Biofilm Biomass Research Articles

Impairment of Listeria monocytogenes biofilm developed on industrial surfaces by Latilactobacillus curvatus CRL1579 bacteriocin

The effect of lactocin AL705, bacteriocin produced by Latilactobacillus (Lat.) curvatus CRL1579 against Listeria biofilms on stainless steel (SS) and polytetrafluoroethylene (PTFE) coupons at 10 °C was investigated. L. monocytogenes FBUNT showed the greatest adhesion on both surfaces associated to the hydrophobicity of cell surface. Partially purified bacteriocin (800 UA/mL) effectively inhibited L. monocytogenes preformed biofilm through displacement strategy, reducing the pathogen by 5.54 ± 0.26 and 4.74 ± 0.05 log cycles at 3 and 6 days, respectively. The bacteriocin-producer decreased the pathogen biofilm by ∼2.84 log cycles. Control and Bac− treated samples reached cell counts of 7.05 ± 0.18 and 6.79 ± 0.06 log CFU/cm2 after 6 days of incubation. Confocal scanning laser microscopy (CLSM) allowed visualizing the inhibitory effect of lactocin AL705 on L. monocytogenes preformed biofilms under static and hydrodynamic flow conditions. A greater effect of the bacteriocin was found at 3 days independently of the surface matrix and pathogen growth conditions at 10 °C. As a more realistic approach, biofilm displacement strategy under continuous flow conditions showed a significant loss of biomass, mean thickness and substratum coverage of pathogen biofilm. These findings highlight the anti-biofilm capacity of lactocin AL705 and their potential application in food industries.

Salt stress responses of microalgae biofilm communities under controlled microcosm conditions

Algal biofilms play an essential role in ecosystem functioning, but their physiological and biochemical changes during salt stress remain poorly understood. This study aimed at investigating how biofilm communities react to different salinity in a microcosm experiment and to offer insights into the potential effects of future freshwater salinization. Biofilm samples collected from Iriri River (Drâa basin, Southern Morocco) were exposed to water gradually enriched with sodium chloride to obtain three final concentrations (1, 10, and 30 g/L) over 14 days, and the changes were compared with control. Several biofilm responses were analyzed throughout the experiment, including biofilm biomass, changes in community structure and composition via eDNA metabarcoding, physiological feedback, biochemical parameters, antioxidant activities, non-enzymatic salt stress markers, osmoprotection indicators, and nitrogen assimilation. High salt concentrations significantly altered biofilm communities' composition, structure, and function, leading to an overall decrease in alpha diversity and a decrease in diatom and cyanobacterial biomass, while green algae remained unchanged. Chlorophyll a content increased in biofilm exposed to low salt concentration (1 g/L) and decreased at high salt concentrations while carotenoid significantly increased even at high salinity (10 g/L). Biofilm also showed an increase in carbohydrates and a decrease in protein content under high salinities (10 and 30 g/L). In addition, salt stress-induced ROS generation in the biofilm, with an increase in H2O2 content, caused oxidative damage and lipid peroxidation with an increase in MDA levels. To prevent this damage, elevated proline content was recorded, and additionally, the biofilm exhibited antioxidant defense mechanisms by rising activity of ROS-scavenger enzymes such as SOD, CAT, and POD. Our experimental results highlighted the salinity effect on algal biofilm as well as physiological and biochemical responses. This study could help predict the consequences of freshwater salinization on river biofilms and its potential impact at the ecosystem level.

