Impact of the neurotoxin ß-N-methylamino-L-alanine on the diatom Thalassiosira pseudonana using metabolomics.

The neurotoxin ß-N-methylamino-L-alanine (BMAA) has emerged as an environmental factor related to neurodegenerative diseases. BMAA is produced by various microorganisms including cyanobacteria and diatoms, in diverse ecosystems. In the diatom Phaeodactylum tricornutum, BMAA is known to inhibit growth. The present study investigated the impact of BMAA on the diatom Thalassiosira pseudonana by exposing it to different concentrations of exogenous BMAA. Metabolomics was predominantly employed to investigate the effect of BMAA on T. pseudonana, and MetaboAnalyst (https://www.metabo-analyst.ca/) was used to identify BMAA-associated metabolisms/pathways in T. pseudonana. Furthermore, to explore the unique response, specific metabolites were compared between treatments. When the growth was obstructed by BMAA, 17 metabolisms/pathways including nitrogen and glutathione (i.e. oxidative stress) metabolisms, were influenced in T. pseudonana. This study has further determined that 11 out of 17 metabolisms/pathways could be essentially affected by BMAA, leading to the inhibition of diatom growth.

Characterization of polyphenols and carbohydrates exuded by Phaeodactylum tricornutum diatom grown under Cu stress.

This study is focused on analysing polyphenols and carbohydrates released by Phaeodactylum tricornutum (P. tricornutum) diatoms cultured in natural seawater enriched with sublethal and lethal Cu doses. Cu concentrations of 0.31, 0.79 and 1.57 µM reduced cell densities by 37, 82 and 91%, respectively, compared to the control. The total sum of all identified polyphenols and total carbohydrates released by cells grown under lethal Cu levels increased up to 18.8 and 107.4 times, respectively, compared to data from a control experiment. Four different in vitro assays were used to estimate the antioxidant activities of the extracellular compounds: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition, cupric ion reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power and Cu complexing ability (CCA). The highest antioxidant activities were observed in the Cu lethal treatments, where the CCA assay exhibited a greater increase (up to 32.2 times higher than that found in the control experiment) to reduce the concentration of free Cu in the medium and its toxicity. The presence of Cu stimulated the release of polyphenols and carbohydrates to the medium as a detoxification mechanism to survive under lethal levels of Cu regulating its speciation.

Physiological responses of the microalgae Thalassiosira weissflogii to the presence of the herbicide glyphosate in the medium.

We evaluated changes in growth, chlorophyll fluorescence and basic physiological and biochemical parameters of the microalgae Thalassiosira weissflogii cells under the influence of the herbicide glyphosate in concentrations 0, 25, 95 and 150µgL-1 . The toxic effect of glyphosate on algae is weakly dependent on the level of cell mineral nutrition. High concentrations of the herbicide do not lead to the death of microalgae but block the process of algae cell division. An increase in the glyphosate concentration in the medium leads to a slowdown or stop of algal growth, a decrease in their final biomass, an increase in the production of reactive oxygen species (ROS), depolarisation of mitochondrial membranes and metabolic activity of algae. Glyphosate inhibits the photosynthetic activity of cells and inhibits the relative rate of electron transport in the photosynthetic apparatus. Glyphosate at the studied concentrations does not affect the size characteristics of cells and the intracellular content of chlorophyll in T. weissflogii . The studied herbicide or products of its decay retain their toxic properties in the environment for at least 9days. This result shows the need for further in-depth studies to assess the physiological response and possible acclimation changes in the functional state of oxygenic phototrophs in response to the herbicide action. The species specificity of microalgae to the effects of glyphosate in natural conditions is potentially dangerous due to a possible change in the species structure of biocoenoses, in particular, a decrease in the contribution of diatoms.

Toxicity of individual and mixture of organic compounds to P. Phosphoreum and S. Capricornutum using interpretable simple structural parameters.

Human and environmental ecosystem beings are exposed to multicomponent compound mixtures but the toxicity nature of compound mixtures is not alike to the individual chemicals. This work introduces four models for the prediction of the negative logarithm of median effective concentration (pEC50) of individual chemicals to marine bacteria Photobacterium Phosphoreum (P. Phosphoreum) and algal test species Selenastrum Capricornutum (S. Capricornutum) as well as their mixtures to P. Phosphoreum, and S. Capricornutum. These models provide the simplest approaches for the forecast of pEC50 of some classes of organic compounds from their interpretable structural parameters. Due to the lack of adequate toxicity data for chemical mixtures, the largest available experimental data of individual chemicals (55 data) and their mixtures (99 data) are used to derive the new correlations. The models of individual chemicals are based on two simple structural parameters but chemical mixture models require further interaction terms. The new model's results are compared with the outputs of the best accessible quantitative structure-activity relationships (QSARs) models. Various statistical parameters are done on the new and comparative complex QSAR models, which confirm the higher reliability and simplicity of the new correlations.

