged PS-MPs may involve more complex sorption mechanisms. This research provides additional insights into the ability of aged MPs as potential carriers of legacy and emerging contaminants in the marine environment.

Comparative evaluation of surface changes and bond strength of microabrasion bleached enamel before and after remineralization with nano-hydroxyapatite paste: In vitro study

Objectives: Comparative evaluation of surface changes and bond strength of Microabrasion Bleached enamel before and after Remineralization with Nano-hydroxyapatite paste, an In vitro study. Methods: Enamel samples were divided into - Group I - Conventional bleaching (HB), Group II - Conventional bleaching with remineralization (HB+N-Hp), Group III - Microabrasion-assisted bleaching (M+HB), and Group IV - Microabrasion-assisted bleaching with remineralization (M+HB+N Hp). Surface roughness was measured using a profilometer. Samples were stored in artificial saliva for two weeks, then bonded with nanofilled composite resin and subjected to shear bond strength (SBS) analysis. Results: Group IV (M+HB+N-Hp) showed higher surface roughness than Groups I (HB) and II (HB+N-Hp), while Group II had significantly lower surface roughness compared to Groups III (M+HB) and IV. In terms of shear bond strength (SBS), Group III exhibited significantly higher SBS than Group I, whereas Group II showed significantly reduced SBS compared to Group I. All values were statistically significant. Conclusions: Remineralization with N-Hp reduces the surface roughness caused by bleaching and microabrasion, potentially decreasing bacterial biofilm adherence. Despite increased surface roughness correlating with better bond strength, microabrasion-assisted bleaching followed by remineralization and direct composite veneering after two weeks is a promising minimally invasive treatment for severe tooth discolorations. Further studies should explore varying frequencies and concentrations of N-Hp application.

Nosocomial Transmission of Necrotizing Fasciitis: A Molecular Characterization of Group A Streptococcal DNases in Clinical Virulence.

Streptococcus pyogenes, or Group A Streptococcus (GAS), is responsible for over 500,000 deaths per year. Approximately 15% of these deaths are caused by necrotizing soft-tissue infections. In 2008, we isolated an M5 GAS, named the LO1 strain, responsible for the nosocomial transmission of necrotizing fasciitis between a baby and a nurse in Belgium. To understand this unusual transmission route, the LO1 strain was sequenced. A comparison of the LO1 genome and transcriptome with the reference M5 Manfredo strain was conducted. We found that the major differences were the presence of an additional DNase and a Tn916-like transposon in the LO1 and other invasive M5 genomes. RNA-seq analysis showed that genes present on the transposon were barely expressed. In contrast, the DNases presented different expression profiles depending on the tested conditions. We generated knock-out mutants in the LO1 background and characterized their virulence phenotype. We also determined their nuclease activity on different substrates. We found that DNases are dispensable for biofilm formation and adhesion to both keratinocytes and pharyngeal cells. Three of these were found to be essential for blood survival; Spd4 and Sdn are implicated in phagocytosis resistance, and Spd1 is responsible for neutrophil extracellular trap (NET) degradation.

Impact of Biofilms on Surface Properties of Polymethyl Methacrylate (PMMA) Resins.

