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Background: In addition to the other uses for macroalgae, since the 1970s, there has been interest in using macroalgae as a source of biofuels, due to the high rates of productivity and intrinsic advantages over other biofuel crops such as not requiring land use or significant freshwater input. A wide range of conversion processes exist but anaerobic digestion was one of the first demonstrated and is still a widely proposed conversion pathway. To be economically viable and scalable within Europe, the industry will need to be based on a small number of fast growing, high-yielding European macroalgae species. There is a wide body of scientific work on the conversion of seaweeds to biofuel via anaerobic digestion. Main text: These studies demonstrate that the efficiency of this conversion pathway is highly variable between species, processing techniques, composition and digestor conditions. In this paper, we review this body of work specifically linking it to candidate species for European macroalgae bio-energy cultivation with the aim to promote the future development of the European macroalgal cultivation sector and allow for a better alignment with the requirements for biofuel production from macroalgae. Conclusions: Overall, anaerobic digestion of seaweed offers opportunities for large-scale energy production which avoids some of the issues that have faced previous generations of biofuels, but there are a number of key challenges to overcome to ensure wider adoption and economic viability. (1) Optimising the biomass production to ensure an economic and uniform feedstock with the composition optimised to increase desirable characteristics such as sugar content and the carbon and nitrogen ratio and to reduce inhibitory factors such as halogenated secondary metabolites, sulphur and heavy metals. (2) Improving conversion rates through co-digestion, pre-treatments and tailored microbial communities, using scalable and economically feasible technology. (3) Developing tailored microbial communities capable of utilising the diverse polysaccharides in seaweed feedstock and being tolerant of the saline conditions associated with them. Addressing these issues will deliver significant benefits towards the development of a bio-energy industry based on the anaerobic digestion of cultured seaweeds. [ABSTRACT FROM AUTHOR]

Biorefinery approaches offer the potential to improve the economics of the microalgae industry by producing multiple products from a single source of biomass. Chromochloris zofingiensis shows great promise for biorefinery due to high biomass productivity and a diverse range of products including secondary carotenoids, predominantly astaxanthin; lipids such as TAGs; carbohydrates including starch; and proteins and essential amino acids. Whilst this species has been demonstrated to accumulate multiple products, the development of an integrated downstream process to obtain these is lacking. The objective of this review paper is to assess the research that has taken place and to identify the steps that must be taken to establish a biorefinery approach for C. zofingiensis. In particular, the reasons why C. zofingiensis is a promising species to target for biorefinery are discussed in terms of cellular structure, potential products, and means to accumulate desirable components via the alteration of culture conditions. Future advances and the challenges that lie ahead for successful biorefinery of this species are also reviewed along with potential solutions to address them. [ABSTRACT FROM AUTHOR]

Poly-γ-glutamic acid (γ-PGA) is a bio-derived water-soluble, edible, non-immunogenic nylon-like polymer with the biochemical characteristics of a polypeptide. This Bacillus-derived material has great potential for a wide range of applications, from bioremediation to tunable drug delivery systems. In the context of oral care, γ-PGA holds great promise in enamel demineralisation prevention. The salivary protein statherin has previously been shown to protect tooth enamel from acid dissolution and act as a reservoir for free calcium ions within oral cavities. Its superb enamel-binding capacity is attributed to the L-glutamic acid residues of this 5380 Da protein. In this study, γ-PGA was successfully synthesised from Bacillus subtilis natto cultivated on supplemented algae media and standard commercial media. The polymers obtained were tested for their potential to inhibit demineralisation of hydroxyapatite (HAp) when exposed to caries simulating acidic conditions. Formulations presenting 0.1, 0.25, 0.5, 0.75, 1, 2, 3 and 4% (w/v) γ-PGA concentration were assessed to determine the optimal conditions. Our data suggests that both the concentration and the molar mass of the γ-PGA were significant in enamel protection (p = 0.028 and p < 0.01 respectively). Ion Selective Electrode, combined with Fourier Transform Infra-Red studies, were employed to quantify enamel protection capacity of γ-PGA. All concentrations tested showed an inhibitory effect on the dissolution rate of calcium ions from hydroxyapatite, with 1% (wt) and 2% (wt) concentrations being the most effective. The impact of the average molar mass (M) on enamel dissolution was also investigated by employing commercial 66 kDa, 166 kDa, 440 kDa and 520 kDa γ-PGA fractions. All γ-PGA solutions adhered to the surface of HAp with evidence that this remained after 60 min of continuous acidic challenge. Inductively Coupled Plasma analysis showed a significant abundance of calcium ions associated with γ-PGA, which suggests that this material could also act as a responsive calcium delivery system. We have concluded that all γ-PGA samples tested (commercial and algae derived) display enamel protection capacity regardless of their concentration or average molar mass. However, we believe that γ-PGA D/L ratios might affect the binding more than its molar mass. [ABSTRACT FROM AUTHOR]

