Seaweed Species Research Articles

Climate Change Amelioration by Marine Producers: Does Dominance Predict Impact?

AbstractClimate change threatens biodiversity worldwide, and assessing how those changes will impact communities will be critical for conservation. Dominant primary producers can alter local-scale environmental conditions, reducing temperature via shading and mitigating ocean acidification via photosynthesis, which could buffer communities from the impacts of climate change. We conducted two experiments on the coast of southeastern Alaska to assess the effects of a common seaweed species, Neorhodomela oregona, on temperature and pH in field tide pools and tide pool mesocosms. We found that N. oregona was numerically dominant in this system, covering >60% of habitable space in the pools and accounting for >40% of live cover. However, while N. oregona had a density-dependent effect on pH in isolated mesocosms, we did not find a consistent effect of N. oregona on either pH or water temperature in tide pools in the field. These results suggest that the amelioration of climate change impacts in immersed marine ecosystems by primary producers is not universal and likely depends on species' functional attributes, including photosynthetic rate and physical structure, in addition to abundance or dominance.

EXTRACTION AND CHARACTERISATION OF CELLULOSE FROM RED SEAWEEDS OF Hypnea musciformis AND Sarconima filliformis

The study shows a comparison of cellulose extracted from two species of red seaweeds, namely Hypnea musciformis and Sarconima filliformis. The celluloses were characterized by FTIR, XRD, TGA and SEM analyses. The studies show similarities in the characteristics of the celluloses extracted from H. musciformis and S. filliformis. FTIR analysis confirms the presence of O-H and C-H bonds in the celluloses of both species, while the XRD patterns of celluloses confirm their crystallinity, with a maximum peak at 22°. The thermal stability of the celluloses from H. musciformis and S. filliformis was observed in the range of 250 to 350 °C. The morphological structure of the celluloses was studied using SEM and both celluloses showed smooth pore-free surface.

Monitoring the stability of the xanthophyll fucoxanthin in microalga and seaweed biomasses, and extracts stored at low temperatures

The analysis of fucoxanthin (FCX) in algal biomasses presents some limitations, especially regarding the sample preservation after collection until extraction of the pigment. FCX stability was evaluated in biomass samples of one diatom and three brown seaweed species (Phaeophyceae) and their extracts stored at -20ºC and -80ºC, for 60 days. Fucoxanthin was quantified through UHPLC-DAD. The methanolic extracts of the micro/macroalga biomasses stored at -20ºC and -80ºC were more effective in preserving the xanthophyll, comparatively to the algal biomasses. Besides, the chromatographic analysis showed an increase in the FCX’s peak retention time along the sample storage, possibly due to the trans→cis isomerization of the molecule. Such information is relevant for choosing the best protocol for storing and preserving at most FCX, because changes in the geometric conformations of the molecule over storage strongly affects its biological activities.

Antifibrosis Efficacy of Apo-9-Fucoxanthinone-Contained Sargassum horneri Ethanol Extract on Nasal Polyp: An In Vitro and Ex Vivo Organ Culture Assay.

Sargassum horneri is a seaweed species with diverse bioactivities. However, its antifibrotic effects during nasal polyp (NP) formation are not clearly understood. Therefore, we investigated the inhibitory effect of S. horneri on fibrosis progression in NP-derived fibroblasts (NPDFs) and NP tissues ex vivo. NPDFs were stimulated with TGF-β1 in the presence or absence of S. horneri ethanol extract (SHE). The extracellular matrix (ECM) protein production levels, myofibroblast differentiation (α-smooth muscle actin, α-SMA), and phosphorylation of Smad 2/3 and -ERK in TGF-β1-stimulated NPDFs were investigated using western blotting. Further, the contractile activity of SHE was assessed by performing a collagen gel contraction assay. The expression levels of collagen-1, fibronectin, and α-SMA were investigated in NP organ cultures treated with SHE. TGF-β1 stimulated ECM protein expression, myofibroblast differentiation, and collagen contractile activity while these were attenuated by pretreatment with SHE. We also found antifibrotic effect of SHE on ex vivo NP tissues. The antifibrotic effects of SHE were modulated through the attenuation of Smad 2/3 and ERK signaling pathways in TGF-β1-stimulated NPDFs. In conclusion, SHE inhibited ECM protein accumulation and myofibroblast differentiation during NP remodeling. Thus, SHE may be helpful as a treatment for NP recurrence after endoscopic sinus surgery.

