Microorganisms with health-promoting potential often experience substantial losses in viability and function due to stresses encountered during manufacturing and gastrointestinal transit. In this study, we investigate whether biofilm can be leveraged to enhance microbial resilience and functional performance. Using Bacillus subtilis as a model biofilm-forming bacterium, we examined strains with defined biofilm phenotypes: a biofilm-deficient mutant (tasA eps), a biofilm-overproducing mutant (sinR), and an isogenic wild-type control. These strains were evaluated across multiple functional benchmarks, including survival in simulated gastric and bile juices, thermotolerance, and intestinal bacterial colonization in the Caenorhabditis elegans model. Commercially available strains Lactobacillus rhamnosus GG and Saccharomyces boulardii were included as reference comparators. The biofilm-overproducing B. subtilis sinR strain demonstrated markedly enhanced survival under simulated gastrointestinal conditions and showed increased colonization within the C. elegans intestine. In contrast, the biofilm-deficient tasA eps mutant exhibited severe sensitivity to gastric stress and reduced the intestinal bacterial load. Furthermore, we demonstrate that cell-free B. subtilis biofilm can function as an effective bioencapsulation matrix. When used to encapsulate multiple probiotic strains, the biofilm matrix significantly improved their survival under acidic gastric conditions by neutralizing the environmental pH, indicating its broad potential for probiotic formulations and targeted gastrointestinal delivery. Overall, biofilms are traditionally studied for their roles in infection and antimicrobial resistance; however, their protective and adaptive traits may be repurposed for beneficial use. As an example of this concept, our findings show that B. subtilis biofilms enhance multiple functional and technological traits and highlight biofilm-based strategies as a promising platform for improving beneficial microbial robustness and the delivery of live biotherapeutics.
There is a growing understanding that slow growth and dormancy due to nutrient deprivation are very common physiological states exhibited by bacterial communities in a myriad of environments. However, very little is known about the role of slow growth and dormancy in biofilm regulation. Here, we utilize tractable dormancy and aggregation assays in nontuberculous mycobacteria (NTM) to ask the fundamental question of how growth arrest impacts the processes of aggregation and dispersal. First, we show that the well-conserved dormancy regulator DosSR affects biofilm formation in Mycobacterium smegmatis, as a dosR deletion mutant undergoes spurious re-aggregation and dispersal during aerobic late stationary phase. Identification of a suppressor mutation blocking re-aggregation in the ΔdosR mutant allowed us to determine a role for the antibiotic resistance factor WhiB7 in driving re-aggregation in M. smegmatis. We utilized BioOrthogonal NonCanonical Amino acid Tagging (BONCAT), qPCR, and quantitative aggregation assays to build a model wherein reductive stress in ΔdosR potentiates stationary phase translation in a WhiB7-dependent manner, permitting aggregation in dormant stationary phase cells. In addition, during stationary phase, WhiB7-activating reducing agents and antibiotics could trigger re-aggregation in both wild-type M. smegmatis and clinical isolates of the opportunistic NTM pathogen Mycobacterium abscessus. Finally, we determined that, in contrast to aerobic stationary phase, M. smegmatis does not aggregate or disperse in response to chemical cues or antibiotics under the Wayne model of hypoxic dormancy. Our work reveals a regulatory interaction between dormancy and aggregation that could have broad implications for treating and preventing NTM biofilms.IMPORTANCEMycobacteria aggregate to form multicellular biofilms that provide protection from external stressors and increase antibiotic tolerance. Understanding the pathways regulating biofilm formation can aid the identification of useful targets for developing new drugs. With a growing appreciation that pathogens are often in a slow growth/dormant state during infection, we investigate how dormancy affects biofilm formation and dispersal in two nontuberculous mycobacteria (NTM) species: Mycobacterium smegmatis and the opportunistic pathogen Mycobacterium abscessus. We find that activation of the WhiB7-mediated antibiotic response permits biofilm formation in aerobic stationary phase by reinitiating protein synthesis; however, cells under hypoxic dormancy are unresponsive. Our work provides important context to combatting biofilm formation in infection sites, informing future studies and aiding design of biofilm dispersal agents.