Abstract The economic and environmental viability of dedicated terrestrial energy crops is in doubt. The production of large scale biomass (macroalgae) for biofuels in the marine environment was first tested in the late 1960’s. The culture attempts failed due to the engineering challenges of farming offshore. However the energy conversion via anaerobic digestion was successful as the biochemical composition of macroalgae makes it an ideal feedstock. The technology for the mass production of macroalgae has developed principally in China and Asia over the last 50 years to such a degree that it is now the single largest product of aquaculture. There has also been significant technology transfer and macroalgal cultivation is now well tried and tested in Europe and America. The inherent advantage of production of biofuel feedstock in the marine environment is that it does not compete with food production for land or fresh water. Here we revisit the idea of the large scale cultivation of macroalgae at sea for subsequent anaerobic digestion to produce biogas as a source of renewable energy, using a European case study as an example.

The health of the world's oceans is intrinsically linked to the biodiversity of the ecosystems they sustain. The importance of protecting and maintaining ocean biodiversity has been affirmed through the setting of the UN Sustainable Development Goal 14 to conserve and sustainably use the ocean for society's continuing needs. The decade beginning 2021–2030 has additionally been declared as the UN Decade of Ocean Science for Sustainable Development. This program aims to maximize the benefits of ocean science to the management, conservation, and sustainable development of the marine environment by facilitating communication and cooperation at the science–policy interface. A central principle of the program is the conservation of species and ecosystem components of biodiversity. However, a significant omission from the draft version of the Decade of Ocean Science Implementation Plan is the acknowledgment of the importance of monitoring and maintaining genetic biodiversity within species. In this paper, we emphasize the importance of genetic diversity to adaptive capacity, evolutionary potential, community function, and resilience within populations, as well as highlighting some of the major threats to genetic diversity in the marine environment from direct human impacts and the effects of global climate change. We then highlight the significance of ocean genetic diversity to a diverse range of socioeconomic factors in the marine environment, including marine industries, welfare and leisure pursuits, coastal communities, and wider society. Genetic biodiversity in the ocean, and its monitoring and maintenance, is then discussed with respect to its integral role in the successful realization of the 2030 vision for the Decade of Ocean Science. Finally, we suggest how ocean genetic diversity might be better integrated into biodiversity management practices through the continued interaction between environmental managers and scientists, as well as through key leverage points in industry requirements for Blue Capital financing and social responsibility. [ABSTRACT FROM AUTHOR]

Blue mussels (Mytilus edulis L. 1758) are important components of coastal ecosystems and in the economy of rural and coastal areas. The understanding of their physiological processes at key life stages is important both within food production systems and in the management of wild populations. Lipids are crucial molecules for bivalve growth, but their diversity and roles have not been fully characterised. In this study, traditional lipid profiling techniques, such as fatty acid (FA) and lipid class analysis, are combined to untargeted lipidomics to elucidate the lipid metabolism in newly settled spat fed on a range of diets. The evaluated diets included single strains treatments (Cylindrotheca fusiformis CCAP 1017/2 –CYL, Isochrysis galbana CCAP 927/1– ISO, Monodopsis subterranean CCAP 848/1 –MONO, Nannochloropsis oceanica CCAP 849/10– NANNO) and a commercial algae paste (SP). Spat growth was influenced by the diets, which, according to their efficacy were ranked as follows: ISO>NANNO/CYL>SP>MONO. A higher triacylglycerols (TG) content, ranging from 4.23±0.82 μg mgashfree Dry weight (DW)-1 at the beginning of the trial (T0) to 51±15.3 μg mgashfreeDW-1 in ISO, characterised significant growth in the spat, whereas, a reduction of TG (0.3±0.08 μg mgashfreeDW-1 in MONO), mono unsaturated FA–MUFA (from 8.52±1.02 μg mgFAashfreeDW-1 at T0 to 2.81±1.02 μg mgFAashfreeDW-1 in MONO) and polyunsaturated FA–PUFA (from 17.57±2.24 μg mgFAashfreeDW-1 at T0 to 6.19±2.49 μg mgFAashfreeDW-1 in MONO) content characterised poor performing groups. Untargeted lipidomics evidenced how the availability of dietary essential PUFA did not influence only neutral lipids but also the membrane lipids, with changes in lipid molecular species in relation to the essential PUFA provided via the diet. Such changes have the potential to affect spat production cycle and their ability to respond to the surrounding environment. This study evidenced the advantages of coupling different lipid analysis techniques, as each technique disclosed relevant information on nutritional requirements of M. edulis juveniles, expanding the existing knowledge on the physiology of this important species. [ABSTRACT FROM AUTHOR]

