Search Results (495)

Biofilms are structured communities of microorganisms encased in a self-produced extracellular matrix, and they represent one of the most widespread forms of microbial life on Earth. Their presence poses serious challenges in both environmental and clinical settings. In natural and industrial systems, biofilms contribute to water contamination, pipeline corrosion, and biofouling. Clinically, biofilm-associated infections are responsible for approximately 80% of all microbial infections, including endocarditis, osteomyelitis, cystic fibrosis, and chronic sinusitis. A particularly critical concern is their colonization of medical devices, where biofilms can lead to chronic infections, implant failure, and increased mortality. Implantable devices, such as orthopedic implants, cardiac pacemakers, cochlear implants, urinary catheters, and hernia meshes, are highly susceptible to microbial attachment and biofilm development. These infections are often recalcitrant to conventional antibiotics and frequently necessitate surgical revision. In the United States, over 500,000 biofilm-related implant infections occur annually, with prosthetic joint infections alone projected to incur revision surgery costs exceeding USD 500 million per year—a figure expected to rise to USD 1.62 billion by 2030. To address these challenges, surface modification of medical devices has emerged as a promising strategy to prevent bacterial adhesion and biofilm formation. This review focuses on recent advances in chemical surface functionalization using non-antibiotic agents, such as enzymes, chelating agents, quorum sensing quenching factors, biosurfactants, oxidizing compounds and nanoparticles, designed to enhance antifouling and mature biofilm eradication properties. These approaches aim not only to prevent device-associated infections but also to reduce dependence on antibiotics and mitigate the development of antimicrobial resistance. Full article

Water systems are highly vulnerable to biofilm formation, which can compromise water quality, operational efficiency, and public health. Factors such as surface material properties and gravitational orientation of the surface play critical roles in the early stages of microbial attachment and biofilm development. This study examines the impact of gravity and surface composition on the initial adhesion of Pseudomonas fluorescens AR11—a model organism for biofilm research. Focusing on stainless steel (SS) and polycarbonate (PC), two materials commonly used in water and wastewater infrastructure, bacterial adhesion was evaluated at surface inclinations of 0°, 45°, 90°, and 180° to assess gravitational impact. After three hours of contact, fluorescence microscopy and image analysis were used to quantify surface coverage and cluster size distribution. The results showed that both material type and orientation significantly affected early biofilm formation. PC surfaces consistently exhibited higher bacterial adhesion at all angles, with modest variations, suggesting that material properties are a dominant factor in initial colonization. In contrast, SS showed angle-dependent variation, indicating a combined effect of gravitational convection and surface characteristics. These insights contribute to a deeper understanding of biofilm dynamics under realistic environmental conditions, including those encountered in space systems, and support the development of targeted strategies for biofilm control in water systems and spaceflight-related infrastructure. Full article

Zwitterionic hydrogels have emerged as eco-friendly anti-fouling materials owing to their superior hydration-mediated resistance to biofouling. Nevertheless, their practical utility remains constrained by intrinsically poor mechanical robustness. Herein, this study proposes a novel strategy to develop novel tough zwitterionic hydrogels by freezing the gels’ polymer network. As a proof of concept, a zwitterionic hydrogel was synthesized via copolymerization of hydrophobic monomer phenyl methacrylate (PMA) and hydrophilic cationic monomer N-(3-dimethylaminopropyl) methacrylamide (DMAPMA), followed by post-oxidation to yield a zwitterionic structure. At service temperature, the rigid and hydrophobic PMA segments remain frozen, while the hydrophilic zwitterionic units maintain substantial water content by osmotic pressure. Synergistically, the zwitterionic hydrogel achieves robust toughness and adhesiveness, with high rigidity (66 MPa), strength (4.78 MPa), and toughness (2.53 MJ/m³). Moreover, the hydrogel exhibits a distinct temperature-dependent behavior by manifesting softer and more stretchable behavior after heating, since the thawing of the gel network at high temperatures increases segmental mobility. Therefore, it achieved satisfactory adhesiveness to substrates (80 kPa). Additionally, the hydrogel demonstrated remarkable anti-fouling performance, effectively suppressing biofilm formation and larval attachment. In summary, this work opens up promising prospects for the development of zwitterionic hydrogels with high application potential. Full article