Lytic activity of phages against bacterial pathogens infecting diabetic foot ulcers

Complications of diabetes, such as diabetic foot ulcers (DFUs), are common, multifactorial in origin, and costly to treat. DFUs are the cause of nearly 90% of limb amputations among persons with diabetes. In most chronic infections such as DFU, biofilms are involved. Bacteria in biofilms are 100–1000 times more resistant to antibiotics than their planktonic counterparts. Multidrug-resistant (MDR) Staphylococcus aureus and Pseudomonas aeruginosa infections in DFUs may require alternative therapeutic agents such as bacteriophages ("phages"). This study describes the lytic activity of phage cocktails AB-SA01 (3-phage cocktail) and AB-PA01 (4-phage cocktail), which target S. aureus and P. aeruginosa, respectively. The host range and lytic effect of AB-SA01 and AB-PA01 on a planktonic culture, single-species biofilm, and mixed-species biofilm were evaluated. In vitro testing showed that 88.7% of S. aureus and 92.7% of P. aeruginosa isolates were susceptible to AB-SA01 and AB-PA01, respectively, in the planktonic state. The component phages of AB-SA01 and AB-PA01 infected 66% to 94.3% of the bacterial isolates tested. Furthermore, AB-SA01 and AB-PA01 treatment significantly (p < 0.05) reduced the biofilm biomass of their hosts, regardless of the antibiotic-resistant characteristics of the isolates and the presence of a non-susceptible host. In conclusion, the strong lytic activity, broad host range, and significant biofilm biomass reduction of AB-SA01 and AB-PA01 suggest the considerable potential of phages in treating antibiotic-resistant S. aureus and P. aeruginosa infections alone or as coinfections in DFUs.

Benzalkonium chloride disinfectant residues stimulate biofilm formation and increase survival of Vibrio bacterial pathogens.

Vibrio spp. are opportunistic human and animal pathogens found ubiquitously in marine environments. Globally, there is a predicted rise in the prevalence of Vibrio spp. due to increasing ocean temperatures, which carries significant implications for public health and the seafood industry. Consequently, there is an urgent need for enhanced strategies to control Vibrio spp. and prevent contamination, particularly in aquaculture and seafood processing facilities. Presently, these industries employ various disinfectants, including benzalkonium chloride (BAC), as part of their management strategies. While higher concentrations of BAC may be effective against these pathogens, inadequate rinsing post-disinfection could result in residual concentrations of BAC in the surrounding environment. This study aimed to investigate the adaptation and survival of Vibrio spp. exposed to varying concentrations of BAC residues. Results revealed that Vibrio bacteria, when exposed, exhibited a phenotypic adaptation characterized by an increase in biofilm biomass. Importantly, this effect was found to be strain-specific rather than species-specific. Exposure to BAC residues induced physiological changes in Vibrio biofilms, leading to an increase in the number of injured and alive cells within the biofilm. The exact nature of the "injured" bacteria remains unclear, but it is postulated that BAC might heighten the risk of viable but non-culturable (VBNC) bacteria development. These VBNC bacteria pose a significant threat, especially since they cannot be detected using the standard culture-based methods commonly employed for microbiological risk assessment in aquaculture and seafood industries. The undetected presence of VBNC bacteria could result in recurrent contamination events and subsequent disease outbreaks. This study provides evidence regarding the role of c-di-GMP signaling pathways in Vibrio adaptation mechanisms and suggests that c-di-GMP mediated repression is a potential avenue for further research. The findings underscore that the misuse and overuse of BAC may increase the risk of biofilm development and bacterial survival within the seafood processing chain.

Antibacterial, antibiofilm, and anticancer activity of silver-nanoparticles synthesized from the cell-filtrate of Streptomyces enissocaesilis

