Antibiofilm Effect Research Articles

Carbon-infiltrated carbon nanotubes inhibit the development of Staphylococcus aureus biofilms

Staphylococcus aureus forms biofilms that cause considerable morbidity and mortality in patients who receive implanted devices such as prosthetics or fixator pins. An ideal surface for such medical devices would inhibit biofilm growth. Recently, it was reported that surface modification of stainless steel materials with carbon-infiltrated carbon nanotubes (CICNT) inhibits the growth of S. aureus biofilms. The purpose of this study was to investigate this antimicrobial effect on titanium materials with CICNT coated surfaces in a variety of surface morphologies and across a broader spectrum of S. aureus isolates. Study samples of CICNT-coated titanium, and control samples of bare titanium, a common implant material, were exposed to S. aureus. Viable bacteria were removed from adhered biofilms and quantified as colony forming units. Scanning electron microscopy was used to qualitatively analyze biofilms both before and after removal of cells. The CICNT surface was found to have significantly fewer adherent bacteria than bare titanium control surfaces, both via colony forming unit and microscopic analyses. This effect was most pronounced on CICNT surfaces with an average nanotube diameter of 150 nm, showing a 2.5-fold reduction in adherent bacteria. Since S. aureus forms different biofilm structures by isolate and by growth conditions, we tested 7 total isolates and found a significant reduction in the biofilm load in six out of seven S. aureus isolates tested. To examine whether the anti-biofilm effect was due to the structure of the nanotubes, we generated an unstructured carbon surface. Significantly more bacteria adhered to a nonstructured carbon surface than to the 150 nm CICNT surface, suggesting that the topography of the nanotube structure itself has anti-biofilm properties. The CICNT surface possesses anti-biofilm properties that result in fewer adherent S. aureus bacteria. These anti-biofilm properties are consistent across multiple isolates of S. aureus and are affected by nanotube diameter. The experiments performed in this study suggest that this effect is due to the nanostructure of the CICNT surface.

Evaluation of the Antioxidant, Antimicrobial, and Anti-Biofilm Effects of the Stem Bark, Leaf, and Seed Extracts from Hymenaea courbaril and Characterization by UPLC-ESI-QTOF-MS/MS Analysis.

Currently, biofilm-forming bacteria are difficult to treat by conventional antibiotic therapy and are, thus, becoming a clinical and epidemiological problem worldwide. Medicinal plants have been identified as novel alternative treatments due to their therapeutic and antimicrobial effects. In this context, the present study aimed to determine the total phenolic content, antioxidant capacity, and antimicrobial and anti-biofilm potential of nine extracts of Hymenaea courbaril (Fabaceae), popularly known as Jatobá. Furthermore, extracts that exhibited biofilm inhibitory activity against S. aureus (ATCC 25923) were selected for UPLC-HRMS/MS chemical analysis. Our results showed a high total phenolic content, mainly in the stem bark extract, and that the plant is rich in compounds with antioxidant activity. In the anti-biofilm analysis, leaf extracts stood out in comparison with chloramphenicol, with inhibition percentages of 78.29% and 78.85%, respectively. Through chemical analysis by UPLC-HRMS/MS, chrysoeriol-7-O-neohesperidoside, isorhamnetin-3-O-glucoside, and 3,7-di-O-methylquercetin were annotated for the first time in the leaves of H. courbaril. Therefore, these results showed the potential use of H. courbaril as an antioxidant and point to its use in antimicrobial therapy with an anti-biofilm effect.

α-Mangostin and lawsone methyl ether in tooth gel synergistically increase its antimicrobial and antibiofilm formation effects in vitro