Benthic macroalgae must attach firmly to the substrate to prevent being detached and washed away by water motion. The success of the bioadhesion system can be strongly influenced by surface chemistry and so this should be optimized for large-scale cultivation. This is especially important during the early stage of cultivation when the juveniles have little thigmotactic attachment, which is needed to interlock with surface rugosity. Juvenile sporophytes of Saccharina latissima (Phaeophyceae) were directly applied onto polymer films of varied surface composition to determine how the attachment force of the developing holdfast was influenced by surface chemistry. Eight polymer chemistries were examined: polyamide (PA), polyethylene (PE), polyester (PES), polypropylene (PP), polymethylacrylate (PMA), polyvinylalcohol (PVA), polyvinylchloride (PVC) and thermoplastic polyurethane (TPU). The PP and PE were also examined as three grades: commercial grade with additives, pure polymer, or pure polymer following a corona treatment. Additive inclusion and corona significantly reduced the water contact angle (p < 0.0001), indicating an increase in the surface free energy available for bioadhesion. After 6 weeks, the attachment force was greatest on PVA, PA and PVC (0.19–0.33 N), correlating strongly with the achieved biomass (R2 = 0.68). Additives and corona treatment improved holdfast attachment force, particularly corona treated PE (0.28 ± 0.08 N: 0 N without corona). Generally, attachment force appeared greatest on chemistries with a contact angle of 60–75°. These results confirm that the bioadhesion of the phaeophyte holdfast is strongly influenced by the surface free energy of the substrate chosen. Through alteration of the additive composition, attachment could be improved to create bespoke cultivation substrates. Corona treatment is highlighted as a very suitable method for improving holdfast attachment force during cultivation. [ABSTRACT FROM AUTHOR]

Abstract Meiospores of Laminariales macroalgae must select a benthic substratum suitable for their attachment and survival, but also suitable for the development of the sessile sporophyte stage which can grow metres in length. In a controlled four month experiment, meiospores of Saccharina latissima were allowed to settle and develop on twelve different polymer surfaces. Highest meiospore settlement was seen where the attachment force of the developing macroscopic sporophytes was weak (<0.3 N), leading to the eventual detachment of the juveniles before they can grow 100 mm. The sporophyte holdfast cover (%) was strongly related to the biomass achieved (R2 = 0.68) and negatively correlated to the water contact angle (θ w) of the polymer (R2 = 0.45). Yet, meiospore settlement was positively correlated to θ w (R2 = 0.24). The study shows that the selective settlement of the meiospore conflicts with the requirements of the macroscopic sporophyte to attach firmly. It is hypothesised that higher θ w is used by kelp meiospores as a cue for recently disturbed environments, allowing gregarious settlement in areas with reduced interspecific competition. Graphical abstract Unlabelled Image Highlights • Saccharina latissima meiospores favour surfaces with high water contact angles (θ w). • The holdfast bioadhesive of the sporophytes binds weakly to high θ w surfaces. • Juvenile sporophytes are then easy detached once 100 mm, so mortality is high. • Settlement selection can conflict with the needs of the sporophyte to attach firmly. • High θ w , may indicate recently disturbed surfaces without intraspecific competition. [ABSTRACT FROM AUTHOR]

