Cellulophaga Lytica Research Articles

Exploring the functional and genomic features of Cellulophaga lytica NFXS1, a zeaxanthin and lytic enzyme-producing marine bacterium that promotes microalgae growth

Beneficial microalgae-bacteria interactions mediate important marine ecological processes and present potential for exploitation in the industrial production of microalgae. Members of the bacterial genus Cellulophaga are known for their ability to interact with several marine organisms, including microalgae, however, not much is understood about their properties. In this work we present the detailed characterization of the marine bacterium, Cellulophaga lytica NFXS1, including its ability to synthesize valuable compounds such as zeaxanthin, its ability to modulate the growth and productivity of two relevant marine microalgae, Nannochloropsis oceanica and Phaeodactylum tricornutum, and the analysis of its complete genome sequence. The obtained results showed that C. lytica NFXS1 used several complex carbohydrates, indicating strong lytic enzymatic activities. Additionally, co-cultivation studies revealed that C. lytica NFXS1 colonized the microalgae phycosphere, catabolized microalgae exudates, promoted the growth of microalgae, and increased fucoxanthin productivity in P. tricornutum. Genomic analysis revealed the basis for the microalgae growth-promoting activities of strain NFXS1, which are mostly mediated by gliding motility, biofilm formation, biosynthesis of phytohormones (auxins, cytokinins), polyamine biosynthesis, and resistance to oxidative stress induced by zeaxanthin production and ROS detoxifying enzymes. A vast array of genes encoding glycosyl hydrolases and pectate lyase family enzymes were also found in the NFXS1 chromosome. Overall, these findings brought new information regarding the properties of C. lytica NFXS1, which can be used as a model organism to study microalgae-bacteria interactions and is a strong candidate for the development of a wide range of marine biotechnological solutions.

Bacterial envelope polysaccharide cues settlement and metamorphosis in the biofouling tubeworm Hydroides elegans

Metamorphosis for many marine invertebrates is triggered by external cues, commonly produced by bacteria. For larvae of Hydroides elegans, lipopolysaccharide (LPS) from the biofilm-dwelling bacterium Cellulophaga lytica induces metamorphosis. To determine whether bacterial LPS is a common metamorphosis-inducing factor for this species, we compare larval responses to LPS from 3 additional inductive Gram-negative marine biofilm bacteria with commercially available LPS from 3 bacteria not known to induce metamorphosis. LPS from all the inductive bacteria trigger metamorphosis, while LPS from non-inductive isolated marine bacteria do not. We then ask, which part of the LPS is the inductive element, the lipid (Lipid-A) or the polysaccharide (O-antigen), and find it is the latter for all four inductive bacteria. Finally, we examine the LPS subunits from two strains of the same bacterial species, one inductive and the other not, and find the LPS and O-antigen to be inductive from only the inductive bacterial strain.

Study of sustainable HDPE-based materials for aquaculture applications: effects on fouling

This study addresses one of the most common problems faced by the marine sector, namely the accumulation of organic matter and organisms on submerged surfaces. This biological phenomenon causes structural problems in aquatic systems and its mitigation implies a large economic outlay for marine aquaculture industry. Antifouling paints are being developed to help control this undesirable process; however, these treatments are problematic as they degrade and release biocides and heavy metals into the environment. In this context, our study focuses on developing more environmentally friendly antifouling strategies. For this purpose, we designed high-density polyethylene (HDPE) material functionalized with different copper compounds or silica, and subsequently tested their effects on biofilm formation by aquatic organisms at both laboratory and pilot scale. Bacterial species (Vibrio harveyi and Cellulophaga lytica) and diatoms (Nitzschia ovalis) known for producing biofilm were used. Our study revealed that material including copper pyrithione (CuPT) was highly effective in inhibiting bacterial and algal biofilm formation. Moreover, the ecotoxicological study covering three trophic levels (bacteria, algae and rotifers) indicated that none of the materials developed and tested herein was toxic. HDPE is easily moldable and suitable to produce built-in aquatic structures, and our results show that its functionalization with CuPT greatly improves its antifouling capacity. These findings represent a step forward in the fight against fouling in marine environments.