Silver nanoparticles (Ag-NPs) have a unique mode of action as antibacterial agents in addition to their anticancer and antioxidant properties. In this study, microbial nanotechnology is employed to synthesize Ag-NPs using the cell filtrate of Streptomyces enissocaesilis BS1. The synthesized Ag-NPs are confirmed by ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Also, the effects of different factors on Ag-NPs synthesis were evaluated to set the optimum synthesis conditions. Also, the antibacterial, antibiofilm, and anticancer activity of Ag-NPs was assessed. The X-ray diffraction (XRD) analysis confirmed the crystalline nature of the sample and validated that the crystal structure under consideration is a face-centered cubic (FCC) pattern. The TEM examination displayed the spherical particles of the Ag-NPs and their average size, which is 32.2 nm. Fourier transform infrared spectroscopy (FTIR) revealed significant changes in functionality after silver nanoparticle dispersion, which could be attributed to the potency of the cell filtrate of Streptomyces enissocaesilis BS1 to act as both a reducing agent and a capping agent. The bioactivity tests showed that our synthesized Ag-NPs exhibited remarkable antibacterial activity against different pathogenic strains. Also, when the preformed biofilms of Pseudomonas aeruginosa ATCC 9027, Salmonella typhi ATCC 12023, Escherichia coli ATCC 8739, and Staphylococcus aureus ATCC 6598 were exposed to Ag NPs 50 mg/ml for 24 hours, the biofilm biomass was reduced by 10.7, 34.6, 34.75, and 39.08%, respectively. Furthermore, the Ag-NPs showed in vitro cancer-specific sensitivity against human breast cancer MCF-7 cell lines and colon cancer cell line Caco-2, and the IC50 was 0.160 mg/mL and 0.156 mg/mL, respectively. The results of this study prove the ease and efficiency of the synthesis of Ag-NPs using actinomycetes and demonstrate the significant potential of these Ag-NPs as anticancer and antibacterial agents.

Human saliva modifies growth, biofilm architecture, and competitive behaviors of oral streptococci.

Dental caries (tooth decay) is the most prevalent disease for both children and adults nationwide. Caries are initiated from demineralization of the enamel due to organic acid production through the metabolic activity of oral bacteria growing in biofilm communities attached to the tooth's surface. Mutans group streptococci are closely associated with caries development and initiation of the cariogenic cycle, which decreases the amount of acid-sensitive, health-associated commensal bacteria while selecting for aciduric and acidogenic species that then further drives the disease process. Defining the exchanges that occur between mutans group streptococci and oral commensals in a condition that closely mimics their natural environment is of critical need toward identifying factors that can influence odontopathogen establishment, persistence, and outgrowth. The goal of our research is to develop strategies, potentially through manipulation of microbial interactions characterized here, that prevent the emergence of mutans group streptococci while keeping the protective flora intact.

Outbreak of Pseudomonas aeruginosa High-Risk Clone ST309 Serotype O11 Featuring blaPER-1 and qnrVC6.

Pseudomonas aeruginosa is a leading cause of hospital-acquired infections worldwide. Biofilm production, antibiotic resistance, and a wide range of virulence factors contribute to their persistence in nosocomial environments. We describe an outbreak caused by a multidrug-resistant P. aeruginosa strain in an ICU. Antibiotic susceptibility was determined and blaPER-1 and qnrVC were amplified via PCR. Clonality was determined using PFGE and biofilm formation was studied with a static model. A combination of antibiotics was assessed on both planktonic cells and biofilms. WGS was performed on five isolates. All isolates were clonally related, resistant to ceftazidime, cefepime, amikacin, and ceftolozane-tazobactam, and harbored blaPER-1; 11/19 possessed qnrVC. Meropenem and ciprofloxacin reduced the biofilm biomass; however, the response to antibiotic combinations with rifampicin was different between planktonic cells and biofilms. WGS revealed that the isolates belonged to ST309 and serotype O11. blaPER-1 and qnrVC6 were associated with a tandem of ISCR1 as part of a complex class one integron, with aac(6')-Il and ltrA as gene cassettes. The structure was associated upstream and downstream with Tn4662 and flanked by direct repeats, suggesting its horizontal mobilization capability as a composite transposon. ST309 is considered an emerging high-risk clone that should be monitored in the Americas.

Repurposing DNase I and alginate lyase to degrade the biofilm matrix of dual-species biofilms of Staphylococcus aureus and Pseudomonas aeruginosa grown in artificial sputum medium: In-vitro assessment of their activity in combination with broad-spectrum antibiotics