The macroalga Saccharina latissima holds promise as a widespread crop in northern Europe. Currently, seeded lines are cultured for 1–2 months within a hatchery until they become ≥1 mm sporophytes, which are then outplanted to a farm. Textiles are being developed as a cultivation substrate for macroalgae, however due to their large surface area, these need either direct in-situ seeding at the farm or a very short, high turnover hatchery period. Two materials, Kuralon twine and non-woven textile, were seeded using three S. latissima developmental stages: meiospore, gametophyte or juvenile sporophyte. The gametophyte and sporophyte stages were applied using a binder solution to adhere them to the materials. These were outplanted at a seaweed farm in the Sound of Kerrera, UK. After 5 weeks, fronds were significantly larger (45 ± 25 mm) and more abundant (20 ± 8·20 cm −1 ) when seeded with sporophytes over gametophytes or meiospores (8 ± 10 mm and 2 ± 2·20 cm −1 ). This reflects the growth advantage of outplanting juvenile sporophytes, since they are larger and more developed when outplanted. Higher fouling of filamentous algae was seen on the non-woven textile but this did not appear to affect growth. After four months, sporophyte seeded materials had the largest fronds and the greatest fresh mass of 2.1 ± 0.8 kg·20 cm −1 , equivalent to simultaneously deployed hatchery reared twine (2.0 ± 0.1 kg·20 cm −1 ). Gametophyte seeding achieved 0.8 ± 0.6 kg·20 cm −1 while meiospore seeding achieved only 0.1 ± 0.1 kg·20 cm −1 . No difference was found between growth on Kuralon twine or non-woven textile ( p  > 0.05), showing that both are suitable growth substrates. Seeding of juvenile sporophytes onto textile using the binder is demonstrated to be a successful method for the cultivation of S. latissima , and may require only 1% of the hatchery tankage, once optimised. It is expected that this method is transferable to the cultivation of other kelp species. [ABSTRACT FROM AUTHOR]

The capacity of macro-algae to remove nutrients means they have the potential to concomitantly bioremediate polluted waters and generate exploitable biomass. The influence of different nitrogen (N) regimes on growth, biochemical composition and bioremediation capacity was studied for two species of the macro-alga Cladophora . These were incubated in media containing four single N sources, ammonium (NH 4 + ), nitrite (NO 2 − ), nitrate (NO 3 − ) and urea (CO(NH 2 ) 2 ), each with four nitrogen/phosphorous (N/P) ratios, followed by equimolar dual mixtures of these N sources at two selected N/P ratios. There were clear differences in growth between species, depending upon the nutrient regime. In every instance, the daily growth rate (DGR) of Cladophora parriaudii (4.75–11.2%) was higher than that of Cladophora coelothrix (3.98–7.37%) with significance when either NO 2 − ( p = 0.025) or urea ( p = 0.002) were the employed N form. Differences in algal productivity were reflected in the corresponding N-uptake, whereby C. parriaudii consistently removed more N than C. coelothrix . There were significant differences in growth ( p = 0.005) when C. parriaudii was cultivated in a single and multi-N source medium: NH 4 + was preferentially removed from the medium, whereas urea was typically removed secondarily. However, the presence of urea in the medium enhanced the uptake of the other co-existing N forms and resulted in an increased DGR and yielded a biomass rich in carbohydrates. The relative composition of C. parriaudii varied depending upon N/P ratio of the medium, with the final proportion of protein and carbohydrate ranging from 5 to 15% and 36 to 54% per unit dry weight, respectively. Results from this study demonstrated that algal strain selection is key to treating waste-streams with specific N profiles. Additionally, the biochemical profile of the biomass produced is dependent on the alga and the N regime, providing the potential for designing processes with specific properties and products. [ABSTRACT FROM AUTHOR]

