Biofouling最新文献

The current work aims to develop a shikonin and tea tree oil loaded nanoemulsion system stabilized by a mixture of GRAS grade surfactants (Tween 20 and monoolein) and a cosurfactant (Transcutol P). This system was designed to address the poor aqueous solubility and photostability issues of shikonin. The authenticity of shikonin employed in this study was confirmed using nuclear magnetic resonance (NMR) spectroscopy. The optimized nanoemulsion exhibited highly favorable characteristics in terms of zeta potential (-23.8 mV), polydispersity index (0.216) and particle size (22.97 nm). These findings were corroborated by transmission electron microscopy (TEM) micrographs which confirmed the spherical and uniform nature of the nanoemulsion globules. Moreover, attenuated total reflectance (ATR) and X-ray diffraction analysis (XRD) analysis affirmed improved chemical stability and amorphization, respectively. Photodegradation studies were performed by exposing pure shikonin and the developed nanoemulsion to ultraviolet light for 1 h using a UV lamp, followed by high performance liquid chromatography (HPLC) analysis. The results confirmed that the developed nanoemulsion system imparts photoprotection to pure shikonin in the encapsulated system. Furthermore, the research investigated the effect of the nanoemulsion on biofilms formed by Candida albicans and methicillin resistant Staphylococcus aureus (MRSA). Scanning electron microscopy, florescence microscopy and phase contrast microscopy unveiled a remarkable reduction in biofilm area, accompanied by disruptions in the cell wall and abnormalities on the cell surface of the tested microorganisms. In conclusion, the nanoencapsulation of shikonin with tea tree oil as the lipid phase showcased significantly enhanced antimicrobial and antibiofilm potential compared to pure shikonin against resistant strains of Candida albicans and Staphylococcus aureus.

Bacterial pathogenesis involves complex mechanisms contributing to virulence and persistence of infections. Understanding the multifactorial nature of bacterial infections is crucial for developing effective interventions. The present study investigated the efficacy of indole-3-acetic acid (IAA) against Pseudomonas aeruginosa with various end points including antibacterial activity, minimum inhibitory concentration (MIC), virulence factor production, biofilm inhibition, bacterial cell detachment, and viability assays. Results showed significant biofilm inhibition, bacterial cell detachment, and modest effects on bacterial viability. Microscopic analysis confirmed the disintegrated biofilm matrix, supporting the inhibitory effect of IAA. Additionally, molecular docking studies revealed potential mechanisms of action through active bond interactions between IAA and virulence proteins. These findings highlight IAA as an effective antibiofilm agent against P. aeruginosa.

In the current study we investigate the antifouling potential of three polyphenolic resveratrol multimers (-)-hopeaphenol, vaticanol B and vatalbinoside A, isolated from two species of Anisoptera found in the Papua New Guinean rainforest. The compounds were evaluated against the growth and settlement of eight marine microfoulers and against the settlement and metamorphosis of Amphibalanus improvisus barnacle cyprids. The two isomeric compounds (-)-hopeaphenol and vaticanol B displayed a high inhibitory potential against the cyprid larvae metamorphosis at 2.8 and 1.1 μM. (-)-Hopeaphenol was also shown to be a strong inhibitor of both microalgal and bacterial adhesion at submicromolar concentrations with low toxicity. Resveratrol displayed a lower antifouling activity compared to the multimers and had higher off target toxicity against MCR-5 fibroblasts. This study illustrates the potential of natural products as a valuable source for the discovery of novel antifouling leads with low toxicity.

Electrochlorination is often used for biofouling control along the water intake pipeline of seawater cooling system, but with the increasing of pipeline length, this process needs to be further improved. In this study, the dynamic circulation and field pilot test were used to simulate the long-distance seawater intake pipeline, investigating total residual oxidant (TRO) decay and its influencing factors by comparing the bench test. The results showed that intermediate dosing could increase terminal TRO, but also reduce the CT value, resulting in decline of local inactivation effect. The initial concentration of dynamic cycle test was higher than that of bench test under the same terminal TRO, and the difference value between the two was affected by holding time. When the initial concentration was greater than 8.5 mg L^-1, TRO decay rate was proportional to the seawater flow rate and inversely proportional to the initial concentration. The initial concentration of 8.5-10 mg L^-1 could meet TRO decay requirement under 3 h holding time, and the dosing concentration could be reduced to 6 mg L^-1 when the temperature was low. The results provided important guidance for the actual operation of biofouling control in long-distance water intake pipelines of cooling system.

Bryozoans are commonly associated with various artificial structures in marine environments and have been responsible for several bioinvasion events worldwide. Understanding the interactions between bryozoans and artificial structures is therefore essential to prevent the establishment and spread of potential bioinvaders. This study investigated bryozoan recruitment on four different substrates (PET, nautical ropes, metal, and PVC) placed in three orientations (vertical, horizontal facing down and facing up) in an area of the Western Atlantic. In total, 15 species of bryozoans were found. The results revealed significant variations in assemblages' richness, with bryozoans showing a preference for settling on PVC (14 species found) and on the underside of horizontal substrates (15 species found), resulting in the higher representativity observed in this study. Cryptogenic (nine species) and exotic (five species) bryozoans dominated the assemblages in all treatments, indicating that the type of substrate (especially artificial) and its orientation can favor the settlement of bryozoans, particularly non-native species. Therefore, the availability of multiple types of artificial substrates in marine environments should be treated as a cause for concern.