BackgroundBiofilm-associated pulmonary infections pose therapeutic challenges in cystic fibrosis patients, especially when involving multiple bacterial species. Enzymatic degradation of the biofilm matrix may offer a potential solution to enhance antibiotic efficacy. This study investigated the repurposing of DNase I, commonly used for its mucolytic activity in cystic fibrosis, to target extracellular DNA within biofilms, as well as potential synergies with alginate lyase and broad-spectrum antibiotics in dual-species biofilms of Pseudomonas aeruginosa and Staphylococcus aureus. MethodsDual-species biofilms were grown in artificial sputum medium using S. aureus and P. aeruginosa isolated by pairs from the same patients and exposed to various combinations of enzymes, meropenem, or tobramycin. Activity was assessed by measuring biofilm biomass and viable counts. Matrix degradation and decrease in bacterial load were visualized using confocal microscopy. Biofilm viscoelasticity was estimated by rheology. ResultsNearly complete destruction of the biofilms was achieved only if combining the enzymatic cocktail with the two antibiotics, and if using supratherapeutic levels of DNase I and high concentrations of alginate lyase. Biofilms containing non-pigmented mucoid P. aeruginosa required higher antibiotic concentrations, despite low viscoelasticity. In contrast, for biofilms with pigmented mucoid P. aeruginosa, a correlation was observed between the efficacy of different treatments and the reduction they caused in elasticity and viscosity of the biofilm. ConclusionsIn this complex, highly drug-tolerant biofilm model, enzymes prove useful adjuvants to enhance antibiotic activity. However, the necessity for high enzyme concentrations emphasizes the need for thorough concentration-response evaluations and safety assessments before considering clinical applications.

Isolation of Biofilm Removing Bacteriophages from the Hot Spring of Mae Chan Fault, Chiang Rai, Northern Thailand

T errestrial hot springs offer unique habitats for various bacteriophages, revealing potential reservoirs and a library for antibiotic-resistant and biofilm-removing bacteriophages. This study aimed to identify biofilm-removing bacteriophages as a potential method to eradicate antibiotic-resistant bacteria. Samples were collected from the Mae Chan Fault geothermal sites in Chiang Rai province, north of Thailand. Our bacteriophages, HSPT1 and HSPT2, effectively infect Pseudomonas aeruginosa TISTR1287, as measured by their plaque sizes (3.23 ± 0.26 mm) and (1.14 ± 0.18 mm), respectively. Thermostability analysis reveals that the optimal temperature for bacteriophage HSPT1 is between 20 and 60 oC, while for bacteriophage HSPT2, it is between 20 and 40 oC. Biofilm biomass was significantly reduced by the bacteriophages HSPT1 and HSPT2 treatments (1.42 ± 0.81 and 2.51 ± 0.71, respectively). The study reveals that hot spring bacteriophages effectively remove bacterial biofilms, proving their potential as a new treatment option for antibiotic-resistant bacteria in clinical and tourism settings. These bacteriophages, derived from hot springs, have effectively reduced biofilm-forming microorganisms and multidrug-resistant pathogenic bacteria.

What Is the Impact of Antimicrobial Photodynamic Therapy on Oral Candidiasis? An In Vitro Study.

This study aimed to evaluate the ability of photodynamic therapy, based on the use of a gel containing 5% delta aminolaevulinic acid (ALAD) for 45' followed by irradiation with 630 nm LED (PDT) for 7', to eradicate Candida albicans strains without damaging the gingiva. C. albicans oral strains and gingival fibroblasts (hGFs) were used to achieve these goals. The potential antifungal effects on a clinical resistant C. albicans S5 strain were evaluated in terms of biofilm biomass, colony forming units (CFU/mL) count, cell viability by live/dead analysis, and fluidity membrane changes. Concerning the hGFs, viability assays, morphological analysis (optical, scanning electronic (SEM), and confocal laser scanning (CLSM) microscopes), and assays for reactive oxygen species (ROS) and collagen production were performed. ALAD-mediated aPDT (ALAD-aPDT) treatment showed significant anti-biofilm activity against C. albicans S5, as confirmed by a reduction in both the biofilm biomass and CFUs/mL. The cell viability was strongly affected by the treatment, while on the contrary, the fluidity of the membrane remained unchanged. The results for the hGFs showed an absence of cytotoxicity and no morphological differences in cells subjected to ALAD-aPDT expected for CLSM results that exhibited an increase in the thickening of actin filaments. ROS production was augmented only at 0 h and 3 h, while the collagen appeared enhanced 7 days after the treatment.