Iridescent biofilms of Cellulophaga lytica are tunable platforms for scalable, ordered materials

Nature offers many examples of materials which exhibit exceptional properties due to hierarchical assembly of their constituents. In well-studied multi-cellular systems, such as the morpho butterfly, a visible indication of having ordered submicron features is given by the display of structural color. Detailed investigations of nature’s designs have yielded mechanistic insights and led to the development of biomimetic materials at laboratory scales. However, the manufacturing of hierarchical assemblies at industrial scales remains difficult. Biomanufacturing aims to leverage the autonomy of biological systems to produce materials at lower cost and with fewer carbon emissions. Earlier reports documented that some bacteria, particularly those with gliding motility, self-assemble into biofilms with polycrystalline structures and exhibit glittery, iridescent colors. The current study demonstrates the potential of using one of these bacteria, Cellulophaga lytica, as a platform for the large scale biomanufacturing of ordered materials. Specific approaches for controlling C. lytica biofilm optical, spatial and temporal properties are reported. Complementary microscopy-based studies reveal that biofilm color variations are attributed to changes in morphology induced by cellular responses to the local environment. Incorporation of C. lytica biofilms into materials is also demonstrated, thereby facilitating their handling and downstream processing, as would be needed during manufacturing processes. Finally, the utility of C. lytica as a self-printing, photonic ink is established by this study. In summary, autonomous surface assembly of C. lytica under ambient conditions and across multiple length scales circumvent challenges that currently hinder production of ordered materials in industrial settings.

Studying the Effect of Pre-Polymer Composition and Incorporation of Surface-Modifying Amphiphilic Additives on the Fouling-Release Performance of Amphiphilic Siloxane-Polyurethane Coatings.

Combining amphiphilic fouling-release (FR) coatings with the surface-active nature of amphiphilic additives can improve the antifouling/fouling-release (AF/FR) properties needed to offer broad-spectrum resistance to marine biofoulants. This work is focused on further tuning the amphiphilic character of a previously developed amphiphilic siloxane-polyurethane (SiPU) coating by varying the amount of PDMS and PEG in the base system. Furthermore, surface-modifying amphiphilic additives (SMAAs) were incorporated into these amphiphilic FR SiPU coatings in varying amounts. ATR-FTIR, contact angle and surface energy measurements, and AFM were performed to assess changes in surface composition, wettability, and morphology. AF/FR properties were evaluated using laboratory biological assays involving Cellulophaga lytica, Navicula incerta, Ulva linza, Amphibalanus amphitrite, and Geukensia demissa. The surfaces of these coatings varied significantly upon changes in PDMS and PEG content in the coating matrix, as well as with changes in SMAA incorporation. AF/FR properties were also significantly changed, with formulations containing the highest amounts of SMAA showing very high removal properties compared to other experimental formulations, in some cases better than that of commercial standard FR coatings.

Multifunctional Enzyme with Endoglucanase and Alginase/Glucuronan Lyase Activities from Bacterium Cellulophaga lytica.

Cellulophaga lytica is a Gram-negative aerobic bacterium in the genome of which there are many genes encoding polysaccharide degrading enzymes. One of the enzymes named ClGP contains a glycoside hydrolase domain from the GH5 family and a polysaccharide lyase domain from the PL31 family. The enzyme also contains the TAT signaling peptide and the TIGR04183 domain that indicates extracellular nature of the enzyme. Phylogenetic analysis has shown that the enzymes most closely related to ClGP and containing all four domains (TAT, GH5, PL31, TIGR04183) are widespread among bacterial species belonging to the Flavobacteriaceae family. ClGP produced by the recombinant strain of E. coli was purified and characterized. ClGP exhibited activity of endoglucanase (EC 3.2.1.4) and catalyzed hydrolysis of β-D-glucan, carboxymethyl cellulose sodium salt (CMC-Na), and amorphous cellulose, but failed to hydrolyze microcrystalline cellulose and xylan. Products of CMC hydrolysis were cellobiose and cellotriose, whereas β-D-glucan was hydrolyzed to glucose, cellobiose, cellotetraose, and cellopentaose. ClGP was more active against the poly-β-D-mannuronate blocks than against the poly-α-L-glucuronate blocks of alginic acid. This indicates that the enzyme is a polyM lyase (EC 4.2.2.3). ClGP was active against polyglucuronic acid, so it displayed a glucuronan lyase (EC 4.2.2.14) activity. The enzyme had a neutral pH-optimum, was stable in the pH range 6.0-8.0, and displayed moderate thermal stability. ClGP effectively saccharified two species of brown algae, Saccharina latissima and Laminaria digitata, that suggests its potential for use in the production of biofuel from macroalgae.