In this study, the effects of surface properties of membrane materials on microalgae cell adhesion and biofilm formation were investigated using Chlorella vulgaris and five different types of membrane materials under hydrodynamic conditions. The results suggest that the contact angle (hydrophobicity), surface free energy, and free energy of cohesion of membrane materials alone could not sufficiently elucidate the selectivity of microalgae cell adhesion and biofilm formation on membrane materials surfaces, and membrane surface roughness played a dominant role in controlling biofilm formation rate, under tested hydrodynamic conditions. A lower level of biofilm EPS production was generally associated with a larger amount of biofilm formation. The zeta potential of membrane materials could enhance initial microalgae cell adhesion and biofilm formation through salt bridging or charge neutralization mechanisms.

This study was designed to evaluate the antimicrobial activity of phage-derived endolysin (LysPB32) and depolymerase (DpolP22) against planktonic and biofilm cells of Salmonella Typhimurium (ST^KCCM). Compared to the control, the numbers of ST^KCCM were reduced by 4.3 and 5.9 log, respectively, at LysPB32 and LysPB32 + DpolP22 in the presence of polymyxin B (PMB) after 48-h incubation at 37 °C. LysPB32 + DpolP22 decreased the relative fitness (0.8) and the cross-resistance of ST^KCCM to chloramphenicol (CHL), cephalothin (CEP), ciprofloxacin (CIP), and tetracycline (TET) in the presence of PMB. The MIC_trt/MIC_con ratios of CHL, CEP, CIP, PMB, and TET were between 0.25 and 0.50 for LysPB32 + DpolP22 in the presence of PMB. These results suggest that the application of phage-encoded enzymes with antibiotics can be a promising approach for controlling biofilm formation on medical and food-processing equipment. This is noteworthy in that the application of LysPB32 + DpolP22 could increase antibiotic susceptibility and decrease cross-resistance to other antibiotics.

The rapidly expanding built environment in the northern Gulf of Mexico includes thousands of human built structures (e.g. platforms, shipwrecks) on the seabed. Primary-colonizing microbial biofilms transform structures into artificial reefs capable of supporting biodiversity, yet little is known about formation and recruitment of biofilms. Short-term seafloor experiments containing steel surfaces were placed near six structures, including historic shipwrecks and modern decommissioned energy platforms. Biofilms were analyzed for changes in phylogenetic composition, richness, and diversity relative to proximity to the structures. The biofilm core microbiome was primarily composed of iron-oxidizing Mariprofundus, sulfur-oxidizing Sulfurimonas, and biofilm-forming Rhodobacteraceae. Alpha diversity and richness significantly declined as a function of distance from structures. This study explores how built structures influence marine biofilms and contributes knowledge on how anthropogenic activity impacts microbiomes on the seabed.

This study aimed to assess the influence of nutrient enrichment on the development of microalgal biofilm on concrete and PVC cubes. Three mesocosms were utilized to create a nutrient gradient over a period of 28 days. Various parameters including biomass, photosynthetic activity, microtopography, and extracellular polymeric substances (EPS) were measured. Imaging PAM techniques were employed to obtain surface-wide data. Results revealed that nutrient availability had no significant impact on Chl a biomass and the maximum quantum efficiency of PSII ($F_v$/$F_m$). The photosynthetic capacity and efficiency were minimally affected by nutrient availability. Interestingly, the relationship between microphytobenthic (MPB) biomass and photosynthesis and surface rugosity exhibited distinct patterns. Negative reliefs showed a strong correlation with $F_v$/$F_m,$ while no clear pattern emerged for biomass on rough concrete structures. Overall, our findings demonstrate that under conditions of heightened eutrophication, biofilm photosynthesis thrives in the fissures and crevasses of colonized structures regardless of nutrient levels. This investigation provides valuable insights into the interplay between nutrient availability and surface rugosity.

Nuclear facility discharge pipelines accumulate inorganic and microbial fouling and radioactive contamination, however, research investigating the mechanisms that lead to their accumulation is limited. Using the Sellafield discharge pipeline as a model system, this study utilised modified Robbins devices to investigate the potential interplay between inorganic and biological processes in supporting fouling formation and radionuclide uptake. Initial experiments showed polyelectrolytes (present in pipeline effluents), had minimal effects on fouling formation. Biofilms were, however, found to be the key component promoting fouling, leading to increased uptake of inorganic particulates and metal contaminants (Cs, Sr, Co, Eu and Ru) compared to a non-biofilm control system. Biologically-mediated uptake mechanisms were implicated in Co and Ru accumulation, with a potential bioreduced Ru species identified on the biofilm system. This research emphasised the key role of biofilms in promoting fouling in discharge pipelines, advocating for the use of biocide treatments methods.