Adsorption of antibiotics on microplastics (MPs) in aqueous environments: The impacts of aging and biofilms

Microplastics (MPs) that accumulate in natural water bodies through various pathways inevitably undergo aging and biofilm attachment. These variations can alter the physicochemical properties of the MPs and thus affect their abilities to adsorb other pollutants. In this study, we chose virgin polyethylene (V-PE) as the experimental MP and generated aged, biofilm-developed and biofilm-developed with aged polyethylene (A-PE, B-PE and B-A-PE) via Fenton advanced oxidation and lake water incubation methods. Then, the adsorption of tetracycline hydrochloride (TC-HCl) and cefalexin (CFX) on V-PE, A-PE, B-PE and B-A-PE was investigated. The results showed that the capacities for adsorption of TC-HCl or CFX on the four polyethylene MPs (PEMPs) increased in the order V-PE < A-PE < B-PE < B-A-PE. The order was attributed to differences in the surface roughnesses, crystallinities, surface functional groups and biofilm biomass of the four PEMPs. Kinetic experiments and isotherms indicated that nonlinear multilayer adsorption occurred via physicochemical actions, such as diffusion, hydrophobic interactions, hydrogen bonding interactions, electrostatic interactions and biodegradation. Specifically, the adsorption of TC-HCl or CFX by V-PE and A-PE was predominantly controlled by diffusion, whereas B-PE and B-A-PE were chemically active. In addition, it is worth noting that biofilms may shield antibiotics from electrostatic interactions with the B-PE and B-A-PE surfaces, and an increase in ionic strength inhibited the adsorption of TC-HCl and CFX by the four PEMPs. Our study provides an important reference for determining the adsorption of antibiotics by MPs in natural waters.

Combination antimicrobial therapy: in vitro synergistic effect of anti-staphylococcal drug oxacillin with antimicrobial peptide nisin against Staphylococcus epidermidis clinical isolates and Staphylococcus aureus biofilms

The ability of Staphylococcus epidermidis and S. aureus to form strong biofilm on plastic devices makes them the major pathogens associated with device-related infections (DRIs). Biofilm-embedded bacteria are more resistant to antibiotics, making biofilm infections very difficult to effectively treat. Here, we evaluate the in vitro activities of anti-staphylococcal drug oxacillin and antimicrobial peptide nisin, alone and in combination, against methicillin-resistant S. epidermidis (MRSE) clinical isolates and the methicillin-resistant S. aureus ATCC 43,300. The minimum inhibitory concentrations (MIC) and minimum biofilm eradication concentrations (MBEC) of oxacillin and nisin were determined using the microbroth dilution method. The anti-biofilm activities of oxacillin and nisin, alone or in combination, were evaluated. In addition, the effects of antimicrobial agents on the expression of icaA gene were examined by quantitative real-time PCR. MIC values for oxacillin and nisin ranged 4–8 µg/mL and 64–128 µg/mL, respectively. Oxacillin and nisin reduced biofilm biomass in all bacteria in a dose-dependent manner and this inhibitory effect was enhanced with combinatorial treatment. MBEC ranges for oxacillin and nisin were 2048–8192 µg/mL and 2048–4096 µg/mL, respectively. The addition of nisin significantly decreased the oxacillin MBECs from 8- to 32-fold in all bacteria. At the 1× MIC and 1/2× MIC, both oxacillin and nisin decreased significantly the expression of icaA gene in comparison with untreated control. When two antimicrobial agents were combined at 1/2× MIC concentration, the expression of icaA were significantly lower than when were used alone. Nisin/conventional oxacillin combination showed considerable anti-biofilm effects, including inhibition of biofilm formation, eradication of mature biofilm, and down-regulation of biofilm-related genes, proposing its applications for treating or preventing staphylococcal biofilm-associated infections, including device-related infections.

Biofilm busters: Exploring the antimicrobial and antibiofilm properties of essential oils against Salmonella Enteritidis.