Astaxanthin from Haematococcus pluvialis is commercially produced in a two-stage process, involving green vegetative (macrozooid) and red aplanospore stages. This approach has been scaled up to an industrial process but constraints limit its commercial success and profitability, including: contamination issues, high pigment extraction costs, requirements for high light levels and photo-bleaching in the red stage. However, in addition to the aplanospore stage, this alga can produce astaxanthin in vegetative palmelloid and motile macrozooid cells. In this study, a two-stage process utilising different media in the green stage, with subsequent re-suspension in medium without nitrate was employed to optimise the formation of red motile macrozooids. Optimal growth in the green phase was obtained on cultivation under mixotrophic conditions in EG:JM media followed by re-suspension in medium without nitrate resulting in red motile macrozooids with an astaxanthin content of 2.74% (78.4% of total carotenoids) and a lipid content of 35.3% (rich in unsaturated fatty acids. It is envisaged that the red motile macrozooids could be harvested and fed as a whole-cell product directly in the animal feed and aquaculture sectors, or used as a blend of carotenoids and polyunsaturated fatty acids (PUFAs) in nutraceutical products. [ABSTRACT FROM AUTHOR]

For the cultivation of the European phaeophyte macroalgae Laminaria digitata and Saccharina latissima , meiospores are settled onto twines within a hatchery, where they are grown for several months. The twine used is often a customarily selected synthetic polymer, polyamide or polypropylene. However, little is known about the impacts of this choice on hatchery performance. To test the effect of substrate material, we settled and cultured meiospores from both L. digitata and S. latissima , independently on twelve polymer blocks for 4 mo. They were first grown for 2 mon under laboratory conditions, then a further 2 mon in outdoor tanks. Meiospore settlement varied significantly between polymers by up to 15-fold ( p < 0.0001) with some species-specific differences also observed ( p < 0.0001). Tufnol was the least suitable polymer, as formaldehyde leachate reduced settlement and inhibited juvenile growth/development. After 8 wk, all polymers excluding Tufnol, were performing similarly with generally ~ 1 mm sporophytes present at a density of 1–2 mm − 2 , A negative density-dependent effect of sporophyte size and density was observed in both species ( p < 0.05). At the end of the experiment, two distinct grouping of polymers were identified regarding S. latissima . Those that initially had very high settlement (high density polyethylene, polymethyl methacrylate, polyoxymethylene copolymer/homopolymer and polytetrafluoroethylene) had the lowest final mean lengths, % cover and biomass (< 0.2 g wet weight·block − 1 ) at the end of the experiment. Conversely many of the polymers with the lowest initial settlement (polyamide, polycarbonate, medium density polyethylene and polyvinylchloride) had the highest final mean lengths, % cover and biomass (1.7–4.9 g wet weight·block − 1 ). This reversal of fortunes is discussed regarding discriminatory meiospore settlement, differences in apparent adhesion strength of the seaweed holdfast and the transition of the growing sporophytes from a viscous force dominated boundary layer environment to a turbulent dominated environment with increasing drag as the sporophyte grows. [ABSTRACT FROM AUTHOR]

Knowledge of biofouling typical of marine structures is essential for engineers to define appropriate loading criteria in addition to informing other stakeholders about the ecological implications of creating novel artificial environments. There is a lack of information regarding biofouling community composition (including weight and density characteristics) on floating structures associated with future marine renewable energy generation technologies. A network of navigation buoys were identified across a range of geographical areas, environmental conditions (tidal flow speed, temperature and salinity), and deployment durations suitable for future developments. Despite the perceived importance of environmental and temporal factors, geographical location explained the greatest proportion of the observed variation in community composition, emphasising the importance of considering geography when assessing the impact of biofouling on device functioning and associated ecology. The principal taxa associated with variation in biofouling community composition were mussels (Mytilus edulis), which were also important when determining loading criteria. [ABSTRACT FROM AUTHOR]

The model diatom Thalassiosira pseudonana is believed to be a single species with a global distribution, but it has not been confirmed previously whether isolates from different environmental and geographic origins are genotypically and phenotypically identical. In the present study, a polyphasic approach was employed to characterize nine clonal isolates, plus an additional replicate of one of the isolates, of the diatom T. pseudonana from culture collections to investigate whether there was any cryptic speciation in the publicly available strains of this species. Morphological analysis using scanning electron microscopy concluded that the strains were indistinguishable. Furthermore, conventional DNA barcoding genes (SSU rDNA, ITS1 and ITS2 rDNA and rbcL), revealed no nucleotide variation among the strains tested. On employing a whole genome fingerprinting technique, Amplified Fragment Length Polymorphism (AFLP), three clusters were revealed, although the level of variation between the clusters was surprisingly low. These findings indicate a low level of diversity among these cultured T. pseudonana strains, despite their wide spatial and temporal distribution and the salinity range of their original habitats. Based on the limited number of available strains, this suggests that T. pseudonana is a highly conserved diatom that nevertheless has an ability to tolerate wide ranges of salinity and populate varied geographic locations. [ABSTRACT FROM PUBLISHER]

