Biofouling最新文献

The efficacy of carbon dioxide (CO₂) to reduce biofouling by quagga mussels (Dreissena rostriformis bugensis) in raw water systems was investigated. Experiments were conducted in a mobile laboratory located at Bureau of Reclamation Davis Dam Hydropower Facility and supplied with raw water from Lake Mohave, a reservoir of the Colorado River, USA. Incoming water was split between five chambers, each infused with CO₂ at a different rate. Raw reservoir water containing quagga larvae (veligers) was mixed with CO₂ chamber outflows and delivered to tanks containing settlement plates. Two experiments were conducted. Experiment 1 tested continuous infusion at target concentrations of 30, 45, 60, 75, and 100 mg L^-1 dCO₂ (dissolved CO₂). Experiment 2 evaluated intermittent infusion schedules: 24 h on/off with 50, 75, and 100 mg L^-1 dCO₂ and 24 h once/week with 100 mg L^-1 dCO₂. In Experiment 1, the percent settlement decreased with mean CO₂ concentration, ranging from 5.0% to < 0.1% in 28.7 and 92.2 mg L^-1 dCO₂, respectively. In Experiment 2, the efficacy of 24 h on/off at dCO₂ > 72.2 mg L^-1 was similar to continuous treatment. The least effective treatment was 24 h once weekly at 95 mg L^-1 dCO₂. These results demonstrate that CO₂ treatment may reduce mussel biofouling in raw water systems.

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.

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.

Histoplasmosis, caused by Histoplasma capsulatum, poses risks for immunocompromised individuals. With limited therapeutic options, this study explores microparticles as antimicrobial delivery systems for Cymbopogon flexuosus and Pelargonium graveolens essential oils against H. capsulatum. The broth microdilution assay showed MICs of 32 to 128 µg/mL in filamentous phase and 8 to 64 µg/mL in yeast phase. Combining microparticles with antifungal drugs demonstrated synergistic effects in both filamentous and yeast-like forms with amphotericin B or itraconazole. Chitosan microparticles reduced H. capsulatum biofilm biomass and metabolic activity by about 60% at 512 µg/mL. In vivo evaluation with Caenorhabditis elegans showed H. capsulatum caused over 90% mortality. These findings highlight the potential use of chitosan microparticles as a delivery system for essential oils against H. capsulatum, especially in combination with other compounds.

The dairy industry faces challenges in controlling spoilage microorganisms, particularly Pseudomonas, known to form resilient biofilms. Conventional disinfection methods have limitations, prompting the exploration of eco-friendly alternatives like ozone. This study focused on Pseudomonas biofilms on polystyrene and polyethylene surfaces, evaluating ozone efficacy when incorporated into different water sources and applied under static and dynamic conditions. Biofilm formation and removal were assessed with conventional microbiological and microscopic techniques. Despite variations in physicochemical properties, ozonized water from different sources showed similar effectiveness in removing Pseudomonas biofilms. Dynamic ozone application was more efficient, achieving a 2.35 log CFU/coupon reduction on polyethylene surfaces, compared to a 1.05 log CFU/coupon reduction under static conditions. These findings highlight the potential of ozonized water for removing Pseudomonas biofilms, especially under dynamic application. This eco-friendly approach could serve as an effective strategy to mitigate biofilm-related challenges in the dairy industry.

Biofilms are a virulence factor for Candida albicans, a common pathogen in human fungal infections, making them resistant to many commercial antifungals. Therefore, the discovery of compounds that inhibit and eradicate biofilms is a priority. As thiosemicarbazones have had their effect on Candida biofilms little explored, this study investigated the inhibitory and eradication activity of 30 thiosemicarbazones and analogues against C. albicans biofilms. After initial screening, four compounds were selected and compound 28 emerged as the most potent with BIC₅₀ at 31.55 ± 1.18 µM. By scanning electron microscopy analysis, blastoconidia adhered to the reduced surface and reduced formation of pseudohyphae and hyphae was revealed. Despite the inhibitory activity, the four compounds failed to eradicate the biofilm by more than 50%. Thus, the results suggest that the compounds evaluated are very promising for the development of effective antibiofilm compounds and open up new perspectives for elucidating the mechanism of action.

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.

Infections caused by multidrug-resistant pathogens, particularly in ICU settings, pose significant health risks globally. Pseudomonas aeruginosa (PA) and methicillin-resistant Staphylococcus aureus (MRSA) are prominent nosocomial pathogens among the ESKAPE group, known for their resistance mechanisms such as biofilm formation and quorum sensing. Quercetin, a flavonoid found in fruits and vegetables, exhibits diverse pharmacological properties, including antimicrobial activity. This study evaluated quercetin's efficacy against PA and MRSA through in vitro and in vivo experiments. Minimum Inhibitory Concentration (MIC) assays showed MIC values of 158 µg mL^-1 for PA and 176 µg mL^-1 for MRSA. Quercetin inhibited PA's swarming motility at concentrations as low as 39.5 µg mL^-1 and reduced MRSA viability in serum by up to 79%. Quercetin treatment significantly reduced biofilm formation by both pathogens, with Pseudomonas aeruginosa showing biomass reductions of 23% at 1/4 MIC (39.5 µg mL^-1) and 48% at 1/2 MIC, while methicillin-resistant Staphylococcus aureus exhibited reductions of 27% at 1/4 MIC and 53% at 1/2 MIC compared to the control. High-content fluorescence imaging demonstrated quercetin's ability to disrupt biofilm structure and viability. Moreover, quercetin suppressed EPS production and protease activity in both PA and MRSA, alongside downregulating virulence-related genes involved in quorum sensing and toxin production. In vivo studies using Caenorhabditis elegans confirmed quercetin's ability to reduce bacterial adherence and colonization. These findings underscore quercetin's potential as a therapeutic agent against multidrug-resistant pathogens in ICU settings, warranting further exploration for clinical applications.

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.