Predicting non-native seaweeds global distributions: The importance of tuning individual algorithms in ensembles to obtain biologically meaningful results

Modelling non-native marine species distributions is still a challenging activity. This study aims to predict the global distribution of five widespread introduced seaweed species by focusing on two mains aspects of the ensemble modeling process: (1) Does the enforcement of less complex models (in terms of number of predictors) help in obtaining better predictions? (2) What are the implications of tuning the configuration of individual algorithms in terms of ecological realism? Regarding the first aspect, two datasets with different number of predictors were created. Regarding the second aspect, four algorithms and three configurations were tested. Models were evaluated using common evaluation metrics (AUC, TSS, Boyce index and TSS-derived sensitivity) and ecological realism. Finally, a stepwise procedure for model selection was applied to build the ensembles. Models trained with the large predictor dataset generally performed better than models trained with the reduced dataset, but with some exceptions. Regarding algorithms and configurations, Random Forest (RF) and Generalized Boosting Models (GBM) scored the highest metric values in average, even though, RF response curves were the most unrealistic and non-smooth and GBM showed overfitting for some species. Generalized Linear Models (GLM) and MAXENT, despite their lower scores, fitted smoother curves (especially at intermediate complexity levels). Reliable and biologically meaningful predictions were achieved. Inspecting the number of predictors to include in final ensembles and the selection of algorithms and its complexity have been demonstrated to be crucial for this purpose. Additionally, we highlight the importance of combining quantitative (based on multiple evaluation metrics) and qualitative (based on ecological realism) methods for selecting optimal configurations.

Red seaweed extracts reduce methane production by altering rumen fermentation and microbial composition in vitro.

A series of in vitro batch culture incubations were carried out to investigate changes in rumen fermentation characteristics, methane (CH4) production, and microbial composition in response to supplementation with five different red seaweed species (Amphiroa anceps, AANC; Asparagopsis taxiformis, ATAX; Chondracanthus tenellus, CTEN; Grateloupia elliptica, GELL; and Gracilaria parvispora, GPAR). Prior to the incubations, the total flavonoid and polyphenol content of the red seaweed extracts was quantified. The incubated substrate consisted of timothy hay and corn grain [60:40 dry matter (DM) basis]. Treatments were substrate mixtures without seaweed extract (CON) or substrate mixtures supplemented with 0.25 mg/mL of red seaweed extract. Samples were incubated for 6, 12, 24, 36, and 48 h. Each sample was incubated in triplicates in three separate runs. In vitro DM degradability, fermentation parameters (i.e., pH, volatile fatty acids, and ammonia nitrogen), total gas production, and CH4 production were analyzed for all time points. Microbial composition was analyzed using 16S rRNA amplicon sequencing after 24 h of incubation. The highest CH4 reduction (mL/g DM, mL/g digested DM, and % of total gas production) was observed in ATAX (51.3, 50.1, and 51.5%, respectively, compared to CON; P < 0.001) after 12 h of incubation. The other red seaweed extracts reduced the CH4 production (mL/g DM; P < 0.001) in the range of 4.6-35.0% compared to CON after 24 h of incubation. After 24 h of incubation, supplementation with red seaweed extracts tended to increase the molar proportion of propionate (P = 0.057) and decreased the acetate to propionate ratio (P = 0.033) compared to the CON. Abundances of the genus Methanobrevibacter and total methanogens were reduced (P = 0.050 and P = 0.016) by red seaweed extract supplementation. The linear discriminant analysis effect size (P < 0.05, LDA ≥ 2.0) showed that UG Succinivibrionaceae, Anaeroplasma, and UG Ruminococcaceae, which are associated with higher propionate production, starch degradation, and amylase activity were relatively more abundant in red seaweed extracts than in the CON. Our results suggest that supplementation with red seaweed extracts altered the microbiota, leading to the acceleration of propionate production and reduction in CH4 production.

