Biofouling最新文献

Technetium metal is renowned for its inertness in environmental conditions, rendering it an optimal candidate for use as a container material for high-level radioactive waste. Alternatively, thin technetium electroplated coatings can be employed to prevent corrosion of steel containers and the subsequent biofouling that may result. The utilization of metallic technetium in the design of containers for radioactive waste in deep burial may be promising from two perspectives: firstly, in terms of increasing their stability, and secondly, in terms of the utilization of technetium, which is a macrocomponent of radioactive waste. In this study, the resilience of the metal technetium and its two derivative coatings (amorphous and crystalline) was assessed under various conditions, including exposure to fresh groundwater and seawater. The multifunctional strain Shewanella xiamenensis DCB-2-1, known for its ability to enzymatically reduce pertechnetate ions, was used to investigate the possibility of microbial biofouling of metallic technetium. Laboratory experiments have demonstrated that amorphous electrodeposited technetium is more susceptible to oxidation processes compared to its crystalline counterpart. Ultimately, the most durable form of technetium was metal foil. The potential for biofouling on Tc surfaces is largely attributed to the diverse nature of the specimens' surface. Research conducted in the Barents Sea has revealed that the accumulation of iron, calcium, and magnesium mineral phases within the microbial biofilm may shield beta radiation, resulting in the establishment of macro-fouling (Balanus and Mutilus).

The aim of this study was to evaluate carvacrol antimicrobial activity in polymicrobial biofilms using a novel controlled-release mucoadhesive systems developed from biopolymers. The natural polymers gellan gum and sodium alginate were used in different concentrations for the development of films, tablets and microparticles containing carvacrol. The systems were characterized as regard their morphological characteristics, carvacrol release and mucoadhesion. Furthermore, the antimicrobial activity of the systems was evaluated on polymicrobial biofilms through biomass quantification and microbial viability assessment. Carvacrol release profile from films, tablets and microparticles was similar; nearly 100% of the carvacrol was released within 15 min. Films showed the best mucoadhesion values. Scanning Electron Microscopy images showed that the films presented a continuous and smooth surface, and the tablets showed a continuous surface with a polymer web appearance. The microparticles were spherical in shape. The films containing carvacrol showed the highest biomass and microbial viability reduction, followed by the tablets. The findings of this study showed that carvacrol incorporated into films and tablets presented antimicrobial activity on polymicrobial biofilm. Controlled-release mucoadhesive systems is a process little explored in dentistry, being the differential of this work, and with great innovative potential for the management of dental diseases.

Microbiologically contaminated water is a significant source of infections in humans and animals, with Pseudomonas aeruginosa (PSA) being particularly concerning due to its ability to thrive in water environments and its resistance to many disinfectants. Therefore, this study investigates the adhesion potential of PSA strains on various materials used in mineral water extraction wells, focusing on hydrophobic and hydrophilic properties. Mineral water samples were collected from three wells (P-01, P-07, and P-08) within the Guarani Aquifer System and Fractured Aquifer System (SAF) in Brazil. The physicochemical properties of the water, including concentrations of Sr (strontium), Fe (iron), Si (silicon), SO₄^2- (sulfate ions), Cl^- (chloride ions), and ORP (oxidation-reduction potential), were analyzed. Results indicated higher PSA adhesion on hydrophobic materials, particularly high-density polyethylene (HDPE) and geomechanically plasticized polyvinyl chloride (PVC). Multiple correlation analyses revealed positive correlations between PSA adhesion on hydrophilic materials and Sr, Fe, Si, SO₄^2-, and Cl^- concentrations. Conversely, ORP negatively correlated with bacterial adhesion on PVC surfaces, suggesting higher ORP values reduced PSA attachment. These findings highlight the importance of water composition and material properties in influencing bacterial adhesion and potential biofilm formation in mineral water extraction systems.

This study compared the influence of growth conditions on the composition and acidogenicity of saliva-derived microcosm biofilms and enamel demineralization. Biofilms grown in sucrose-supplemented modified McBain medium, containing 25/50 mmol/L PIPES (buffer), under anaerobiosis/microaerophilia, for 3 and 7 days were evaluated for their acidogenicity, microbial composition, matrix, and enamel mineral content. The viability of total lactobacilli was higher in the group containing 25 mmol/L PIPES grown under anaerobiosis, which also showed lower pH values. The viability of total streptococci and total microorganisms was significantly higher at 7 days in the groups with 50 mmol/L PIPES than at 3 days, regardless of the incubation atmosphere. No significant differences were observed in lactic acid, calcium, superficial hardness loss, or lesion depth. In conclusion, the incubation atmosphere, buffer content in the growth media, and duration of biofilm formation displayed species-varied influence on microcosm biofilms, without causing significant changes in acid metabolism or enamel demineralization.

Extracts of certain fodder grasses may be viewed as powerful agents against infections induced by avian pathogenic Escherichia coli strains. Here we demonstrated ability of Galega orientalis and Rhaponticum carthamoides extracts, alone or in combination with antibiotics, to inhibit growth, viability and biofilm formation in avian pathogenic Escherichia coli strains with different sensitivity to antibiotics and non-pathogenic laboratory strain E. coli BW25113 as well as its mutant derivatives. Modulation of motility and production of extracellular structures in the presence of the extracts correlated with their anti-biofilm effects. Interestingly, an increase in antibacterial action of kanamycin, streptomycin, ciprofloxacin, and cefotaxime on both biofilms and planktonic cultures of the studied strains was observed in the presence of the extracts, including antibiotic resistant APEC strain #45. The extracts alone showed weak prooxidant activity which could contribute to modification of redox-sensitive sites of various regulatory circuits, resulting to synergetic effects in combination with antibiotics.