Aging increases the particulate- and leachate-induced toxicity of tire wear particles to microalgae.

The toxic effects of tire wear particles (TWPs) on organisms have attracted widespread concerns over the past decade. However, the underlying toxicity mechanism of TWPs, especially aged TWPs to marine microalgae remains poorly understood. This study investigated the physiological and metabolic responses of Phaeodactylum tricornutum to different concentrations of TWPs (Experiment 1), virgin and differently aged TWPs (Experiment 2) as well as their leachates and leached particles (Experiment 3). Results demonstrated that TWPs promoted the growth of microalgae at low concentrations (0.6 and 3 mg L-1) and inhibited their growth at high concentrations (15 and 75 mg L-1). Moreover, aged TWPs induced more profound physiological effects on microalgae than virgin TWPs, including inhibiting microalgae growth, decreasing the content of Chla, promoting photosynthetic efficiency, and causing oxidative damage to algal cells. Untargeted metabolomics analysis confirmed that aged TWPs induced more pronounced metabolic changes than virgin TWPs. This study represented the first to demonstrate that both particulate- and leachate-induced toxicity of TWPs was increased after aging processes, which was confirmed by the changes in the surface morphology of TWPs and enhanced release of additives. Through the significant correlations between the additives and the microalgal metabolites, key additives responsible for the shift of microalgal metabolites were identified. These results broaden the understanding of the toxicity mechanism of aged TWPs to microalgae at the physiological and metabolic levels and appeal for considering the effects of long-term aging on TWP toxicity in risk assessment of TWPs.

Sol-gel-derived hard coatings from tetraethoxysilane and organoalkoxysilanes bearing zwitterionic and isothiazolinone groups and their antifouling behaviors.

Current environmentally friendly marine antifouling (AF) coatings are mainly polymeric with a relatively low hardness. Hard sol-gel-derived AF coatings for underwater robot-cleaning are seldom used. In this work, two new organoalkoxysilanes, i.e., (N-methoxyacylethyl)-3-aminopropyltriethoxysilane and 2-(2-hydroxy-3-(3-(trimethoxysilyl)propoxy)propyl)benzo[d]isothiazol-3(2H)-one, were synthesized by a facile method. These two precursors were used with tetraethoxysilane (TEOS) to produce three series of hybrid AF coatings with zwitterionic group (Z-χ), antibacterial group (1,2-benzisothiazolin-3-one) (A-χ) and zwitterionic and antibacterial groups (S-χ) by a sol-gel process. The hardness of the coatings was measured using a pencil hardness tester and the AF behaviors of the coatings were examined by laboratory and field assays. A pencil hardness up to 5 H was achieved and slight deterioration was observed after 9 months of immersion in artificial seawater for the A-χ and S-χ coatings at a sufficiently high TEOS content. A synergistic effect between the zwitterion and antimicrobial agents existed but was not obvious. A higher TEOS content led to a higher hardness and better AF performance regardless of the type of AF group. Even with the same biofilm formation after field assay, coatings with a higher TEOS content exhibited a better resistance to mussel settlement.

Influence of nutrient status on the response of the diatom Phaeodactylum tricornutum to oil and dispersant.

Phytoplankton play a central role in our ecosystems, they are responsible for nearly 50 percent of the global primary productivity and major drivers of macro-elemental cycles in the ocean. Phytoplankton are constantly subjected to stressors, some natural such as nutrient limitation and some manmade such as oil spills. With increasing oil exploration activities in coastal zones in the Gulf of Mexico and elsewhere, an oil spill during nutrient-limited conditions for phytoplankton growth is highly likely. We performed a multifactorial study exposing the diatom Phaeodactylum tricornutum (UTEX 646) to oil and/or dispersants under nitrogen and silica limitation as well as co-limitation of both nutrients. Our study found that treatments with nitrogen limitation (-N and-N-Si) showed overall lower growth and chlorophyll a, lower photosynthetic antennae size, lower maximum photosynthetic efficiency, lower protein in exopolymeric substance (EPS), but higher connectivity between photosystems compared to non-nitrogen limited treatments (-Si and +N+Si) in almost all the conditions with oil and/or dispersants. However, certain combinations of nutrient limitation and oil and/or dispersant differed from this trend indicating strong interactive effects. When analyzed for significant interactive effects, the-N treatment impact on cellular growth in oil and oil plus dispersant conditions; and oil and oil plus dispersant conditions on cellular growth in-N-Si and-N treatments were found to be significant. Overall, we demonstrate that nitrogen limitation can affect the oil resistant trait of P. tricornutum, and oil with and without dispersants can have interactive effects with nutrient limitation on this diatom.