Comparative analysis of proximate compositions, mineral and functional chemical groups of 15 different seaweed species

Seaweed is a popular edible source and is associated with many foods and pharmaceutical industries around the world. The current research aims to provide information on the chemical composition of 15 seaweed species, consisted of Chlorophyta, Ochrophyta/Phaeophyceae, and Rhodophyta macroalgae, collected from coastal areas of Sri Lanka. Seaweed samples were subjected to the analysis of lipids, proteins, ash and macro, micro, trace and ultra-trace elements. The highest protein content was recorded in the brown algae. Maximum dietary fiber and ash contents were recorded from green algae. The highest predominant fatty acids were observed from green seaweeds (Caulerparacemosa); however, linoleic acid (C18:2n6) is the dominant fatty acid of all macroalgae. Mineral contents were highest in the red macroalga; however, copper, zinc and magnesium were also comparatively higher in green alga Ulvalactuca. In conclusion, 15 seaweed species belonging to the three different classes of seaweeds are investigated in details to obtain their biochemical, mineral and fatty acid compositions for the synthesis of novel therapeutic agents. In order to explore biorefinery processes for these seaweeds, as well as how they can potentially be cultivated, more extensive studies are required. Studying and determining the nutritional values of seaweeds will be beneficial with the potentials for future industrial uses and research.

Evaluation of rumen in vitro gas production and fermentation characteristics of four tropical seaweed species

Studies on the identification and characterization of numerous seaweed species from tropical oceans have not been widely reported. The objective of this study was to evaluate the rumen in vitro gas production and fermentation characteristics of four tropical seaweed species. The design of treatments was a randomized complete block design with four different seaweed species (brown seaweed: Laminaria sp. and Padina australis; red seaweed: Gracilaria sp. and Eucheuma cottonii) and four replications for each treatment. For the gas production, easily degraded fraction (a), potentially degraded fraction (b), rate of gas production of b fraction (c), and total fraction degraded (a+b) parameters of brown seaweed were higher and faster than those of red seaweed. The lowest methane production at 24 hours incubation was obtained for Gracilaria sp., which reduced methane production from blank (44.38%) and standard (Pangola substrate) samples (60.63%), followed by Padina australis at 28.98 and 49.73% respectively. Padina australis resulted in the highest propionate proportion (16.03%), lowest butyrate (11.92%) and A:P ratio (4.52) (P&lt;0.05). There were no differences in NH3 (34.17-37.31 mg/100 mL) or microbe protein concentration (9.03-10.60 mg/100 mL) among the seaweed species. It was concluded that brown seaweed (Laminaria sp. and Padina australis) were more degradable than red seaweed (Gracilaria sp. and Eucheuma cottonii) in the rumen. Padina australis is the most potential as ruminant feed because it resulted in the highest propionate proportion, the lowest butyrate and A:P ratio, and low methane production and did not disturb the NH3 and microbe protein concentrations.

A comparative study on pre-treatment methods for enhanced saccharification from tropical seaweeds to aid in bioethanol production

The selection of suitable pretreatment strategy that facilitates saccharification is the most critical step in the valorisation of seaweed biomass into bioethanol. Considering the scarcity of data on the comparative efficacy of different pretreatments particularly in tropical seaweed species, 50 pretreatment strategies were analysed on three major species representing all the three broad seaweed categories, viz. Ulva fasciata (green algae), Sargassum wightii (brown algae), and Gracilaria corticata (red algae). An improved release of reducing sugars was observed in all the tested pretreatments, with different conversion ratios for different species in each pretreatment. Ultrasonication and magnetic stirring showed maximum yield among physical pretreatments. In thermal methods, microwave oven incubation resulted in maximum yield from both U. fasciata and S. wightii, while it was autoclaving for G. corticata. Sulphuric acid was the best chemical for U. fasciata and G. corticata, while it was orthophosphoric acid for S. wightii. Hydrochloric acid was the best chemical for physicothermochemical pretreatment in all species. Maximum conversion ratios of 2.58, 2.11, and 2.0 were recorded in U. fasciata, G. corticata, and S. wightii respectively. In short, the paper sketches the best pretreatment method for three major tropical seaweeds along with their proximate composition. The results can be applied for aiding the valorisation of biomass of these seaweeds through a cost-effective manner.