Streptococcus mutans is a primary architect of dental caries, utilizing complex genetic networks to build resilient, acid-producing biofilms. While pooled screens (Tn-seq) have identified important fitness factors, they often fail to capture extracellular or moderate-effect determinants due to community-level masking. Therefore, to study biofilm phenotypes, we constructed a comprehensive arrayed library of 9,216 mutants and used Cartesian Pooling-Coordinate Sequencing (CP-CSeq) to establish a sequence-defined resource covering 51% of non-essential genes. By screening the entire collection in isolation, we identified several novel biofilm determinants, including the putative metal transporter SMU_635 and the glycosylation-associated protein SMU_2160. However, systematic whole-genome sequencing (WGS) of our hits revealed an interesting level of genomic instability: 25% of biofilm-defective mutants had undergone spontaneous recombination at the gtfBC locus, while 7% had lost the TnSmu1 element, an excision rate 1,000-fold higher than previously reported. While targeted mutagenesis confirmed that TnSmu1 loss does not impact biofilm integrity, the gtfBC deletions directly accounted for the most severe phenotypes, highlighting a systemic risk of misattributing gene functions to primary transposon insertions. Our findings provide a powerful new genetic resource for the S. mutans community while establishing a critical new standard: an arrayed library is only as defined as its underlying genome, making systematic genomic verification an essential prerequisite for accurate functional genomics. Streptococcus mutans causes dental caries through resilient, acidogenic biofilm formation. While pooled screens often overlook extracellular or moderate-effect determinants due to community masking, this study presents a sequence-defined arrayed mutant library to dissect individual gene functions in isolation. Beyond known machinery, we identified novel biofilm determinants, including metal transporter SMU_635 and glycosylation-associated protein SMU_2160. Crucially, we uncovered pervasive genomic instability at the gtfBC and TnSmu1 loci. This reveals a systemic functional genomics risk: misattributing phenotypes to primary mutations when backgrounds undergo large-scale rearrangements. By establishing whole-genome verification as a necessary standard, this research ensures that future therapeutic target identification is built upon a verified genetic foundation.
Foodborne pathogens pose a serious public health threat, causing widespread illness and severe consequences. A major challenge in their control is the formation of biofilms on surfaces in food production environments, enhancing bacterial survival, antimicrobial resistance, and persistence. This review investigates biofilm formation strategies employed by key pathogens like Salmonella, Escherichia coli, and Listeria monocytogenes, emphasizing the pivotal role of biofilm management in addressing food safety concerns. The study explores the genetic, molecular, and environmental factors influencing biofilm development, which are crucial for devising effective control measures. Strategies employed by bacteria, such as quorum sensing, adhesion mechanisms, and extracellular polymeric substance production, are detailed. This review also discusses current control measures, including chemical and physical interventions, novel approaches like bacteriophages and biofilm-disrupting enzymes, and considerations in surface material design to minimize biofilm formation. In conclusion, a comprehensive understanding of biofilm formation strategies and effective control measures is essential for ensuring food safety. This review provides insights into managing biofilm-associated risks in the food industry, contributing to innovative and sustainable approaches for mitigating the impact of foodborne pathogens.
Pseudomonas aeruginosa is a prevalent healthcare pathogen. It forms biofilms, which significantly increase antibiotic resistance, escalating the burden on healthcare systems. While global biofilm phenomena are observable experimentally, understanding local behaviours of bacteria and their environment, and how these factors drive biofilm formation, is challenging. Agent-based modelling (ABM) offers a computational solution to simulate these local behaviours and resulting large-scale phenomena. ABMs can simulate physical mechanisms like erosion and sloughing but often lack the ability to capture them during biofilm growth and validate them experimentally. We present a three-dimensional ABM of P. aeruginosa biofilms growing under constant flow. This model is the first of its kind to accurately capture the change in physical shape of biofilms growing under constant flow, as well as capture erosion and sloughing as natural byproducts of local bacteria interactions. The model is validated both qualitatively and quantitatively against experimental culture results, providing a general framework that can be adapted to simulate different environments or other biofilm-forming species.