Poly(methyl methacrylate) (PMMA) resins are widely used in medical and dental applications. Their susceptibility to bacterial biofilm formation poses significant challenges related to material degradation and infection risk. This study investigated the effects of Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) biofilms on PMMA resin surface properties over a 45-day period at 35°C. The study examined various parameters including biofilm adhesion, morphology, surface roughness, hydrophobicity, solid fraction, and zeta potential. PMMA resin specimens were inoculated with bacteria and incubated for 45 days. Biofilm adhesion was visually assessed, while surface characterization was conducted using scanning electron microscopy (SEM), atomic force microscopy (AFM), roughness analysis, contact angle measurements, solid fraction determination, and zeta potential analysis. The P. aeruginosa and S. aureus isolates were selected based on their biofilm-positive characteristics, which were further confirmed using Congo red and biofilm formation assays through crystal violet staining and spectrophotometric analysis. The results demonstrated robust biofilm adhesion on PMMA surfaces. SEM and AFM imaging revealed textured surfaces with elevated structures and depressions within the biofilm matrix. Biofilm-exposed resins exhibited significantly increased roughness (Ra = 164.5 nm, Rq = 169.5 nm) and hydrophobicity (mean angle = 85.5°-90.5°) compared to control samples (Ra = 38-50 nm, angle = 55°). Solid fraction measurements indicated a denser biofilm matrix on exposed resins (0.908) compared to controls (0.65). Additionally, zeta potential values were more negative for biofilm-exposed resins (mean = -84.2 mV) than controls (-45.0 mV). These findings underscore the substantial alterations in PMMA resin surface properties induced by bacterial biofilms, emphasizing the critical need for strategies to prevent biofilm formation and mitigate associated risks in healthcare settings. Future research should focus on developing anti-biofilm coatings or treatments to preserve the integrity and functionality of PMMA materials.

Exploring NRB Biofilm Adhesion and Biocorrosion in Oil/Water Recovery Operations Within Pipelines.

Microbially influenced corrosion represents a critical challenge to the integrity and durability of carbon steel infrastructure, particularly in environments conducive to biofilm formation by nitrate-reducing bacteria (NRB). This study investigated the impact of NRB biofilms on biocorrosion processes within oil/water recovery operations in Algerian pipelines. A comprehensive suite of experimental and analytical techniques, including microbial analysis, gravimetric methods, and surface characterization, were employed to elucidate the mechanisms of microbially influenced corrosion (MIC). Weight loss measurements revealed that carbon steel samples exposed to injection water exhibited a corrosion rate of 0.0125 mm/year, significantly higher than the 0.0042 mm/year observed in crude oil environments. The microbial analysis demonstrated that injection water harbored an average of (4.4 ± 0.56) × 106 cells/cm2 for sessile cells and (3.1 ± 0.25) × 105 CFU/mL for planktonic cells, in stark contrast to crude oil, which contained only (2.4 ± 0.34) × 103 cells/cm2 for sessile cells and (4.5 ± 0.12) × 102 CFU/mL for planktonic cells, thereby highlighting the predominant role of injection water in facilitating biofilm formation. Contact angle measurements of injection water on carbon showed 45° ± 2°, compared to 85° ± 4° for crude oil, suggesting an increased hydrophilicity associated with enhanced biofilm adhesion. Scanning electron microscopy further confirmed the presence of thick biofilm clusters and corrosion pits on carbon steel exposed to injection water, while minimal biofilm and corrosion were observed in the crude oil samples.

The effect of attachment systems and denture cleaning methods on microbial biomass and composition in implant-supported overdentures: an experimental study

ObjectiveThis research endeavors to scrutinize the influence of attachment systems and denture cleaning methodologies on microbial biomass and composition within the realm of implant-supported overdentures, a crucial consideration for patients with dentition defects necessitating such prosthetic solutions.Subjects and methodsEmploying five polymethyl methacrylate specimens designed to emulate the fitting surfaces of traditional dentures and implant-supported overdentures. Following the polishing of each specimen and the quantification of its roughness, co-cultivation with three distinct microbial strains ensued, culminating in ultrasonic cleaning in water. The bar-clip group, differentiated by the depth of attachment, underwent cleaning employing four diverse methods. Biomass quantities were meticulously recorded both pre and post cleaning interventions, with subsequent data analysis via t-testing and one-way ANOVA, maintaining a significance level of α = 0.05.ResultsThe bar-clip groups demonstrated an elevated degree of microbial adhesion, with the deeper locator group exhibiting heightened biomass residue post-cleaning, indicative of increased cleaning complexity. Ultrasonic cleaning predominantly targeted biofilm and deceased bacteria, whereas chemical cleaners primarily reduced the quantity of viable bacteria. The synergistic application of ultrasonics and chemical cleaning treatments yielded the minimal biomass residue.ConclusionIn contemplating the utilization of dentures milled by dental computer-aided design/manufacturing systems, meticulous pre-use surface polishing is imperative. The extent of biofilm adhesion correlates with the chosen attachment system. This study advocates for the incorporation of ultrasonic cleaning in conjunction with chemical cleaning solutions to optimize the removal of biofilm and live cellular entities in the context of implant-supported overdentures.

