Enteromorpha Research Articles

Algal Growth and Morphogenesis-Promoting Factors Released by Cold-Adapted Bacteria Contribute to the Resilience and Morphogenesis of the Seaweed Ulva (Chlorophyta) in Antarctica (Potter Cove)

AbstractMacroalgae are found in a variety of marine vegetation ecosystems around the world, contributing significantly to global net primary production. In particular, the sea lettuce species, i.e., members of the genus Ulva (Chlorophyta), are located in many ecological niches and are characterized by excellent adaptability to environmental changes but depend on essential associated bacteria, which release algal growth and morphogenesis-promoting-factors (AGMPFs). Our work investigated the hypothesis that bacteria need to be stress-adapted to provide sufficient amounts of AGMPFs for the growth and morphogenesis of Ulva throughout its life cycle, even under severe environmental conditions. Our study thus aimed to understand which bacteria contribute to overcoming a variety of stressors in polar regions. Green macroalgae were collected from Potter Cove, King George Island (Isla 25 de Mayo), Antarctica, to study the associated microbiome and, subsequently, to identify AGMPFs releasing bacteria. Therefore, microbiome analysis was combined with morphogenetic bioassays and chemical analysis, identifying bacteria essential for algal growth under Antarctic conditions. Hereby, axenic cultures of Ulva compressa (cultivar Ulva mutabilis, Ria Formosa, Portugal), previously developed as a model system for bacteria-induced algal growth and morphogenesis, were inoculated with freshly isolated and cultivable Antarctic bacteria to determine their morphogenetic activity. The exploratory microbiome investigation identified numerous cold-adapted AGMPF-producing bacteria. Unlike the temperate-adapted bacterial strains originally isolated from the U.mutabilis holobiont, the cold-adapted isolates Maribacter sp. BPC-D8 and Sulfitobacter sp. BPC-C4 released sufficient amounts of AGMPFs, such as thallusin and still unknown compounds, necessary for the morphogenesis of the Antarctic Ulva even at 2 °C. Our results illustrate the role of chemical mediators provided by bacteria in cross-kingdom interactions under cold conditions within aquatic systems. The newly isolated bacteria will enable further functional studies to understand the resilience of the holobiont Ulva and might be applied in algal aquaculture even under adverse conditions. The study highlights the importance of eco-physiological assays in microbiome analysis.

A new method for protein extraction from sea lettuce (Ulva fenestrata) via surfactants and alkaline aqueous solutions

Alternative protein sources such as seaweed can help relieve the pressure on land-based protein supply. This proof-of-concept study developed an extraction method to recover soluble and lipophilic proteins from the seaweed Ulva fenestrata. The method consisted of processing U. fenestrata with 0.1–0.5 % aqueous Triton X-114 solution and reprocessing the pellet with an alkaline aqueous solution. Then, the solubilized proteins were precipitated via acidification. The new method extracted 3.4-times more protein, measured as total amino acids, compared to the control with two alkaline aqueous extraction cycles. Triton disrupted the chloroplasts and likely solubilized lipophilic membrane proteins as supported by microstructure and polypeptide pattern analysis. Triton-derived protein extracts contained lipids inside the precipitates/aggregates and were richer in fatty acids typical of photosynthetic membranes. The higher extraction yields are proposed to result from membrane charge neutralization upon acidification, triggering interactions between the membrane lipids and their subsequent precipitation with the lipophilic membrane protein.

Ulva sp.'nin aktif bileşiklerinin elde edilmesi için ekstraksiyon koşullarının optimizasyonu

Ulva sp., a green macroalgae known as sea lettuce, is rich in polysaccharides, proteins, minerals, and bioactive compounds with antimutagenic, anticoagulant, anticancer, anti-inflammatory, antibacterial, and nutraceutical properties. Its abundance along the Aegean Sea coast poses an environmental challenge, as it is often disposed of as waste. However, Ulva sp. holds potential for high-value products in cosmetics and dietary supplements. Optimizing the extraction of its bioactive compounds using response surface methodology involved adjusting ethanol concentration, solid/liquid ratio, and extraction time. Key responses evaluated included yield, total polysaccharides, total protein, total phenol, total antioxidant activity, alpha-glucosidase inhibitory activity, and yeast cell glucose uptake. In this study, extraction yields ranged from 0.86% to 22.47% based on variations in extraction conditions. The highest total protein content was 106.88 mg BSA/g dry extract, while the polysaccharide content was determined to be 15.42%. The highest values for total phenol content and antioxidant capacity were found to be 82.15 mg GAE/g dry extract and 63.63 mg Trolox/g dry extract, respectively. The determination of the total amounts of antioxidants and phenolic compounds in extracts may expand their potential applications. In addition, the potential application of Ulva sp extracts as inhibitors for the treatment of diabetes has been demonstrated through experiments assessing both alpha-glucosidase enzyme inhibition and glucose uptake in yeast cells. The results support an environmentally friendly approach for the utilization of Ulva sp. from waste into valuable antidiabetic products.

