Search Results (324)

Streptococcus uberis is a bovine mastitis pathogen with a demonstrated ability to form biofilms. However, the dynamics of this process remain poorly characterized. This study aimed to comprehensively characterize biofilm formation in four S. uberis strains that differed in their biofilm-forming capacity, from weak to strong producers, and in the presence of key virulence-associated genes, such as sua, hasA and hasC. To achieve this, we integrated structural, biochemical, physiological and transcriptional analyses using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), spectral flow cytometry and qRT-PCR. The multi-faceted analysis revealed a coordinated maturation peak at 48 h, characterized by a structured architecture with water channels, a distinct biochemical signature rich in polysaccharides and proteins, and a predominantly viable bacterial population. This peak coincided with a marked upregulation of key virulence-associated genes, with sua expression increasing 2.5-fold and hasA increasing 3-fold at 48 h. This mature biofilm conferred high tolerance to antibiotics, with eradication concentrations (>256 µg/mL) exceeding planktonic MICs, although tetracycline was notably effective. At 72 h, the biofilm entered a dispersion phase characterized by structural collapse and reduced viability. These findings establish S. uberis biofilm maturation as a highly coordinated process, providing new insights into the biofilm lifecycle of this important pathogen and identifying key temporal and molecular targets for future interventions. Full article

Pseudomonas aeruginosa (P. aeruginosa) forms biofilms that are difficult to eliminate. The matrix protects the cells, efflux pumps reduce intracellular drug levels, and dormant subpopulations survive treatment. Routine minimum inhibitory concentration (MIC) testing does not account for these features, which helps explain why infections often continue even when therapy appears appropriate. This review describes how quorum-sensing (QS) and cyclic di-guanosine monophosphate (c-di-GMP) regulate matrix production, efflux activity, and dormancy within P. aeruginosa biofilms. Important matrix components, including Psl, Pel, alginate, and extracellular DNA, slow the movement of antimicrobial agents. Regulatory proteins such as sagS and brlR increase the activity of the MexAB-OprM and MexEF-OprN efflux systems, further reducing intracellular drug concentrations. Oxygen and nutrient limitation promote persister cells and viable but nonculturable cells, with both having the ability to survive antibiotic levels that would normally be lethal. These defenses explain the gap between MIC values and biofilm-specific measurements, such as the minimum biofilm inhibitory concentration and the minimum biofilm eradication concentration. This review also summarizes emerging antibiofilm strategies. These include QS inhibitors, compounds that lower c-di-GMP, such as nitric oxide donors, nanoparticles, depolymerases, bacteriophages, and therapies that are directed at host targets. Modern diagnostic tools, such as confocal laser scanning microscopy, optical coherence tomography, and Raman spectroscopy, improve detection and guide treatment planning. A staged therapeutic approach is presented that begins with the dispersal or loosening of the matrix, continues with targeted antibiotics, and concludes with support for immune clearance. Viewing these strategies within a One Health framework highlights the role of biofilms in clinical disease and in environmental reservoirs and supports more effective surveillance and prevention. Full article

Microbial biofilms in food processing environments pose significant challenges due to their exceptional resistance to conventional sanitation methods, presenting substantial risks to food safety and public health. This review systematically evaluates recent advances in understanding biofilm development across key stages, i.e., initial microbial adhesion, extracellular polymeric substance production, biofilm maturation including resistant phenotypes such as persister cells, and dispersion. Particular emphasis is placed on the molecular mechanisms underlying biofilm formation and the regulatory roles of cyclic-di-GMP and quorum sensing. Crucially, we highlight emerging targeted interventions including enzyme-mediated extracellular polymeric substance disruption, microenvironmental manipulation, quorum sensing inhibitors, metabolic reactivation of persisters (“wake-and-kill”), and controlled biofilm dispersion techniques, clearly outlining their practical applicability and potential limitations in real-world food industry contexts. Moreover, this review uniquely integrates innovative technological developments such as responsive antimicrobial coatings, real-time biosensors, predictive modeling systems, and precision biotechnology approaches. Uniquely, this review integrates molecular mechanisms with practical, stage-specific sanitation strategies and provides actionable insights that can enhance biofilm control, contributing to safer food production practices and im-proved public health outcomes. Full article

