Prevention Of Biofouling Research Articles

High performance long-afterglow phosphor-based ZnIn2S4/Sr2MgSi2O7:Eu2+,Dy3+ photocatalyst capable of dark state long-term application for photocatalytic sterilization

Eco-friendly photocatalytic sterilization utilizing solar energy via the generation of reactive radicals excited by light irradiation devastating bacterial cells and mineralizing organic pollutants effectively exhibits vast application potential in marine biofouling prevention due to the abundant solar energy available in the ocean. Focusing on the issue of the cessation of photocatalytic processes in the absence of light, in this study, we selected the long afterglow material Sr2MgSi2O7:Eu2+,Dy3+ (SMSO), which exhibits persistent sky-blue luminescence after brief illumination, as the substrate for in situ compositing with the visible-light-responsive ZnIn2S4 (ZIS). The emission spectrum of SMSO partially overlaps with the absorption spectrum of ZIS, and their energy bands were well-matched. Consequently, the ZIS/SMSO=1:0.5 (mass ratio) exhibited the synergistic degradation and bactericidal performance under both light and dark conditions. ZIS/SMSO=1:0.5 exhibited the degradation rate of methyl orange (MO) of 72.4 % when exposed to 5 minutes of simulated sunlight, 2.6-fold increase compared to ZIS, and especially, it exhibited the sustained degradation rate of 38.7 % after 5 h in darkness. Besides, ZIS/SMSO=1:0.5 exhibited the bactericidal rate of 28.9 % under simulated visible light of 1 h, which was 2.9 and 2.5 times the bactericidal rate of ZIS and SMSO, respectively; and especially, after 6 h in darkness, it reached 64.4 %, which was 2.8 and 1.9 times the bactericidal rate of ZIS and SMSO, respectively. The Electron Spin Resonance (ESR) test validated the notably higher ·OH and ·O2- signals of the ZIS/SMSO=1:0.5 complex than those of individual components when exposed to light, and the sustained existence of ·OH signal even in darkness, revealing that the continuously generation of active free radicals even in the absence of light due to that the SMSO can continuously excite the ZIS. Combining with the in situ XPS analysis and the density functional theory calculations, an S-scheme heterojunction between ZIS and SMSO is formed which contribute to the higher yield of ·OH for ZIS/SMSO=1:0.5 under both light and dark conditions. And the calculation of the adsorption energies of ZIS and SMSO for O2 and OH- in the composite revealed that the ZIS component is more favorable for adsorbing O2, while the SMSO component is more favorable for adsorbing OH-. These analyses manifested the S-scheme electron transfer of the system. Finally, the ZIS/SMSO=1:0.5 composite of environmentally friendly broad-spectral-responsive ternary metal sulfides with the long afterglow materials is capable of a sustained degradation and bactericidal effect, not only under light irradiation but also in the subsequent darkness. It offers valuable insights into photocatalytic materials that overcome light availability limitations for preventing marine biofouling.

Design and research of a total-auxiliary-system (TAS) for temperature and humidity control of underwater data center

ABSTRACT Underwater data centers, with their low energy use, cost, and latency, are seen as the future of data centers. This paper designs a Total Auxiliary System (TAS) for underwater data centers, including temperature and humidity control unit, biofouling prevention, and seawater corrosion prevention. In this paper, a model for the temperature and humidity control unit was developed, and key parameters such as heat load, specific moisture extraction rate (SMER), coefficient of performance (COP), and dehumidification volume were simulated. The effectiveness of the cooling performance was verified using Computational Fluid Dynamics (CFD) simulations. The system design also includes biofouling prevention via electric pulse and seawater corrosion prevention using cathodic protection with plastic coating and applied current. Calculations and verifications show that this system reduces energy consumption and ensures the long-term stable operation of underwater data centers.

