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The Ulva prolifera bloom is considered one of the most serious ecological disasters in the Yellow Sea in the past decade, forming a carbon sink in its source area within a short period but becoming a carbon source at its destination. To explore the effects of different environmental changes on seawater dissolved carbon pools faced by living U. prolifera in its originating area, U. prolifera were cultured in three sets with different light intensity (54, 108, and 162 μmol m -2  s -1 ), temperature (12, 20, and 28 °C) and nitrate concentration gradients (25, 50, and 100 μmol L -1 ). The results showed that moderate light (108 μmol m -2  s -1 ), temperature (20 °C), and continuous addition of exogenous nitrate significantly enhanced the absorption of dissolved inorganic carbon (DIC) in seawater by U. prolifera and most promoted its growth. Under the most suitable environment, the changes in the seawater carbonate system were mainly dominated by biological production and denitrification, with less influence from aerobic respiration. Facing different environmental changes, U. prolifera continuously changed its carbon fixation mode according to tissue δ 13 C results, with the changes in the concentrations of various components of DIC in seawater, especially the fluctuation of HCO 3 - and CO 2 concentrations. Enhanced light intensity of 108 μmol m -2  s -1 could shift the carbon fixation pathway of U. prolifera towards the C 4 pathway compared to temperature and nitrate stimulation. Environmental conditions at the origin determined the amount of dissolved carbon fixed by U. prolifera. Therefore, more attention should be paid to the changes in marine environmental conditions at the origin of U. prolifera, providing a basis for scientific management of U. prolifera., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The potential of the green macroalga Ulva lactuca is increasingly recognized, not only for its environmental benefits, but also for its applications in various industries, including food, pharmaceuticals, and cosmetics. Given this insight, a comprehensive analysis of the chemical profile of U. lactuca from the Adriatic Sea was carried out. The hydrodistillate, rich in ( Z , Z , Z )-hexadeca-7,10,13-trienal and hexadecanoic acid, underlines its importance for health-related uses, particularly in lipid metabolism and cellular integrity. Fatty acid analysis showed a predominance of palmitic acid and a favorable n-6/n-3 polyunsaturated fatty acid ratio, suggesting that U. lactuca can make a valuable contribution to a balanced diet. In addition, essential amino acids, including leucine, valine, and isoleucine, support its use as a functional ingredient for muscle repair and metabolic health. The ethanol extract contained 56 compounds, including derivatives of fatty acids, phenolic acids, pigments, flavonoids, and steroids. Many of them, such as hexadecasphinganine, azelaic acid, 5-sulfosalicylic acid, and pheophytin a , have proven roles or potentials in promoting human health. These results confirm that U. lactuca is a rich source of bioactive compounds, emphasizing its potential in scientific research and its expanding industrial applications in health, nutrition, and cosmetics.

The pollution by heavy metals in coastal waters has gradually intensified due to industrial development. In this study, physiological responses of Ulva lactuca, one of the most common green seaweeds with important ecological and economic value in the global intertidal zone, to acute copper stress were investigated. Results showed that an increase in copper ions concentration significantly inhibited photosynthetic activity and inorganic nitrogen utilization by U. lactuca but, increased its respiration. Copper stress limited the activity and gene expression of enzymes related to carbon and nitrogen assimilation of U. lactuca. Under moderate copper stress, U. lactuca had higher soluble carbohydrate and soluble protein contents, whereas under high copper stress, these components decreased sharply. Copper stress increased malonaldehyde content, and relative electrical conductivity in U. lactuca, but changes in antioxidant enzyme activities were not significant and even slightly decreased. Moreover, the contents of 8-hydroxy-deoxyguanosine and polyADP ribose polymerase in U. lactuca increased by high Cu 2+ concentration culture, indicating that oxidative damage caused by high Cu 2+ level involved its DNA damage and interfered with DNA repair in the alga. Copper stress seemed to be more damaging to the carbon assimilation process of U. lactuca, resulting in weakened resistance to copper stress and lower growth rate. This reflected the threat of coastal high copper stress to intertidal biodiversity. This provided ecological reference for the assessment of offshore heavy metal pollution represented by copper., (© 2024. The Author(s).)