Bacterial diseases of forest trees represent an increasing threat to ecosystem health and the sustainability and resilience of forest management, particularly under changing climate conditions. One of the key yet still insufficiently understood adaptive mechanisms of pathogens is biofilm formation—a structured community of bacterial cells embedded in a matrix of extracellular polymeric substances (EPS), which provides protection against stress factors, biocides, and the host’s defensive responses such as antimicrobial compounds or immune reactions. This paper presents a comprehensive review of current knowledge on the role of biofilms in the bacterial pathogenesis of forest trees, covering their formation mechanisms, molecular regulation, and ecological significance. Four key stages of biofilm development are discussed—adhesion, microcolony formation, EPS production, and dispersion—along with the roles of quorum sensing systems and c-di-GMP-based signaling in regulating these processes. Examples of major tree pathogens are presented, including Pseudomonas syringae, Erwinia amylovora, Xylella fastidiosa, the Brenneria–Gibbsiella complex associated with Acute Oak Decline (AOD) and Lonsdalea populi. Biofilm formation is shown to play a crucial role in the colonization of xylem, leaf surfaces, and tissues undergoing necrosis, where biofilms may stabilize decomposition zones and support saprophytic–pathogenic transitions. In the applied section, the concept of “biofilm-targeted control” is discussed, encompassing both chemical and biological strategies for disrupting biofilm structure—from quorum-sensing inhibitors and EPS-degrading enzymes to the use of biosurfactants and antagonistic microorganisms. The need for in situ research in forest environments and the adaptation of advanced imaging (CLSM, micro-CT) and metagenomic analyses to tree systems is also emphasized. This review concludes that biofilms are not merely a physiological form of bacterial organization but a complex adaptive system essential for the survival and virulence of pathogens in forest ecosystems. Understanding their functions is fundamental for developing sustainable and ecologically safe phytosanitary strategies for forest protection. Full article

The advances in biofilm research have provided the scientific community with a clear understanding that biofilm formation is not simply a matter of cells sticking to surfaces but rather a dynamic, regulated process involving adhesion, cell communication, the production of extracellular polymeric substances, community maturation, spatial heterogeneity, dispersal, and interactions with the environment and host [...] Full article

Background/Objectives: Biofilm-associated infections pose a major clinical challenge since bacteria within biofilms exhibit highly antibiotic tolerance. Pseudomonas aeruginosa forms persistent biofilms that cause chronic infections in vulnerable patients, including those with cystic fibrosis, burns, or medical implants. Such biofilm-associated chronic infections require prolonged treatments that promote antimicrobial resistance. To address this, recent strategies focus on enhancing biofilm dispersion. Methods: Thirty-six N-arylimino-1,2,3-dithiazoles were screened for their biofilm dispersal activity using a crystal violet assay. Their cytotoxicity was assessed on A549 and HaCat eukaryotic cells. Moreover, their influence on bacterial growth and virulence was investigated. Lastly, fluorescence anisotropy was used to measure membrane fluidity to obtain the first insights on the mechanism of action of these chemicals. Results: Our results showed that quinazoline-derivatives of imino-1,2,3-dithiazoles display biofilm dispersion activity. These compounds do not increase virulence through pyocyanin production, do not modify the growth kinetics of P. aeruginosa, and do not show cytotoxicity towards eucaryotic cells. Conclusions: These findings highlight the potential use of N-arylimino-1,2,3-dithiazole-derived compounds as safe and effective dispersal agents of P. aeruginosa biofilms. Full article

The recirculating aquaculture system (RAS) provides a sustainable approach to sustaining aquaculture output while reducing environmental pollution and excessive water consumption. Nonetheless, high concentrations of Total Ammonia Nitrogen (TAN) continue to be a significant obstacle in RAS operations. To address this issue, the Moving Bed Biofilm Reactor (MBBR), with bubble aeration, is important for promoting ammonia degradation. Bubble size impacts the effectiveness of bubble aeration, influencing both oxygen transfer and microbial activity. This research involved a 35-day experiment to evaluate the effects of bubble size, produced by nanobubble and coarse bubble aerators, on biofilm development and TAN decrease. The maximum biofilm thickness of 172.88 µm was recorded during nanobubble aeration, which also produced a higher quantity of microbial colonies (293 × 10⁷ CFU) in comparison to coarse bubble aeration (89 × 10⁷ CFU), as validated by Total Plate Count analysis. SEM–EDX imaging additionally demonstrated a more compact and consistent biofilm structure in the presence of nanobubbles. These results align with an increased TAN degradation efficiency, achieving 83.33% with nanobubble aeration, while coarse bubble aeration reached only 50%. The findings indicate that nanobubble aeration enhances biofilm functionality by improving bacterial dispersion and oxygen availability within the biofilm matrix, thereby promoting a more uniform distribution of microorganisms and nutrients. This mechanism represents a promising approach for improving water quality and overall treatment efficiency in recirculating aquaculture systems (RAS). Full article