KOMPOSISI PROKSIMAT RUMPUT LAUT HIJAU ASAL PANTAI TELUK SEPANG KOTA BENGKULU

Green seaweesd has a high abundance in Indonesia, including on Teluk Sepang Beach, Bengkulu City. However, until now, there is no information about the composition of the green seaweeds from Teluk Sepang Beach, Bengkulu City. This research was held to determine proximate composition of dry green seaweeds from Teluk Sepang Beach, Bengkulu City. This research was conducted from November 2021-April 2022. Green seaweeds was taken from Teluk Sepang Beach. Sample preparation and moisture content were carried out at the Fisheries Laboratory, and for other proximate analyzes (ash content, protein content, fat content, carbohydrate content, and crude fiber) were carried out at the Animal Husbandry Laboratory. The methode of moisture content, ash content, fat content, protein content, and crude fiber refer to the AOAC (2016), while the carbohydrate content based on by difference which refers to FAO (2002). From 6 species of green seaweeds, the largest composition is carbohydrates (27.44±2.80%-50.49±3.27%) and ash (12.23±0.44%-41.22±0.06%) which plays an important role in the intake of nutrients for humans and the food industry. The protein content (0.50±0.03%-4.81±0.17%) and crude fat (0.40±0.00%-2.40±0.30%) is relatively low, so green seaweeds is good for health. Crude fiber (1.37±0.00%-6.26±0.10%.) is relatively low, but not different from several existing studies.Keywords:green seaweeds, proximate composition, Teluk Sepang Beach

Valorization of the chemical diversity of the tropical red seaweeds Acanthophora and Kappaphycus and their applications in aquaculture: A review

The role that seaweeds play as primary producers and ecosystems engineers in marine coastal ecosystems is widely acknowledged. Seaweeds, however, are also important drivers in the development of the blue bioeconomy due to their vast diversity of unique chemicals with a broad range of industrial and biotechnological applications. In tropical regions, seaweed production has been focused on a few species only, because of their hydrocolloids used in the food industry. There is a strong need to identify new applications of red seaweed species in other sectors such as aquaculture. Therefore, to diversify the culture of red seaweeds, more tropical species need to be investigated for their chemical composition and potential application in aquaculture, and then, to develop a method for a sustainable cultivation of new seaweed candidates and enhance their economic potential. Based on this context, we analyze the potential value of the red edible seaweed Acanthophora spp., an under-valued seaweed species which is naturally abundant in tropical countries, and Kappaphycus spp., a commercially valuable seaweed commonly used for polysaccharide extraction. The vast chemical diversity of seaweeds (polysaccharides, phytohormones, amino acids, and pigments) has led to research on a wide range of applications in aquaculture, including pathogen control, immunostimulant, antioxidant, bioremediation, feed, UV protectants, increase in seafood shelf life, animal colorant, and growth regulator for microalga culture. This review hopes to stimulate the interest among seaweed researchers to investigate other local seaweed species and seek greater added value of their biomass and chemical compounds and their applications in the aquaculture sector. Additionally, this information will help stakeholders to benefit from these two red seaweeds by contributing to the diversification of the blue bioeconomy in tropical countries.

Element pattern in two dominant species of seaweed from Betsukari coastline - Mashike, Hokkaido, Japan

The present study investigated the monthly of element accumulation in seaweeds. Patterns of As, Ba, Cd, Cu, Fe, Mn, Pb, and Zn concentrations in dominant species of Phaeophyceae and Rhodophyceae, namely Saccharina japonica and Pterocladiella tenuis respectively, collected from the Betsukari coastline-Mashike, Hokkaido, Japan, were investigated. Our results indicated that element accumulation was more related to specific seaweed species than to their supply in seawater concentration. S. japonica was found to be an accumulator of As, whereas P. tenuis notably accumulated Mn. The accumulation of specific elements also affects the coupled patterns between closely related elements. The monthly pattern of Cd was similar to that of As in S. japonica, and it is an element with unknown biological function in the seaweed. The monthly accumulation pattern of Fe and Mn, a well-known closely related element that forms the extracellular surface in seaweed, was found to be similar in P. tenuis. A similar transport mechanism affected the antagonistic pattern of Cd and Zn accumulation in S. japonica. Our data can be employed in the assessment of biomonitoring of element cycles in the environment.