The emergence of drug-resistant Pseudomonas aeruginosa is an increasing global concern affecting human and animal health, food production systems, and environmental safety. This study investigated its occurrence, antimicrobial resistance, and biofilm-forming ability using phenotypic assays, and identify the biofilm-associated genetic markers in 120 cheese samples including 30 samples each of (Kariesh, Tallaga, Processed, and Romy) collected from various retail sources in Cairo and Giza, Egypt. Pseudomonas aeruginosa isolates were identified using both biochemical tests and molecular confirmation using 16 S rRNA gene. Antimicrobial susceptibility was evaluated using the disk diffusion method. Biofilm formation was assessed phenotypically through the microtiter plate and tube assays, while the biofilm-associated genes pelA and pslA were detected using PCR. Pseudomonas aeruginosa was detected in 18 samples (15%), and identification was confirmed through biochemical and molecular methods. Antimicrobial susceptibility testing revealed that 55% of isolates were extensively drug-resistant, while 45% exhibited multidrug resistance, with MAR indices ≥ 0.2 and an average MAR index of 0.68, indicating exposure to high-risk environments with frequent antibiotic use. Phenotypic assays showed strong biofilm-forming capabilities among isolates, with 100% positive by microtiter plate and 95% by tube method. Molecular screening further confirmed the prevalence of biofilm-associated genes, detecting pelA in 72% and pslA in 61% of isolates. Overall, Pseudomonas aeruginosa isolated from cheese samples exhibited substantial antimicrobial resistance and robust biofilm-forming ability, posing significant concerns to cheese quality and consumer health. These findings highlight the urgent need for continuous surveillance, improved dairy hygiene, effective sanitation, responsible antimicrobial practices, and alternative control strategies within the dairy sector to reduce potential public health hazards.
Objective: To evaluate the effects of carbon monoxide-releasing molecule-3 (CORM-3) on Enterococcus faecalis biofilm inhibition and eradication, and assess its biosafety. Methods: CO release kinetics were measured by UV spectrophotometry. Mature biofilm eradication was assessed using 72-h biofilm models with crystal violet staining and XTT assay. Colonization inhibition was observed by scanning electron microscopy (SEM). Expression of biofilm-associated genes (esp, gelE, fsrB, cylL) was quantified by RT-qPCR. Cytocompatibility was evaluated in human oral keratinocytes (HOK) and human gingival epithelial cells (HGE). Systemic toxicity was assessed in SD rats through hematological and histopathological analyses. Results: CORM-3 released CO time-dependently with a half-release time of approximately 1.5 min. Treatment with 200 μM and 400 μM CORM-3 achieved biofilm clearance rates of 42.8 ± 5.8% and 65.3 ± 4.7%, with metabolic activity reductions of 38.5 ± 6.2% and 61.7 ± 5.3%, respectively. SEM revealed significantly reduced bacterial adhesion in treated groups. RT-qPCR showed 400 μM CORM-3 downregulated esp, gelE, fsrB, and cylL expression by 64.2%, 68.7%, 55.3%, and 42.1%, respectively. Cell viability remained above 87% after 24 h exposure to 400 μM CORM-3. No hematological abnormalities or organ damage were observed following 7-day intraperitoneal administration. Conclusion: CORM-3 exhibits dual anti-biofilm activity against E. faecalis through controlled CO release, inhibiting bacterial colonization and preventing recolonization while eradicating mature biofilms, with favorable biocompatibility at effective concentrations, supporting its potential as an adjunctive agent in endodontic treatment.
Calcium ions (Ca2+) are known to enhance biofilm structural integrity in many bacteria, including Pseudomonas aeruginosa, by cross-linking exopolysaccharides. Still, their role in the soil bacterium P. putida remains largely unexplored. Here, we investigated the dose-dependent effects of calcium chloride on P. putida KT2442 biofilm architecture, matrix properties, nanomechanics, and global gene expression. Contrary to the stabilizing role observed in P. aeruginosa, calcium induced complex biphasic responses in P. putida. Calcium elicited complex, non-monotonic effects: while 1.5 mM CaCl₂ increased biofilm biovolume, a moderate 3 mM concentration limited architectural expansion and corresponded with the lowest measured biofilm stiffness in exploratory AFM assays. At 15 mM, biofilm thickness increased, but mechanical rigidity did not fully recover, and the molecular weight of matrix polysaccharides decreased. Transcriptomic analysis revealed dose-dependent reprogramming affecting approximately 3,600 genes at 3 mM and 15 mM calcium, with downregulation of genes involved in exopolysaccharide biosynthesis, large adhesins (lapA, lapF), and motility, alongside upregulation of stress response and ribosomal biogenesis pathways. These correlative findings suggest that calcium may act not merely as a structural ion but as a potent environmental signal that triggers species-specific adaptive responses correlated with altered biofilm architecture, mechanics, and transcriptional networks in P. putida. The direct causal links and the unique responses of calcium in comparison to other divalent cations have yet to be confirmed.