Objectivesα-Mangostin (α-MG) and lawsone methyl ether (LME) show antimicrobial and anti-biofilm activities. The objectives of this study were to develop a herbal tooth gel containing α-MG and LME plus fluoride and determine its antimicrobial, anti-biofilm formation, anti-cancer, anti-inflammatory, wound healing, and enamel microhardness effects.MethodsAntimicrobial assays against Streptococcus mutans, Porphyromonas gingivalis, and Candida albicans were performed. The microbes’ ultrastructural morphology was assessed using Transmission Electron Microscopy. The effect on microbial biofilm formation was tested by a broth microdilution. Cell viability was assessed with MTT assay. The anti-inflammatory effect was investigated by measuring inhibition of nitric oxide production. Enamel microhardness was measured via Vickers microhardness testing. The enamel chemical composition was investigated with Fourier Transform Spectrometer. The enamel surface morphology and fluoride content were examined by Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy.ResultsThe results show synergistic effects of α-MG and LME on antimicrobial activity and antibiofilm formation without cytotoxicity at a therapeutic dose. At a higher dose, the tooth gel inhibited proliferation of cancer cell line. Enamel microhardness was increased after brushing with the tooth gel plus fluoride. A large amount of fluoride was detected on the enamel surface.ConclusionThe tooth gel containing α-MG and LME synergized its antimicrobial activity and antibiofilm formation and inhibited oral cancer cell proliferation. Incorporating fluoride into the tooth gel increased enamel microhardness. Thus, the herbal tooth gel containing α-MG and LME plus fluoride may be useful for preventing dental caries and promoting oral health.

Reduction of Salmonella enterica & Staphylococcus aureus Biofilm Development on Glass Tube by Plant Extracts

The objective of the present study is to evaluate anti-biofilm effect of the water soluble plant extracts such Coccinia grandis, Terminalia arjuna, Centella asiatica against Salmonella enterica and Staphylococcus aureus biofilm. Crude water soluble extracts of respective plants with different concentration was evaluated against biofilm adopting glass tube. Then washed with crystal violet dye and PBS buffer for observing the ring formation. Biofilm inhibition study revealed water soluble plant extracts inhibited biofilm formation. In our experiment we found that the plant extracts Coccinia grandis, Terminalia arjuna & Centella asiatica gave excellent result for the reduction of biofilm of Salmonella enteric & Staphylococcus aureus. Water soluble Coccinia grandis extract is very effective for biofilm reduction than alcoholic C. grandis extracts. We measured the antiplantonic effect of these extracts by including the extracts into the nutrient agar media that containing respective organism by creating the hole into the plate then observed the result after 24-hour incubation. We also measured minimum inhibition concentration of these extracts through spectrophotometer with the help of the nutrient broth media. Bacterial motality was tested in petri plates with semi-solid medium (LB+0.4% agar) containing plant extracts and culture were inoculated in the center of the plate. This research will be very beneficial for us to reduce the pathogenic S, aureus & S. enterica biofilm by natural source especially plant extracts.

Selected flavonoids exhibit antibiofilm and antibacterial effects against Vibrio by disrupting membrane integrity, virulence and metabolic activities

Vibrio parahaemolyticus is a high-risk foodborne pathogen associated with raw or undercooked seafoods and its biofilm forming potential has become a threat to food safety and economic values. Hence, this study aims to examine the antibacterial and antibiofilm activities as well as virulence inhibitory effects of selected flavonoids against V. parahaemolyticus. Out of the sixteen flavonoid derivatives, 6-aminoflavone (6-AF), 3,2-dihydroxyflavone (3,2-DHF) and 2,2-dihydroxy-4-methoxybenzophenone (DHMB) were found as active biofilm inhibitors. 3,2-DHF and DHMB had minimum inhibitory concentrations of 20 and 50 μg/mL respectively against Vibrio planktonic cells and displayed superior antibacterial activities to standard controls. Also, they disrupted preformed biofilms and suppressed virulence properties including motilities, cell hydrophobicity and aggregation. They impaired iron acquisition mechanism and hemolysin production at sub-MICs as supported by transcriptomic studies. Interestingly, the flavonoids interfered with the metabolic activity, cell division and membrane permeability to exert antibiofilm and antibacterial activities. 6-AF and 3,2-DHF were non-toxic in the C. elegans model and showed excellent capacity to protect shrimps from biodeterioration. Furthermore, the flavonoids inhibited biofilm formation by V. harveyi, Staphylococcus aureus and Salmonella typhimurium and the mixed-species biofilm with Vibrio. This study discovered flavonoid derivatives, especially 3,2-DHF as potential bioactive compounds capable of offering protection from risks associated with biofilm formation by V. parahaemolyticus and other food pathogens.

Aqueous Extracts from Hemp Seeds as a New Weapon against Staphylococcus epidermidis Biofilms.