This study reports the biosynthesis of selenium nanoparticles (Se-NPs) using four newly isolated strains of lactic acid bacteria, molecularly identified as Lactiplantibacillus pentosus, Lactiplantibacillus plantarum, Lactiplantibacillus plantarum, and Lactobacillus acidophilus. The synthesized Se-NPs were characterized using Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), and UV-Vis Spectroscopy, and zeta potential analysis. The result revealed that their size ranged from 16 nm to 90 nm with favorable stability and purity. The Se-NPs exhibited significant antimicrobial and antibiofilm activities against certain Gram-positive, Gram-negative bacteria, and Candida albicans, particularly those produced by isolate S4, which showed the lowest MIC values and highest biofilm inhibition. Furthermore, MTT assays revealed selective cytotoxicity against the A549 cancerous lung cell line, with minimal toxicity toward normal Wi38 cells. These findings suggest that biosynthesized Se-NPs are a promising, biocompatible candidate for combating antibiotic-resistant pathogens and biofilm-associated infections. Full article

Background/Objectives: Fungal colonization and biofilm formation on intrauterine device (IUD) strings are known to contribute to recurrent infections and decreased contraceptive efficacy. This study aims to develop a novel approach to prevent Candida reservoir and biofilm formation on IUD strings, thereby lowering the risk of IUD-associated vulvovaginal candidiasis (VVC). Methods: Cervicovaginal samples were collected from human cervix using a sterile cytobrush, avoiding microbial contamination. Cytological examination using the Papanicolaou method was performed to detect the presence of Candida. The antifungal effect of the essential oils (EOs) was determined by broth dilution and disk diffusion methods. Antifungal and biofilm inhibitory effects of Thymus zygis (Tz) EO-coated IUD strings were determined by agar diffusion and crystal violet binding assays, while fungal growth on the coated strings was assessed using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray (EDX) analysis. Results: Tz EO exhibited significantly lower minimum inhibitory concentration (MIC ≤ 0.06 µL/mL) and minimum fungicidal concentration (MFC = 0.24 µL/mL) values compared to Melaleuca alternifolia (Ma) EO (MIC > 0.24 µL/mL, MFC = 1.95 µL/mL), along with larger zones of inhibition (ZOI) against both Candida albicans (110.0 ± 6.0 mm vs. 91.3 ± 7.0 mm) and Candida glabrata (84.0 ± 13.1 mm vs. 50.0 ± 9.2 mm), indicating a stronger antifungal potential. On IUD strings coated with 4% (40 μL/g) Tz EO in hypromellose ointment, the biofilm formation of both C. albicans and C. glabrata strains was inhibited by 58.9% and 66.7%, respectively, as confirmed by SEM and EDX. Conclusions: Tz EO-coated IUD strings effectively inhibit Candida growth, suggesting a promising natural strategy to reduce recurrent IUD-associated fungal infections. However, before these results can be translated to clinical practice, additional research is needed. Future investigations may encompass an extended number of Candida isolates, stability and release studies of the EO in relation to the formulation, toxicity to vaginal mucosa, epithelial cells and sperm motility, and the effect on vaginal microbiotia. Full article

Chronic wounds and post-operative complications generate significant biomedical challenges due to impaired tissue regeneration and persistent microbial infections, often aggravated by biofilm formation and antibiotic resistance. To address these issues, this study investigates the development and in vitro evaluation of electrospun polyvinylpyrrolidone (PVP) scaffolds embedded with silver nanoparticles (AgNPs), designed as multifunctional bioactive platforms for wound healing and implant applications. AgNPs were synthesized and uniformly incorporated into the PVP matrix using optimized electrospinning parameters, harnessing their antimicrobial and anti-inflammatory properties alongside the hydrophilicity, biocompatibility, and chemical stability of PVP. Structural and mechanical characterization, including Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM), homogenous nanoparticle dispersion, and favorable mechanical properties, such as Young’s modulus. In vitro cytotoxicity assays with fibroblast cell lines demonstrated good biocompatibility, while antibiofilm activity against Staphylococcus aureus revealed significant microbial inhibition. Overall, electrospun PVP+AgNPs scaffolds demonstrate strong potential as multifunctional biomaterials for wound healing and implant coating due to their synergistic capacity to support tissue regeneration and inhibit infection. These promising results highlight the need for further in vitro and in vivo investigation to confirm their therapeutic efficacy, biocompatibility, and long-term stability in physiological environments. Full article