Brining as an effective method to stabilise sea lettuce (Ulva fenestrata) -impact on colour, texture, chemical characteristics and microbial dynamics

Brining as a cost-effective stabilising method to preserve the quality of fresh Ulva fenestrata was studied. The brines contained from 0 to 25 % (w/w) of sodium chloride or from 0 to 50 % sucrose and were combined with seaweed at a ratio of 1: 10 (w/v) prior to storage at 4 °C for up to 3 months. During this storage, the water activity of U. fenestrata was reduced from 0.94 to ≤0.89 with ≥15 % salt brines, which kept the microbial load <7 log (CFU/g) for 78 days. Among the sucrose brines, 50 % provided microbial shelf life <7 log (CFU/g) for 48 days. Further, 25 % salt or 50 % sucrose brines effectively retained the greenness (a*) of the U. fenestrata blades (< −20 a*-value for 80 days), while the tensile strength was only retained with 25 % salt brine (>3 Newton for 80 days). There was a time-dependent loss of crude proteins and fatty acids during storage, especially for 50 % sugar brined seaweed, where 58 % and 28 %, respectively, were lost after 20 days. Nutrients were best preserved in the 5 % salt-brine. Overall, the results indicate that brining with 25 % salt or 50 % sugar yields microbial stability and maintained colour of U. fenestrata for at least 48 days, with the former even exceeding 78 days at 4 °C, however, at a cost of nutritional value.

Sensory and consumer aspects of sea lettuce (Ulva fenestrata) – impact of harvest time, cultivation conditions and protein level

The green seaweed Ulva fenestrata is a future food candidate, however, both compositional, e.g. protein content, and sensory qualities depend on cultivation and harvest conditions. The aim was to explore sensory qualities of, and consumer attitudes to, U. fenestrata derived from three different cultivation conditions and three harvest times. U. fenestrata was cultivated at sea and in two different land-based tank settings, one mimicking seawater and one with added process water from fishing industry to increase protein content. The seaweed was subjected to sensory analysis performed by an analytical sensory panel and a focus group consisting of consumers. The former assessed the seaweed as dried whole blades (9 samples) and as emulsions (9 samples). Consumers assessed whole blades and a vegan spread enriched with powdered U. fenstrata. All seaweed samples were intensely green; had tastes of umami, salt, bitter, and sour; odours and flavours of grass and fresh seaweed; and had a crispy texture. Cultivation in tanks resulted in a crispier texture than sea cultivation (p<0.001). Protein content increased from 14.4% to 21.6% in tank cultivation with process waters, which increased green colour intensity (p<0.007) and decreased intensity of bitterness (p<0.001). Overall, consumers were positive towards seaweeds as foods.

Enhancing Flame Retardancy and Smoke Suppression in EPDM Rubber Using Sepiolite-Based Systems.

The burning of Ethylene-Propylene-Diene Monomer (EPDM) rubber generates substantial smoke, posing a severe threat to the environment and personal safety. Considering the growing emphasis on safety and environmental protection, conventional non-smoke-suppressing flame retardants no longer satisfy the present application requirements. Consequently, there is an urgent need to develop a novel flame retardant capable of suppressing smoke formation while providing flame retardancy. Sepiolite (SEP), a porous silicate clay mineral abundant in silica and magnesium, exhibits notable advantages in the realm of flame retardancy and smoke suppression. This research focuses on the synthesis of two highly efficient flame-retardant smoke suppression systems, namely AEGS and PEGS, using Enteromorpha (EN), graphene (GE), sepiolite (SEP), ammonium polyphosphate (APP), and/or piperazine pyrophosphate (PPAP). The studied flame-retardant systems were then applied to EPDM rubber and the flame-retardant and smoke suppression abilities of EPDM/AEGS and EPDM/PEGS composites were compared. The findings indicate that the porous structure of sepiolite plays a significant role in reducing smoke emissions for EPDM composites during combustion.