This study investigated the antibiofilm activity of water-soluble extracts obtained under different pH conditions from Cannabis sativa seeds and from previously defatted seeds. The chemical composition of the extracts, determined through GC-MS and NMR, revealed complex mixtures of fatty acids, monosaccharides, amino acids and glycerol in ratios depending on extraction pH. In particular, the extract obtained at pH 7 from defatted seeds (Ex7d) contained a larger variety of sugars compared to the others. Saturated and unsaturated fatty acids were found in all of the analysed extracts, but linoleic acid (C18:2) was detected only in the extracts obtained at pH 7 and pH 10. The extracts did not show cytotoxicity to HaCaT cells and significantly inhibited the formation of Staphylococcus epidermidis biofilms. The exception was the extract obtained at pH 10, which appeared to be less active. Ex7d showed the highest antibiofilm activity, i.e., around 90%. Ex7d was further fractionated by HPLC, and the antibiofilm activity of all fractions was evaluated. The 2D-NMR analysis highlighted that the most active fraction was largely composed of glycerolipids. This evidence suggested that these molecules are probably responsible for the observed antibiofilm effect but does not exclude a possible synergistic contribution by the other components.

Antifungal Activity and Type of Interaction of Melissa officinalis Essential Oil with Antimycotics against Biofilms of Multidrug-Resistant Candida Isolates from Vulvovaginal Mucosa.

(1) Background: Vulvovaginal candidosis (VVC) is a major therapy issue due to its high resistance rate and virulence factors such as the ability to form biofilms. The possibility of combining commonly used antifungals with natural products might greatly improve therapeutic success. (2) Methods: A total of 49 vulvovaginal isolates, causative agents of recurrent VVC, were tested for their susceptibility to fluconazole, nystatin, and Melissa officinalis essential oil (MOEO). This examination included testing the antibiofilm potential of antifungals and MOEO and the determination of their types of interaction with mature biofilms. (3) Results: Antimicrobial testing showed that 94.4% of the Candida albicans isolates and all the Candida krusei isolates were resistant to fluconazole, while all strains showed resistance to nystatin. The same strains were susceptible to MOEO in 0.156-2.5 mg/mL concentrations. Additionally, the results revealed very limited action of fluconazole, while nystatin and MOEO reduced the amount of biofilm formed by as much as 17.7% and 4.6%, respectively. Testing of the combined effect showed strain-specific synergistic action. Furthermore, the lower concentrations exhibited antagonistic effects even in cases where synergism was detected. (4) Conclusions: This study showed that MOEO had a very good antibiofilm effect. However, combining MOEO with antimycotics demonstrated that the type of action depended on the choice of antifungal drugs as well as the applied concentration.

Evaluation of anti-biofilm effect of antimicrobial sonodynamic therapy-based periodontal ligament stem cell-derived exosome-loaded kojic acid on Enterococcus faecalis biofilm.

Introduction. Antimicrobial sonodynamic therapy (aSDT) is an approach that uses ultrasound waves (UWs) and a sonosensitizer to generate reactive oxygen species (ROS) to damage microbial cells in biofilms. Using nano-carriers, such as exosomes (Exos), to deliver the sonosensitizer can potentially enhance the effectiveness of aSDT.Hypothesis/Gap Statement. aSDT can downregulate the expression of gelE and sprE genes, increasing the production of endogenous ROS and degradation of pre-formed Enterococcus faecalis biofilms.Aim. This study investigated the anti-biofilm effect of aSDT-based periodontal ligament stem cell-derived exosome-loaded kojic acid (KA@PDL-Exo) on pre-formed E. faecalis biofilms in root canals.Methodology. Following the isolation and characterization of PDL-Exo, KA@PDL-Exo was prepared and confirmed. The minimal biofilm inhibitory concentration (MBIC) of KA, PDL-Exo, KA@PDL-Exo and sodium hypochlorite (NaOCl) was determined, and their anti-biofilm effects were assessed with and without UWs. The binding affinity of KA with GelE and SprE proteins was evaluated using in silico molecular docking. Additionally, the study measured the generation of endogenous ROS and evaluated changes in the gene expression levels of gelE and sprE.Results. The results revealed a dose-dependent decrease in the viability of E. faecalis cells within biofilms. KA@PDL-Exo was the most effective, with an MBIC of 62.5 µg ml-1, while NaOCl, KA and PDL-Exo had MBIC values of 125, 250 and 500 µg ml-1, respectively. The use of KA@PDL-Exo-mediated aSDT resulted in a significant reduction of the E. faecalis biofilm (3.22±0.36 log10 c.f.u. ml-1; P<0.05). The molecular docking analysis revealed docking scores of -5.3 and -5.2 kcal mol-1 for GelE-KA an SprE-KA, respectively. The findings observed the most significant reduction in gene expression of gelE and sprE in the KA@PDL-Exo group, with a decrease of 7.9- and 9.3-fold, respectively, compared to the control group (P<0.05).Conclusion. The KA@PDL-Exo-mediated aSDT was able to significantly reduce the E. faecalis load in pre-formed biofilms, decrease the expression of gelE and srpE mRNA, and increase the generation of endogenous ROS. These findings imply that KA@PDL-Exo-mediated aSDT could be a promising anti-biofilm strategy that requires additional in vitro and in vivo investigations.