Staphylococcal bacterial biofilm plays an important role in the pathogenesis and bacterial persistence of chronic rhinosinusitis. N-acetyl cysteine (NAC) has an inhibitory role in biofilm formation, suppressing adhesion and matrix production or favoring dispersal of preformed biofilm. The aim of this study was to examine the in vitro effect of NAC on Staphylococcal biofilm formation by bacterial strains isolated from tissue samples of patients with chronic rhinosinusitis with or without nasal polyps (CRSwNP and CRSsNP). Prospective study included 75 patients with CRS. The biofilm-forming capacity of isolated strains was detected by microtiter-plate method and the effects of sub-inhibitory (1/2x, 1/4x, and 1/8x minimal inhibitory concentration, MIC) and supra-inhibitory minimal concentrations (2x, 4x, and 8xMIC) of NAC on biofilm production were investigated. Staphylococcal bacterial strains were isolated in 54 (72%) patients, and the most frequently isolated species were Staphylococcus aureus (40.7%). Coagulase-negative Staphylococci species were weak producers of biofilm, while S. aureus was a strong biofilm producer. Concentration of 3.1 mg/mL (1/2 MIC) was sufficient to completely prevent biofilm formation in 77.8% of the isolates, where 49.6 mg/mL (8xMIC) led to the complete eradication of formed biofilm in 81.5% of the isolates. The subinhibitory and eradication effects were dose- and strain-dependent. There were no significant differences in MIC values between isolates from patients with CRSwNP and CRSsNP isolates. NAC proved to be effective in inhibiting biofilm formation and reducing formed biofilm by Staphylococcal isolates from patients with CRS. A comparable antibiofilm effect was exhibited in both phenotypes of CRS, indicating that NAC’s antibiofilm activity was independent of the underlying clinical phenotype, and more targeted on biofilm matrix components. Full article

The use of orthodontic aligners has increased significantly due to their convenience and esthetic advantages. However, understanding their microbiological behavior and cytotoxicity is essential. This study aimed to evaluate the metabolic activity (MA) and proliferation of different bacterial strains—assessed through colony-forming unit (CFU) counts—as well as the cytotoxicity of three widely used aligner systems: Spark, Invisalign, and Smile. Wettability and surface free energy (both dispersive and polar components) were determined using the sessile drop technique. The bacterial strains Streptococcus oralis, Actinomyces viscosus, Streptococcus gordonii, Enterococcus faecalis, and Porphyromonas gingivalis were cultured, and their behavior on the aligner surfaces was assessed under simulated oral cavity conditions in both aerobic and anaerobic environments using a bioreactor. Cytocompatibility was evaluated with HFF-1 human fibroblasts. Distinct strain-specific behaviors were observed. For Spark aligners, the contact angle was 70.5°, Invisalign 80.6°, and Smile 91.2°, and the surface free energy was 60.8, 66.7, and 74. 2 mJ/m², respectively, highlighting the high polar component of the Spark aligner of 31.9 mJ/m² compared to 19.3 and 20.2 mJ/m² for Invisalign and Smile, respectively. The Spark aligner exhibited the lowest metabolic activity for Streptococcus oralis (23.1%), Actinomyces viscosus (43.2%), Porphyromonas gingivalis (17.7%), and biofilm formation (2.4%), likely due to its higher hydrophilicity. The Smile aligner showed the lowest metabolic activity for Streptococcus gordonii (23.6%) and Enterococcus faecalis (51.1%), attributed to its low polar surface free energy component. CFU counts were minimal for all aligners and bacterial strains, including biofilm. All aligners demonstrated cytocompatibility above 70% (Spark: 71.0%, Invisalign: 75.7%, and Smile: 75.6%). These findings highlight the importance of considering aligner material properties in clinical practice and underscore the need for proper oral hygiene and aligner maintenance. Full article