Investigation of an Antifouling Compound from Sponge Siphonodictyon coralliphagum

Marine fouling is attaching organisms to objects floating or submerged in seashores, such as ships, docks, and offshore structures. The impact caused is the reduced lifespan of the thing attached to the biofouling. In addition, there was a spread of invasive species. The government and industries in the United States spend over 6.5 million dollars annually on their budget to overcome this problem. So far, the prevention of marine biofouling is using antifouling paint on ships and submerged structures. One of them is organotin tributyltin (TBT) proven effective for preventing fouling; however, it is not environmentally friendly. Sponge Siphonodictyon coralliphagum growing in Salibabu Island waters, Talaud Islands, with previously shown activities against prokaryotes, was collected and extracted by maceration using ethanol as a solvent. The extract was then added to the base paint with several compositions of 5%, 10%, and 25% applied to the paving block surface. Positive control uses paint with copper additives. The objects are then immersed in the seashore below subtidal depths. The observation was carried out every seven days until day 28. The paving block was observed on day 90 after immersion. Significant results were obtained where macrofouling was only able to grow in negative control and positive control. The extract sponge S. coralliphagum has vigorous antifouling activity against marine biofouling. Furthermore, the extract was fractionated using liquid chromatography and continued by testing their activity against Gram-positive and negative bacteria. Further investigation of NMR spectra from the active fraction to prokaryotic cells shows a cyclic aliphatic compound with several keto-enol functional and methyl aliphatic groups on their chain.

The mitigation potential of synergistic quorum quenching and antibacterial properties for biofilm proliferation and membrane biofouling

Biofouling has been a persistent problem hindering the application of membranes in water treatment, and quorum quenching has been identified as an effective method for mitigating biofouling, but surface accumulation of live bacteria still induces biofilm secretion, which poses a significant challenge for sustained prevention of membrane biofouling. In this study, we utilized quercetin, a typical flavonoid with the dual functions of quorum quenching and bacterial inactivation, to evaluate its role in preventing biofilm proliferation and against biofouling. Quercetin exhibited excellent antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and the decreased bioactivity was positively correlated with the quercetin concentration, with inhibition rates of 53.1 % and 57.4 %, respectively, at the experimental concentrations. The RT-qPCR results demonstrated that quercetin inhibited AI-2 of E. coli and AGR of S. aureus mediated quorum sensing system, and reduced the expression of genes such as adhesion, virulence, biofilm secretion, and key regulatory proteases. As a result, the bacterial growth cycle was retarded and the biomass and biofilm maturation cycles were alleviated with the synergistic effect of quorum quenching and antibacterial activity. In addition, membrane biofouling was significantly declined in the dynamic operation experiments, dead cells in the biofilm overwhelmingly dominated, and the final normalized water fluxes were increased by more than 49.9 % and 34.5 % for E. coli and S. aureus, respectively. This work demonstrates the potential for mitigating biofouling using protocols that quorum quenching and inactivate bacteria, also provides a unique and long-lasting strategy to alleviate membrane fouling.

Lotic‐SIPCO2: Adaptation of an open‐source CO2 sensor system and examination of associated emission uncertainties across a range of stream sizes and land uses

AbstractRiver networks play a crucial role in the global carbon cycle, as relevant sources of carbon dioxide (CO2) to the atmosphere. Advancements in high‐frequency monitoring in aquatic environments have enabled measurement of dissolved CO2 concentration at temporal resolutions essential for studying carbon variability and evasion from these dynamic ecosystems. Here, we describe the adaptation, deployment, and validation of an open‐source and relatively low‐cost in situ pCO2 sensor system for lotic ecosystems, the lotic‐SIPCO2. We tested the lotic‐SIPCO2 in 10 streams that spanned a range of land cover and basin size. Key system adaptations for lotic environments included prevention of biofouling, configuration for variable stage height, and reduction of headspace equilibration time. We then examined which input parameters contribute the most to uncertainty in estimating CO2 emission rates and found scaling factors related to the gas exchange velocity were the most influential when CO2 concentration was significantly above saturation. Near saturation, sensor measurement of pCO2 contributed most to uncertainty in estimating CO2 emissions. We also found high‐frequency measurements of pCO2 were not necessary to accurately estimate median emission rates given the CO2 regimes of our streams, but daily to weekly sampling was sufficient. High‐frequency measurements of pCO2 remain valuable for exploring in‐stream metabolic variability, source partitioning, and storm event dynamics. Our adaptations to the SIPCO2 offer a relatively affordable and robust means of monitoring dissolved CO2 in lotic ecosystems. Our findings demonstrate priorities and related considerations in the design of monitoring projects of dissolved CO2 and CO2 evasion dynamics more broadly.