Sea Anemone Aiptasiomorpha minuta (Verrill, 1867) as a Possible Agent to Control Biofouling in Oyster Culture and the Optimal Conditions for Its Mass Rearing under Laboratory Conditions

The potential use of the sea anemone Aiptasiomorpha minuta as an agent for controlling biofouling on cultured oysters and the optimum culture conditions for its mass culture were evaluated. Field experiments showed that nineteen species (eight phyla), including two seaweed species, sponges, hydroids, bryozoans, mollusk/bivalve species, barnacles, and tunicates were found as biofouling assemblages on the oyster collectors. The ability of A. minuta to accumulate biomass on oyster collectors, thus, minimizing colonization by problem species; was also demonstrated to promote better oyster growth, condition index, and survival. Favorable mass culture conditions of A. minuta in laboratory trials were found at 28 °C, fed with Artemia salina (1000 individuals/day), and at 23 psu for the optimum temperatures, diet regimen, and salinity, respectively. These mass culture conditions could be useful for the purpose of producing enough biomass for attaching the sea anemones, A. minuta, to oyster collectors. The use of A. minuta could be a preventive strategy against biofouling that may be useful for oyster farmers; it is safe from the viewpoint of food hygiene, and is also environment-friendly.

Ecofriendly Bioremediation of Water: Repurposed Macroalgae Removes Eliminates and Neutralizes Heavy Metals

As pollutant contamination in water becomes more and more common, the adverse effects of water pollution is increasingly perceptible, as demonstrated by the destruction of various aquatic ecosystems and pollutant-caused illnesses in humans. Thus, it is pertinent to discover a cost-effective and efficient method that is able to reduce concentrations of water-based pollutants. Current systems in place to remove heavy metal contaminants from the water include chemical chelation, coagulation, and ion exchange, but each have their own pitfalls and are all relatively expensive. Previous research has demonstrated that specific species of seaweeds can absorb water-based pollutants; however, there are limited studies that have tested whether certain species of seaweeds can naturally metabolize and thus neutralize such pollutants after being absorbed. Therefore, this study aims to study the seaweed Sargassum and its ability to metabolize and neutralize iron, a common heavy metal water-based pollutant. Sargassum seaweed was cultured with and without iron, and at varying concentrations of iron, for two weeks to allow for Sargassum growth and thus absorption of the iron. A brine shrimp lethality bioassay was used to compare the cytotoxicity of the water treated with Sargassum against water untreated with Sargassum, thus indirectly measuring relative iron toxicity and concentration. Artemia cysts were put into 24 well plates, and the hatch rate and survival rate of Artemia was calculated in 12-hour increments up to the 48 hour mark. The brine shrimp lethality bioassay demonstrated that Artemia within Sargassum treated water have an increased hatch rate and survival rate compared to Artemia within water untreated with Sargassum. Artemia fed with Sargassum also demonstrated similar survival rates as Artemia within Sargassum treated water. This indicates that Sargassum can absorb iron contaminants from the water and naturally metabolize the iron into a non-toxic form. As Sargassum is readily cheap to obtain and grow, Sargassum serves as a promising cost-effective and efficient alternative to conventional methods of water-based pollutant absorption.

Prospects of dietary seaweeds and their bioactive compounds in sustainable poultry production systems: A symphony of good things?

Modern poultry production systems face numerous economic, environmental, and social sustainability challenges that threaten their viability and acceptability as a major source of animal protein. As scientists and producers scramble to find cost-effective and socially acceptable solutions to these challenges, the dietary use of marine macroalgae (seaweeds) could be an ingenious option. Indeed, the incredible array of nutritive and bioactive compounds present in these macroscopic marine organisms can be exploited as part of sustainable poultry production systems of the future. Incorporating seaweeds in poultry diets could enhance feed utilization efficiency, growth performance, bird health, meat stability and quality, and consumer and environmental health. Theoretically, these benefits are mediated through the putative antiviral, antibacterial, antifungal, antioxidant, anticarcinogenic, anti-inflammatory, anti-allergic, antithrombotic, neuroprotective, hypocholesterolemic, and hypoglycemic properties of seaweed bioactive compounds. Despite this huge potential, exploitation of seaweed for poultry production appears to be constrained by a variety of factors such as high fibre, phenolics, and ash content. In addition, conflicting findings are often reported when seaweeds or their extracts are used in poultry feeding trials. Therefore, the purpose of this review paper is to collate information on the production, phytochemical components, and nutritive value of different seaweed species. It provides an overview ofin vivoeffects of dietary seaweeds as measured by nutrient utilization efficiency, growth performance, and product quality and stability in poultry. The utility of dietary seaweeds in sustainable poultry production systems is explored, while gaps that require further research are highlighted. Finally, opportunities that exist for enhancing the utility of seaweeds as a vehicle for sustainable production of functional poultry products for better global food and nutrition security are presented.

Optimization of nucleic acid extraction and amplification of a thiamine biosynthesis gene fragment from selected Malaysian seaweeds.