Healthcare-associated infection, mainly through medical device-associated infection, remains a critical issue in hospital care. Bacterial adhesion, proliferation, and biofilm formation on the device surface have been considered the foremost cause of medical device-associated infection. Different means have been explored to reduce microbial attachment and proliferation, including forming a bactericidal or microbial adhesion-resistant surface layer. Fear of limited bactericidal capability if the dead microbes remained adhered to the surface has withheld the widespread use of a bactericidal surface in medical devices if it was intended for long-term use. By contrast, constructing a microbial adhesion-resistant or antifouling surface, such as a surface with zwitterionic functionality, would be more feasible for devices intended to be used for the long term. Nevertheless, a sophisticated multi-step chemical reaction process would be needed. Instead, a simple immersion method that utilized a novel mussel-inspired catechol compound with zwitterionic sulfobetaine functionality, ZDS, was explored in this investigation for the surface modification of substrates with distinctively different surface characteristics, including titanium and polyvinyl chloride. Dopamine, NaIO₄ oxidants, and chemicals that could affect ionic interactions (NaCl and polyethyleneimine) were added to the ZDS-containing immersion solution to compare their effects on modifying titanium and PVC substrates. Furthermore, a layer-by-layer immersion method, in which the substrate was first immersed in the no-ZDS-added dopamine-containing solution, followed by the ZDS-containing solution, was also attempted on the PVC substrate. By properly selecting the immersion solution formulation and additional NaIO₄ oxidation modification, the antibacterial capability of ZDS-modified substrates can be optimized without causing cytotoxicity. The maximum antibacterial percentages against S. aureus were 84.2% and 81.7% for the modified titanium and PVC substrate, respectively, and both modified surfaces did not show any cytotoxicity. Full article

Periodontitis is a chronic inflammatory disease caused by periodontopathic bacteria such as Porphyromonas gingivalis (P. gingivalis), which leads to alveolar bone destruction and systemic inflammation. Emerging evidence suggests that probiotics may mitigate periodontal pathology. To systematically evaluate the alleviative effects and mechanisms of different forms of probiotics, including live bacteria and postbiotics, on periodontitis, we first screened and identified Ligilactobacillus salivarius CCFM1332 (L. salivarius CCFM1332) through in vitro antibacterial and anti-biofilm activity assays. Subsequently, we investigated its therapeutic potential in a rat model of experimental periodontitis. The results demonstrated that both live L. salivarius CCFM1332 (PL) and its postbiotics (PP) significantly reduced the gingival index (GI) and probing depth (PD) in rats, while suppressing oral colonization of P. gingivalis. Serum pro-inflammatory cytokine levels were differentially modulated: the PL group exhibited reductions in interleukin-17A (IL-17A), interleukin-6 (IL-6), and interleukin-1β (IL-1β) by 39.31% (p < 0.01), 17.26% (p < 0.05), and 14.74% (p < 0.05), respectively, whereas the PP group showed decreases of 34.79% (p < 0.05), 29.85% (p < 0.01), and 19.74% (p < 0.05). Micro-computed tomography (Micro-CT) analysis demonstrated that compared to the periodontitis model group (PM), the PL group significantly reduced alveolar bone loss (ABL) by 30.1% (p < 0.05) and increased bone volume fraction (BV/TV) by 49.5% (p < 0.01). In contrast, while the PP group similarly decreased ABL by 32.7% (p < 0.05), it resulted in a 40.4% improvement in BV/TV (p > 0.05). Histological assessments via hematoxylin and eosin (H&E) and tartrate-resistant acid phosphatase (TRAP) staining confirmed that both the PL group and the PP group alleviated structural damage to alveolar bone-supporting tissues and reduced osteoclast-positive cell counts. This study suggests that live L. salivarius CCFM1332 and its postbiotics reduce alveolar bone resorption and attachment loss in rats through antibacterial and anti-inflammatory pathways, thereby alleviating periodontal inflammation in rats. Full article