Bacterial lipopolysaccharide induces settlement and metamorphosis in a marine larva

How larvae of the many phyla of marine invertebrates find places appropriate for settlement, metamorphosis, growth, and reproduction is an enduring question in marine science. Biofilm-induced metamorphosis has been observed in marine invertebrate larvae from nearly every major marine phylum. Despite the widespread nature of this phenomenon, the mechanism of induction remains poorly understood. The serpulid polychaete Hydroides elegans is a well established model for investigating bacteria-induced larval development. A broad range of biofilm bacterial species elicit larval metamorphosis in H. elegans via at least two mechanisms, including outer membrane vesicles (OMVs) and complexes of phage-tail bacteriocins. We investigated the interaction between larvae of H. elegans and the inductive bacterium Cellulophaga lytica, which produces an abundance of OMVs but not phage-tail bacteriocins. We asked whether the OMVs of C. lytica induce larval settlement due to cell membrane components or through delivery of specific cargo. Employing a biochemical structure–function approach with a strong ecological focus, the cells and OMVs produced by C. lytica were interrogated to determine the class of the inductive compounds. Here, we report that larvae of H. elegans are induced to metamorphose by lipopolysaccharide produced by C. lytica. The widespread prevalence of lipopolysaccharide and its associated taxonomic and structural variability suggest it may be a broadly employed cue for bacterially induced larval settlement of marine invertebrates.

Amphiphilic marine coating systems of self-stratified PDMS-PEG surfaces with an epoxy-polyurethane matrix

Marine coatings protect submerged surfaces from the negative effects of biofouling. In this work, we demonstrate a new method to prepare self-stratified, amphiphilic glycidyl-carbamate (GC)-based (epoxy urethane-based) coatings (AmpSiGC coatings) that have fouling-release properties making them suitable for marine use. The prepared coating systems are unique and durable in character as the bulk coating takes advantage of both epoxy and urethane functionalities while the surface is comprised of both hydrophilic and hydrophobic domains, granting it an amphiphilic characteristic. The experimental approach aimed to evaluate several factors that influence coating performance, including molecular weight of poly (ethylene glycol) (PEG) and PDMS moieties, ratio of hydrophobic (PDMS) and hydrophilic (PEG) components in the system, and the effect of different curing agents. The results demonstrated that polymeric chains of 10,000 $${\overline{M} }_{n}$$ PDMS and 750 $${\overline{M} }_{n}$$ PEG at 10–15 wt.% each offer substantially improved or comparable fouling-release performance in comparison to commercial marine coatings. This paper reports on the facile synthesis and characterization of the GC resin and GC prepolymers using FTIR and epoxy titrations; surface characterization of the coatings using ATR-FTIR, XPS, and AFM; and fouling-release assessment of the surfaces using laboratory biological assays with the barnacle Amphibalanus amphitrite, the algae Ulva linza and Navicula incerta, and the bacteria Cellulophaga lytica. Several of the AmpSiGC coatings exhibited promising performance, which were better or comparable to the internal and commercial reference coatings. The performance of the systems was dependent on all of the factors considered in this study.

Surface modifying amphiphilic additives and their effect on the fouling-release performance of siloxane-polyurethane coatings

In this work, surface-modifying amphiphilic additives (SMAAs) were synthesized via hydrosilylation using various polymethylhydrosiloxanes (PMHS) and allyl-terminated polyethylene glycol monomethyl ethers (APEG) of varying molecular weights. The additives synthesized were incorporated into a hydrophobic, self-stratifying siloxane-polyurethane (SiPU) coating system to produce an amphiphilic surface. Contact angle experiments and atomic force microscopy (AFM), in a dry and hydrated state, were performed to assess changes in surface wettability and morphology. The antifouling and fouling-release (AF/FR) performances were evaluated by performing laboratory biological assays using the marine bacterium Cellulophaga lytica, the microalga Navicula incerta, the macroalga Ulva linza, the barnacle Amphibalanus amphitrite, and the marine mussel, Geukensia demissa. Several of the formulations showed improved AF/FR performance vs the base SiPU and performed better than some of the commercial standard marine coatings. Formulations containing SMAAs with a low grafting density of relatively high molecular weight PEG chains showed the best performance overall.