Diatoms: Miniscule biological entities with immense importance in synthesis of targeted novel bioparticles and biomonitoring.

Diatoms are the most abundant microscopic unicellular protists in natural lotic ecosystems. They are the major component of the producer community in aquatic ecosystems that also play important roles in biostratigraphy, paleoclimatology and overall ecosystem functioning. In recent times as ultrastructural details of diatom frustule has been established, it has become evident that frustule nanoscale structures play a significant role in adsorption and bioaccumulation of heavy metals. Physical processes like bioaccumulation in conjunction with cell surface ligands and functional groups allow diatoms to convert toxic forms of metals to their more utilizable forms. This unique aspect of diatom has been exploited in recent times for the synthesis of novel nanoparticles under in vitro conditions. Moreover, biomonitoring using diatoms is increasingly becoming a preferred choice for assessment of water quality due to their time-integrative characteristic. Although both these aspects include diatom and metal speciation under in vitro and in situ conditions, a comprehensive study addressing both these areas has remained obscure. Thus, the present work aims at integrating the aspects of novel metal particle synthesis and biomonitoring of habitats with diatom as the principal biological entity involved in these processes.

Molecular mechanism of oil induced growth inhibition in diatoms using Thalassiosira pseudonana as the model species.

The 2010 Deepwater Horizon oil-spill exposed the microbes of Gulf of Mexico to unprecedented amount of oil. Conclusive evidence of the underlying molecular mechanism(s) on the negative effects of oil exposure on certain phytoplankton species such as Thalassiosira pseudonana is still lacking, curtailing our understanding of how oil spills alter community composition. We performed experiments on model diatom T. pseudonana to understand the mechanisms underpinning observed reduced growth and photosynthesis rates during oil exposure. Results show severe impairment to processes upstream of photosynthesis, such as light absorption, with proteins associated with the light harvesting complex damaged while the pigments were unaffected. Proteins associated with photosynthetic electron transport were also damaged, severely affecting photosynthetic apparatus and depriving cells of energy and carbon for growth. Negative growth effects were alleviated when an organic carbon source was provided. Further investigation through proteomics combined with pathway enrichment analysis confirmed the above findings, while highlighting other negatively affected processes such as those associated with ferroxidase complex, high-affinity iron-permease complex, and multiple transmembrane transport. We also show that oxidative stress is not the primary route of negative effects, rather secondary. Overall, this study provides a mechanistic understanding of the cellular damage that occurs during oil exposure to T. pseudonana.

Zwitterionic Peptides Reduce Accumulation of Marine and Freshwater Biofilm Formers.

Zwitterionic peptides are facile low-fouling compounds for environmental applications as they are biocompatible and fully biodegradable as their degradation products are just amino acids. Here, a set of histidine (H) and glutamic acid (E), as well as lysine (K) and glutamic acid (E) based peptide sequences with zwitterionic properties were synthesized. Both oligopeptides (KE)4K and (HE)4H were synthesized in d and l configurations to test their ability to resist the nonspecific adsorption of the proteins lysozyme and fibrinogen. The coatings were additionally tested against the attachment of the marine organisms Navicula perminuta and Cobetia marina as well as the freshwater bacterium Pseudomonas fluorescens on the developed coatings. While the peptides containing lysine performed better in protein resistance assays and against freshwater bacteria, the sequences containing histidine were generally more resistant against marine organisms. The contribution of amino acid-intrinsic properties such as side chain pKa values and hydrophobicity, as well as external parameters such as pH and salinity of fresh water and seawater on the resistance of the coatings is discussed. In this way, a detailed picture emerges as to which zwitterionic sequences show advantages in future generations of biocompatible, sustainable, and nontoxic fouling release coatings.