Background: Periodontitis is a chronic inflammatory disease characterized by the destruction of periodontal tissues due to biofilm deposits and altered host immune response. Non-surgical periodontal therapy (NSPT) still represents the gold standard for treatment; however, its effectiveness in deep periodontal pockets is limited. Probiotics seem to modulate both oral microbiota and inflammatory response and have been proposed as an adjunctive therapy to NSPT. Methods: An electronic search was conducted on PubMed, Scopus, Medline, and Google Scholar to identify English randomized controlled trials (RCTs) evaluating probiotics as adjunctive treatments to NSPT. Studies were selected based on inclusion and exclusion criteria, and clinical outcomes such as probing depth (PD) and clinical attachment level (CAL) were extracted and analyzed. Results: Seven RCTs met the inclusion criteria. These studies showed significant improvements in PD and CAL when probiotics were used, specifically with Lactobacillus and Bifidobacterium species. However, outcomes ranged depending on the strain, dosage, and delivery method. Conclusions: Probiotics may be used as an adjunct treatment to NSPT; however, further studies are needed to define valid clinical guidelines. Full article

Long-chain imidazolium-based ionic liquids (ILs) possess a broad-spectrum biological activity and are considered promising antifouling agents for protective coatings. A new hydrophobic IL, 1-dodecyl-3-methylimidazolium dodecylbenzenesulfonate (C₁₂C₁IM-DBS), has been synthesized, and a modified epoxy coating material containing 10, 20, and 30 wt% of this IL was prepared by dissolution of C₁₂C₁IM-DBS in commercial DER 331 epoxy resin, followed by a curing phase with diethylenetriamine. Infrared analysis revealed physicochemical interactions between the hydroxyl groups of the resin and the IL. Spectrophotometric studies showed no release of C₁₂C₁IM-DBS after 30 days of exposure of the modified coatings to water. The plasticizing effect of the IL on the epoxy resin was established by differential scanning calorimetry analysis. The introduction of 10 and 20% C₁₂C₁IM-DBS into DER 331 reduced its glass transition temperature from 122.8 °C to 109.3 and 91.5 °C, respectively. The hardness of epoxy resin decreased by approximately 26% after the introduction of the IL. Moreover, DER 331/C₁₂C₁IM-DBS coatings on steel substrates showed significantly improved impact resistance compared to neat resin. The antibiofilm efficiency of DER 331/C₁₂C₁IM-DBS coatings was evaluated by assessing the capability of two biofilm-forming model strains, Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa PA01, to form attached biofilms on the surface. The IL effectively inhibited S. aureus surface-associated biofilm development even at the lowest content of 10%. On the contrary, an approximately 50% inhibition of biofilm metabolic activity was detected for DER 331/C₁₂C₁IM-DBS coatings containing 20% and 30% of the IL. Overall, the results of this study indicate that the hydrophobic IL C₁₂C₁IM-DBS is an efficient modifying additive for epoxy resins, which can significantly improve their operational properties for various industrial applications. Full article

Acne is a highly prevalent skin condition with multifactorial pathophysiology, where Cutibacterium acnes (C. acnes) overgrowths generate inflammation. C. acnes can grow and adhere, through the formation of biofilms, to almost any surface, which enables chronic infections. Acne treatment with antibiotics can induce topical antimicrobial resistance, impair microbiome biodiversity and cause cutaneous dysbiosis. In this study, we assess the effect of a standardized propolis extract (PE) from Greece against C. acnes, whilst maintaining skin’s microbiome biodiversity, and we investigate its effect against genes related to the attachment and colonization of C. acnes, as well as against biofilm formation. The extract has been chemically characterized by GC-MS and was additionally tested for its antioxidant properties by the Folin–Ciocalteu method and the 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) assay and its regulatory activity on the expression of antimicrobial and anti-inflammatory genes in normal human epidermal keratinocytes (NHEKs). The suggested efficacy of PE in targeting pathogenic C. acnes biofilm, via downregulation of virulence genes, represents an alternative strategy to modulate the behavior of skin microbiota in acne, paving the way for next-generation acne-targeting products. Full article