The seasonal chemical profiling of kelp species has historically either being carried out on only a single species or the data dates back over 60 years. This research highlights a detailed chemical composition profile of the four kelp species Laminaria digitata, Laminaria hyperborea, Saccharina latissima and Alaria esculenta over a 14-month period. These kelp species were selected due to their identified potential for cultivation. They were chemically characterised to identify seasonal variations and predict best harvest times. Components of interest included the carbohydrates cellulose, laminarin, alginate and mannitol as well as proteins, ash, metals, moisture, polyphenolics, total carbon and nitrogen content. The highest yields of lamianrin and mannitol coincided with the lowest yields in ash, protein, moisture and polyphenols. The implications of these observations for use of kelp species as a fermentation substrate are discussed. [ABSTRACT FROM AUTHOR]

Background. Diatoms are unicellular algae responsible for approximately 20% of global carbon fixation. Their evolution by secondary endocytobiosis resulted in a complex cellular structure and metabolism compared to algae with primary plastids. Methodology/Principal Findings. The whole genome sequence of the diatom Phaeodactylum tricornutum has recently been completed. We identified and annotated genes for enzymes involved in carbohydrate pathways based on extensive EST support and comparison to the whole genome sequence of a second diatom, Thalassiosira pseudonana. Protein localization to mitochondria was predicted based on identified similarities to mitochondrial localization motifs in other eukaryotes, whereas protein localization to plastids was based on the presence of signal peptide motifs in combination with plastid localization motifs previously shown to be required in diatoms. We identified genes potentially involved in a C4-like photosynthesis in P. tricornutum and, on the basis of sequence-based putative localization of relevant proteins, discuss possible differences in carbon concentrating mechanisms and CO2 fixation between the two diatoms. We also identified genes encoding enzymes involved in photorespiration with one interesting exception: glycerate kinase was not found in either P. tricornutum or T. pseudonana. Various Calvin cycle enzymes were found in up to five different isoforms, distributed between plastids, mitochondria and the cytosol. Diatoms store energy either as lipids or as chrysolaminaran (a β-1,3-glucan) outside of the plastids. We identified various β-glucanases and large membrane-bound glucan synthases. Interestingly most of the glucanases appear to contain C-terminal anchor domains that may attach the enzymes to membranes. Conclusions/ Significance. Here we present a detailed synthesis of carbohydrate metabolism in diatoms based on the genome sequences of Thalassiosira pseudonana and Phaeodactylum tricornutum. This model provides novel insights into acquisition of dissolved inorganic carbon and primary metabolic pathways of carbon in two different diatoms, which is of significance for an improved understanding of global carbon cycles. [ABSTRACT FROM AUTHOR]

Adhesion of raphid diatoms to natural surfaces, which is mediated by the secretion of extracellular polymeric substances (EPS), is an important strategy for growth and survival and contributes to the economically important process of biofouling. An understanding of adhesion processes requires that the genes involved in the EPS biosynthetic pathways and their regulation be characterized. Phaeodactylum tricornutum provides a model system in which to do this but the quantitative adhesion characteristics of the various morphotypes and isolates of this species are currently unknown. The present paper reports on the use of a calibrated fully turbulent flow cell to characterize the whole cell adhesion properties of morphotypes and strains of this species. It has been shown that only the oval cell morphotype adheres to a surface. There are strain/isolate differences in adhesion strength: some strains including strain Pt 1.8.6, the genome of which has been sequenced, show adhesion strengths comparable to other raphid diatoms. In common with some other raphid diatom species, adhesion strength of oval cells of some isolates of P. tricornutum was greater on a hydrophobic surface (Silastic T2 silicone elastomer), than on hydrophilic acid-washed glass. These studies provide a baseline for future molecular genetic and gene expression studies. [ABSTRACT FROM AUTHOR]