This study delves into an exploration of the antimicrobial and antibiofilm properties of the essential oils (EOs) of cinnamon, garlic, and onion on Salmonella Enteritidis. Firstly, disc diffusion and minimum inhibitory concentration (MIC) techniques were employed to assess the antibacterial activity of the EOs. Additionally, the study explored the effect of these EOs on both initial cell attachment and 24 h-preformed biofilms. The crystal violet assay was implemented to evaluate biofilm biomass. The findings revealed that cinnamon EO exhibited the highest anti-biofilm activity. Furthermore, initial cell attachment inhibition at MIC ranged between 50 and 65% for the three oils, while inhibition rates on preformed structures were lower than 40% for all EOs at this MIC concentration. The study also found that the effects of these oils were dosage- and time-dependent (p < 0.05), thereby urging the adoption of these natural extracts as effective strategies for combating Salmonella biofilms.

The effects of photoactivated ciprofloxacin and bile acids on biofilms on bile duct catheters

ObjectivesThis study examined the potential of a novel photoactivatable ciprofloxacin to act against bacterial infections and microbiomes related to biliary diseases. It also evaluated treatment by combining the impact of bile acids and antibiotics on biofilms. Innovative strategies were evaluated to address the elusive bile duct microbiome resulting in biofilm-related infections linked to biliary catheters. The healthy biliary system is considered sterile, but bile microbiomes can occur in disease, and these correlate with hepatobiliary diseases. Causes include biofilms that form on internal-external biliary drainage catheters. These biliary catheters were used to noninvasively study the otherwise elusive bile microbiome for a pilot study. MethodsA new photoactivatable antibiotic was tested for efficacy against human-derived pathogenic bacterial isolates – Salmonella enterica and Escherichia coli – and catheter-derived bile duct microbiomes. In addition, the effect of bile acids on the antibiotic treatment of biofilms was quantified using crystal violet staining, confocal laser scanning microscopy, and biofilm image analysis. Two novel approaches for targeting biliary biofilms were tested. ResultsA photoactivated antibiotic based on ciprofloxacin showed efficacy in preventing biofilm formation and reducing bacterial viability without harming eukaryotic cells. Furthermore, combination treatment of antibiotics with bile acids, such as ursodesoxycholic acid, mildly influenced biofilm biomass but reduced bacterial survival within biofilms. ConclusionBile acids, in addition to their endocrine and paracrine functions, may enhance antibiotic killing of bacterial biofilms compared with antibiotics alone. These approaches hold promise for treating biliary infections such as cholangitis.

In vitro effects of selective serotonin reuptake inhibitors on Cryptococcus gattii capsule and biofilm.

Infections caused by Cryptococcus gattii mainly affect immunocompetent individuals and the treatment presents important limitations. This study aimed to validate the efficacy of selective serotonin reuptake inhibitors (SSRI), fluoxetine hydrochloride (FLH), and paroxetine hydrochloride (PAH) in vitro against C. gattii. The antifungal activity of SSRI using the microdilution method revealed a minimal inhibitory concentration (MIC) of 31.25µg/ml. The combination of FLH or PAH with amphotericin B (AmB) was analyzed using the checkerboard assay and the synergistic effect of SSRI in combination with AmB was able to reduce the SSRI or AmB MIC values 4-8-fold. When examining the effect of SSRI on the induced capsules, we observed that FLH and PAH significantly decreased the size of C. gattii capsules. In addition, the effects of FLH and PAH were evaluated in biofilm biomass and viability. The SSRI were able to reduce biofilm biomass and biofilm viability. In conclusion, our results indicate the use of FLH and PAH exhibited in vitro anticryptococcal activity, representing a possible future alternative for the cryptococcosis treatment.

Saliva biofilm-derived outer membrane vesicles regulate biofilm formation and immune response of oral epithelial cells on titanium surfaces.