Critical Amphiphilic Concentration: Effect of the Extent of Amphiphilicity on Marine Fouling-Release Performance

Amphiphilic surfaces, containing both hydrophilic and hydrophobic domains, offer desirable performance for many applications such as marine coatings or anti-icing purposes. This work explores the effect of the concentration of amphiphilic moieties on converting a polyurethane (PU) system to a coating having fouling-release properties. A novel amphiphilic compound is synthesized and added at increasing amounts to a PU system, where the amount of the additive is the only variable in the study. The additive-modified surfaces are characterized by a variety of techniques including ATR-FTIR, XPS, contact angle measurements, and AFM. Surface characterizations indicate the presence of amphiphilic domains on the surface due to the introduction of the self-stratifying amphiphilic additive. The fouling-release properties of the surfaces are assessed with three biological assays using Ulva linza, Cellulophaga lytica, and Navicula Incerta as the test organisms. A change in the fouling-release performance is observed and plateaued once a certain amount of amphiphilicity is attained in the coating system, which we call the critical amphiphilic concentration (CAC).

Anti-biofouling properties of poly(dimethyl siloxane) with RAFT photopolymerized acrylate/methacrylate surface grafts against model marine organisms

Biofouling of man-made surfaces by marine organisms is a global problem with both financial and environmental consequences. However, the development of non-toxic anti-biofouling coatings is challenged by the diversity of fouling organisms. One possible solution leverages coatings composed of diverse chemical constituents. Reversible addition-fragmentation chain-transfer (RAFT) photopolymerization was used to modify poly(dimethylsiloxane) (PDMSe) surfaces with polymeric grafts composed of three successive combinations of acrylamide, acrylic acid, and hydroxyethyl methacrylate. RAFT limited conflicting variables and allowed for the effect of graft chemistry to be isolated. While all compositions enhanced the anti-biofouling performance compared with the PDMSe control, the ternary, amphiphilic copolymer was the most effective with 98% inhibition of the attachment of zoospores of the green alga Ulva linza, 94% removal of cells of the diatom Navicula incerta, and 62% removal of cells of the bacterium Cellulophaga lytica. However, none of the graft compositions tested were able to mitigate reattachment of adult barnacles, Amphibalanus amphitrite.

Comparative analysis of two isocyanate-free urethane-based gels for antifouling applications

Amphiphilic gels consisting of acrylamide (AAM)/2-hydroxyethyl methacrylate (HEMA), hexafluorobutyl methacrylate (HFBMA) and non-isocyanate urethane dimethacrylate (NIUDMA) of varying molecular weights were compared. A three-level Taguchi analysis was performed using the amount of AAM/HEMA, HFBMA, NIUDMA and reaction time as dependent variables to determine the optimal formulation of the gels with maximized toughness and elastic modulus. The results were compared with commercial AF/FR Intersleek® coatings (IS 700, IS 900 and IS 1100SR) for their antifouling performance against a marine microalga (Navicula incerta), a marine bacterium (Cellulophaga lytica) and adult barnacles (Amphibalanus amphitrite). The toughness, elastic modulus and strain at break of the optimized AAM gels ranged from 3 to7 MPa, 25 to 72 MPa and 80% to 170%, respectively, whereas those of the optimized HEMA gels ranged from 1 to 3 MPa, 13 to 23 MPa and 76% to 160%, respectively. The gels, particularly AHN(E9) and HHN(E12), showed reductions of attachment compared with IS700 of up to 93% and 58%, respectively.

Tough amphiphilic antifouling coating based on acrylamide, fluoromethacrylate and non-isocyanate urethane dimethacrylate crosslinker

This study is focused on the development of tougher gels using combinations of acrylamide, fluoromethacrylate and a non-isocyanate urethane dimethacrylate (NIUDMA) crosslinker. The NIUDMA was tailored with 2, 3-epoxypropoxy propyl-polydimethylsiloxane segments E9 (MW = 0.36 kg mol−1), E11 (MW = 0.5-0.6 kg mol−1) and E12 (MW = 1-1.4 kg mol−1). A 3 level Taguchi design was used to evaluate the role of each component of the ternary copolymer gel on the elastic modulus and toughness. The toughness ranged from 2.5-7 MJ m−3 whereas the modulus ranged from 27-70 MPa. The formulations with the highest toughness and modulus were screened for their antifouling potential in biological assays against the microalga Navicula incerta and the bacterium Cellulophaga lytica. The E9 gels showed the best performance, achieving a 73% reduction in N. incerta cells and a 92% reduction in C. lytica biofilm remaining after water jetting treatments, when compared with the commercial Intersleek product IS700.