Molecular epidemiological analysis of blaNDM-5-producing Klebsiella pneumoniae ST2407-K25 causing infection outbreaks in pediatric patients based on whole genome sequencing

BackgroundPediatric patients are vulnerable to the threat of carbapenem-resistant Klebsiella pneumoniae (CRKP) due to their limited immunity and few available antibiotics. Especially when these pathogens exhibit hypervirulent phenotypes, they are often associated with poor clinical outcomes.MethodsIn this study, we investigated a CRKP outbreak in pediatric patients from 2019 to 2021 in a teaching hospital in China based on whole genome sequencing. We sequenced twenty-nine CRKP isolates isolated from unduplicated pediatric patients to understand their genetic relationships, virulence factors, resistance mechanisms, and transmission trajectories. Conjugation experiments were performed to evaluate the horizontal transfer ability of carbapenem resistance determinants in twenty-nine CRKP isolates. We then characterized these isolates for biofilm formation ability and serum resistance. Genetic relatedness, comparison of plasmids, and chromosomal locus variation of CRKP isolates were analyzed by bioinformatics.ResultsAll the isolates were carbapenemase-producers harbouring blaNDM−5. Among them, twenty-eight isolates belonged to the ST2407 group, with the consistent capsular serotype K25. The virulence-related factors: ureA, fim, ybtA, irp1/irp2, and mrkA were prevalent in these isolates. Additionally, most CRKP isolates showed moderately adherent biofilm formation. Although the ST2407 clonal group did not exhibit serum resistance, the heterogeneous level of serum resistance was related to the disruption of oqxR. Conjugation and WGS revealed that the blaNDM−5 carried by the twenty-eight CRKP ST2407 isolates was located on nonconjugative IncX3 plasmids associated with deleting the T4SS-encoding genes. Clonal transmission of CRKP ST2407 in pediatric patients was suggested by the phylogenetic tree.ConclusionsOur study provides evidence of the clonal spread of blaNDM−5-producing K. pneumoniae in pediatric patients and the necessity for the T4SS system for horizontal transfer of the IncX3 plasmid carrying blaNDM−5. Additionally, the disruption of oqxR may have affected the serum resistance of CRKP. The results of this study emphasize the importance of continuously monitoring for CRKP infection in pediatric patients to prevent recurrent infections.

Transcriptome analysis reveals a new virulence-associated trimeric autotransporter responsible for Glaesserella parasuis autoagglutination.

Capsular polysaccharide is an important virulence factor of Glaesserella parasuis. An acapsular mutant displays multiple phenotype variations, while the underlying mechanism for these variations is unknown. In this study, we created an acapsular mutant by deleting the wza gene in the capsule locus. We then used transcriptome analysis to compare the gene expression profiles of the wza deletion mutant with those of the parental strain to understand the possible reasons for the phenotypic differences. The mutant Δwza, which has a deleted wza gene, secreted less polysaccharide and lost its capsule structure. The Δwza exhibited increased autoagglutination, biofilm formation and adherence to eukaryotic cells, while the complementary strain C-Δwza partially restored the phenotype. Transcriptome analysis revealed several differentially expressed genes (DEGs) in Δwza, including up-regulated outer membrane proteins and proteins involved in peptidoglycan biosynthesis, suggesting that wza deletion affects the cell wall homeostasis of G. parasuis. Transcriptome analysis revealed the contribution of non-coding RNAs in the regulation of DEGs. Moreover, a new virulence-associated trimeric autotransporter, VtaA31 is upregulated in Δwza. It is responsible for enhanced autoagglutination but not for enhanced biofilm formation and adherence to eukaryotic cells in Δwza. In conclusion, these data indicate that wza affects the expression of multiple genes, especially those related to cell wall synthesis. Furthermore, they provide evidence that vtaA31 is involved in the autoagglutination of G. parasuis.

