Biofouling最新文献

Biofouling communities were examined at five depths at two salmon farms (Doctor Islets (DI), Wicklow Point (WP)) in British Columbia, Canada from April/May to October 2020. In addition, various water quality parameters were measured and the jellyfish numbers were quantified. Biofouling communities were mainly composed of Mollusca (primarily Mytilus spp.), arthropods (mostly harpacticoids), and hydroids (predominantly Obelia sp.), while jellyfish samples were made up mostly of medusa-form Obelia sp. At DI, all variables except ammonia were associated with biofouling counts, all variables except depth were associated with hydroid biomass, while only temperature, dissolved oxygen, ammonia, and nitrate were associated with jellyfish. At WP, all variables except phosphate and silica were associated with biofouling counts, only depth was associated with hydroid biomass, and only ammonia was associated with jellyfish. Insights into what environmental variables are correlated with biofouling organisms and jellyfish may assist with the development of effective mitigation strategies.

Bacteria possess hair-like projections on their surface termed pili. The primary function of a pilus is to enable bacterial cell attachment to the host. Since pili are associated with cell adhesion, they play a major role in bacterial colonization and infection. Due to their important functional role, these surface appendages become ideal drug targets, hence it is essential to study the mechanism associated with pilus assembly, elongation, and attachment. Several enzymes are required for pilus biosynthesis, and their adhesion to the host. In this review paper, we have described the importance of the Sortase C (SrtC) protein which is required for pilus assembly and pilin polymerization. We also provide a detailed structural comparison of the protein from various pathogenic bacteria and highlight the importance of SrtC as a drug target. In addition to this, we have also reported structural studies of SrtC from the pathogenic bacteria Enterococcus faecalis using homology modelling.

To inform the performance of ecological engineering designs for artificial structures at sea, it is essential to characterise their impacts on the epibenthic communities colonising them. In this context, the present study aims to compare the community structure among natural and four different artificial hard habitats with different ages and features installed in the Bay of Cherbourg (English Channel): i) cinder blocks and ii) boulders, both installed six years prior to the study, and iii) smooth and iv) rugous concrete dykes, both installed one year prior to this study. Results showed that artificial habitats installed six years ago harboured communities with functional and taxonomic diversity characteristic of mature communities but were still different from those of natural habitat. Conversely, the two dyke habitats installed one year prior to this study presented a poorly diversified community dominated by opportunistic taxa. Furthermore, while the concrete used for the two dyke habitats presented different rugosity properties, both habitats supported similar communities, suggesting that such eco-engineering measures did not affect the settlement of early colonisers. Overall, this study highlights the need for long-term monitoring to comprehensively evaluate epibenthic colonisation of artificial structures.

Candida auris and Staphylococcus aureus are associated with a wide range of infections, as they exhibit multidrug resistance - a growing health concern. In this study, gaseous ozone, and ultraviolet-C (UVC) radiation are applied as infection control measures to inactivate dry biofilms of these organisms on polystyrene surfaces. The dosages utilised herein are 1000 and 3000 ppm.min for ozone and 2864 and 11592 mJ.cm^-2 for UVC. Both organisms showed an increased sensitivity to UVC relative to ozone exposure in a bespoke decontamination chamber. While complete inactivation of both organisms (>7.5 CFU log) was realized after 60 mins of UVC application, this could not be achieved with ozonation for the same duration. However, a combined application of ozone and UVC yielded complete inactivation in only 20 mins. For both treatment methods, it was observed that dry biofilms of S. aureus were more difficult to inactivate than dry biofilms of C. auris. Compared to dry biofilms of C. auris, micrographs of wet C. auris biofilms revealed the presence of an abundance of extracellular material after treatments. Interestingly, wet biofilms were more difficult to inactivate than dry biofilms. These insights are crucial to preventing recalcitrant and recurrent infections via contact with contaminated polymeric surfaces.

This study aimed to evaluate the effectiveness of ozonation in controlling Pseudomonas spp. biofilm in the food industry, and present possible parameters influencing this process. The study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search was conducted in the PubMed, EMBASE, ScienceDirect, and Scopus databases. Eleven articles published between 1993 and 2023 were included in the study, indicating that the topic has been under investigation for several decades, gaining more prominence in recent years. Studies have demonstrated the antimicrobial effect of ozone under different experimental conditions, indicating that it is an effective strategy. Furthermore, they suggest that, in addition to ozone concentration and exposure time, other parameters such as the type of materials used in processing plants, hydrodynamic conditions, water temperature, and knowledge of commonly found microorganisms contribute to the effectiveness of the process aimed at reducing microbial counts. In conclusion, the available evidence suggests that ozonation in controlling Pseudomonas spp. can be considered a promising antimicrobial strategy. More efforts are needed to adapt the different methodologies according to each industrial reality.

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).

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.