Production performance and biochemical profile of sea lettuce (Ulva lactuca): Influence of site-specific ecological factors and cultivation strategies

Production performance and biochemical characteristics of seaweed under varying cultivation strategies and ecological conditions provide crucial insights for improving sustainable farming practices. Therefore, this study aims to investigate the production performance and biochemical profile of sea lettuce (Ulva lactuca) under three farming systems, namely floating long-line (FLL), off-bottom long-line (OBLL), and off-bottom net (OBN), and three site-specific (Khurushkul, Nuniachora, and Sonapara) ecological conditions for a period of nine months (October 2022 to June 2023). Depending on the site suitability for different cultivation systems, 15 plots (5 FLL, 5 OBLL, and 5 OBN) were established in Nuniachora, 10 plots (5 FLL, 5 OBLL) were established in Sonapara, and 5 plots (FLL) were established in Khurushkul of the Cox's Bazar district, Bangladesh. Depending on the cultivation months, we partially harvested U. lactuca every 15–30 days once it reached 25–35 cm in length. Results showed that the gross weight biomass (GWB) of U. lactuca cultured in the FLL (F = 200.43, p < 0.001) cultivation system was 45.38% and 39.85% higher compared to OBN and OBLL, respectively. The average daily growth rate (DGR) was found to be 11%–13% higher in the FLL method (F = 236.11, p < 0.001). Location-based comparisons indicated a significantly higher (p < 0.05) U. lactuca production in Khurushkul, followed by the Nuniarchora, and the lowest was observed in Sonapara. Seasonality influenced the production performances of U. lactuca, with significantly higher (p < 0.05) growth observed from December to March due to favourable physio-chemical parameters. Multivariate analysis revealed that high salinity, pH, and nutrient concentrations positively influenced growth performances, while high temperature, turbidity, and total suspended solids (TSS) had negative effects. U. lactuca harvested from the FLL and OBN systems contained 14.3% and 9.44% higher amounts of protein (F = 36.77, p < 0.001) than the OBN system. The fatty acid analysis showed that U. lactuca from the FLL and OBN systems contained a significantly lower amount of saturated fatty acids but a higher amount of monounsaturated and n-6 polyunsaturated fatty acids compared to the OBLL system. Among the heavy metals and minerals analyzed, U. lactuca harvested from the FLL system contained significantly (p < 0.05) higher amounts of Na and K and lower amounts of Pb, Cr, Co, and Fe. The findings of the present study underscore the superiority of the floating long-line cultivation system for U. lactuca, highlighting its potential for sustainable farming practices to address global food security and utilization in various industrial applications.

Some Phytochemical and Nutraceutical Properties of Sea Lettuce (Ulva Lactuca) from Bushehr Coasts, Iran

Some Phytochemical and Nutraceutical Properties of Sea Lettuce (Ulva Lactuca) from Bushehr Coasts, Iran

Development of an artificial propagation and breeding method for the beehorn snail (Clithon diadema)