Listeria monocytogenes biofilms persist in food processing environments and pose a serious threat to food safety. This study aimed to comprehensively characterize Lactiplantibacillus plantarum L-1, a strain isolated from traditional Chinese Jiangshui, and to evaluate the anti-biofilm activity of its crude bacteriocin against L. monocytogenes. The strain exhibited promising probiotic attributes, including high survival rates under simulated gastrointestinal conditions (68.9% at pH 2.0, 85.0% in the presence of 0.3% bile salts) and a satisfactory safety profile (antibiotic susceptibility, γ-hemolysis, and no toxicity in mice). Whole-genome sequencing identified genetic determinants for stress tolerance and a gene cluster encoding multiple bacteriocins, including pln EF, pln J, pln N, and a putative bacteriocin. LC-MS identified three expressed bacteriocins: Plantaricin E, F, and N. The crude bacteriocin showed high stability under a range of temperatures (60-121 °C) and pH (2.0-12.0), with a MIC of 2.2 mg/mL against L. monocytogenes. At sub-inhibitory concentrations that did not affect planktonic growth (1/32×, 1/16×, 1/8× MIC), it significantly inhibited biofilm formation in a concentration-dependent manner, achieving 89.5% inhibition at 1/4 × MIC. The bacteriocin suppressed metabolic activity, reduced exopolysaccharide (EPS) production, and inhibit the integrity of biofilm structure, and downregulated the expression of key biofilm-related genes without affecting bacterial growth. These findings highlight the potential of L. plantarum L-1 as a dual-functional probiotic and a natural biocontrol agent against L. monocytogenes biofilms in the food industry.
Nosocomial infections are a major health problem worldwide. The increasing time patients spend in hospitals has led to an increase in mortality. Acinetobacter baumannii is an opportunistic pathogen that is a significant factor in nosocomial infections. The main aim of the current study was to investigate biofilm and pathogenicity-related genes among multidrug-resistant A. baumannii strains (n = 54) obtained from patients with respiratory infections. ERIC-PCR was also used to determine their molecular typing correlation. Disk diffusion and MIC methods were used to test antibiotic susceptibility. Biofilm formation was evaluated using crystal violet staining and SEM imaging. In this study, 96.30% of isolates formed biofilms, and 59.25% were strong biofilm producers. The most prevalent biofilm-related genes were pgaC (98.15%), pgaB (92.6%), and pgaA (79.6%), followed by epsA and ompA (74.1%). The isolates demonstrated high resistance to imipenem (100%), cefotaxime (98.15%), followed by cefepime, ceftazidime, levofloxacin, and piperacillin/tazobactam (96.3%). The presence of antibiotic-resistant genes was as follows: blaOXA-58 (20.4%), blaOXA-23 (5.55%), aacC1 (50.0%), aphA6 (45.45%), sulⅡ (63.25%), and sulⅠ (32.65%). The sulⅢ gene was not detected. A dendrogram based on UPGMA revealed significant genetic diversity among the 54 A. baumannii strains. Twenty-two ERIC types were identified, with 14 unique types and 8 common types. This study illuminates a concerning rise in antibiotic resistance and the widespread presence of resistance genes in A. baumannii strains. Furthermore, the high ability of these isolates to form biofilms likely contributes to their enhanced resistance, further complicating eradication efforts. Molecular typing demonstrated considerable genetic diversity.
This study examines the antibacterial and antibiofilm activities of essential oils from Thymus vulgaris, Rosmarinus officinalis, and Lavandula angustifolia. Chemical analysis identified carvacrol, linalool, and camphor as key constituents contributing to activity against E. coli, S. aureus, and P. aeruginosa. T. vulgaris oil, rich in phenolic and flavonoid content, showed the strongest efficacy. R. officinalis and L. angustifolia oils also demonstrated notable antimicrobial effects, reducing bacterial viability, biofilm biomass, and metabolic activity, although effectiveness varied with species and biofilm structure. T. vulgaris oil effectively removed E. coli and P. aeruginosa biofilms at 2 × MIC (log reduction 7) but was less effective against S. aureus (log reduction 1.7) at 2 × MIC. The activity of these oils may be associated with disruption of bacterial membranes, biofilm architecture, and induction of oxidative stress. Mammalian toxicity at 3 × MIC shows a low toxic profile for T. vulgaris and R. officinalis, but a high toxic profile for L. angustifolia. These findings highlight T. vulgaris and R. officinalis essential oils as promising antibacterial agents in terms of both efficacy and safety.