Stone cleaning for cultural heritage monuments is a critical conservation intervention that must effectively eliminate harmful surface contaminants while preserving the material’s physical, chemical, and historical integrity. This study investigated the removal of tenacious black biofilms formed by Nocardia species previously isolated from deteriorated limestone from the Bastet tomb in Tell Basta, Zagazig City, Egypt, using a Q-switched 1064 nm Nd:YAG laser. Experimental limestone specimens were systematically inoculated with Nocardia sp. under controlled laboratory conditions to simulate biodeterioration processes. Comprehensive testing revealed that a laser fluence of 0.03 J/cm² with a 5 ns pulse duration, applied under wet conditions with 500 pulses, achieved the complete elimination of the biological black film without damaging the underlying stone substrate. The cleaning efficacy was evaluated through an integrated analytical framework combining stereomicroscopy, scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX), X-ray diffraction (XRD), and laser-induced plasma spectroscopy (LIPS). These analyses demonstrated a remarkable transformation from a compromised mineralogical composition dominated by gypsum (62%) and anhydrite (13%) to a restored state of 98% calcite, confirming the laser treatment’s effectiveness in reversing biodeterioration processes. SEM micrographs revealed the complete elimination of mycelial networks that had penetrated to depths between 984 μm and 1.66 mm, while LIPS analysis confirmed the restoration of elemental signatures to near-control levels. The successful application of LIPS for real-time monitoring during cleaning provides a valuable tool for preventing overcleaning, addressing a significant concern in laser conservation interventions. This research establishes evidence-based protocols for the non-invasive removal of Nocardia-induced black biofilms from limestone artifacts, offering conservation professionals a precise, effective, and environmentally sustainable alternative to traditional chemical treatments for preserving irreplaceable cultural heritage. Full article

Microbiologically influenced corrosion (MIC) represents a critical challenge to the integrity of pipelines, piping, and metal structures in offshore environments, directly affecting the safety and operational costs of companies in the energy sector. However, conventional control methods, such as the use of chemical inhibitors, raise environmental and economic concerns. To face this problem, a biosurfactant produced by Pseudomonas cepacia CCT 6659 was tested as a biocorrosion inhibiting agent on carbon steel specimens immersed in seawater. For this purpose, static and dynamic conditions were simulated using different concentrations of the biosurfactant. Furthermore, analyses were performed using Scanning Electron Microscopy paired with Energy Dispersive Spectroscopy (SEM/EDS) to visualize the morphology of the biofilm and its chemical components. Laboratory tests indicated that the biosurfactant formulated in a 1:5 (v/v) ratio reduced the mass loss of test specimens (119.72 ± 2.64 g/m²) by no less than 57.3% compared to the control (280.28 ± 4.58 g/m²). Under dynamic conditions, the 1:2 (v/v) formulation showed greater protection, being able to reduce specimen corrosion (578.87 ± 7.01 g/m²) by 69.6% compared to the control (1901.41 ± 13.53 g/m²). SEM/EDS analyses revealed changes in surface composition and a reduction in corrosive elements associated with sulfur in the formed biofilms, which may be associated with a decrease in sulfate-reducing bacteria (SRB) activity, suggesting microbial inhibition by the biosurfactant. The results obtained in this study highlight the biosurfactant as a viable and ecological alternative to synthetic inhibitors, with potential application in the protection of metal structures exposed to corrosive environments in offshore energy systems, promoting greater durability, sustainability, and less environmental impact. Full article

Chronic lung infection is the main predictor of morbidity and mortality in cystic fibrosis (CF), and current pharmacological alternatives are ineffective against Pseudomonas aeruginosa infections. We developed ciprofloxacin (CIP) for inhalation, aiming at improving its solubility through the formation of an amorphous solid dispersion (ASD) using gelatin (GA). CIP and GA were dissolved in varying ratios and then spray-dried, obtaining CIP-GA microspheres in a single step. The dissolution rate, size distribution, morphology, and aerodynamic properties of CIP-GA microspheres were studied, as well as their antimicrobial activity on P. aeruginosa biofilms. Microspheres formulated with a higher GA ratio increased the dissolution of CIP ten-fold at 6 h compared to gelatin-free CIP. Formulations with 75% GA or more could form ASDs and improve CIP’s dissolution rate. CIP-GA microspheres outperformed CIP in eradicating P. aeruginosa biofilm at 24 h. The spray-drying process produced CIP-GA microspheres with good aerodynamic properties, as indicated by a fine particle fraction (FPF) of 67%, a D₅₀ of 3.52 μm, and encapsulation efficiencies above 70%. Overall, this study demonstrates the potential of gelatin to enhance the solubility of poorly soluble drugs by forming ASDs. As an FDA-approved excipient for lung delivery, these findings are valuable for particle engineering and facilitating the rapid translation of technologies to the market. Full article