Biofouling最新文献

Enterobacter hormaechei and Klebsiella pneumoniae, key members of the ESKAPE group of hospital-acquired pathogens, are driving forces behind numerous infections due to their potent biofilm formation and the growing threat of antimicrobial resistance. Ferulic acid (FA) is known for its strong antioxidant properties and is recognized for its numerous physiological benefits, including anti-inflammatory, antimicrobial, anticancer, and antidiabetic effects. The current investigation delves into the antimicrobial and antibiofilm ability of FA against E. hormaechei and K. pneumoniae. Using different assays, we confirmed that FA inhibits the biofilm formation of these pathogens. Through computational studies involving molecular docking and molecular dynamics simulations, it was found that FA exhibits a strong affinity for binding with MrkB in E. hormaechei and MrkH in K. pneumoniae, crucial proteins involved in biofilm formation. We hypothesise that FA might interfere with adhesion-associated molecules and inhibit biofilms through the c-di-GMP pathway and proves as an effective antibiofilm compound.

Biofilms are bacterial communities encapsulated in a self-produced extracellular polymeric matrix comprising carbohydrates, proteins, lipids, and DNA. This matrix provides structural integrity while significantly enhancing bacterial antibiotic resistance, presenting substantial disinfection challenges. The persistence of biofilm-associated infections and foodborne outbreaks underscores the need for more effective disinfection strategies. Conventional antibacterial agents often are less effective against biofilm-protected cells compared to their efficacy against planktonic (non-attached) bacteria. Integrating hydrolytic enzymes, such as cellulases, proteases, and DNases, into disinfection protocols offers a promising approach by breaking down the biofilm matrix to expose the bacteria. However, the follow-up use of antibacterial agents is important, as enzymes alone do not possess bactericidal properties. Unlike traditional disinfectants, natural antibacterial agents work synergistically with enzymes, enhancing biofilm disruption without compromising the enzymatic activity through oxidation. This review offers a comprehensive analysis of the current knowledge and potential of combining hydrolytic enzymes with disinfectants to disrupt biofilms and eradicate the released bacterial cells, emphasizing applications for clinical and foodborne pathogens.

In this study, we evaluated the impact of Epigalocatechin-3-gallate (EGCG) on S. mutans biofilm development for 24 and 46 h using high-resolution confocal laser scanning microscopy. EGCG treatment led to the formation of interspaced exopolysaccharide (EPS)-microcolony complexes unevenly distributed on the surface of hydroxyapatite disc, forming a thinner and less complex biofilm structure with significantly reduced biomass, matrix volume, and thickness compared to the NaCl treated group (negative control). At 46 h, the biofilm of the EGCG-treatment group failed to form the bacterial-EPS superstructures which is characteristic of the biofilm in the negative control group. EGCG treatment seems to significantly delay biofilm development, with the 46 h biofilm in the EGCG treatment group resembling the negative control group at 24 h. EGCG topical treatments impaired S. mutans biofilm initial growth and maturation, suggesting its potential to be used as a preventive agent against dental caries.

Soft corals produce a diverse range of natural products with pharmaceutical potential, such as antiproliferative and anti-inflammatory effects. The Alcyoniidae family, particularly the genera Sarcophyton and Sinularia, is rich in bioactive terpenoids. However, despite extensive research, their anti-biofouling properties against the mussel Mytilus galloprovincialis remain underexplored. This study investigates these compounds as potential eco-friendly antifouling agents. A new cembrane-type diterpenoid, 11,12-epoxycembrene A (1), and 15 known compounds were isolated from three soft corals distributed in Okinawa, Japan. The chemical structures of these secondary metabolites were elucidated based on spectroscopic analysis. Moreover, an anti-biofouling assay of potential anti-biofouling agents against M. galloprovincialis was performed and their toxicities were assessed by means of the brine shrimp mortality test. In conclusion, this study identifies new and known bioactive compounds from soft corals, introduces an improved anti-biofouling assay, and highlights the potential of dimethylamine-containing diterpenes as environmentally friendly antifouling agents.

This study hypothesizes that eugenol, due to its structural properties, can inhibit glucosyltransferase activity, thereby reducing polysaccharide synthesis in Salmonella Typhimurium biofilms. It was found that eugenol exhibited minimum inhibitory and bactericidal concentrations of 0.6 mg mL^-1 and 0.8 mg mL^-1, respectively, against planktonic S. Typhimurium growth. It also demonstrated minimum biofilm eradication and inhibition concentrations of 1.8 mg mL^-1 and 0.7 mg mL^-1, respectively. At 0.3 mg mL^-1, eugenol reduced biofilm formation and affected polysaccharide production. Moreover, eugenol reduced glucosyltransferase activity. Computational analysis indicated strong interactions between eugenol and the enzyme's active site residues with affinity energy -8.5 kcal mol^-1. Real-time PCR revealed a significant increase in bcsA gene expression in the presence of eugenol. These findings suggest that eugenol's ability to inhibit glucosyltransferase activity effectively reduces biofilm formation and polysaccharide content.

Chromobacterium violaceum is a pathogenic bacterium that can infect humans and animals, yet the role of its outer membrane vesicles (OMVs) in mediating pathogenicity remains underexplored. This study evaluated the effects of linoleic acid (LA) and stearic acid (SA) on quorum sensing (QS)-mediated violacein production, biofilm formation, and OMV biogenesis in C. violaceum. Our findings revealed that 2 mM LA and 1 mM SA effectively quench QS, leading to a significant reduction in violacein production, biofilm formation, and OMV biogenesis. Gene expression analysis confirmed the downregulation of QS-related genes, including cviI, cviR, vioA, vioB, and vioC, in fatty acid-treated C. violaceum. Additionally, we assessed the antimicrobial activity of C. violaceum-derived OMVs on Rhizobium sp., a PGPR and observed a marked reduction in bactericidal activity in the treated OMVs. This study suggests that LA and SA have potential as anti-infective agents to mitigate OMV-mediated virulence and combat antibiotic resistance in pathogens.