Blueberry extract inhibits quorum-sensing regulators and controls Vibrio parahaemolyticus biofilms and virulence

Anti-biofilm and anti-virulence effects of blueberry extract (BE) at sub-inhibitory of concentrations (SICs) against Vibrio parahaemolyticus were investigated in this study. When three V. parahaemolyticus strains were exposed to BE at 6.25 mg/mL and 9.38 mg/mL, swarming and twitching motility were suppressed by 40.4%–57.1% and 20.8%–39.1%, respectively. Hydrophobicity and auto-aggregation were decreased by 63.2%–94.5% and 43.8%–88.4%, respectively. The decrease in AI-2 production ranged from 24.8% to 76.8%. The biofilm formation index remained less than 0.64 after 24−72h incubation. Microscopic analyses further evidenced that the dense and thick biofilm architecture were significantly weaken. Meanwhile, BE differentially repressed the expression of the critical genes involved in flagellum (mshA), pili (oxyR), QS (aphA, opaR, and luxS), EPS (cpsA and cpsF), and T3SS (vcrD1, vopD1, and vopS). These results suggested that BE could suppress the motility and cellular surface properties by controlling QS regulators, which further inhibited biofilm formation of V. parahaemolyticus. Thus, BE may be a new alternative natural antibiofilm agent in the future.

Evaluation of the Antibacterial and Anti-Adherent Activities of Eucalyptus globulus and Eucalyptus citriodora Essential Oils against Pseudomonas aeruginosa Strains

Biofilm can be defined as a complex sessile microbiological ecosystem formed by one or more species of bacteria, fungi or protozoa. Among the microorganisms capable of forming biofilms is Pseudomonas aeruginosa, a gram-negative bacterium with extensive virulence factors and high resistance to antimicrobials, making it difficult to treat infections caused by it. In this sense, phytotherapy and essential oils are promising therapeutic alternatives to multi-resistant microorganisms. The aim of this study was to evaluate the antibacterial and anti-adherent activities of Eucalyptus globulus and Eucalyptus citriodora essential oils against clinical strains of P. aeruginosa, and to compare their antibiofilm effects with 0.12% chlorhexidine digluconate. To determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the oils, the broth microdilution technique was used in 96-well plates. To determine the Minimum Adherence Inhibitory Concentration (MAIC), the inclined glass tube technique was used in the presence of 5% sucrose, using proportions corresponding to the pure essential oil up to a dilution of 1:1024, and its positive control was 0.12% chlorhexidine digluconate. It was therefore concluded that the essential oils under study had an antibacterial effect against the strains tested, varying between bactericidal and bacteriostatic action, as well as demonstrating an effective anti-adherence effect that was superior to the positive control.