Anti-biofouling performance and microbial communities of an integrated fixed-film activated sludge membrane bioreactor with a fibrous carrier material: Pilot-scale demonstration

Widespread use of membrane bioreactors for high-performance wastewater treatment depends on the prevention of biofouling during membrane filtration, which can reduce operating costs. Biofouling is usually prevented using mechanical and chemical membrane treatment methods, which can be time-consuming and expensive. In this study, we developed bio-capsules as a fluidizing carrier material in an integrated fixed-film activated sludge membrane bioreactor (IFAS-MBR). The bio-capsules were prepared from moniliform polyvinylidene chloride fibrous balls enclosed in a spherical plastic basket, and could harbor protozoa and metazoa. A pilot-scale anoxic–oxic IFAS-MBR system with a total volume of 132 m3 was operated to remove organic carbon and nitrogen from municipal wastewater at a high permeate flux (0.84 m3/m2/day). The efficacy of the bio-capsules and the prokaryotic/eukaryotic community structures in the system were investigated. After operation for 1 year, the system demonstrated stable removal of organic carbon (76.0 % ± 15.5 % as total organic carbon, 93.1 ± 5.3 % as BOD, and 88.5 ± 5.2 % as CODMn) and nitrogen (71.3 % ± 9.3 %) despite fluctuations in the influent concentrations. Increases in transmembrane pressure (TMP) were retarded from its increase rates from 0.56 kPa/day to 0.149–0.224 kPa/day by the bio-capsules, and the TMP was kept constant at around 20 kPa throughout the operational period. High-throughput sequencing of 16S rRNA gene amplicons showed that the prokaryotic family Pirellulaceae was metabolically active and correlated with the TMP. According to the 18S rRNA gene sequencing, the eukaryotic metazoan Bdelloidea was more abundant in the bio-capsules than in activated sludge, which was supported by microscopic observations. These results suggest that the application of bio-capsules prevents increases in the TMP by harboring the procaryotes and eukaryotes responsible for biofouling mitigation in the IFAS-MBR system.

Prevention of marine biofouling in the aquaculture industry by a coating based on polydimethylsiloxane-chitosan and sodium polyacrylate

In this study, a series of novel hydrophobic/hydrophilic hybrid (HHH) coatings with the feature of preventing the fouling phenomenon was fabricated based on polydimethylsiloxane (PDMS), as matrix and two hydrophilic polymers: chitosan and sodium polyacrylate, as dispersed phases. Antibacterial activity, pseudo-barnacle adhesion strength, surface free energy, water contact angle, and water absorption were performed for all samples. Evaluating field immersion of the samples was performed in the natural seawater. The results showed that the dispersed phase containing PDMS coatings showed simultaneously both of antibacterial activity and foul release behavior. Among the samples, the PCs4 coating containing 4 wt% Cs indicated the lowest pseudo barnacle adhesion strength (0.04 MPa), the lowest surface free energy (18.94 mN/m), the highest water contact angle (116.05°), and the percentage of fouling organisms 9.8 % after 30 days immersion. The HHH coatings can be considered as novel eco-friendly antifouling/foul release coatings for aquaculture applications.

Antimicrobial Nanoparticles Mediated Prevention and Control of Membrane Biofouling in Water and Wastewater Treatment: Current Trends and Future Perspectives.