The emergence of antimicrobial resistance and the increasing demand for a healthier lifestyle have set new goals for science and industry. In the search for new, more effective, and environmentally friendly antimicrobial agents, special attention is being paid to natural resources. In this regard, essential oils derived from plants, which are widely used in the cosmetic, food, and pharmaceutical industries, are one of the solutions. In view of the above, this study aims to investigate the biological effects of Abies alba essential oil (AAEO). The chemical profile of AAEO was evaluated by GC/MS analysis, which revealed a high abundance of limonene (52.2%) and α-pinene (36.2%). Antioxidant activity evaluation showed a higher potential of AAEO in scavenging ABTS radical species with an IC₅₀ value of 1.18 ± 0.05 mg/mL. In vitro antimicrobial activity was determined by disc diffusion and minimum inhibitory concentration assays and showed that AAEO was more efficient in inhibiting the growth of G⁺ bacterial species. On contrary, in situ evaluations of antimicrobial effects of AAEO on different food models (strawberry, kiwi, white radish, and beetroot) resulted in more efficient suppression of G⁻ bacterial species. Although AAEO showed low effects on yeasts determined by in vitro methods, in situ investigations showed its higher potential in eradication of Candida yeast. The antibiofilm properties of the AAEO matrix were determined by means of crystal violet assay and MALDI-TOF MS Biotyper analysis against biofilm-forming Salmonella enterica. The analysis performed led to the conclusion that AAEO, when applied prior to biofilm formation, may contribute to the removal of planktonic cells and alter the abiotic surface, thereby reducing the suitability of Salmonella enterica for microbial attachment. Full article

Microbial Fuel Cell (MFC) is a novel bioelectrochemical system that catalyzes the oxidation of chemical energy in organic waste and converts it directly into electrical energy through the attachment and growth of electroactive microorganisms on the electrode surface. This technology realizes the synergistic effect of waste treatment and renewable energy production. A CF-NiO-PANI capacitor composite anode was prepared by loading polyaniline on a CF-NiO electrode to improve the capacitance of a CF electrode. The electrochemical characteristics of the composite anode were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and the electrode materials were analyzed comprehensively by scanning electron microscopy (SEM), energy diffusion spectrometer (EDS), and Fourier transform infrared spectroscopy (FTIR). MFC system based on CF-NiO-PANI composite anode showed excellent energy conversion efficiency in potato starch wastewater treatment, and its maximum power density increased to 0.4 W/m³, which was 300% higher than that of the traditional CF anode. In the standard charge–discharge test (C1000/D1000), the charge storage capacity of the composite anode reached 2607.06 C/m², which was higher than that of the CF anode (348.77 C/m²). Microbial community analysis revealed that the CF-NiO-PANI anode surface formed a highly efficient electroactive biofilm dominated by electrogenic bacteria (accounting for 47.01%), confirming its excellent electron transfer ability. The development of this innovative capacitance-catalytic dual-function anode material provides a new technical path for the synergistic optimization of wastewater treatment and energy recovery in MFC systems. Full article

Biofilms represent a prevalent and highly adaptable microbial lifestyle across diverse environments. With increasing understanding of quorum sensing (QS), its crucial role in regulating biofilm development in wastewater treatment systems has gained widespread recognition. This review systematically summarizes the role of QS in biofilm formation, encompassing the stages of initial attachment, irreversible adhesion, maturation, and dispersal. Additionally, the impacts of conventional environmental factors and specific stressors on QS-mediated biofilm regulation are discussed. Finally, the review highlights the positive regulatory effects of QS on biofilm performance. This review aims to offer practical insights into enhancing biofilm stability and optimizing wastewater treatment efficiency through QS-based regulatory strategies. Full article

E. coli attaches to, and forms biofilms on various surfaces, including latex and polystyrene, contributing to nosocomial spread. E. coli responds to both exogenous and endogenous insulin, which induces behavioral changes. Human insulin, a quorum signal surrogate for microbial insulin, may affect the ability of E. coli to interact with latex and polystyrene in the presence of various sugars. E. coli ATCC 25923 was grown in peptone (1%) yeast nitrogen base broth to either the logarithmic or stationary growth phase. Adherence to latex was determined using 6 × 6 mm latex squares placed in a suspension of washed cells (10³ CFU/mL; 30 min; 37 °C) in buffer containing insulin at 2, 20, and 200 µU/mL (Humulin^® R; Lilly) with and without mannose, galactose, fructose, sorbose, arabinose, xylose, lactose, maltose, melibiose, glucose-6-phosphate, glucose-1-phosphate, and glucosamine at concentrations reported to affect behavioral response. Attachment levels to latex were determined by the press plate method. Biofilm levels were measured in a similar fashion but with overnight cultures in flat bottom uncoated polystyrene plates. Controls were media, insulin, sugar, or buffer alone. Glucose served as the positive control. Overall, the stationary phase cells’ adherence to latex was greater, regardless of the test condition, than was measured for the logarithmic phase cells. The effect of insulin on adherence to latex was insulin and sugar concentration dependent. The addition of insulin (200 µU/mL) resulted in a significantly (p < 0.05) increased adherence to latex and biofilm formation on polystyrene compared with sugar alone for 12 of the 13 sugars tested with stationary phase bacteria and 10 of the 13 sugars tested with logarithmic phase bacteria. Adherence in response to sorbose was the only sugar tested that was unaffected by insulin. These findings show that insulin enhances E. coli’s association with materials in common usage in medical environments in a nutrition-dependent manner. Full article