Obtaining high-quality nucleic acid extracted from seaweeds is notoriously difficult due to contamination with polysaccharides and polyphenolic compounds after cell disruption. Specific methods need to be employed for RNA isolation in different seaweed species, and therefore studies of the thiamine biosynthesis pathway have been limited. Two selected Malaysian species which are highly abundant and underutilized, namely Gracilaria sp. and Padina sp., representing the red and brown seaweeds, respectively, were collected to develop optimized total RNA extraction methods. Prior to that, DNA was extracted, and amplification of the 18S rRNA gene and the THIC gene (encoding the first enzyme in the pyrimidine branch of the thiamine biosynthesis pathway) from the DNA template was successful in Gracilaria sp. only. RNA was then extracted from both seaweeds using three different existing methods, with some modifications, using cetyltrimethylammonium bromide, guanidine thiocyanate and sodium dodecyl sulphate. Methods I and III proved to be efficient for Padina sp. and Gracilaria sp., respectively, for the extraction of highly purified RNA, with A260/A280 values of 2.0 and 1.8. However, amplification of the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase and the THIC gene was successful in only Gracilaria sp. cDNA derived from extracted RNA. Further modifications are required to improve the exploitation of nucleic acids from brown seaweeds, which has been proven to be difficult. This work should pave the way for molecular studies of seaweeds generally and for the elucidation, specifically, of the thiamine biosynthesis pathway.

Evaluation of Different Brown Seaweeds as Feed and Feed Additives Regarding Rumen Fermentation and Methane Mitigation

This study investigated the impacts of different brown seaweed species—Ascophyllum nodosum, Sargassum fulvellum, Ecklonia maxima, Lessonia flavicans, Lessonia nigrescens, and Laminaria japonica—on rumen fermentation and methane (CH4) mitigation. The current in vitro batch culture study for 24 h at 39 °C evaluated these species in two experimental designs: as feed additive and as feed. The control group for both experimental designs was composed of 500 mg of basal diet (50% grass hay/50% concentrate). For the feed additives experimental design, each seaweed species was evaluated when it was added at 20% of the basal diet, while as a feed, the inclusion level of each species was 20% to partially replace the concentrate in the basal diet as follows (50% hay/30% concentrate/20% seaweed). Chemical analyses showed that the seaweeds were characterized by a high fiber content and high amounts of minerals such as calcium, potassium, and phosphorus, while the protein content ranged within 7 and 13%. When they were applied as feed additives, they increased the production of volatile fatty acids, with L. japonica being the most effective; however, they failed to suppress CH4 production. In contrast, their inclusion as a feed in the basal diet led to a significant reduction (p &lt; 0.05) in CH4, especially for E. maxima and L. japonica, by up to 18 and 21%, respectively, but this was associated with general inhibition of the rumen fermentation. Therefore, the tested seaweeds could be used as a source of minerals and as a feed additive to improve rumen fermentation, but without anti-methanogenic potential. Meanwhile, their inclusion as feed at 20% could reduce CH4 production with an adverse effect on fermentation. Thus, further trials are needed to identify the appropriate inclusion level to achieve effective CH4 reduction without any detrimental effects on rumen fermentation.

Thermogravimetric Analysis of Marine Macroalgae Waste Biomass as Bio-Renewable Fuel

Macroalgae are considered as the 3rd generation of biofuels and a future feedstock for biorefinery. This research aims to provide simple and dependable analytical techniques for measuring the thermal characteristics of dried seaweed. The main objective was to investigate the thermal characteristics of four seaweed species utilizing a thermogravimetric analyzer. The seaweeds Gracilaria fisheri, Caulerpa lentillifera, Ceramium rubrum, and Eucheuma cottonii were collected from the Pahang state of Peninsular Malaysia. The calorific value of the samples was revealed by using a calorimeter. Ceramium rubrum showed the highest calorific value, while Gracilaria fisheri had the most negligible calorific value among the selected samples. The thermogravimetric analysis (TGA) data revealed that the most significant weight loss for this biomass occurred between 160 and 300° for the selected species. Gracilaria fisheri has shown the highest decomposition with the minor residue at 30.26%, whereas Caulerpa lentillifera has a slow weight loss rate in the mentioned range. SEM analysis has been used to perform the morphology of samples, which shows differences in the concentration of epiphytic diatoms with different structural shapes. Based on the results, macroalgae is a promising sustainable biomass feedstock for biofuel application.