Adhesion of Candida albicans on preformed crowns used to restore primary molars: An in vitro study

BackgroundAssessing microbial biofilm adhesion to the restorative material’s surface is a key factor in determining its success. This study aimed to compare the adhesion of Candida albicans (C. albicans) on stainless steel crowns (SSCs) versus zirconia crowns (ZCs) used for primary molars. Study designThis in vitro study involved 20 full-coverage crowns, with 10 SSCs and 10 ZCs. A fungal adhesion assay was performed to evaluate C. albicans adhesion, using colony-forming units (CFU) and cell proliferation assays. StatisticsThe Wilcoxon–Mann–Whitney test was applied to compare the groups, with statistical significance set at 5 %. ResultsThe study revealed that SSCs had a lower mean CFU value (28.28 ± 4.557 CFU/ml) and cell proliferation rate (49.74 ± 0.4367) compared to the ZC group (30.70 ± 11.0760 CFU/ml and 74.53 ± 0.7014, respectively). However, these differences were not statistically significant. ConclusionThe findings suggest that the selection of crowns for restoring primary molars may not be influenced by C. albicans adhesion.

Effect of the Sho1 gene on the pathogenicity of Candida albicans and immune function in vivo

ObjectivesSho1, a ubiquitous membrane protein in fungi, plays a pivotal role in various physiological processes, such as osmotic stress, oxidative stress, temperature response, and virulence regulation across different fungal species. This study aimed to investigate the effect of the Sho1 gene on the pathogenicity of Candida albicans and its immune function in vivo. Materials and methodsNinety-nine clinical strains from various infection sites were collected to investigate the expression levels of the Sho1 gene compared to its levels in the standard strain (SC5314). Sho1-knockout strains (Sho1Δ/Δ) were constructed to investigate the impact of the Sho1 gene deletion on the biofilm formation, adhesion, and flocculation abilities of C. albicans. A mouse model of systemic infection was established to evaluate the impact of Sho1 deletion on survival, organ pathology, and immune cell function, as assessed by flow cytometry. ResultsThe expression level of the Sho1 gene was found to be higher in clinical strains derived from sterile fluids, sputum, and secretions compared to that in the standard strains. Deletion of the Sho1 gene diminished the biofilm-formation capacity of C. albicans, leading to a sparse structure and reduced thickness, as well as diminished adhesion and flocculation abilities. Deletion of the Sho1 gene prolonged mouse survival; decreased the fungal load in the liver, kidney, and spleen; and reduced inflammatory cell infiltration into the kidney. In the spleens of mice injected with the Sho1Δ/Δ strain, a decrease was observed in the percentage of M1-type macrophages and an increase in M2-type macrophages, resulting in a decreased M1/M2 macrophage ratio. Additionally, an increase was observed in the number of Th1 cells and a decrease in the number of Th2 and Th17 cells, leading to an increased Th1/Th2 ratio. ConclusionThe Sho1 gene significantly contributes to the pathogenesis of C. albicans by influencing its biological behaviour and immune response in vivo.

The Oral Microbiome of Peri-Implant Health and Disease: A Narrative Review.

Peri-implantitis disease has increased significantly over the last years, resulting in increased failure of implants. Many factors may play a role in implant complications and failure, including ones related to the oral microbiota. This literature review aims to summarize the current knowledge of microbiome of implants in health and disease, focusing not only on the presence/absence of specific microbiota or on their relative abundance, but also on their phenotypic expression and their complex relationships with the host. The authors examined the MEDLINE database and identified key topics about peri-implant oral microbiome in health and disease. The peri-implant microbiome differs from that of the tooth, both in health and disease, as they are structurally and chemically different. The adhesion and formation of the peri-implant biofilm can be affected by the surface energy, topography, wettability, and electrochemical charges of the implant surface. In addition, the morphogenesis of the tissues surrounding the dental implant also differs from the tooth, making the dental implant more susceptible to bacterial infection. This interplay between the microbiome and the host immune system in peri-implant infections still needs to be elucidated.