This work investigated the effect of Desulfovibrio caledoniensis (D. caledoniensis) and Pseudomonas aeruginosa (P. aeruginosa) on the microbiologically influenced corrosion (MIC) behaviour of 70Cu-30Ni alloy using surface analysis and electrochemical techniques. The results demonstrated that the mixed medium containing D. caledoniensis and P. aeruginosa further accelerated the MIC of 70Cu-30Ni alloy compared to the single species medium. The addition of exogenous pyocyanin (PYO) to the D. caledoniensis medium increased the maximum pit depth on 70Cu-30Ni alloy from 5.40 μm to 6.59 μm, and the corrosion current density (i_corr) increased by one order of magnitude. From the perspective of bioenergetics and extracellular electron transfer (EET), the comprehensive MIC mechanism of 70Cu-30Ni alloy induced by D. caledoniensis and P. aeruginosa was proposed.

This study evaluated conventional and alternative irrigation solutions combined with ultrasonic irrigant activation (UIA) against Fusobacterium nucleatum (F. nucleatum) and its endotoxin (LPS) in main root canal and dentinal tubules, using a new intratubular infection model. Seventy dentin cylinders were infected with F. nucleatum for seven days under anaerobic conditions and treated with 2.5% sodium hypochlorite (NaOCl), limewater + 2.5% NaOCl, and 10% ethanolic propolis extract (EEP), administered by syringe irrigation (SI) or UIA. Microbiological samples were collected before and after irrigation to determine CFU ml^-1 and LPS levels. Confocal microscopy assessed bacterial membrane damage with Live/Dead staining. Irrigation solutions effectively reduced CFU ml^-1. UIA caused greater damage to the bacterial membranes and reduced LPS levels. The ultrasonic activation of 10% EEP and limewater + 2.5% NaOCl were comparable to 2.5% NaOCl (p > 0.05). UIA improved the effectiveness of solutions, suggesting potential for alternative substances. Randomized clinical trials using these protocols are recommended.

The purpose of this study was to investigate dynamics of biofilm biomass on microparticles of natural material quartz sand and the artificial material polypropylene (plastisphere) as well as change in biofilm-forming microorganisms' number under a short-term in situ field study. In this study microparticles of polypropylene and quartz sand ranging in size from 3 to 5 mm were used. The total microbial count and the number of sulfate-reducing bacteria in the biofilm (by traditional culture-based microbiological methods) and the biofilm biomass (by the method with the crystal violet) were investigated. According to the determined microbiological indicators, over time (90 days) on the polypropylene it was observed decreasing of both the number of studied groups of microorganisms and the formation of a microbial biofilm, compared to the quartz sand. Determination of microbiological indicators of the materials surface allows understanding the aspects of their preservation/removal from the environment and requires additional research.

Simvastatin had minimum inhibitory concentrations of 32 to 128 µg/mL against Klebsiella pneumoniae isolates and hindered the biofilm-formation ability of 58.54% of the isolates. It considerably diminished the bacterial cell counts in the biofilms as revealed by scanning electron microscope. Also, qRT-PCR revealed a downregulation of the biofilm genes (bcsA, wza, and luxS) by simvastatin in 48.78% of the isolates. Moreover, simvastatin has significantly improved the survival of mice and decreased the burden of bacteria in the infected lungs. Also, the histological architecture was substantially improved in the simvastatin-treated group, as the alveolar sacs and bronchioles appeared normal with minimal collagen fiber deposition. The immunohistochemical studies exposed that the TNF-α, NF-kβ, and COX-2 immunostaining considerably declined in the simvastatin-treated group. Furthermore, ELISA exposed that both IL-1β and IL-6 were considerably diminished in the lungs of the simvastatin-treated group.

Extracts of Cryptocarya species have been shown to reduce biofilms, demonstrating their antimicrobial effects. The extracts can be fractionated to optimize their potential. In this study, we evaluated the antimicrobial activity of Cryptocarya moschata fractions against planktonic cells and biofilms of Candida albicans and Streptococcus mutans. Four fractions were prepared: 100% hexane, acetate/hexane 1:1, 100% ethyl acetate, and water. The effect of the fractions on planktonic cells was assessed by counting the colony-forming units per milliliter (CFU/mL). Biofilm tests included CFU/mL, cell metabolic activity, and qualitative analysis using confocal laser scanning microscopy (CLSM). Results were analyzed by the Mann-Whitney U test (α = 0.05). The fractions contained lipophilic constituents, styrylpyrones, glycosylated flavonoids, and alkaloids. Acetate/hexane (1:1) and 100% ethyl acetate fractions reduced the CFU/mL of planktonic C. albicans. C. moschata fractions did not affect planktonic S. mutans. For biofilms, the fractions reduced the CFU/mL (from 2-5 logs) and cell metabolic activity (approximately 80% reduction in a single-species biofilm). CLSM showed the fractions reduced microorganism viability and damaged the extracellular matrix of biofilms. We conclude that the acetate/hexane 1:1 and 100% ethyl acetate C. moschata fractions exhibit antimicrobial effects against biofilms.