Proximate Composition, Physicochemical and Microbiological Characterization of Edible Seaweeds Available in the Portuguese Market.

The aim of this work was the study of the proximate composition and profile of fatty acids, minerals, and some microbiological aspects of four edible seaweed species (Chondrus crispus, Palmaria palmata, Porphyra sp., and Ulva sp.) available in the Portuguese market for food consumption, and produced in a national Integrated Multi-Trophic System (IMTA). Moisture, ash, and total lipids were determined gravimetrically. Crude protein was analysed by Duma's combustion procedures. The total carbohydrate content was assayed by the phenol/sulphuric acid method. The assessment of the fatty acids methyl esters (FAMEs) was determined through GC-MS. Characterization of elemental analysis was performed by ICP-AES. Different standard microbiological methods were applied for microorganisms. Statistics were performed using the non-parametric Mann-Whitney U test to assess significant differences between samples. Lipid contents (n = 3) were very low (1.6-2.3%), particularly in Palmaria palmata, and Chondrus crispus (1.6-1.7%). The protein content (n = 4) varied from 14.4% in P. palmata to 23.7% in Porphyra sp. Carbohydrates (n = 3) were the major constituent of most seaweeds (31-34%), except in Porphyra sp., with higher content in proteins than carbohydrates. Regarding the fatty acid content (n = 4), in general, saturated fatty acids (SFAs) were the most abundant followed by polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs). Among macro and trace elements (n = 3), Chondrus crispus shows the highest average content in Zn (71.1 mg ⋅ kg - 1 D.W.), Palmaria palmata the highest average content in K (124.8 g ⋅ kg - 1 D.W.), Porphyra sp. the highest average content in P (2.1 g ⋅ kg - 1 D.W.), and Ulva sp. the highest average content of Ca (5.5 g ⋅ kg - 1 D.W.), Mg (55.8 g ⋅ kg - 1 D.W.), and Fe (336.3 mg ⋅ kg - 1 D.W.). In general, Na and K were the most abundant elements among analysed seaweed. Additionally, the microbiological results (n = 4) comply with the Portuguese guidelines (subgroup 2D) on the application of general principles of food hygiene in ready-to-eat foods. Overall, the results highlight the potential of using these seaweeds as an alternative and sustainable source of elements and bioactive compounds to produce enriched food products with a beneficial potential for human nutrition.

In Vitro Anti-Inflammatory Activities of Fucoidans from Five Species of Brown Seaweeds.

This study aimed to compare the anti-inflammatory effects of fucoidans from brown seaweeds (Saccharina japonica (SJ), Fucus vesiculosus (FV), Fucus distichus (FD), Fucus serratus (FS), and Ascophyllum nodosum (AN)), and determine the relationship between composition and biological activity. The anti-inflammatory activity was tested in vitro. It is believed that inflammation could be triggered by free radicals. Fucoidans from F. vesiculosus (FV1 and FV3) showed the strongest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity with an IC50 = 0.05 mg/mL. In the total antioxidant capacity (TAC) test, the activity was concentration-dependent. Notable, the TAC of fucoidans except samples of FV2 and SJ (which have a lower phenolic content) was higher than that of phloroglucinol. The TAC of fucoidans strongly and positively correlated with polyphenol content. A weak correlation was associated with xylose content. The synergistic effect for fucoidans was calculated for the first time using carbohydrates and polyphenols as model mixtures. The synergy in the DPPH test was found only for FV1 and FV3 (mixture effect ME = 2.68 and 2.04, respectively). The ME strongly positively correlated with polyphenols. The relationship of ME with fucose content was positive but moderate. It was first established that the anti-inflammatory effects of fucoidan could be mediated via the inhibition of protein denaturation. The inhibition was concentration-dependent and strongly correlated with the fucose content and moderate with sulfate content. The purified fucoidan FV2 showed the most promising activity (IC50 = 0.20 mg/mL vs. IC50 = 0.37 mg/mL for diclofenac sodium). Similar relations were also observed in the membrane protection model. Fucoidans were able to stabilize the cell membrane integrity of human red blood corpuscles (HRBC). The results of our study support the rationality of fucoidan use as a promising agent for the treatment of inflammatory-related diseases via mechanisms of radical scavenging, antioxidant activity, inhibition of protein denaturation, and HRBC membrane stabilization.