Global water scarcity and water pollution necessitate wastewater reclamation for further use. As an alternative to conventional techniques, membrane technology is extensively used as an advanced method for water purification and wastewater treatment due to its selectivity, permeability, and efficient removal of pollutants. However, microbial biofouling is a major threat that deteriorates membrane performance and imparts operational challenges. It is a natural phenomenon caused by the undesirable colonization of microbes on membrane surfaces. The economic penalties associated with this menace are enormous. The traditional preventive measures are dominated by biocides, toxic chemicals, cleaners and antifouling surfaces, which are costly and often cause secondary pollution. Recent focus is thus being directed to promote inputs from nanotechnology to control and mitigate this major threat. Different anti-microbial nanomaterials can be effectively used to prevent the adhesion of microbes onto the membrane surfaces and eliminate microbial biofilms, to provide an economical and eco-friendly solution to biofouling. This review addresses the formation of microbial biofilms and biofouling in membrane operations. The potential of nanocomposite membranes in alleviating this problem and the challenges in commercialization are discussed. The antifouling mechanisms are also highlighted, which are not widely elucidated.

Microfiltration Membranes Modified with Zinc by Plasma Treatment.

Polymer membranes play an important role in various filtration processes. The modification of a polyamide membrane surface by one-component Zn and ZnO coatings and two-component Zn/ZnO coatings is presented in this work. The technological parameters of the Magnetron Sputtering-Physical Vapor Deposition method (MS-PVD) for the coatings deposition process show an impact on the influence on the membrane's surface structure, chemical composition, and functional properties. The characterization of surface structure and morphology were analyzed by scanning electron microscopy. In addition, surface roughness and wettability measurements were also made. For checking the antibacterial activity, the two representative strains of bacteria Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) were used. The filtration tests showed that polyamide membranes covered with three types of coatings, one-component Zn coatings, ZnO coatings, and two-component Zn/ZnO coatings, presented similar properties. The obtained results show that using the MS-PVD method for modification of the membrane's surface is a very promising perspective in the prevention of biofouling.

Efficacy testing of non-oxidizing biocides for polyamide membrane biofouling prevention using a modified CDC biofilm reactor

AbstractBiofouling is one of the most challenging obstacles faced by reverse osmosis (RO) membrane systems to supply potable water. Currently, biofouling is imperfectly handled by RO feed water pre-chlorination, which is associated with the production of carcinogenic disinfection by-products. To propose a safer alternative to control biofouling in RO drinking water applications, this study investigates the efficacy of five biocides to prevent and remove Pseudomonas aeruginosa biofilms from RO membranes: 2-methyl-4-isothiazolin-3-one (MIT); 2,2-dibromo-3-nitrilopropionamide (DBNPA); sodium bisulfite (SBS); sodium benzoate (SB); and ethyl lauroyl arginate (LAE). Experiments were conducted on the Center for Disease Control (CDC) Biofilm Reactor (CBR) with biocidal dosing estimated on 96-well microtiter plates. Confocal Scanning Laser Microscopy (CLSM) and Scanning Electron Microscopy (SEM) were used to analyze the biocides' anti-biofilm efficacies under dynamic conditions relative to minimum biofilm inhibitory and eradication concentrations. The results in this study indicated that LAE presented the best anti-biofilm efficacies in treating P. aeruginosa biofilms when compared to all studied biocides; it not only prevented biofilm formation (>98%) but also it effectively removed pre-established biofilms (>99%) from RO membrane coupons. Therefore, due to safety and efficacy, LAE is an excellent candidate for controlling biofouling in drinking water RO membrane systems.

Using Cell Membranes as Recognition Layers to Construct Ultrasensitive and Selective Bioelectronic Affinity Sensors.

Conventional sandwich immunosensors rely on antibody recognition layers to selectively capture and detect target antigen analytes. However, the fabrication of these traditional affinity sensors is typically associated with lengthy and multistep surface modifications of electrodes and faces the challenge of nonspecific adsorption from complex sample matrices. Here, we report on a unique design of bioelectronic affinity sensors by using natural cell membranes as recognition layers for protein detection and prevention of biofouling. Specifically, we employ the human macrophage (MΦ) membrane together with the human red blood cell (RBC) membrane to coat electrochemical transducers through a one-step process. The natural protein receptors on the MΦ membrane are used to capture target antigens, while the RBC membrane effectively prevents nonspecific surface binding. In an attempt to detect tumor necrosis factor alpha (TNF-α) cytokine using the bioelectronic affinity sensor, it demonstrates a remarkable limit of detection of 150 pM. This new sensor design integrates natural cell membranes and electronic transduction, which offers synergistic functionalities toward a broad range of biosensing applications.