Microbial fuel cells (MFCs) generate electricity through the microbial oxidation of organic waste. However, the inherent electrochemical performance of carbon felt (CF) electrodes is relatively poor and requires enhancement. In this study, nickel oxide (NiO) was successfully loaded onto CF to improve its electrode performance, thereby enhancing the electricity generation capacity of MFCs during the degradation of treated wastewater. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy diffusion spectrometer (EDS) analyses confirmed the successful deposition of NiO on the CF surface. The modification enhanced both the conductivity and capacitance of the electrode and increased the number of microbial attachment sites on the carbon fiber filaments. The prepared CF–NiO electrode was employed as the anode in an MFC, and its electrochemical and energy storage performance were evaluated. The maximum power density of the MFC with the CF–NiO anode reached 0.22 W/m², compared to 0.08 W/m² for the unmodified CF anode. Under the C1000-D1000 condition, the charge storage capacity and total charge output of the CF–NiO anode were 1290.03 C/m² and 14,150.03 C/m², respectively, which are significantly higher than the 452.9 C/m² and 6742.67 C/m² observed for the CF anode. These results indicate notable improvements in both power generation and energy storage performance. High-throughput gene sequencing of the anodic biofilm following MFC acclimation revealed that the CF–NiO anode surface hosted a higher proportion of electroactive bacteria. This suggests that the NiO modification enhances the biodegradation of organic matter and improves electricity generation efficiency. Full article

Salmonella spp. represent a food safety risk in the production chain because of their potential for biofilm development. This study examined the biofilm formation of eight Salmonella serotypes from diverse foodborne outbreaks on three food-contact surfaces, stainless steel, silicone, and nylon, at 10 °C and 37 °C. The effect of temperature was observed in slower biofilm formation at 10 °C with about 5-log (cfu/cm²) after 24 h, contrasting with 7-log (cfu/cm²) at 37 °C. The material also influenced biofilm formation, with the strongest biofilms on stainless steel at 10 °C and silicone at 37 °C. The serotypes producing the strongest biofilms were S. Enteritidis, S. Saint Paul, and S. Montevideo. The weakest serotypes were S. Senftenberg, S. Anatum, and the avirulent S. Typhimurium. The production of extra-polymeric substances was evident with S. Enteritidis. The biofilm index showed the highest value for low temperature, nylon, and silicone, and for S. Montevideo, S. Enteritidis, and S. Saint Paul. The whole-genome sequencing of each serovar suggested that single nucleotide polymorphisms in the curli (csg) genes may have contributed to the strong biofilm-forming ability of S. Montevideo and S. Saint Paul and the weaker ability of S. Senftenberg. These results can help with the correct development of sanitizing interventions based on the Salmonella strain of concern. Full article

With the rapid development of the livestock farming industry, the treatment of livestock farming wastewater has become increasingly important. The microbial-algal biofilm method has gained widespread attention for cattle wastewater treatment owing to its non-toxic nature, resistance to shock loading, and high treatment efficiency. In this study, three types of substrates—polyurethane sponge, ceramic material, and moving bed biofilm reactor media—were evaluated. The formation of biofilms was assessed through variations in chlorophyll content, microscopic observations, and measurements of biofilm dry weight and attachment rate. Biofilm characterization on the different substrates was conducted via Fourier transform infrared spectroscopy, confocal laser scanning microscopy, and scanning electron microscopy. The results demonstrated that polyurethane sponge was the most effective substrate. Furthermore, a single-factor experiment was conducted to optimize the cultivation conditions for the microbial-algal biofilms and identify the optimal parameters based on the ability of the biofilm to remove COD, TN, TP, and NH₄⁺-N. The optimal conditions were as follows: an illumination intensity of 8000 lux, red light, a temperature of 20 °C, a pH of 7, and an aeration intensity of 8 L/min. Under these conditions, the pollutant removal rates were exceptionally high: ~73.4% for COD, 51.8% for TP, 57.0% for TN, and 75.1% for NH₄⁺-N. Full article