While the significant roles of outer membrane vesicles (OMVs) from individual oral bacterial species in bacterial-host interactions are known, the involvement of saliva biofilm-derived OMVs in peri-implant disease pathogenesis remains unclear. This study aimed to investigate the effect of saliva biofilm-derived OMVs on regulating saliva biofilm formation and modulating the immune response of the epithelial cells on titanium surfaces. Saliva derivedbiofilms were cultured on tissue culture plates (TCP) for 4 days using pooled saliva from four healthy donors. OMVs secreted from the TCP bound biofilm (referred to as OMVs or healthy saliva biofilm OMVs) were enriched using the size-exclusion chromatography method. We then evaluated the effects of these OMVs on theviability, metabolic activity, and the presence oforal pathogens in saliva biofilm grownon titanium discs for 24 h and 72 h. Furthermore, the impact of OMVs on the mRNA expression and inflammatory cytokines [interleukin (IL)-6, IL-1α, and monocyte chemoattractant protein-1 (MCP-1)] in human oral epithelial cells (OKF6/TERT-2) was investigated using RT-qPCR and enzyme-linked immunosorbent assay(ELISA), respectively. Healthy saliva biofilm OMVs improved the biomass and activity of saliva biofilm cultured on the titanium surfaces, with inhibited Porphyromonas gingivalis and Fusobacterium nucleatum, and enhanced Streptococcus mutansexpression. Additionally, OMVs increased pro-inflammatory cytokine IL-6 mRNA and IL-6cytokine expression in human oral epithelial cells. However, IL-1α and MCP-1 cytokines were inhibited 24-hour post-incubation with OMVs. Healthy saliva biofilm derivedOMVs regulate the activity and pathogen composition of biofilms formed on titanium, while modulating the secretion of pro-inflammation factors of oral epithelial cells grownon titanium surfaces. Healthy saliva biofilm OMVs may regulate the early biofilm formation on abutment surfaces and modulate epithelial cell immune response, which may alter the peri-implant niche and participate in the pathogenesis of peri-implant disease.

Effects of large dams on the aquatic food web along a coastal stream with high sediment loads

The contribution of two basal energy sources – detrital organic matter and primary producers – as part of aquatic food webs varies typically along river continua. A host of barriers to river flow increase the water residence time and sediment and nutrient retention in reservoirs worldwide, and potentially alter the balance between detritus-based and algae-based energy pathways in the downstream food webs. We explored this issue on the Sélune River (Normandy, France), a small coastal stream that drains an agricultural catchment with high sediment runoff. Seasonal measurements of the following parameters were compared upstream and downstream of the reservoirs of two large dams (16 m and 36 m high): sediment fluxes, nutrient and chlorophyll a concentrations, algal communities in the epilithic biofilm (taxonomic composition, biomass and growth), and benthic invertebrate communities (abundance and trophic guild structure). As anticipated, annual sediment fluxes were much lower downstream of the reservoirs, where significant decreases in water turbidity, phosphate and silicate concentrations were recorded. A higher chlorophyll a concentration in water and a higher contribution of pelagic algae taxa to the photosynthetic biofilm suggested drifting and deposition of reservoir-borne phytoplankton downriver. Photosynthetic biofilm growth was higher downstream of the reservoirs in spring and fall, and so was the abundance of herbivores in the invertebrate community, notably scrapers and algae eaters. Energy pathways within riverine food webs were traced using stable isotope analyses of carbon (C) and nitrogen in the tissues of aquatic consumers (invertebrates and fish). Mixing models revealed a discontinuity in the origin of the C entering the food webs along the river continuum, confirming a greater contribution of algal C to aquatic consumers downstream of the reservoirs. These results illustrate mechanisms whereby large reservoirs can modulate C flow in food webs along a small coastal river with high sediment loads, and make it possible to anticipate the effects of dam removal on the future river ecosystem.

Biofouling on titanium implants: a novel formulation of poloxamer and peroxide for in situ removal of pellicle and multi-species oral biofilm.