Potentiation of the antibiofilm effect of natural compound analogs in a marine bacterium by the cell permeabilization mechanism

The potentiation of the anti-adhesion and anti-biofilm effects of the three compounds (OB1, AS194, AS162) was evaluated in this study. This potentiation is demonstrated by the combination of each of the three compounds with molecules of permeabilizing types which are Polymyxin B nanopeptide hydrochloride (PMBN), Phenylalanine-Arginine Beta-Naphthylamide (PAßN) and Carbonyl cyanide chlorophenylhydrazone (CCCP). The association of this type of molecule with antibiofilm compounds showed a synergistic effect in TC14. This effect was more pronounced with CCCP (5µM). Thus, the AS162 having the highest effect between the three compounds previously induced a reduction in adhesion of up to 30.80% at only 10µM. In combination with the CCCP and at the same concentration, AS162 reduces TC14's adherence by up to 11.23%, a reduction of more than 63.53%. The AS162 also reduces the biofilm mass of the same bacterium to 10.15% in the presence of CCCP, i.e. a reduction of 89.75%. When taking the case of compounds with relatively low anti-biofilm effect such as OB1 and AS194, the reduction rate under the effect of the combinations is found to be higher than that of AS162. Thus, OB1 with an EC50 of 75.39 µM when used alone, in the presence of the CCCP, experiences a reduction of this EC50 up to 3.6 µM, i.e. 95.22% reduction. In AS194 (with a relatively stronger effect than OB1), the EC50 is reduced by 74.02% and 52.79% for AS162. This method has been shown to be effective in enhancing the anti-biofilm effect of the compounds. It is therefore important to note that the less active the compound, the greater the synergistic effect with the permeabilizers.

Biofilm formation of C. albicans on occlusal device materials and antibiofilm effects of chitosan and eugenol

Microbial adhesion on occlusal devices may lead to oral diseases such as candidiasis. Whether chitosan and eugenol provide antibiofilm effects is unclear. The purpose of this in vitro study was to evaluate the biofilm formation of C. albicans strains on occlusal device materials and the antibiofilm effects of chitosan and eugenol against C. albicans on these surfaces. A total of 88 specimens (5×10×2mm) were produced from occlusal device materials with 4 production techniques: vacuum-formed thermoplastic (Group V), head-press (Group H), computer-aided design and computer-aided manufacture (CAD-CAM) (Group C), and 3-dimensionally (3D) printed (Group D) (n=22). After various finishing procedures, the surface properties of the specimens were evaluated by using surface free energy (SFE), surface roughness (SR) measurements, and elemental and topographic analysis. Biofilm formation of C. albicans strain and the antibiofilm effects of chitosan and eugenol against biofilm formation on these surfaces were also examined with a crystal violet assay. The distribution's normality was statistically analyzed with the Kolmogorov-Smirnov test. One-way and two-way analysis of variance with post hoc Tukey tests were used for statistical evaluations (α=.05). Surface roughness values in Groups D and H were significantly higher than in other groups (P<.05). While the highest surface free energy values (except γp) were in Group V, Group C had the highest γp. The lowest biofilm value appeared in Group H. Chitosan exhibited an antibiofilm effect in all groups except Group H, while eugenol was effective in all groups. The production method affected the susceptibility of occlusal device materials to the adhesion of C. albicans. Eugenol was an effective antibiofilm agent for device materials.

Antibacterial, bacteriolytic, antibiofilm, and synergistic effects of the peel oils of Citrus microcarpa and Citrus x amblycarpa with tetracycline against foodborne Escherichia coli.

Citrus essential oils (EOs) have shown significant antibacterial activity. The present study was undertaken to evaluate the antibacterial activity of the peel oils of Citrus microcarpa and C. x amblycarpa against Escherichia coli. The minimum inhibition concentration (MIC) was determined by using the broth microdilution assay. The checkerboard method was used to identify synergistic effects of the EOs with tetracycline, while bacteriolysis was assessed by calculating the optical density of the bacterial supernatant, crystal violet assay was used to assess their antibiofilm. Ethidium bromide accumulation test was employed to assess efflux pump inhibition. Electron microscope analysis was performed to observe its morphological changes. The EOs of C. microcarpa and C. x amblycarpa were found to contain D-limonene major compound at 55.78% and 46.7%, respectively. Citrus microcarpa EOs exhibited moderate antibacterial against E. coli with a MIC value of 200 μg/mL. The combination of C. microcarpa oil (7.8 μg/mL) and tetracycline (62.5 μg/mL) exhibited a synergy with FICI of 0.5. This combination inhibited biofilm formation and disrupt bacterial cell membranes. Citrus microcarpa EOs blocked the efflux pumps in E. coli. Citrus microcarpa EOs demonstrated promising antibacterial activity, which can be further explored for the development of drugs to combat E. coli.