The colonization of textiles by axillary skin bacteria produces an unpleasant odour due to the rapid growth of a selective community of bacteria. Such colonized textiles subsequently act as vectors for transmitting nosocomial infections among healthcare workers and patients. An in-depth understanding of bacterial behaviour on soft surfaces like fabrics is necessary to mitigate the transmission of infections. This study examined the effect of artificial human sweat on biofilm formation by Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa, on three fabrics, viz. polyester, cotton, and polyester-cotton (70:30) blend. Artificial sweat was constituted to replicate the natural human sweat on textiles. Using atomic force microscopy, the three-dimensional topography of the biofilm was determined, and scanning electron microscopy was employed to visualise the biofilm that had developed on the fabrics. All bacterial strains showed maximum growth on polyester fabric in the presence of sweat. P. aeruginosa and S. aureus were found to be strong biofilm producers, whereas E. coli and E. faecalis were moderate producers. The ability of the four bacterial strains to form biofilm was related to their production of extracellular polymeric substances (EPS). P. aeruginosa produced viscous EPS in contrast to the EPS produced by other bacterial strains. In conclusion, this study corroborates that sweat plays a major role in the colonization of textiles by bacteria. Regular practice of fabric hygiene, and the development of modified fabrics with anti-pathogen properties, could potentially reduce the prevalence of nosocomial infections in healthcare settings. The online version contains supplementary material available at 10.1007/s12088-024-01409-0.
Food safety incidents associated with bacterial biofilms and peanut allergies continue to increase annually. Although yeasts have been proposed as biocontrol agents, the effectiveness of commercial brewer's yeasts against bacterial biofilms and peanut allergens remains insufficiently explored. This study evaluated the biocontrol potential of brewer's yeasts by characterizing their properties and determining removal efficiencies. Cell surface hydrophobicity was measured, and binding and removal efficiencies toward biofilms formed by Escherichia coli and Listeria monocytogenes and peanut allergens were assessed. The hydrophobicity of Saccharomyces cerevisiae (2.75‒90.52%) was higher and broader than that of S. pastorianus (10.92‒43.79%). Both species exhibited binding efficiencies to bacterial biofilms (7.11‒26.68%) and peanut allergens (3.57‒22.03%). Removal efficiencies reached 99.30% for L. monocytogenes biofilms and 86.07% for peanut allergens. Higher hydrophobicity and binding affinity were positively correlated with improved removal performance. These findings support the potential application of commercial brewer's yeasts as yeast-based cleaning agents for food safety management.
Polymicrobial communities impose a great challenge for clinical management of chronic infections. It is a consensus now that microbes exist as aggregated colonies shielded within polymeric matrix. Within this matrix more than one bacterial species can exist either in symbiotic or rival relationships. Herein, we investigated the host-specific interspecies interactions between Staphylococcus aureus and Pseudomonas aeruginosa in chronic rhinosinusitis (CRS). The indirect interaction between the two species was assessed using Transwell co-culture chambers, where S. aureus and P. aeruginosa (n = 3 each) derived from CRS patients were cultured in separate chambers that allowed exchange of soluble factors. Later the biofilm biomass of each species was evaluated and compared to single species biofilm. Further, the influence of the co-culture conditions on antibiotic tolerance was evaluated. When derived from the same patient, co-cultured bacteria increased the biofilm biomass of each other significantly by 3.0-4.9 fold (p < 0.01) and exhibited higher tolerance to amikacin compared to co-cultures of isolates from two different patients and monocultured biofilms. Moreover, the incubation of one bacterial protein-enriched secreted fractions (PESF) with alternative species form same patient significantly increased biomass by 1.5-4.8 fold (p < 0.01), while similar trend was not observed among randomly cultured species. These data underscore the synergistic growth pattern between different bacterial species growing in the same niche and highlight the importance of further studies to aid the selection of antibiotics targeting polymicrobial biofilms.