There is a general lack of genomic information available for chlorophyte seaweed genera such as Ulva, and in particular there is no information concerning the genes that contribute to adhesion and cell wall biosynthesis for this organism. Partial sequencing of cDNA libraries to generate expressed sequence tags (ESTs) is an effective means of gene discovery and characterization of expression patterns. In this study, a cDNA library was created from sporulating tissue of Ulva linza L. Initially, 650 ESTs were randomly selected from a cDNA library and sequenced from their 5′ ends to obtain an indication of the level of redundancy of the library (21%). The library was normalized to enrich for rarer sequences, and a further 1920 ESTs were sequenced. These sequences were subjected to contig assembly that resulted in a unigene set of approximately 1104 ESTs. Forty-eight percent of these sequences exhibited significant similarity to sequences in the databases. Phylogenetic comparisons are made between selected sequences with similarity in the databases to proteins involved in aspects of extracellular matrix/cell wall assembly and adhesion. [ABSTRACT FROM AUTHOR]

Green algae of the genus Ulva (syn. Enteromorpha) are common, green macroalgae found throughout the world in the upper intertidal zone of seashores and as a fouling organism on a variety of man-made structures including ships' hulls. Adhesion of motile spores is achieved via the secretion of an adhesive, which is present in spores in highly condensed form within membrane-bound vesicles. The adhesive is initially liquid and displays a hydrogel-like behavior on release. It then starts to undergo "curing reactions," becoming progressively less soluble with time in anionic detergents, less sensitive to proteolysis, and less viscoelastic, which suggests that extensive cross-linking occurs. Spores also become progressively more difficult to detach from a surface. However, the nature of this adhesive curing process is totally unknown. In the present article we have tested the hypothesis that thiol cross-linking may be involved. We show that nontoxic concentrations of the thiol-capping reagent (Ellman's reagent) or thiol-reducing agent (dithiothreitol) effectively inhibit the time-dependent development of adhesive spore strength after attachment to a surface. Furthermore, we show by SDS-PAGE immunoblot analysis of extracted adhesive proteins that the major adhesive antigen retains solubility in the presence of these reagents, after release from spores, which suggests that cross-linking had been inhibited. [ABSTRACT FROM AUTHOR]

The attachment of motile spores of the green alga Enteromorpha to the substratum is an active process involving an irreversible commitment to adhesion and the secretion of an adhesive. This paper provides an overview of the spore adhesion processes and outlines the results of an experimental approach towards the molecular characterisation of the adhesive, based on the use of monoclonal antibody (mAb) technology. Hybridomas were produced to settled spores displaying secreted adhesive. Candidates producing mAbs to putative adhesive were selected using a range of criteria based on cellular localisation, time of secretion and functional inhibition of adhesion. MAb Ent 6 immunolabelled fibrillar material which was secreted during the early stages of adhesion and low (nM) concentrations of this mAb, or its F(ab)2 fragments, strongly inhibited the attachment of zoospores. A related antibody (Ent 1) also labelled the spore adhesive apparatus, but the antigen appeared to be secreted later during the adhesion process and was predominantly associated with the developing cell wall. Ent 1 also inhibited settlement in spore adhesion assays but the effect was most pronounced at later time points which suggests that this antigen does not have a role in the earliest stages of adhesion. Immunolocalisation showed that both antigens were absent from the cytoplasm or organelles of vegetative tissue but labelled the vegetative cell wall, suggesting a relationship between cell wall components and materials involved in primary adhesion. Both mAbs labelled the Golgi region of settled spores, suggesting continued synthesis of both antigens after adhesion. Both mAbs recognised a 110 kDa N‐linked polydisperse and heterogeneous glycoprotein in extracts of swimming spores under denaturing conditions. In native form the antigens behaved as high molecular weight aggregates (Mr>1.3 × 106). The antigens became progressively insoluble after zoospore attachment. Taken together, the data suggest that the two antibodies recognise closely related, polydisperse, self‐aggregating cell wall glycoproteins in which there is some structural variation to suit alternative roles in primary adhesion and cell wall formation. The two mAbs Ent 1 and Ent 6 partially discriminate between these structural and functional variants. A model for zoospore adhesion is discussed in which adhesion is viewed as an extension of cell wall synthesis, with cross‐links between glycoproteins and other cell wall matrix components providing a strong physical continuum between the cell and the adhesive at the substratum interface. [ABSTRACT FROM AUTHOR]