Comparison of disinfection-residual-bacteria (DRB) after seven different kinds of disinfection: Biofilm formation, membrane fouling and mechanisms

Membrane fouling is the Achilles' heel of the reverse osmosis (RO) system for high-quality reclaimed water production. Previous studies have found that after the significant selection effect of traditional disinfection, the remaining disinfection-residual bacteria (DRB) may possess more severe biofouling potentials. To provide more constructive advice for the prevention of biofouling, we compared the RO membrane fouling characteristics of DRB after using five commonly used disinfection methods (NaClO, NH2Cl, ClO2, UV, and O3) and two novel disinfection methods (K2FeO4 and the flow-through electrode system (FES)). Compared with the control group (undisinfected, 21.1 % flux drop), the UV-DRB biofilm aggravated biofouling of the RO membrane (23.4 % flux drop), while the FES, K2FeO4, and NH2Cl treatments showed less severe biofouling, with final flux drops of 6.9 %, 8.1 %, and 8.1 %, respectively. Adenosine triphosphate (ATP) was found to be a capable indicator for predicting the biofouling potential of DRB. Systematic analysis showed that the thickness and density of the DRB biofilms were most closely related to the different fouling degree of RO membranes. Moreover, the relative abundance of bacteria with higher extracellular polymeric substance (EPS) secretion levels, such as Pseudomonas and Sphingomonas, was found closely related with the biofouling degree of RO membranes.

Application of ZIF-8 nanocomposite membrane in microbial desalination cells for simultaneous heavy metal removal and biofouling prevention

Microbial desalination cells (MDC) syndicate the advantage of physical separation by using membranes to create conditions required for Bioelectrochemical processes for the treatment of various domestic and industrial wastewater, while simultaneously desalinating saline water and generating bioenergy. However, since the introduction of this technology, heavy metal removal has been a challenge, and membrane fouling has become a major bottleneck limiting the optimum performance and efficiency of this technology. This study incorporated the use of ZIF-8 nanocomposite membrane via phase inversion mechanism in MDC for simultaneous heavy metal removal and membrane biofouling prevention. The study was conducted in two MDC systems; MDC-Control (without the ZIF-8 nanocomposite membrane) and MDC with ZIF-8 nanocomposite membrane. The results from the experiment shown that maximum removal efficiency of 85.7%, 84.3%, 84.0%, and 90.61% was obtained for Cu2+, Zn2+, Pb2+, and Cd2+ respectively in MDC-ZIF-8, while MDC control showed 54.17%, 59.71%, 51.94%, and 54.17%. The results were well fitted to the Langmuir adsorption isotherm with correlation coefficients (R2) > 0.99 in all cases for MDC-ZIF-8. A maximum adsorption capacity (Qmax) of 292 mg g−1 was attained for all four metal ions in MDC-ZIF-8. Besides, after 38 days of continuous operation with two complete desalination for both systems, the SEM-EDS characterization analysis, polarization characteristics, and power generation revealed antifouling characteristics of ZIF-8 nanocomposite membrane incorporated in MDC. The integration of the ZIF-8 nanocomposite membrane proved to be simultaneously efficient in biofouling prevention and heavy metal removal without jeopardizing the system's ability for wastewater treatment, bioelectricity generation, and desalination processes.

Synthesis of a Stretchable Polyampholyte Hydrophilic Film with Compositional Gradient for Long‐Term Stable, Substrate‐Independent Fouling‐Resistant Coating