Beehorn snail (Clithon diadema), known for its vibrant colors, is threatened with extinction due to excessive field collection. Therefore, this study investigated the effects of different diets and salinity (0‰–35‰) on the gonadal development, capsule productivity, embryonic development, and larval survival and growth of C. diadema. Adult snails (shell length: 9.09 ± 0.87 mm) were fed diatoms, including pennate marine diatom (Nitzschia grossestriata), boat-shaped diatom algae (Navicula sp.) and Cylindrotheca sp., along with giant tiger prawn (Penaeus monodon) commercial feed, sea lettuce (Ulva lactuca), or Cladophora fascicularis, while snail larvae (shell length: 154.85 ± 6.03 μm) were fed Isochrysis galbana or Chaetoceros muelleri. The diatom group outperformed commercial feed and U. lactuca groups. The highest capsule productivity, yielding 79–82 capsules in 4 weeks, occurred at 15‰-20‰ salinity for diatom-fed adults. Embryos thrived at 0‰ but didn't hatch; hatching required salinities above 0‰, highlighting saline necessity. In addition, acute salinity changes (0‰ to 30‰) can deform embryo. Embryonic development at 15‰–20‰ salinity lasted 13.56–14.33 days with 100% larval hatching. However, larvae hatched at >20‰ salinity exhibit improved the percentage of survival without feeding (longer median lethal times). I. galbana-fed larvae survived 68 days with a 75% rate, outlasting C. muelleri-fed larvae which perished within 28 days. I. galbana-fed larvae, raised for 68 days at 25‰ salinity, showed 100% survival, 44.44% metamorphosis, and a 3.1 times growth increase. Metamorphosis rates were highest at 25‰ salinity with I. galbana, exceeding the 20‰ group by 3.2 times. Mucus of C. diadema boosts larval metamorphosis to 50.00%, 9 times higher than without inducers. Based on previous results, we developed an artificial propagation and breeding method for C. diadema. Artificially propagating C. diadema in large quantities could reduce the need for wild harvesting, thereby mitigating negative ecological impacts from excessive collection.

Facilitating Ulvan Extraction from Ulva lactuca via Deep Eutectic Solvent and Peracetic Acid Treatment

Ulva lactuca is a green seaweed and commonly referred to as sea lettuce and contains sulphated polysaccharides that have biological activity. Strong acids (HCl) and strong bases (NaOH) are commonly used as solvents in the conventional extraction process for ulvan, despite its lack of ecological sustainability. Deep Eutectic Solvent (DES) is an alternative to ulvan extraction solvent which is more environmentally friendly and has low toxicity. Ulvan extraction using DES with a temperature of 85-95ºC for 1 hour, and adding 2% peracetic acid pretreatment, 0.1%, 0.5%, and 2% peracetic acid posttreatment were conducted. Peracetic acid pre- and post-treatment (PAA) was carried out with a 1:10 (w/v) ratio at room temperature for 30 minutes. This study aims to optimize the use of DES in ulvan extraction with pre- and post-treatment of ulvan quality. The analysis performed included moisture content, yield, functional groups, sulphate content, and color. The test results revealed that ulvan treated with 2% PAA pretreatment had the highest moisture content and sulphate content, at 18.71% and 33.39%, respectively, while ulvan treated with 0.1% PAA posttreatment had the highest yield, at 41.96%. The addition of peracetic acid concentration can increase the color quality of the ulvan. PAA pre- and post-treatment had a significant effect on all ulvan quality parameters.

Benefit of the nutritional and mineral composition of sea lettuce from a traditional salina: Implications for human consumption

The proximal composition and its seasonal variation of the green seaweed Ulva sp. harvested in a traditional saline (earthen ponds used for marine salt extraction) from Cadiz Bay (Southern Spain) was evaluated. Ulva sp. was also collected in a reference location within the Bay in order to compare and evaluate the effects of the particular characteristics of the saline in the composition of the macroalgae. Moisture, protein, lipid, ash, carbohydrate, fiber and macro- (Na, K, Ca, Mg), micro-mineral contents (Fe, Zn, Cu) and heavy metals (As, Cd, Co, Cr, Hg, Ni, Pb, Sn) of harvested biomass samples as well as environmental parameters of seawater (temperature, salinity, pH, DO, NH4+, NO3−, NO2− and PO43−) were measured. The results showed that Ulva sp. from the earthen ponds in the traditional salina was a better source of proteins, lipids, K and Mg, highlighting in summer with values of 27.54 % versus 6.11 %; 6.71 % versus 3.26 %; 26.60 mg g−1 versus 14.21 mg g−1 and 23.13 mg g−1 versus 17.79 mg g−1, respectively. It also had Na/K and Ca/Mg ratios of less than one, suggesting a healthy food source. Considering the Commission Recommendation (EU) 2018/464 as a working reference, Ulva sp. did not exceed the limit of toxic metals for human consumption.A season and site-season significant interaction on the composition of the seaweeds was observed. The proximal and mineral composition of Ulva sp. was influenced by the special features and environmental conditions of the earthen ponds. Hence, significant differences were observed in the macroalgae collected in the earthen ponds in summer and autumn, in contrast to the winter and spring samples, whose characteristics were similar to those from the inner bay. The closure of the lock-gates in summer to favor the production of salt significantly modified the environmental characteristics of the saline, affecting the physiological capacity of Ulva sp. to assimilate and storage nutrients, and therefore its tissue composition. As a consequence, the highest contents of lipid, ash, Ca, K, Mg and Fe were estimated in the macroalgae.