A scanning electron microscope evaluation of surface roughness of different clear aligners – A comparative in-Vitro study

Clear aligner are thermoplastic polyurethane materials which produces small increments of tooth movements by each aligner tray. Clinical effectiveness of the treatment largely depend on the mechanical properties of the material. The use of scanning electron microscopy (SEM) in invitro environment allows to evaluate the surface morphology of the aligners The aim of the study is to compare the surface roughness of different types of clear aligners after thermoforming and after invitro aging. A sample of 15 aligners from Group A (DURAN), Group B (ERKODUR), Group C (MONOFLEX) were taken for this study. After screening the subjects were scanned by intraoral scanner and STL file were imported to Maestero 3D software. Then resin models were printed and aligners were fabricated in the models by thermoforming machine. The first set of aligners were scanned by Scanning Electron Microscope and another set of aligners were placed in chewing simulator for simulating intraoral environment. Then the second set of aligners were sent for SEM evaluation. Mean comparison of surface roughness and root mean square surface roughness was compared by paired t test and comparison among the groups was done by one way ANOVA test. The surface roughness of both aligners increased after thermoforming. This could be due to thermoforming process which could be due to temperature variation. After the ageing of the aligners in the invitro environment, there is homogenous and smooth layer of the aligner surfaces which could be due to adhesion of biofilm and polishing effect by chewing strokes.

Microbial adhesion on different types of orthodontic brackets and wires: An in vitro study

ObjectiveThe objective of this study was to compare the microbial adhesion of different oral pathogens on different wires used in orthodontic treatment and to evaluate the potential of these pathogens to form biofilms on different types of orthodontic wires and brackets. MethodsIn this in vitro investigation, we calculated that the sample size for each group (i.e., those with brackets [metal braces, ceramic braces, and self-ligating braces] and wires [nickel titanium, titanium molybdenum, and stainless steel]) should be 15 individuals. Five types of microbes (Streptococcus mutans, Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, and Candida albicans) were used. Three types of brackets and three types of wires were used with five types of bacteria, and the process was repeated three times to collect the average. ResultsNo significant differences were observed in the mean concentrations of bacteria in the different brackets (p > 0.05) or in the mean concentrations in the different orthodontic materials used in these brackets. In contrast, there were considerable differences between the concentrations of bacteria in the wires and those in the brackets (p < 0.05). ConclusionDifferent wires and brackets have different associations with bacterial adhesion and concentration. The wires exhibited more substantial biofilm absorbance and concentrations than the brackets. The adhesion of biofilm may be a decisive factor when choosing a type of orthodontic wire, particularly for individuals at high risk of developing bacterial oral diseases, such as periodontal diseases and dental caries.

Mixed microalgal culture enhances biofilm adhesion during treatment of livestock wastewater: The role of extracellular polymeric substances

Microalgal biofilm can remove nutrients and refractory pollutants from livestock wastewater, transforming them into biomass or fuel. However, these applications are hampered by biofilm shedding. Coculture enhances effects, and its influence on the adhesion of attached microalgal biofilms requires exploration. In this study, two unicellular algae, Euglena (E) and Chlorella pyrenoidosa (C). and two filamentous algae, Klebsodium sp. (K) and Phormidium sp. (P), were paired two by two, aiming to investigate the effect of mixing on the adhesion of microalgal biofilm. The results showed that suitable microalgal combinations significantly enhanced the performance of the co-cultured microalgal biofilm. Biomass enhancement of 35 % and 21.9 % was observed in the PC group compared to the individual P and C groups, respectively. The content of tightly bound extracellular polymeric substances (TB-EPS) and its protein and polysaccharide content significantly correlating with the net biomass increase in all treatments, p < 0.05. Furthermore, measurement of zeta potentials and water contact angles indicated that alterations in protein secondary structures contributed to a lower intermolecular repulsion and greater hydrophobicity of the TB-EPS, which together with the stability provided by the higher β-glucan content supported the adhesion of the co-cultured microalgal biofilm.