Bioinspired Durable Antibacterial and Antifouling Coatings Based on Borneol Fluorinated Polymers: Demonstrating Direct Evidence of Antiadhesion.

Substituting natural products for traditional poison-killing antifouling agents is an efficient and promising method to alleviate the increasingly serious ecological crisis and aggravate the loss due to marine biofouling. Herein, the successful synthesis of poly(methyl methacrylate-co-ethyl acrylate-co-hexafluorobutyl methacrylate-co-isobornyl methacrylate) copolymer (PBAF) with borneol monomers and fluorine by a free radical polymerization method is reported. The PBA0.09F coating exhibits outstanding antibacterial and antifouling activity, achieving 98.2% and 92.3% resistance to Escherichia coli and Staphylococcus aureus, respectively, and the number of Halamphora sp. adhesion is only 26 (0.1645 mm2) in 24 h. This remarkable antibacterial and antifouling performance is attributed to the incorporation of fluorine components into the copolymer, which induces a low surface energy and hydrophobicity and the complex molecular structure of the natural nontoxic antifouling agent borneol. In addition, the results showed that the contents of the adhesion-related proteins mfp-3, mfp-5, and mfp-6 were significantly reduced, which proved that natural substances affect the secretion of biological proteins. Importantly, the PBAF coating exhibits excellent environmental friendliness and long-term stability. The antifouling mechanism is clarified, and an effective guide for an environmentally friendly antifouling coating design is proposed.

Time lapse synchrotron IR chemical imaging for observing the acclimation of a single algal cell to CO2 treatment.

Algae are the main primary producers in aquatic environments and therefore of fundamental importance for the global ecosystem. Mid-infrared (IR) microspectroscopy is a non-invasive tool that allows in principle studying chemical composition on a single-cell level. For a long time, however, mid-infrared (IR) imaging of living algal cells in an aqueous environment has been a challenge due to the strong IR absorption of water. In this study, we employed multi-beam synchrotron radiation to measure time-resolved IR hyperspectral images of individual Thalassiosira weissflogii cells in water in the course of acclimation to an abrupt change of CO2 availability (from 390 to 5000 ppm and vice versa) over 75 min. We used a previously developed algorithm to correct sinusoidal interference fringes from IR hyperspectral imaging data. After preprocessing and fringe correction of the hyperspectral data, principal component analysis (PCA) was performed to assess the spatial distribution of organic pools within the algal cells. Through the analysis of 200,000 spectra, we were able to identify compositional modifications associated with CO2 treatment. PCA revealed changes in the carbohydrate pool (1200-950 cm[Formula: see text]), lipids (1740, 2852, 2922 cm[Formula: see text]), and nucleic acid (1160 and 1201 cm[Formula: see text]) as the major response of exposure to elevated CO2 concentrations. Our results show a local metabolism response to this external perturbation.

Pheromone Mediated Sexual Reproduction of Pennate Diatom Cylindrotheca closterium.

Benthic diatoms dominate primary production in marine subtidal and intertidal environments. Their extraordinary species diversity and ecological success is thought to be linked with their predominantly heterothallic sexual reproduction. Little is known about pheromone involvement during mating of pennate diatoms. Here we describe pheromone guided mating in the coastal raphid diatom Cylindrotheca closterium. We show that the two mating types (mt+ and mt-) have distinct functions. Similar to other benthic diatoms, mt+ cells are searching for the mt- cells to pair. To enhance mating efficiency mt- exudes an attraction pheromone which we proved by establishing a novel capillary assay. Further, two more pheromones produced by mt- promote the sexual events. One arrests the cell cycle progression of mt+ while the other induces gametogenesis of mt+. We suggest that C. closterium shares a functionally similar pheromone system with other pennate diatoms like Seminavis robusta and Pseudostaurosira trainorii which synchronize sexual events and mate attraction. Remarkably, we found no evidence of mt+ producing pheromones, which differentiates C. closterium from other pennates and suggests a less complex pheromone system in C. closterium.

Bacterial diketopiperazines stimulate diatom growth and lipid accumulation.