Fast screening method to identify salinity tolerant strains of foliose Ulva species. Low salinity leads to increased organic matter of the biomass

Sea lettuce (Ulva) is recognised for its potential in food, pharmaceutical, nutraceutical, biorefinery and bioremediation industries and is increasingly being cultivated. The requirements of those industries vary widely in terms of biomass composition. Ulva biomass composition and growth is known to be directly influenced by environmental factors, e.g., temperature, light, salinity, nutrient availability as well as by genetic factors and likely by microbiome composition. In order to select for the highest yielding strains in a given environment, we tested the suitability of common-garden experiments, i.e., the co-cultivation of different strains grown under shared conditions. Fifteen strains from six different foliose Ulva species were grown together under two different salinities, 35 ppt and 15 ppt. After 32 days, only U. australis strains remained at both salinities. If selection at low salinity was mostly based on survival, the selection process at seawater salinity was driven by competition, largely based on growth performance. Growth rates after a month were very similar at both salinities, suggesting the U. australis strains cope equally well in either condition. However, the composition of the biomass produced in both environments varied, with the content of all organic compounds being higher at low salinity, and the ash content being reduced in average by 66%. To summarize, this study provides an established bulk-selection protocol for efficiently screening large numbers of locally-sourced strains and highlights the potential of low salinity treatments for increased organic matter content, particularly in carbohydrates.

A life cycle assessment of early-stage enzyme manufacturing simulations from sustainable feedstocks

Enzyme-catalyzed reactions have relatively small environmental footprints. However, enzyme manufacturing significantly impacts the environment through dependence on traditional feedstocks. With the objective of determining the environmental impacts of enzyme production, the sustainability potential of six cradle-to-gate enzyme manufacturing systems focusing on glucose, sea lettuce, acetate, straw, and phototrophic growth, was thoroughly evaluated. Human and ecosystem toxicity categories dominated the overall impacts. Sea lettuce, straw, or phototrophic growth reduces fermentation-based emissions by 51.0, 63.7, and 79.7%, respectively. Substituting glucose-rich media demonstrated great potential to reduce marine eutrophication, land use, and ozone depletion. Replacing organic nitrogen sources with inorganic ones could further lower these impacts. Location-specific differences in electricity result in a 14% and a 27% reduction in the carbon footprint for operation in Denmark compared to the US and China. Low-impact feedstocks can be competitive if they manage to achieve substrate utilization rates and productivity levels of conventional enzyme production processes.

Pemberdayaan Usaha Mikro Produk Rumput Laut

Based on the program of the Ministry of Maritime Affairs and Fisheries, namely Indonesia, the largest producer of marine and fishery products in 2015, empowerment activities were carried out for the people of Kemadang Village. This was done, because the geographical condition of Kemadang Village is close to Kukup beach, Baron beach and Krakal beach. Natural resources used are sea lettuce (seaweed). These natural resources will be processed into processed food products. However, the people of Kemadang Village have not done marketing well. Therefore, it is necessary to empower the people of Kemadang Village with a marketing mix approach (product, price, place and promotion) to produce a good marketing strategy. The empowerment activity was attended by 40 people from Kemadang Village, of which 72.5% were female and 27.5% were male. To test the level of understanding in this activity, questionnaires were distributed before and after the empowerment activities were carried out. The results obtained are that there are 24-28 people who attend this activity who understand the material presented.

Characterization of a Bioplastic Product from the Ulva reticulata (Ribbon Sea Lettuce) Extract

Humans have a strong reliance in using petroleum-based plastics which take several decades to degrade and cause a lot of environmental problems such as pollution. This study intended to develop bioplastics from Ulva reticulata (Ribbon sea lettuce) and to determine the bioplastic’s physicochemical properties. The sample was collected in Allen, Northern Samar, Philippines, water samples were also collected. After the extraction, development of bioplastic from the sample extract commenced. The developed bioplastic underwent several test to check the stability of the product – its includes physicochemical analysis, tensile strength, thickness, moisture content, and soil degradation test. The Ribbon sea lettuce bioplastic solution was slightly acidic. The seaweed bioplastic have an average thickness of 0.30mm. The Ribbon sea lettuce bioplastic sample was both insoluble in the three solvents. The sample bioplastic can handle an average load of 55.12g. An average moisture content of 51.534% have been observed in the three trial of the seaweed bioplastic sample. The seaweed bioplastic sample naturally degraded during the soil biodegradation test and have lost an average weight percentage of 82.05% after 21 days of being buried in soil. The results showed that the seaweed bioplastic has a potential as an alternative to the non-biodegradable plastic and can be used in agricultural, industrial and economic purposes.

