This study aimed to systematically evaluate the antibiofilm efficacy of curcumin-mediated antimicrobial photodynamic therapy (aPDT) activated by 450 nm LED light against biofilm formation and mature biofilms of clinically relevant Candida species, with particular emphasis on preventive potential and species-dependent susceptibility; Biofilm formation and maturation were investigated in five standard Candida strains. Biofilm formation (preventive approach) and established biofilms were treated with curcumin followed by irradiation with 450 nm LED light. Biofilm biomass was quantitatively assessed using the crystal violet assay. Comparative analyses were performed to determine species-dependent responses to aPDT. Data normality was assessed using the Shapiro-Wilk test, and intergroup comparisons were performed using the Kruskal-Wallis test followed by Dunn's post hoc test when appropriate. All Candida strains demonstrated a pronounced ability to form biofilms, being classified as strong biofilm producers, except Candida dubliniensis, which exhibited moderate biofilm formation. Curcumin-mediated aPDT significantly inhibited biofilm development across all tested species (p < 0.05), achieving reductions of 86.82% for C. metapsilosis, 85.05% for C. orthopsilosis, 83.33% for C. parapsilosis, 75.34% for C. dubliniensis, and 68.19% for C. albicans. This preventive antibiofilm effect is likely associated with reactive oxygen species generation, resulting in oxidative damage to essential cellular structures and impairment of early extracellular matrix establishment. In contrast, aPDT activity against mature biofilms was significantly attenuated and highly species-dependent, with reductions ranging from 49.63% (C. parapsilosis) to 0.64% (C. dubliniensis); however, these reductions were not statistically significant (p > 0.05). Curcumin-mediated aPDT exerted a significant preventive antibiofilm effect against Candida biofilm formation but showed limited and non-significant activity against mature biofilms. These findings position curcumin-mediated aPDT as a promising strategy for preventing Candida biofilm establishment, while indicating that improved photosensitizer delivery and optimized irradiation protocols are required to enhance activity against established biofilms.
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.
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.
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.
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.
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.
Biofilm formation and antibiotic tolerance are major contributors to the persistence of Staphylococcus aureus infections, yet how the host environment affects these phenotypes remains poorly understood. Here, we show that incubation in human serum primes S. aureus to form robust biofilms and tolerate vancomycin and daptomycin, last resort antibiotics for the treatment of antibiotic-resistant staphylococcal infections. Mechanistically, we demonstrate that the staphylococcal Geh lipase is essential for serum-induced biofilm formation by liberating glycerol from host lipids, which is then used to promote increased synthesis of D-alanylated wall teichoic acids, driving biofilm development. Inhibition of the Geh lipase or wall teichoic acid synthesis markedly reduces biofilm formation and restores antibiotic susceptibility, highlighting clinically achievable strategies to inhibit host-induced biofilm formation and prevent the associated antibiotic tolerance. Together, our findings reveal a host-driven mechanism of biofilm-associated antibiotic tolerance in S. aureus and provide rational targets for therapeutic intervention.
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.
Biofilm formation in marine Streptomyces is a dynamic yet poorly understood process, that limits their functional exploitation. This study investigated the biofilm development and extracellular polymeric substances (EPS) synthesis by Streptomyces nigra strain KDS4, a promising marine Actinobacterium, aiming to optimize EPS yield and characterize its bio-functional properties. Biofilm and EPS formation began with spore germination and hyphal growth, maturing by 60 h with dense hyphal intertwining, sporulation, and EPS secretion, followed by dispersal at 84 h. The bacterium showed the highest biofilm height (~ 2.35 μm) over the polypropylene substrate. Upregulated expression of the cslA gene, associated with biofilm matrix production, was confirmed during biofilm development. Structural analysis of EPS revealed α- and β-glycosidic linkages, hydroxyl, and alkyne groups, along with an amorphous morphology and diverse elemental composition. EPS exhibited thermal transition up to 300 °C and antioxidant and emulsifying properties. Notably, EPS demonstrated hydrogel-forming capability, with 5% (wt/wt) EPS-based hydrogel exhibiting rapid gelation (73 s), high porosity and pore size (31.66 μm), excellent swelling (53.54%), and strong viscoelasticity (G' > G''). At 20% (wt/wt) EPS, the hydrogel achieved a compressive strength of 36.83 kPa, demonstrating its mechanical robustness. These findings highlight S. nigra strain KDS4 as a promising source of multifunctional EPS for sustainable environmental and biomedical applications. While the study provides detailed in vitro insights, evaluation of EPS functionality and biocompatibility remain to be explored. Future work should focus on scale-up production, structural-functional correlations, and validation of EPS-based hydrogels in environmental remediation and biomedical models.
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.
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.
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.
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.
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.
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.
The diminishing efficacy of gentamicin against methicillin-resistant Staphylococcus aureus (MRSA) necessitates novel adjuvant strategies, prompting our investigation into repurposing the calcium channel blocker nifedipine. Here, we demonstrate that a sub-inhibitory concentration of nifedipine synergizes with gentamicin against MRSA T144, achieving rapid bactericidal killing within 2 hours. Mechanistic studies reveal that nifedipine functions as a bacterial ion modulator, inhibiting Ca2+/Cl- influx and increasing membrane fluidity, which leads to membrane hyperpolarization, cytoplasmic acidification, and a significant enhancement of gentamicin uptake. Furthermore, nifedipine exhibits direct anti-virulence activity by enhancing membrane permeability, suppressing amyloid fibril formation, and potently inhibiting biofilm development. Collectively, our findings highlights the promising potential of nifedipine as a repurposed adjuvant against resilient MRSA infections.
Candida albicans adhesion and biofilm formation on prosthetic surfaces drive denture-associated candidiasis and are unaffected by traditional fungicidal treatments. Pre-emptive prevention of fungal attachment to prosthetic devices is a rational strategy to avoid recurrent infections. We utilized a mechanism-based computational pipeline to screen peptides with activity centred on inhibiting fungal adhesion instead of viability. We chose two colonization-relevant targets: agglutinin-like protein 3 (Als3), involved in surface attachment, and 1,3-β-glucan synthase (GS), involved in glucan-dependent biofilm-support processes. Peptides were ranked using protein-peptide docking, 100-ns molecular dynamics simulations, and MM/PBSA binding free energy calculations to determine metrics of interface coverage, interaction persistence, and dynamic energetic favourability. We found that tachystatin consistently and stably occupied the highest proportion of adhesion-related interfaces on both Als3 and GS. Tachystatin dynamics demonstrated lower residue-level fluctuations in functionally relevant residues and preservation of hydrogen bonds throughout the simulation. MM/PBSA assessments revealed favourable and consistent binding energetics facilitated by van der Waals forces. These findings suggest that the peptide may comparatively maintain interface occupancy consistent with a potential steric hindrance effect at adhesion-relevant regions. The selected control peptides failed to occupy the predicted interfaces and demonstrated inadequate stabilities. Targeting Als3-mediated adhesion together with GS-associated biofilm-support processes represent a promising preventive strategy for denture-associated candidiasis. Tachystatin emerged as the most promising peptide within this comparative computational screen and may warrant further evaluation as a candidate for reducing biofilm formation on dental prosthetics Overall, this interaction- and simulation-based framework may support antimicrobial peptide selection focused on biofilm prevention.