Antibacterial and antibiofilm effects of gold and silver nanoparticles against the uropathogenic &lt;i&gt;Escherichia coli&lt;/i&gt; by scanning electron microscopy (SEM) analysis

Uropathogenic Escherichia coli (UPEC) is a nosocomial pathogen associated with urinary tract infections and biofilm formation, which contributes to antibiotic resistance. Discovering potent antibacterial agents is crucial. This study aimed to assess the antibacterial and antibiofilm effects of gold and silver nanoparticles on UPEC using Scanning Electron Microscopy (SEM). UPEC biofilms were cultivated on nitrocellulose membranes for 48 hours at 37°C, then treated with gold nanoparticles (50 ppm and 100 ppm) and silver nanoparticles (50 ppm and 100 ppm) for another 48 hours. Antibacterial and antibiofilm activities were evaluated through cell density and SEM analysis. SEM revealed lower cell density, reduced biofilm formation, and altered cell morphology with rough, wrinkled surfaces after nanoparticle treatment. In conclusion, gold and silver nanoparticles exhibit antibacterial and antibiofilm properties, as observed in SEM analysis. SEM is a valuable tool for studying the antimicrobial effects of nano gold and silver on bacterial cell morphology and biofilm populations.

Inhibition of the Biofilm Formation of Anaerobic Bacteria Involved in Secondary Caries by Dental Adhesive

Secondary caries is a type of carious lesion found at the margins of or next to an existing restoration after the filling has been used for a period of time. It generally arises from the formation of defects or cracks in the filling material after restoration. This can create gaps between the material and the tooth tissue, which will allow bacteria in the biofilm to enter the interface. Dental adhesives are commonly used to provide retention for composite cement or filling materials. A good adhesive should be able to prevent leakage along the restoration margin as well as resist the mechanical load of chewing pressure. Recently, the inclusion of calcium in the adhesive monomer has been produced as Bio-Coat Ca, and its antimicrobial property against some oral bacteria has been studied. No information was found on anaerobes. The aim of this study was to evaluate the antimicrobial potential of dental adhesive on the biofilm formation of anaerobic bacteria involved in secondary caries. An adhesive containing CMET (calcium salt of 4-methacryloxyethyl trimellitic acid) and 10-methacryloyloxydecyl dihydrogen calcium phosphate (MDCP) (Bio-Coat Ca, Sun Medical, Moriyama, Shiga, Japan) was applied to the flat-bottom surface of the saliva-coated 96-well plate. Then it was polymerized with LED light at 460 nm and sterile with UV light. Porphyromonas gingivalis ATCC 33277, Prevotella intermedia ATCC 25611, and Fusobacterium nucleatum ATCC 25586 were prepared as a suspension of approximately 1 × 108 CFU/mL and added to the well. The plate was left for 120 min at 37°C in a shaking incubator (120 r/min) to allow bacterial adhesion. After removing non-adherent cells, Schaedler broth was added and further incubated for 48-72 h to grow the biofilm. The culture medium was changed every 24 h. A biofilm formed on a 96-well plate surface without the adhesive was set up as a control. The amount of vital biofilm was assessed by the WST Microbial Cell Counting Kit (Dojindo Molecular Technologies, USA). All tests were triplicated performed and repeated three times. As a statistical analysis, the Mann-Whitney U test was applied. The results showed that dental adhesive exhibited significant anti-biofilm formation of P. gingivalis and F. nucleatum at a percent inhibition of 56% and 46%, respectively. On the other hand, no significant effect was found on P. intermedia. This was similar to our previous report on bacteria associated with primary caries, which revealed that the anti-biofilm effect of Bio-Coat Ca adhesive on Streptococcus mutans was 65% while no significant suppressive action was observed Lactobacillus casei and Actinomyces viscosus. The inhibitory effect of the adhesive was proposed to be the acidic characteristic of the monomers. This newly developed adhesive could be a promising material for the prevention of secondary caries. However, this study was done on the single-species biofilm formation in vitro and conducted in a short time. Long-term clinical studies are needed to evaluate the effect on the patients.