AbstractThe prevention of nonspecific biofouling is crucial for technological development in biomaterials and medical devices. Thus, zwitterionic materials have attracted significant attention due to their effective fouling‐resistance, long‐term durability against oxidation, and biocompatibility. However, fabricating a substrate‐independent zwitterionic surface with outstanding fouling‐resistance remains a challenge. In this study, a polyampholyte coating that satisfies the aforementioned requirements is obtained using a vapor‐phase method. The polyampholyte coating consists of a bilayer of poly(1,3,5,7‐tetramethyl‐1,3,5,7‐tetravinyl cyclotetrasiloxane) (pV4D4) and polyampholyte, poly(2‐carboxyethyl acrylate‐co‐2‐(dimethylamino)ethyl acrylate) (pCD), stacked with compositional gradient, which are obtained via sequential deposition using initiated chemical vapor deposition. The heavily crosslinked pV4D4 acts as an adhesion promoter layer that may be applied conformally to various substrate materials with high interfacial adhesion. The pCD surface exhibits a long‐lasting, superior fouling‐resistance to proteins (20.3 ± 1.8 ng cm−2 for undiluted human serum) and microorganisms. The pCD‐grad‐pV4D4 films, coupled with the stress‐dissipative gradient interface, are highly stretchable up to 50% without compromising the fouling‐resistance. The fouling‐resistance is maintained after 1 day of sonication, 10 days of water flushing, and 30 days of water shearing. Further, the pCD‐grad‐pV4D4 films are fully transparent and patternable, making them a prospective alternative for future non‐fouling biomedical applications.

Bioinspired Self-Adhesive Lubricating Copolymer with Bacteriostatic and Bactericidal Synergistic Effect for Marine Biofouling Prevention

Bioinspired Self-Adhesive Lubricating Copolymer with Bacteriostatic and Bactericidal Synergistic Effect for Marine Biofouling Prevention

Nylon Oxygen Barrier Tubing Reduces Biofouling in Beer Draught Lines

Beer draught lines are frequently contaminated with biofilm-forming microorganisms, which forces retailers to spend considerable time and money cleaning and replacing lines. In light of this financial burden, draught tubing composition was examined for its role in the prevention of biofouling in beer lines. Three types of draught tubing - vinyl, polyethylene, and nylon barrier - were inoculated with a combination of biofilm-forming microorganisms (Hafnia paralvei, Raoultella planticola, Pediococcus damnosus and Saccharomyces cerevisiae) and used to simulate a bar environment for sixteen weeks. Following simulation, the degree of biofouling in each draught line was determined by spectrophotometry and microscopy. Absorption values and fluorescence images showed that nylon barrier tubing was superior to the other lines at resisting biofilm maturation.These results suggest that tubing composition plays a significant role in the prevention of biofilm formation in beer draught lines and supports the adoption of nylon barrier tubing as an effective strategy against biofouling in a variety of applications.

Preparation and mechanical properties of green epoxy/chitosan/silver nanocomposite

Epoxy is being extensively used in various engineering and structural applications. Epoxy is non-biodegradable, thus creating ecological problems. Apart from ecological problems, epoxy resin shows poor biofouling prevention in marine, freshwater and offshore environments. In the search for an eco-friendly solution to this problem, epoxy/chitosan/silver nanocomposites were devised. Chitosan was extracted from shrimp shells following deacetylation of chitin, and silver (Ag) nanoparticles synthesized using a chemical reduction process of silver salts. All the composite samples were prepared utilizing the solution casting method. The X-ray diffraction pattern and Fourier transform infrared analysis predict the successful creation of silver nanoparticles and chitosan, respectively. Different mechanical testings elaborate the fact that addition of chitosan into epoxy resin increases hardness, lowering tensile and flexural strength, whereas incorporation of silver nanoparticles reverses those properties, resulting in mechanical properties analogous with neat epoxy resin. Additionally, soil burial biodegradation testing ensured relatively greener characteristics of the final nanocomposites. Herein, the combined effect of chitosan and silver nanoparticles on an epoxy matrix is reported for the first time.