Diatoms are photosynthetic microalgae that fix a significant fraction of the world's carbon. Because of their photosynthetic efficiency and high-lipid content, diatoms are priority candidates for biofuel production. Here, we report that sporulating Bacillus thuringiensis and other members of the Bacillus cereus group, when in co-culture with the marine diatom Phaeodactylum tricornutum, significantly increase diatom cell count. Bioassay-guided purification of the mother cell lysate of B. thuringiensis led to the identification of two diketopiperazines (DKPs) that stimulate both P. tricornutum growth and increase its lipid content. These findings may be exploited to enhance P. tricornutum growth and microalgae-based biofuel production. As increasing numbers of DKPs are isolated from marine microbes, the work gives potential clues to bacterial-produced growth factors for marine microalgae.

Copper Tannic Acid-Coordinated Metal-Organic Nanosheets for Synergistic Antimicrobial and Antifouling Coatings.

The copper tannic acid (CuTA) nanosheets with an excellent antibacterial activity were successfully prepared, which showed fine antibacterial and antifouling performance after hybridization with acrylic resin. The morphology and structure characterization of CuTA nanosheets were studied by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, etc. The plate counting method, zone of inhibition test, and minimum inhibitory concentration (MIC) method were used to detect the antibacterial activity of the prepared samples against Gram-positive Bacillus subtilis (B. subtilis) and Gram-negative Escherichia coli (E. coli). The results showed that the killing rates of 2 and 0.5 mg/mL of CuTA powder were close to 100% after 24 h. The MIC values of E. coli and B. subtilis were 0.25 and 0.5 mg/mL, respectively. The results of morphology and element distribution of bacteria, after treating with CuTA powder, revealed that Cu2+ and TA destroyed their cell walls and inhibited the proliferation and growth of the bacteria. Furthermore, the hybrid coating of CuTA nanosheets and acrylic resin showed brilliant antimicrobial performance for E. coli and B. subtilis and antialgae properties under a lower CuTA load (≤5%). The CuTA nanosheets with a low copper content (30.9 wt %) and low pollution have promising applications in marine antifouling coatings.

Characterization of river biofilm responses to the exposure with heavy metals using a novel micro fluorometer biosensor.

River biofilms are a suitable indicator of toxic stress in aquatic ecosystems commonly exposed to various anthropogenic pollutants from industrial, domestic, and agricultural sources. Among these pollutants, heavy metals are of particular concern as they are known to interfere with various physiological processes of river biofilm, directly or indirectly related to photosynthetic performance. Nevertheless, only limited toxicological data are available on the mechanisms and toxicodynamics of heavy metals in biofilms. Pulse Amplitude Modulated (PAM) fluorometry is a rapid, non-disruptive, well-established technique to monitor toxic responses on photosynthetic performance, fluorescence-kinetics, and changes in yield in other non-photochemical processes. In this study, a new micro-PAM-sensor was tested to assess potential acute and chronic effects of heavy metals in river biofilm. Toxicity values across the three parameters considered in this study (photosynthetic yield YII, non-photochemical quenching NPQ, and basal fluorescence F0) were comparable, as determined EC50 were within one order of magnitude (EC50 ∼1-10 mg L-1). However, the stimulation of NPQ was more clearly associated with early acute effects, especially in illuminated samples, while depression of YII and F0 were more prevalent in chronic tests. These results have implications for the development of functional indicators for the biomonitoring of aquatic health, in particular for the use of river biofilm as a bioindicator of water quality. In conclusion, the approach proposed seems promising to characterize and monitor the exposure and impact of heavy metals on river periphyton communities. Furthermore, this study provides a fast, highly sensitive, inexpensive, and accurate laboratory method to test effects of pollutants on complex periphyton communities that can also give insights regarding the probable toxicological mechanisms of heavy metals on photosynthetic performance in the river biofilm.

Prescribing sea water quality criteria for arsenic, cadmium and lead through species sensitivity distribution.