Variation in heavy metals concentrations among seaweed species from Mkwiro seaweed farm, Kwale County, Kenya

This study, conducted at the Mkwiro seaweed farm in Kwale County, Kenya, aimed to assess the concentrations of heavy metals (Cd and Pb) and essential elements (Na, Fe, Ca, and K) in selected edible seaweed species. The study used a cross-sectional, descriptive research design and probability sampling method to collect data. Seaweed samples of three selected species, Cottonii (Kappaphycus alvarezii), Sea lettuce (Ulva lactuca), and Bubble-green seaweed (Boergesenia forbesii) were collected in quadrants and subjected to chemical analysis. Statistical analyses were conducted using R Studio version 4.3.2, with a significance level set at α=0.05. The Kruskal-Wallis test revealed significant differences in lead concentrations among seaweed types (χ² (2) = 7.01, p = 0.03). Cadmium concentrations did not show significant differences (χ² (2) = 3.88, p = 0.14). For calcium concentrations, ANOVA indicated no significant effect of seaweed type (F (2,33) = 0.6381, p = 0.5347). Iron concentrations differed significantly among seaweed types (χ² (2) = 23.35, p = 0.00000849), with B. forbesii having the highest median concentration. Potassium and sodium concentrations did not significantly vary among seaweed types (p &gt; 0.05). The study uncovers elevated cadmium levels in seaweed, indicating potential contamination risks. However, concentrations of essential elements were lower. To address these findings, it is recommended to initiate regular monitoring and pollution control measures in seaweed farms. Additionally, diversifying cultivation with low-metal species can enhance product safety and quality.

Growth, productivity and nutrient removal rates of sea lettuce (Ulva lactuca) in a land-based IMTA system with white seabass (Atractoscion nobilis) in Southern California

Three consecutive 3-week trials were conducted to assess the growth, productivity, and nutrient removal rates of sea lettuce (Ulva lactuca) cultured in effluents from white seabass (Atractoscion nobilis) raceways. All U. lactuca cultivation trials were conducted in 175 L tanks with a surface area of 0.89 m2 run in triplicate, with water quality and growth measurements taken weekly. For the shading trial, U. lactuca was stocked at 0.56 kg/m2 with either 0%, 30%, or 60% shade and seawater supplied at 63 tank volumes per day (vol./day) water exchange (7.6 L/min) for each tank. The removal rate of total ammonia nitrogen (TAN) decreased with increasing shade levels, and the peak exceeded 80% removal at 0% shading. Growth rate and productivity of U. lactuca under 0% shading was 12.09 ± 3.13%/d and 13.28 ± 4.66 g DW/m2/d, which were both significantly higher than other shading levels. For the stocking density and water exchange rate trial, the stocking density of U. lactuca was 0.56 or 1.12 kg/m2, and seawater exchange rates were 4, 12, or 63 vol./day in a 2-factor design. In this trial, TAN removal rates were 100% across all treatment combinations. Growth rate of U. lactuca was highest (20.36 ± 2.36%/d) at 0.56 kg/m2 under the exchange rate of 63 vol./day, and the productivity reached up to 30.89 ± 6.53 g DW/m2/d, which was not different than that of U. lactuca stocked with 1.12 kg/m2 at the same exchange rate (p = 0.47). In a trial comparing sand-filtered seawater (RAW seawater) with seawater effluent from a raceway containing A. nobilis (FISH seawater), TAN removal rate by U. lactuca was consistently nearly 100% when supplied with FISH seawater with a TAN concentration ranging from 0.11 to 0.18 mg/L. Growth rate and productivity of U. lactuca supplied with FISH seawater were 21.36 ± 2.25%/d and 33.83 ± 7.29 g DW/m2/d, respectively, which was not different than that for U. lactuca supplied with RAW seawater. However, the protein content of U. lactuca cultured with FISH seawater was significantly higher and C/N ratio significantly lower than those cultured with RAW seawater (p < 0.01), which indicated that U. lactuca was in a nitrogen-limited situation when cultured with RAW seawater. In light of the better understanding of U. lactuca performance achieved in our study, the optimum U. lactuca and A. nobilis density combinations will be confirmed in future studies based on nitrogen balance to maximize the nutrient removal rates and diversity of seafood production.