Urushiol-based benzoxazine copper polymer with low surface energy, strong substrate adhesion and antibacterial for marine antifouling application

Biofouling is a common problem, has serious impact on the biomedical applications and maritime activities by human beings, and developing eco-friendly antifouling coatings is the key to the prevention of biofouling. Traditional low surface energy antifouling coatings, such as silicones and fluororesins, have the inherent defects of weak substrate adhesion and poor static antifouling performance. Herein, a low surface energy marine antifouling coating, urushiol-based benzoxazine copper polymer (UBCP), was synthesized using natural product urushiol and n-octylamine, paraformaldehyde as the reactants, and then CuCl2 as the catalyst for further reaction. UBCP can be cured into films at room temperature, which have strong substrate adhesion, smooth and dense surface, and controllable release of effective copper ion at minimized concentrations. Moreover, UBCP exhibits excellent antifouling performance, with both fouling release and antifoulant release characteristics. The antibacterial performance of UBCP towards typical Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. aureus) both reach almost 100%, while its ability to inhibit algal activity is above 99%, and the surface of UBCP can effectively prevent microbial adhesion. In summary, UBCP is a highly effective and eco-friendly coating material and provides a promising approach to address the economic and operational issues caused by marine biofouling.

Effects of nanostructure antifouling biocides towards a coral species in the context of global changes

Biofouling prevention is one of the biggest challenges faced by the maritime industry, but antifouling agents commonly impact marine ecosystems. Advances in antifouling technology include the use of nanomaterials. Herein we test an antifouling nano-additive based on the encapsulation of the biocide 4,5-dichloro-2-octyl-4-isothiazolin-3-one (DCOIT) in engineered silica nanocontainers (SiNC). The work aims to assess the biochemical and physiological effects on the symbiotic coral Sarcophyton cf. glaucum caused by (1) thermal stress and (2) DCOIT exposure (free or nanoencapsulated forms), in a climate change scenario. Accordingly, the following hypotheses were addressed: (H1) ocean warming can cause toxicity on S. cf. glaucum; (H2) the nanoencapsulation process decreases DCOIT toxicity towards this species; (H3) the biocide toxicity, free or encapsulated forms, can be affected by ocean warming.Coral fragments were exposed for seven days to DCOIT in both free and encapsulated forms, SiNC and negative controls, under two water temperature regimes (26 °C and 30.5 °C). Coral polyp behavior and photosynthetic efficiency were determined in the holobiont, while biochemical markers were assessed individually in the endosymbiont and coral host. Results showed transient coral polyp retraction and diminished photosynthetic efficiency in the presence of heat stress or free DCOIT, with effects being magnified in the presence of both stressors. The activity of catalase and glutathione-S-transferase were modulated by temperature in each partner of the symbiosis. The shifts in enzymatic activity were more pronounced in the presence of free DCOIT, but to a lower extent for encapsulated DCOIT. Increased levels of oxidative damage were detected under heat conditions. The findings highlight the physiological constrains elicited by the increase of seawater temperature to symbiotic corals and demonstrate that DCOIT toxicity can be minimized through encapsulation in SiNC. The presence of both stressors magnifies toxicity and confirm that ocean warming enhances the vulnerability of tropical photosynthetic corals to local stressors.

Horseradish Essential Oil as a Promising Anti-Algal Product for Prevention of Phytoplankton Proliferation and Biofouling.

Increased proliferation of algae is a current problem in natural and artificial water bodies. Controlling nutrients is the most sustainable treatment of increased algal proliferation, however in certain cases, it is not sufficiently available, or it does not provide results fast enough. Chemicals derived from natural sources, which could be effective in low concentrations and are biodegradable, may have an advantage over conventional chemical treatments. The main aim of the present study was to investigate the anti-cyanobacterial and anti-algal properties of allyl-isothiocyanate-containing essential oil produced from horseradish roots with a complex approach of the topic: on laboratory strains of cyanobacteria and eukaryotic algae, on microcosms containing natural phytoplankton assemblages, and on semi-natural biofilms. The results show that acute treatment can significantly reduce the viability of all the tested cyanobacteria and eukaryotic algae. Results of microcosm experiments with natural phytoplankton assemblages show that horseradish essential oil from 7.1 × 10−6% (v/v) is applicable to push back phytoplankton proliferation even in natural assemblages. The individual number in the biofilm was dropped down to one-fifth of the original individual number, so 7.1 × 10−6% (v/v) and higher concentration of the essential oil can be considered as a successful treatment against biofouling.