The prevalence of cariogenic bacteria in dental caries is attributed to acidification of the oral microenvironment. Cariogenic Pseudomonas aeruginosa strains were isolated from dental caries. A total of 101 P. aeruginosa strains were isolated from 55 samples (n = 55). The isolates were classified based on their acid tolerance and acidogenic properties. The isolated bacterial strains were cultured in soy peptone (2%) and maintained in a simulated oral environment. The survival rate of the isolates varied from 40.2 ± 2.1 to 74.7 ± 1.8%, and only 11 strains had a significant survival rate (> 60%). Among these DS47 strain exhibited strong biofilm production, with an optical density value significantly higher than that of the other isolates (p < 0.01). This strain was further tested to determine its demineralization effect on teeth. The biofilm-forming bacteria DS47 released Ca2+ ions in a time-dependent manner (p < 0.01), indicating its potential role in enamel demineralization. Additionally, the DS47 isolate was found to be multidrug-resistant, showing resistance to tobramycin, cefotaxime, ceftazidime, amoxicillin, trimethoprim, ciprofloxacin, levofloxacin, amikacin, ceftazidime, cefoxitin, and gentamicin. The New Delhi metallo β-lactamase-1 (NDM-1) gene and blaVIM-1 genes were detected in the drug-resistant P. aeruginosa DS47. The biofilm-producing P. aeruginosa showed cariogenicity and contributed to dental caries. These findings suggest that biofilm-producing P. aeruginosa plays a significant role in cariogenicity and contributes to dental caries.
This study is aimed at evaluating the phytochemical constituents and antimicrobial potential of Ruta chalepensis (Rue) and Allium sativum (Garlic), with a focus on their antibiofilm activity against selected bacterial strains. Ethanolic extracts of R. chalepensis leaves and fresh A. sativum bulbs were subjected to qualitative phytochemical screening, antibacterial testing, biofilm suppression assay, FT-IR spectroscopy, and elemental analysis. Phytochemical analysis confirmed the presence of metabolites including phenols, tannins, saponins, alkaloids, and terpenoids. The extracts exhibited significant antibacterial activity (p < 0.05) against all tested reference strains. In the biofilm suppression assay using a microtiter plate method and crystal violet staining, both extracts effectively inhibited biofilm formation, with absorbance values ranging from 0.6-1.22 for A. sativum and 0.45-0.88 for R. chalepensis, compared to the untreated control. FT-IR spectroscopy identified functional groups such as hydroxyl, carbonyl, carboxylic, and organosulfur compounds in garlic, and N-H, C-H aliphatic, C=C unsaturated, and aromatic rings in rue. Flame atomic absorption spectroscopy (FAAS) revealed essential elements including K, P, Mg, Ca, and Al in A. sativum, and Zn, Cu, Cr, and Mo in R. chalepensis. These findings support the traditional use of these plants in Ethiopian medicine and underscore their potential as natural, affordable alternatives for managing biofilm-associated infections, particularly in oral health applications.
Serratia sp. are opportunistic Gram-negative bacteria capable of forming robust biofilms and expressing a wide range of quorum sensing (QS)-regulated virulence factors, including motility, protease secretion, and prodigiosin production. The rise of multidrug-resistant strains has emphasized the urgent need for alternative therapeutic strategies targeting bacterial virulence rather than viability. In this context, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ketoprofen have emerged as potential quorum-quenching agents. This study explores the antivirulence activity of ketoprofen against Serratia sp. through a combination of in-vitro phenotypic assays and an advanced in-silico framework. In-vitro assays demonstrated that sub-inhibitory concentrations of ketoprofen significantly impair key virulence traits. Ketoprofen exhibited up to 90.68% inhibition of initial bacterial adhesion and disrupted mature biofilms, reducing biomass by up to 79.1%. Furthermore, motility assays revealed profound inhibition of both swimming and swarming behaviors, alongside a 100% suppression of protease activity and a 60.4% reduction in prodigiosin production, without exerting direct bactericidal effects. To elucidate the molecular basis of this competitive antagonism, an integrative computational approach was deployed. Deep learning-driven molecular docking (GNINA) revealed that ketoprofen targets the LuxR-type QS receptor SmaR with exceptional and reproducible affinity (mean Vina affinity of -9.51 kcal/mol), vastly outperforming natural acyl-homoserine lactone (AHL) autoinducers. Kinetic stability was validated through 5 ns vacuum molecular dynamics (MD), followed by 100 ns explicit solvent MD simulations in independent replicates. The trajectories confirmed remarkable positional retention of the ligand (Ligand RMSD ~ 0.08-0.16 nm) within the binding pocket. Rigorous MM/PBSA free energy calculations on the equilibrated trajectories yielded highly favorable binding free energies (ΔG ranging from - 19.90 to -30.11 kcal/mol), driven by massive enthalpic contributions (ΔH up to -34.20 kcal/mol) and a persistent network engaging 10 to 14 key interacting residues. Overall, these findings demonstrate that ketoprofen acts as a highly stable "molecular plug", effectively outcompeting endogenous AHL signals to lock the SmaR receptor in an inactive state. This highlights ketoprofen's immense potential as a repurposed antivirulence agent for combating biofilm-associated and multidrug-resistant Serratia infections.