From marine to fork: Effects of different cooking methods on the composition of sea lettuce

The nutritional, functional and technological richness exhibited by seaweeds has encouraged in recent years their use for culinary purposes. Their broad range of colors, textures and flavors makes of them an ideal ingredient for the preparation of a wide variety of novel and imaginative dishes. However, few studies have been carried out on the effect that thermal cooking treatments have on seaweeds. This study intends to evaluate the influence of certain cooking processes (boiling, steaming and sous-vide) on the physicochemical and functional composition of Ulva sp. collected from the earthen ponds in Cadiz. Sea lettuce has been cooked using three different methods and at three different temperatures (50, 70 and 100 °C) for three different periods of time (5, 10 and 15 min). After the treatments, it could be observed that the structure, physicochemical composition and functional characteristics of Ulva sp. were significantly affected by the cooking method used. The effect of cooking on the alga's properties depended both on the method itself and on the time used. In relation to its nutritional composition, boiling was the culinary method that most affected ash, protein, lipid, unsaturated fatty acid and mineral (K, Ca, Mg and Cu) contents, with longer cooking times leading to their significant or total loss either through chemical reactions or leaching. In contrast, sous-vide cooking proved to be a technique that preserves and can even enhance the nutritional benefits of raw seaweeds.

The Effect of Vermicompost Enriched with Ulva Lactuca on Germination of Cucumber Seeds

Vermicompost was obtained from farmyard manure compost enriched with sea lettuce (Ulva lactuca), which grows naturally on the Ordu coast, and its effects on the germination of cucumber seeds were investigated. The seaweeds collected from the sea and dried and composted in the natural environment together in 5 different groups with cattle manure after grinding. Eisenia fetida, known as Red California Worm, was used as worm species.The composts obtained were fed to earthworms according to different dose ratios. These dose ratios were determined as G1 group 9000 gr 100 % Ç.G (farm manure), G2 group 8100 gr Ç.G + 900 gr U.L (Ulva lactuca), G3 group 7200 gr Ç.G + 1800 gr U.L, G4 group 6300 gr Ç.G + 2700 gr U.L. and G5 group 5400 gr Ç.G + 3600 gr. U.L. The vermicompost was applied directly to the soil. The experiment was designed according to the randomised plots experimental design with one control and three replicates. The experiment was carried out with local Cucumis sativus (cucumber) seeds in plastic containers in open field. Including the control group, 15 saddles were used. Sowing was done by hand at a depth of 5-6 cm with 7 seeds/saddle. The 6-day development process of the seeds was observed and germination rates were analysed. At the end of the study, significant differences were found between the groups.

Determination of the Optical Band gap Energy from the Extraction and Evaporation of Anthocyanin Compound Sea Lettuce (Ulva Lactuca L.) Using Tauc Plot Method

The optical energy gap of anthocyanin compounds from sea lettuce extract (Ulva lactuca L.) has been calculated using the Tauc plot method. Sea lettuce plants taken at Sanur Beach Bali. The sea lettuce was dried then mashed and extracted for 24 hours, the last being macerated through three cycles. The extraction results are then evaporated to obtain a thick extract solution. Extracted and evaporated-extraction samples were characterized by UV-Vis in the wavelength range of 200-800 nm. From the characterization results, it was found that the absorption of anthocyanin compounds for the extracted samples was at a wavelength of 268 and 412 nm. Meanwhile, for the extraction-evaporation sample, the absorption is at a wavelength of 286.5 and 408 nm. By using the Tauc plot method, the optical energy gap values ??for the extracted and extraction-evaporated samples were 2.69 and 2.54 eV, respectively. Therefore, anthocyanin compounds from both extracted and evaporation-extracted samples qualify as dye sensitized solar cells (DSSC) for TiO2 semiconductors.