Within Europe over the last 10 years, there has been an increase in seaweeds cultivated for human consumption. For food safety reasons, it is important to assess the microbiological and nutritional quality of the biomass. The fresh and dried edible seaweeds Alaria esculenta and Saccharina latissima were assessed over two consecutive years for the presence of microorganisms. Seaweed samples supplied from Scotland were stored under isothermal conditions for specific time intervals depending on the sample's condition (fresh, dried or rehydrated). During storage, microbiological analyses were performed for the enumeration of Total Viable Counts (TVC), Pseudomonas spp., Enterobacteriaceae and Bacillus spp., as well as yeasts and molds. Additionally, bacterial colonies from the Marine Agar growth medium were isolated and subjected to PCR-RAPD analysis for characterization of the bacterial diversity of seaweeds. Bacterial isolates with different fingerprint patterns were further subjected to sequencing (16S rDNA, V1–V4 region). The presence of human pathogenic bacteria was also investigated. Results showed that the initial population of TVC was differentiated depending on the year of seaweed harvest, being closer to the enumeration limit (1.0 log CFU/g) in fresh samples from 2020 and higher in samples from 2019 (6.7 and 3.9 log CFU/g in A. esculenta and S. latissima, respectively). DNA-based analysis revealed the presence of Psychrobacter, Cobetia and Pseudomonas species in A. esculenta, while Psychrobacter and Micrococcus species were present in S. latissima. [ABSTRACT FROM AUTHOR]

With more than 156,000 described species, eukaryotic algae (both macro- and micro-algae) are a rich source of biological diversity, however their chemical diversity remains largely unexplored. Specialised metabolites with promising biological activities have been widely reported for seaweeds, and more recently extracts from microalgae have exhibited activity in anticancer, antimicrobial, and antioxidant screens. However, we are still missing critical information on the distinction of chemical profiles between macro- and microalgae, as well as the chemical space these metabolites cover. This study has used an untargeted comparative metabolomics approach to explore the chemical diversity of seven seaweeds and 36 microalgal strains. A total of 1390 liquid chromatography-mass spectrometry (LC-MS) features were detected, representing small organic algal metabolites, with no overlap between the seaweeds and microalgae. An in-depth analysis of four Dunaliella tertiolecta strains shows that environmental factors may play a larger role than phylogeny when classifying their metabolomic profiles. [ABSTRACT FROM AUTHOR]

Abstract: Terrestrial crops for biofuel may make a negligible contribution to net greenhouse gas emissions [1,2] and may cause other environmental impacts such as reducing freshwater resources and food security [3]. In light of these facts there is increasing interest in the production of marine biofuels [4,5], and so the recent paper in Marine Policy by Roberts and Upham [6] reviewing the cultivation and harvest of UK and Irish seaweeds for biofuels is very pertinent and timely. However it contains a number of factual errors that need correcting and raises several issues, which need fuller clarification. These issues centre around three main themes: (1) a confusion between the occurrence and harvest of intertidal and subtidal species, (2) the relative suitability of seaweeds, and their source (wild harvest versus culture) as feedstock for biofuel generation and (3) an appreciation of the scale at which macroalgae would have to be produced to make any impact on biofuel targets. [Copyright &y& Elsevier]

Microalgae produce a variety of compounds that are beneficial to human and animal health. Among these compounds are carotenoids, which are microalgal pigments with unique antioxidant and coloring properties. The objective of this review is to evaluate the potential of using microalgae as a commercial feedstock for carotenoid production. While microalgae can produce some of the highest concentrations of carotenoids (especially astaxanthin) in living organisms, there are challenges associated with the mass production of microalgae and downstream processing of carotenoids. This review discusses the synthesis of carotenoids within microalgae, their physiological role, large-scale cultivation of microalgae, up- and down-stream processing, commercial applications, natural versus synthetic carotenoids, and opportunities and challenges facing the carotenoid markets. We emphasize legal aspects and regulatory challenges associated with the commercial production of microalgae-based carotenoids for food/feed, nutraceutical and cosmetic industry in Europe, the USA, the People's Republic of China, and Japan. This review provides tools and a broad overview of the regulatory processes of carotenoid production from microalgae and other novel feedstocks. [ABSTRACT FROM AUTHOR]