A novel antibacterial and anti-biofilm material: Biosynthetic silver nanoparticles mediated by extract from Oplopanax elatus adventitious roots

The search for plant resources involved in the biosynthesis of silver nanoparticles (AgNPs) is crucial for the diversity of AgNP materials. Oplopanax elatus is a valuable medicinal shrub and its adventitious root (AR) culture is a modern method for producing the raw material. To explore an efficient biosynthetic AgNPs, this study synthesized AgNPs using O. elatus AR extract (OE-AgNPs) and the characterization of OE-AgNPs was performed. Finally, the antibacterial and anti-biofilm effects of OE-AgNPs were investigated. The result showed that OE-AgNPs had an obvious absorption peak of nanosilver with a spherical shape and a silver-like face-centered cubic structure, which the OE-AgNPs were capped by compounds with aliphatic amine, amide, carbonyl, and hydroxyl groups of O. elatus AR extract, indicating a successful synthesis of OE-AgNPs. The 10–40 nm particles were the most abundant in the OE-AgNPs, accounting for 70%. OE-AgNPs had the strongest antibacterial activity against Escherichia coli and Pseudomonas aeruginosa among six bacterial species tested, with a minimum inhibitory concentration (MIC) of 0.75 μg/mL, and the cell contents of E. coli and P. aeruginosa leaked out by OE-AgNP treatment, and bacterial respiration was inhibited. After OE-AgNP treatment, biofilms of E. coli and P. aeruginosa were efficiently scavenged with a scavenging rate of more than 60%; the extracellular polysaccharide concentrations in biofilms were also ruduced. The findings of this study suggested that OE-AgNPs could be used as a potential antibacterial and antibiofilm substance to apply in the product production and indicated the feasibility of expanding the application of O. elatus ARs.

Antibacterial, antibiofilm, and antivirulence effects of nanoparticles synthesized from Colletotrichum gloeosporioides in pathogenic E.coli

Antimicrobial resistance is a global problem and antibiotics are becoming ineffective due to the resistance developed by bacteria. In this current research, silver nanoparticles were synthesized from aqueous extract of endophytic fungi Colletotrichum gloeosporioides (CgAgNPs) and characterized by various methods. CgAgNPs efficacy was analyzed by performing antimicrobial assays in Escherichia coli ATCC 25922 and antibiotic resistant pathogenic strains. Upon treatment with CgAgNPs biofilm formation was reduced in all E.coli strains. In vitro cytotoxicity assays revealed that CgAgNPs were able to increase the membrane permeability and induced leakage of sugars and proteins. CgAgNPs induced oxidative stress in E. coli strains led to lipid peroxidation and release of malonaldehyde. The CgAgNPs were able to modulate the anti-oxidant system of cells hence there was a reduction in Glutathione reductase, Catalase and Superoxide dismutase enzymes activities. Analysis of expression of gene encoding CTX-M-15 showed the down regulation upon treatment with ampicillin and CgAgNPs. Overall, the results suggest that CgAgNPs control growth, biofilm formation in E. coli through induction of oxidative stress, interference with antioxidant enzymes, cell content leakage and finally downregulating the virulence gene by interfering with transcription and translation in E. coli. In future, CgAgNPs can be incorporated in formulations to break antibiotic resistance in antibiotic resistant pathogenic E. coli.

Chemical Composition, Antibacterial Properties, and Anti-Enzymatic Effects of Eucalyptus Essential Oils Sourced from Tunisia.