Amphiphilic zwitterionic-PDMS-based surface-modifying additives to tune fouling-release of siloxane-polyurethane marine coatings

Amphiphilic coatings have shown promising performance for marine applications to deter and limit biofouling. Hydrophobic marine coatings are unable to deter marine organisms that prefer hydrophobic surfaces for settlements, thus a series of amphiphilic additives were prepared and introduced to a hydrophobic system to attain surface amphiphilicity and improved performance without changing the base matrix. In this work, we report the successful synthesis of amphiphilic additives where highly incompatible blocks of hydrophobic polydimethylsiloxane (PDMS) and hydrophilic poly(sulfobetaine methacrylate) (poly(SBMA)) were connected, using ARGET ATRP (activators regenerated by electron transfer atom transfer radical polymerization) controlled radical polymerization technique. The surface characterization confirmed the presence of self-migrated amphiphilic additives to the surface of hydrophobic coating systems, and biological assessments indicated that the additives desirably improved fouling-release performance of the base hydrophobic system against macroalgal spores (Ulva linza) and barnacles (Amphibalanus amphitrite) while these additives had no detrimental effect on ability of the base matrix to release bacteria (Cellulophaga lytica), diatoms (Navicula incerta), and mussels (Geukensia demissa). Furthermore, this study not only reported the outstanding contribution of poly(SBMA)-PDMS additives towards contending with marine biofouling as well as the facile preparation of amphiphilic additives, but also concluded that several factors should be considered in the design of these additives for tailoring hydrophobic coatings: 1) PDMS block with a molecular weight of 1000 M¯n is preferred over higher molecular weights of PDMS; 2) hydrophilic portion between a range of 50% to 80% provides the desired amphiphilicity on a surface; and 3) poly(SBMA) block size does not necessarily impact the effectiveness of an additive.

Colony analysis and deep learning uncover 5-hydroxyindole as an inhibitor of gliding motility and iridescence in Cellulophaga lytica.

Iridescence is an original type of colouration that is relatively widespread in nature but has been either incompletely described or entirely neglected in prokaryotes. Recently, we reported a brilliant 'pointillistic' iridescence in agar-grown colony biofilms of Cellulophaga lytica and some other marine Flavobacteria that exhibit gliding motility. Bacterial iridescence is created by a unique self-organization of sub-communities of cells, but the mechanisms underlying such living photonic crystals are unknown. In this study, we used Petri dish assays to screen a large panel of potential activators or inhibitors of C. lytica's iridescence. Derivatives potentially interfering with quorum-sensing and other communication or biofilm formation processes were tested, as well as metabolic poisons or algal exoproducts. We identified an indole derivative, 5-hydroxyindole (5HI, 250 µM) which inhibited both gliding and iridescence at the colonial level. 5HI did not affect growth or cell respiration. At the microscopic level, phase-contrast imaging confirmed that 5HI inhibits the gliding motility of cells. Moreover, the lack of iridescence correlated with a perturbation of self-organization of the cell sub-communities in both the WT and a gliding-negative mutant. This effect was proved using recent advances in machine learning (deep neuronal networks). In addition to its effect on colony biofilms, 5HI was found to stimulate biofilm formation in microplates. Our data are compatible with possible roles of 5HI or marine analogues in the eco-biology of iridescent bacteria.

Cloning, identification and characterization of a novel κ-carrageenase from marine bacterium Cellulophaga lytica strain N5-2

A novel κ-carrageenase gene (Cly-κ-car) was cloned and heterologously expressed from marine bacterium Cellulophaga lytica strain N5-2. The gene comprised an open reading frame of 1488bp encoding 495 amino acid residues. The deduced protein had a calculated molecular weight of 55.24kDa with an estimated isoelectric point of 9.90. Multiple alignment analysis revealed that Cly-κ-CAR shared identity with κ-carrageenases from Zobellia sp. M-2 (46%), Zobellia galactanivorans (42%) and Rhodopirellula islandica (38%). Recombinant Cly-κ-CAR (R-Cly-κ-CAR) had maximum specific activity of 620.08U/mg at 35°C, pH 7.0, 0.7% κ-carrageenan and in the presence of 0.6% NaCl. It retained >75% of its initial activity after heat treatment below 35°C for 2h. More than 50% of its activity was maintained after incubation at pH 5.0-8.0 and 4°C for 6h. The Km and Vmax values for κ-carrageenan were 0.94mg/ml and 13.42mM/min/mg, respectively. Thin layer chromatographic analysis of the R-Cly-κ-CAR hydrolysis products revealed that the enzyme hydrolyzed κ-carrageenan into neo-κ-carraoctaose and neo-κ-carrahexaose. R-Cly-κ-CAR is a novel κ-carrageenase enzyme and could be a valuable tool to produce high degree of polymerization κ-carrageenan oligosaccharides with various biological activities.