Plastic has introduced a novel and persistent substrate into natural ecosystems, rapidly colonised by microbial biofilms collectively termed the plastisphere. Since its introduction, the concept has catalysed interdisciplinary research and shaped scientific and public discourse on plastic pollution. Yet, a central question remains unresolved: do plastisphere communities represent a fundamentally distinct ecological entity, or are they conventional biofilms forming on an unconventional material? Here, we synthesise current evidence across marine and terrestrial systems to argue that plastisphere communities are not consistently taxonomically or functionally unique. Instead, they largely reflect established biofilm assembly processes governed by environmental conditions, source communities, and successional dynamics. Claims of plastic biodegradation, pathogen enrichment, or antimicrobial resistance hotspots remain context-dependent and often lack robust comparative frameworks. We propose that the ecological significance of the plastisphere lies not in microbial novelty, but in the properties of the substrate itself. Plastics are uniquely persistent and, in many environments, highly mobile, enabling microbial communities to disperse across ecosystems and extend residence times beyond those of natural particles. By reframing the plastisphere as a condition of microbial life on durable, mobile substrates, we retain its conceptual value while aligning it with ecological theory and advancing a more precise research agenda.
Artificial synthesis of compounds to mimic the catalytic functions of natural enzymes and investigate their underlying mechanisms is challenging work. The development of glycoside hydrolase mimics encounters significant obstacles due to the complex stereochemistry and reaction mechanisms involved. Metal-organic frameworks (MOFs) have become promising candidates for artificial enzymes due to their ordered structure and ability to precisely control the active sites. Herein, a bimetallic MOF (CZPDC) containing bimetallic nodes is synthesized as an enzyme mimic to hydrolyze glycosidic molecules. X-ray absorption near-edge structure confirms the coexistence of Ce and Zr in the metal cluster nodes. DFT calculations reveal the unique adsorption behavior of CZPDC toward the negatively charged functional group connected to the C atom at the C2 position on the Ce site, thereby avoiding the stereoisomerism-induced selectivity between glycoside atoms and heteroatom carbons, making it suitable for the degradation of more complex polysaccharide systems. The catalytic behavior enables efficient hydrolysis of complex biological tissues containing multiple chemical bonds, disrupts bacterial biofilms, and kills internal bacteria. These characteristics endow CZPDC with strong potential for application in areas such as glycoside-catalyzed hydrolysis and bacterial biofilm removal.
This study aims to check how well three fluoride varnishes work. The varnishes are GC MI Varnish, Ultradent Enamelast, and Ivoclar Fluor Protector. They are tested to see if they can lower Streptococcus mutans levels in biofilm samples from children aged 6-10 years. A randomized controlled trial was conducted with 144 children divided into three groups. Samples of plaque were gathered initially and then again at intervals of 1, 3, and 6 months following the application of fluoride varnish. The levels of S. mutans were measured using culture methods and reported as colony-forming units per milliliter (CFU/mL). All three fluoride varnishes significantly reduced S. mutans counts over the 6-month period. GC MI Varnish showed the greatest reduction, particularly at 1 and 3 months (p < 0.0001 and p = 0.01, respectively). The mean CFU/mL for GC MI Varnish decreased from 7.64 ± 0.18 at baseline to 5.76 ± 2.05 at 6 months. Ultradent Enamelast and Fluor Protector S also demonstrated significant reductions but to a lesser extent than GC MI Varnish. GC MI Varnish containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) demonstrated superior antimicrobial efficacy against S. mutans compared to Ultradent Enamelast and Fluor Protector S. All three fluoride varnishes were effective in reducing S. mutans counts, with GC MI Varnish showing the most significant and consistent reductions over time. Baidya D, Pathivada L, Garg N, et al. Effect of Three Different Topical Fluoride Varnishes on Streptococcus mutans Count in Biofilm Samples of Children Aged 6-10 Years: A Randomized Controlled Trial. Int J Clin Pediatr Dent 2026;19(3):343-349.