Water quality standards are essential for regulation of contaminants in marine environment. Seawater quality criteria (SWQC) for arsenic (As), cadmium (Cd) and lead (Pb) have not been developed for India. The aim of this study is to derive the SWQC for the metals based on Species Sensitivity Distribution (SSD). Eight species of sensitive marine organisms belonging to five phyla were assessed for their sensitivity to toxicity of As, Cd and Pb. Median effective concentrations (EC50) and Median Lethal Concentrations (LC50) were derived from the acute toxicity bio-assays. No Observed Effect Concentrations (NOEC), Lowest Observed Effect Concentrations (LOEC) and chronic values were derived from chronic toxicity bio-assays. Diatoms were more sensitive to As with 96 h EC50 of 0.1 mg/l and copepods were more sensitive to Cd and Pb with 96 h EC50 of 0.019 mg/l and 0.05 mg/l respectively. Estimated NOECs ranged from 4.87 to 21.55 µg/l of As, 1.0 to 120 µg/l of Cd and 5.67 to 91.67 µg/l of Pb. Similarly, chronic values (µg/l) were in the range of 6.71-26.1, 1.38-170, and 7.67-91.67 of As, Cd and Pb respectively. The Criterion Maximum Concentration (CMC), Criterion Continuous Concentration (CCC) and Predicted No Effect Concentration (PNEC) values were prescribed as SWQC. The CMC (µg/l) of 19, 1.7 and 17 for As, Cd, and Pb were derived respectively for acute exposure during accidental marine outfalls. The CCC (µg/l) for As was 4.6, 1.1 for Cd and 5.9 for Pb are recommended as SWQC for protection of 95% of marine organisms. PNEC (µg/l) of 3.8 for As, 0.92 for Cd and 4.3 for Pb are suggested for highly disturbed ecosystems, shell fishing and mariculture uses of water bodies. These values are recommended as a baseline for site specific water quality criteria for the coastal waters of the country.

Synthesis and Characterization of Dendritic and Linear Glycol Methacrylates and Their Performance as Marine Antifouling Coatings.

Dendritic polyglycerol (PG) was covalently coupled to 2-hydroxyethyl methacrylate (HEMA) by an anionically catalyzed ring-opening polymerization generating a dendritic PG-HEMA with four PG repetition units (PG4MA). Coatings of the methacrylate monomer were prepared by grafting-through and compared against commercially available hydrophilic monomers of HEMA, poly(ethylene) glycol methacrylate (PEGMA), and poly(propylene) glycol methacrylate (PPGMA). The obtained coatings were characterized by modern surface analytical techniques, including water contact angle goniometry (sessile and captive bubble), attenuated total internal reflection Fourier transform infrared spectroscopy, and atomic force microscopy. The antifouling (AF) and fouling-release (FR) properties of the coatings were tested against the model organisms Cobetia marina and Navicula perminuta in laboratory-scale dynamic accumulation assays as well as in a dynamic short-term field exposure (DSFE) in the marine environment. In addition, the hydration of the coatings and their susceptibility toward silt uptake were evaluated, revealing a strong correlation between water uptake, silt incorporation, and field assay performance. While all glycol derivatives showed good resistance in laboratory settlement experiments, PPGMA turned out to be less susceptible to silt incorporation and outperformed PEGMA and PG4MA in the DSFE assay.

Layer-by-Layer Deposited Hybrid Polymer Coatings Based on Polysaccharides and Zwitterionic Silanes with Marine Antifouling Properties.

Polyelectrolyte multilayer (PEM) assembly is a versatile tool to construct low-fouling coatings. For application in the marine environment, their structure needs to be stabilized by covalent linkage. Here, we introduce an approach for spin coating of silane-based sol-gel chemistries using layer-by-layer assembly of polysaccharide-based hybrid polymer coatings (LBLHPs). The silane sol-gel chemistry allows the films to be cross-linked under water-based and mild reaction conditions. Two different silanes were used for this purpose, a conventional triethoxymethyl silane and a de novo synthesized zwitterionic silane. The polysaccharide-silane hybrid polymer coatings were thoroughly characterized with spectroscopic ellipsometry, water contact angle (WCA) goniometry, attenuated total reflection-Fourier transform infrared spectroscopy, and atomic force microscopy. The coatings showed good stability in seawater, smooth surfaces, a high degree of hydration, and WCAs below or close to the Berg limit. LBLHPs showed low-fouling properties in biological assays against nonspecific protein adsorption, attachment of the diatom Navicula perminuta, and settlement of zoospores of the macroalga Ulva linza.

Cochliomycin G, a 14-membered resorcylic acid lactone from a marine-derived fungus Cochliobolus lunatus.

Cochliomycin G (1), a new 14-membered resorcylic acid lactone, together with six known analogues (2-7), was isolated from the culture broth of a marine-derived fungus Cochliobolus lunatus. The planar structure of 1 was established by extensive NMR spectroscopy, and the absolute configuration was elucidated by the combination of empirical rules, CD data, and 13C chemical shift calculations. Compound 1 exhibited potent antifouling activity against Chlorella vulgaris, Chaetoceros socialis, and Navicula exigua, with EC50 values of 1.09, 0.92, and 0.61 µg/mL, respectively.