This study was conducted to examine the chemical composition of the essential oils (EOs) from six Tunisian Eucalyptus species and to evaluate their anti-enzymatic and antibiofilm activities. The EOs were obtained through hydro-distillation of dried leaves and subsequently analyzed using GC/MS. The main class of compounds was constituted by oxygenated monoterpenes, particularly prominent in E. brevifolia (75.7%), E. lehmannii (72.8%), and E. woollsiana (67%). Anti-enzymatic activities against cholinesterases, α-amylase, and α-glucosidase were evaluated using spectrophotometric methods. Notably, the E. brevifolia, E. extensa, E. leptophylla, E. patellaris, and E. woollsiana EOs displayed potent acetylcholinesterase (AChE) inhibition (IC50: 0.25-0.60 mg/mL), with E. lehmannii exhibiting lower activity (IC50: 1.2 mg/mL). E. leptophylla and E. brevifolia showed remarkable α-amylase inhibition (IC50: 0.88 mg/mL), while E. brevifolia and E. leptophylla significantly hindered α-glucosidase (IC50 < 30 mg/mL), distinguishing them from other EOs with limited effects. Additionally, the EOs were assessed for their anti-biofilm properties of Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative (Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli) bacterial strains. The E. extensa EO demonstrated the main antibiofilm effect against E. coli and L. monocytogenes with an inhibition > 80% at 10 mg/mL. These findings could represent a basis for possible further use of Eucalyptus EOs in the treatment of human microbial infections and/or as a coadjutant in preventing and treating Alzheimer's disease and/or diabetes mellitus.

Novel Remineralizing and Antibiofilm Low-Shrinkage-Stress Nanocomposites to Inhibit Salivary Biofilms and Protect Tooth Structures.

Recurrent caries remain a persistent concern, often linked to microleakage and a lack of bioactivity in contemporary dental composites. Our study aims to address this issue by developing a low-shrinkage-stress nanocomposite with antibiofilm and remineralization capabilities, thus countering the progression of recurrent caries. In the present study, we formulated low-shrinkage-stress nanocomposites by combining triethylene glycol divinylbenzyl ether and urethane dimethacrylate, incorporating dimethylaminododecyl methacrylate (DMADDM), along with nanoparticles of calcium fluoride (nCaF2) and nanoparticles of amorphous calcium phosphate (NACP). The biofilm viability, biofilm metabolic activity, lactic acid production, and ion release were evaluated. The novel formulations containing 3% DMADDM exhibited a potent antibiofilm activity, exhibiting a 4-log reduction in the human salivary biofilm CFUs compared to controls (p < 0.001). Additionally, significant reductions were observed in biofilm biomass and lactic acid (p < 0.05). By integrating both 10% NACP and 10% nCaF2 into one formulation, efficient ion release was achieved, yielding concentrations of 3.02 ± 0.21 mmol/L for Ca, 0.5 ± 0.05 mmol/L for P, and 0.37 ± 0.01 mmol/L for F ions. The innovative mixture of DMADDM, NACP, and nCaF2 displayed strong antibiofilm effects on salivary biofilm while concomitantly releasing a significant amount of remineralizing ions. This nanocomposite is a promising dental material with antibiofilm and remineralization capacities, with the potential to reduce polymerization-related microleakage and recurrent caries.

Potential of Marine Strains of Pseudoalteromonas to Improve Resistance of Juvenile Sea Bass to Pathogens and Limit Biofilm Development.

The European sea bass (Dicentrarchus labrax), one of the most produced marine fish species in Europe, is acutely vulnerable to multiple infectious hazards. In this study, we investigated the potential probiotic effect of some marine Pseudoalteromonas bacterial strains against two major pathogens of this species, Vibrio harveyi and the nervous necrosis virus (NNV), and examined their antibiofilm effect. Impregnation phase was done by repeated immersion of juvenile's sea bass during 8 to 12weeks in seawater containing the probiotic candidates at a concentration of 106CFU/mL. Four candidates were tested: (1) a combination of two strains producing antimicrobial compounds, hCg-42 and hOe-125; (2) strain 3J6, with known antibiofilm properties; (3) strain RA15, from the same genus, but with no identified probiotic effect; and (4) a control group without probiotics. At the end of the impregnation phase, fish underwent an infection challenge with V. harveyi or with a pathogenic strain of NNV and mortality was monitored. For the V. harveyi challenge, improved survival rates of 10 and 25% were obtained for the RA15 and the mix hCg-42 + hOe-125-impregnated groups, respectively. For the NNV challenge, no significant benefic effect of the probiotics on infection kinetics or cumulative mortality was observed. At the end of the impregnation phase, the maximal thickness of biofilm was significantly lower in the 3J6, double strain, and RA15 groups, compared with the non-impregnated control group. This study highlights the interesting probiotic potential of marine bacteria to limit mortalities induced by bacterial pathogens as well as biofilm development.