The goal of this study was to evaluate if a magnetic water treatment device could be used to mitigate biofilms in water systems. Magnetic treatment was applied to water upstream of a modified Robbins device in which Pseudomonas fluorescence biofilms were formed. Duration of magnetic treatment, system flow rate, and field strength were varied to assess the impacts on the biofilm. A control system was concurrently established in which no magnetic treatment was applied. After treatment, the number of viable cells in the biofilm was reduced by up to 2.46 log₁₀ CFU cm^-2 depending on the operational conditions. Increased cell stress, and ultimately death, was observed during treatment as indicated by an elevated AMPi stress index. These results indicate that magnetic water treatment may be an effective technology to decrease the extent of biofilms in water systems and a reduced need for chemical treatment. A mechanism is proposed in which metabolic processes are hindered due to the magnetic field effects on ions in the water. However, a mechanistic investigation remains outside the scope of this study. Future studies should aim to characterize both the impacts of treatment on the matrix and cellular processes to determine a mechanism for the observed effects.

Compared to antimicrobial agents, anti-adhesive surfaces can reduce bacteria adhesion and biofilm formation in catheters, providing better selectivity, efficiency, and device life span. In this research, novel anionic surface biomaterials were created and tested to reduce microbial adhesion and colonization in medical device coating. Maleic anhydride (MA) was polymerized with 2-HEMA in varying amounts to produce a p(HEMA-co-MA) hydrogel copolymer. Fourier transforms infrared characterization (ATR-FTIR), thermal analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, swelling capacity, cytotoxicity evaluation, and mixed biofilm formation ability were used to characterize the copolymer hydrogels. Hydrogels were evaluated by considering the guidance and regulations of ISO and ASTM standards. The polymers were dense, had stable cross-linking between both monomers, were non-toxic to the Human Embryonic Kidney (HEK) 293 cell line, and reduced bacterial biofilm formation statistically significantly. Furthermore, increasing the amount of MA affected TGF-1 gene expression, where the gene expression was significantly elevated, especially at the highest percentage of MA. Furthermore, the high percentage of MA in the polymer improved the new polymer's thermal properties, film flexibility, and swelling capacity. These novel polymers could be promising materials for improving catheter biomaterial properties and modifying the surfaces of designated devices to reduce microbial infections and growth.

The efficacy of Zerumbone (ZER) against mixed biofilms of fluconazole-resistant Candida albicans (ATCC 96901) and Streptococcus mutans (UA159) was evaluated. Biofilms were cultivated on acrylic resin specimens for 48 h, with alternating supplementation of glucose and sucrose. ZER's ability to inhibit biofilm formation (pre-treatment) and eradicate mature biofilms (post-treatment) was assessed. Control groups were treated with Chlorhexidine (CHX), Nystatin (NYS), Penicillin (ATB), and distilled water. The efficacy was measured by colony forming units (CFU/mm²) counts, biomass and biofilm's matrix components quantification (water-soluble polysaccharides [WSP], alkali-soluble polysaccharides [ASPs], proteins, and extracellular DNA [eDNA]). Data were analyzed by one-way ANOVA with Tukey's or Gammes-Howell post-hoc test for normal data and Kruskal-Wallis test for data that did not meet the assumption of normality (α = 0,05). In the biofilm inhibition assay, ZER decreased total microbiota (C. albicans + S. mutans) (2.7 log₁₀; p < 0.005), C. albicans (1.4 log₁₀; p < 0.038) and S. mutans (1.9 log₁₀; p < 0.048) counting (vs control group), and biofilm components [insoluble proteins: 37% (p < 0.001); WSP: 13% (p < 0.042); ASP: 46% (p < 0.001); eDNA: 11% (p < 0.048)]. Post-treatment with ZER reduced total microbiota (3.2 log₁₀; p < 0.001), C. albicans (3 log₁₀; p < 0.001) and S. mutans (2 log₁₀; p < 0.001) counting (vs control group), and biofilm components [soluble proteins: 20% (p < 0.001); WSP: 20% (p < 0.001); ASP: 51% (p < 0.001); and eDNA: 33% (p < 0.001)]. The positive control groups demonstrated similar or lower efficacy than ZER under all experimental conditions. ZER demonstrates efficacy against mixed biofilms by reducing C. albicans and S. mutans counting and disrupting the extracellular matrix in both assays.

Burkholderia pseudomallei biofilm is a significant virulence factor in infection. This study aimed to investigate antibacterial and antibiofilm activities of Piper betle extract against B. pseudomallei. The MIC and MBC values of the extract against the isolates were 0.5-1.0 mg/mL. At 2 × MIC, the cells showed cell shrinkage and abnormalities. At 1/2 × MIC, the extract displayed 40-71% inhibition of biofilm formation. At 8 × MIC, the extract reduced the viability of mature biofilms by 60-86%. Hydroxychavicol and eugenol, the main compounds in the extract, showed binding activity to CdpA, an enzyme implicated in biofilms as observed by in silico studies. Hydroxychavicol exhibited the highest affinity for CdpA, with a distance of 2.27 Å. Molecular dynamics simulations revealed that hydroxychavicol forms a stable complex with cyclic di-GMP phosphodiesterase, maintaining protein structural integrity with minimal conformational changes. The results suggested that Piper betle may have medicinal benefits by inhibiting biofilm-related infections.