Eradicating biofouling from implant surfaces is essential in treating peri-implant infections, as it directly addresses the microbial source for infection and inflammation around dental implants. This controlled laboratory study examines the effectiveness of the four commercially available debridement solutions '(EDTA (Prefgel®), NaOCl (Perisolv®), H2O2 (Sigma-Aldrich) and Chlorhexidine (GUM® Paroex®))' in removing the acquired pellicle, preventing pellicle re-formation and removing of a multi-species oral biofilm growing on a titanium implant surface, and compare the results with the effect of a novel formulation of a peroxide-activated 'Poloxamer gel (Nubone® Clean)'. Evaluation of pellicle removal and re-formation was conducted using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy to assess the surface morphology, elemental composition and chemical surface composition. Hydrophilicity was assessed through contact angle measurements. The multi-species biofilm model included Streptococcus oralis, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans, reflecting the natural oral microbiome's complexity. Biofilm biomass was quantified using safranin staining, biofilm viability was evaluated using confocal laser scanning microscopy, and SEM was used for morphological analyses of the biofilm. Results indicated that while no single agent completely eradicated the biofilm, the 'Poloxamer gel' activated with 'H2O2' exhibited promising results. It minimized re-contamination of the pellicle by significantly lowering the contact angle, indicating enhanced hydrophilicity. This combination also showed a notable reduction in carbon contaminants, suggesting the effective removal of organic residues from the titanium surface, in addition to effectively reducing viable bacterial counts. In conclusion, the 'Poloxamer gel + H2O2' combination emerged as a promising chemical decontamination strategy for peri-implant diseases. It underlines the importance of tailoring treatment methods to the unique microbial challenges in peri-implant diseases and the necessity of combining chemical decontaminating strategies with established mechanical cleaning procedures for optimal management of peri-implant diseases.

Cepacian degrading Cytobacillus sp. strain Dbc1 with anti-biofilm activity potentiating antibiotic efficacy against Burkholderia cepacia biofilm development

Aim: Inhibition of biofilm formation in Burkholderia cepacia through enzymatic degradation of predominant exopolysaccharide (cepacian) of B. cepacia. Methodology: Cepacian was extracted from B. cepacia followed by isolation and identification of potent cepacian utilizing bacteria based on planktonic growth using cepacian as sole carbon source. Effective lyase activity (responsible for cepacian breakdown) and anti-biofilm activity of potent isolate against B. cepacia was determined. Effect of biofilm disintegration on antibiotic penetration into biofilm was detected. Lastly, inhibition of biofilm formation by crude lyase preparation of the isolate inside an external medical device was detected. Results: Cytobacillus sp. strain Dbc1 was the most potent cepacian degrading bacteria which showed significant lyase activity and reduced total biomass of both newly formed and pre-formed biofilm of B. cepacia. Cepacian degradation potentiated chloramphenicol penetration within pre-formed biofilm leading to cell mortality in B. cepacia. Cytobacillus sp. strain Dbc1significantly reduced total biomass of established biofilm inside nasal oxygen catheter. Interpretation: It can be concluded that Cytobacillus sp. strain Dbc1 significantly controlled mature B. cepacia biofilm through potent cepacian degrading and anti-biofilm activity along with better antibiotic targeting into established biofilm. Strain Dbc1 can be used to inhibit medical device- associated biofilms in vitro. Key words: Antibiotic susceptibility, Biofilm inhibition, Burkholderia cepacia, Cepacian breakdown, Multi-drug resistance

Phyllosphere bacteria with antiquorum sensing and antibiofilm activities against fish pathogenic bacteria

ObjectiveThis research aims to quantify antiquorum sensing and antibiofilm activity of f phyllosphere bacteria against biofilm formed by pathogenic fish bacteria such as Aeromonas hydrophila, Streptococcus agalactiae, and Vibrio harveyi.ResultsAntiquorum sensing assay using Chromobacter violaceum as indicator bacteria and antibiofilm assay showed six phyllosphere bacteria have antiquorum sensing and antibiofilm activities against tested bacteria. The highest inhibition and destruction activity was showed by metabolite of JB 3B and EJB 5 F against A. hydrophila, respectively. Determination using light microscope and scanning electron microscope performed decreaing in biomass of biofilm observed after treated with metabolite from phyllosphere bacteria.