Complete genome sequence and analysis of three kinds of β-agarase of Cellulophaga lytica DAU203 isolated from marine sediment

Cellulophaga lytica DAU203 (KACC 19187), isolated from the marine sediment in Korea, has a strong ability to degrade agar. The genome of C. lytica DAU203 contains a single chromosome that is 3,952,957bp in length, with 32.02% G+C contents. The genomic information predicted that the DAU203 has the potential to be utilized in various enzymatic industries.

Induction of Invertebrate Larval Settlement; Different Bacteria, Different Mechanisms?

Recruitment via settlement of pelagic larvae is critical for the persistence of benthic marine populations. For many benthic invertebrates, larval settlement occurs in response to surface microbial films. Larvae of the serpulid polychaete Hydroides elegans can be induced to settle by single bacterial species. Until now, only Pseudoalteromonas luteoviolacea had been subjected to detailed genetic and mechanistic studies. To determine if the complex structures, termed tailocins, derived from phage-tail gene assemblies and hypothesized to be the settlement cue in P. luteoviolacea were present in all inductive bacteria, genomic comparisons with inductive strains of Cellulophaga lytica, Bacillus aquimaris and Staphylococcus warneri were undertaken. They revealed that the gene assemblies for tailocins are lacking in these other bacteria. Negatively stained TEM images confirmed the absence of tailocins and revealed instead large numbers of extracellular vesicles in settlement-inductive fractions from all three bacteria. TEM imaging confirmed for C. lytica that the vesicles are budded from cell surfaces in a manner consistent with the production of outer membrane vesicles. Finding multiple bacteria settlement cues highlights the importance of further studies into the role of bacterial extracellular vesicles in eliciting settlement and metamorphosis of benthic marine larvae.

Poly(ethylene) glycol-modified, amphiphilic, siloxane–polyurethane coatings and their performance as fouling-release surfaces

Amphiphilic siloxane–polyurethane (AmSiPU) coatings were prepared using a series of polyisocyanate prepolymers modified with polydimethyl siloxane (PDMS) and poly(ethylene glycol) (PEG). Fouling-release performance of the AmSiPU coatings was evaluated through laboratory biological assays using several representative marine organisms. First, polyisocyanate prepolymers with compositional variation in PDMS and PEG were synthesized and characterized using Fourier transform infrared spectroscopy (FTIR) and isocyanate titrations. Then, the prepolymers were incorporated into coatings. Surface wettability of the coatings was evaluated using contact angle and surface energy measurements. Coatings’ surfaces were also characterized using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). ATR-FTIR and XPS experiments revealed that both PDMS and PEG moieties were present on the surface suggesting amphiphilic character. AFM phase images show microphase separation. AmSiPU coatings show excellent fouling-release performance toward bacteria (Cellulophaga lytica), the diatoms (Navicula incerta), and the green algae (Ulva linza), demonstrating comparable or superior performance to many commercial amphiphilic fouling-release coatings. Despite the incorporation of hydrophilic PEG, AmSiPU coatings show good macrofouling release which is often challenging with amphiphilic coating systems. AmSiPU coatings are a nontoxic and tough fouling-release solution with comparable performance to benchmarks in the fouling-release coatings market.

Comparison of laboratory and field testing performance evaluations of siloxane-polyurethane fouling-release marine coatings

A series of eight novel siloxane-polyurethane fouling-release (FR) coatings were assessed for their FR performance in both the laboratory and in the field. Laboratory analysis included adhesion assessments of bacteria, microalgae, macroalgal spores, adult barnacles and pseudobarnacles using high-throughput screening techniques, while field evaluations were conducted in accordance with standardized testing methods at three different ocean testing sites over the course of six-months exposure. The data collected were subjected to statistical analysis in order to identify potential correlations. In general, there was good agreement between the laboratory screening assays and the field assessments, with both regimes clearly distinguishing the siloxane-polyurethane compositions comprising monofunctional poly(dimethyl siloxane) (PDMS) (m-PDMS) as possessing superior, broad-spectrum FR properties compared to those prepared with difunctional PDMS (d-PDMS). Of the seven laboratory screening techniques, the Cellulophaga lytica biofilm retraction and reattached barnacle (Amphibalanus amphitrite) adhesion assays were shown to be the most predictive of broad-spectrum field performance.