Light quality is a key factor affecting algal growth and biomass composition, particularly pigments such as carotenoids, known for their antioxidant properties. Light-emitting diodes (LEDs) are becoming a cost-effective solution for indoor seaweed production when compared to fluorescent bulbs, allowing full control of the light spectra. However, knowledge of its effects on Ulva biomass production is still scarce. In this study, we investigated the effects of LEDs on the phenotype of an Ulva lacinulata strain, collected on the Northern Portuguese coast. Effects of white (W), green (G), red (R), and blue (B) LEDs were evaluated for growth (fresh weight and area), photosynthetic activity, sporulation, and content of pigments and antioxidant compounds. The results showed that there were no significant differences in terms of fresh weight accumulation and reduced sporulation among the tested LEDs, while W light induced the highest expansion rate. Under G, U. lacinulata attained a quicker photoacclimation, and the highest content of pigments and total antioxidant activity; but with R and W, antioxidant compounds against the specific radicals O 2 •- and • NO were produced in a higher content when compared to other LEDs. Altogether, this study demonstrated that it is possible to modulate the bioactive properties of U. lacinulata by using W, R, and G light, opening the path to the production of biomass tailored for specific nutraceutical applications.

To analyze the mechanism of copper accumulation in the marine alga Ulva compressa , it was cultivated with 10 μM of copper, with 10 μM of copper and increasing concentrations of a sulfide donor (NaHS) for 0 to 7 days, and with 10 μM of copper and a concentration of the sulfide acceptor (hypotaurine) for 5 days. The level of intracellular copper was determined as well as the level of glutathione (GSH) and phytochelatins (PCs) and the expression of metallothioneins (UcMTs). The level of intracellular copper in the algae treated with copper increased at day 1, slightly increased until day 5 and remained unchanged until day 7. The level of copper in the algae cultivated with copper and 100 or 200 μM of NaHS continuously increased until day 7 and the copper level was higher in the algae cultivated with 200 μM of NaHS compared to 100 μM of NaHS. In contrast, the level of intracellular copper decreased in the algae treated with copper and hypotaurine. The level of intracellular copper did not correlate with the level of GSH or with the expression of UcMTs, and PCs were not detected in response to copper, or copper and NaHS. Algae treated with copper and with copper and 200 μM of NaHS for 5 days were visualized by TEM and the elemental composition of electrondense particles was analyzed by EDXS. The algae treated with copper showed electrondense particles containing copper and sulfur, but not nitrogen, and they were mainly located in the chloroplast, but also in the cytoplasm. The algae treated with copper and NaHS showed a higher level of electrondense particles containing copper and sulfur, but not nitrogen, and they were located in the chloroplast, and in the cytoplasm. Thus, copper is accumulated as copper sulfide insoluble particles, and not bound to GSH, PCs or UcMTs, in the marine alga U. compressa .

Ulva is globally distributed specie and has a high economic value. Ulvan is one of the main active substances in Ulva, which has a variety of biological properties. Ulvan lyase degrades ulvan through a β-elimination mechanism which cleaves the β-glycosidic bond between Rha3S and GlcA or IdoA. The complex monosaccharide composition of ulvan makes it promising for use in food and pharmaceutical applications. This thesis explores a putative ulvan lyase from Alteromonas sp. KUL_42. We expressed and purified the protein, performed a series of characterizations and signal peptide had been removed. The results showed that the protein molecular weight of ULA-2 was 53.97 kDa, and it had the highest catalytic activity at 45 °C and pH 8.0 in Tris-HCl buffer. The Km and Vmax values were 2.24 mg · mL-1 and 2.048 μmol · min-1 · mL-1, respectively. The activity of ULA-2 was able to maintain more than 80% at 20 ~ 30 °C. ESI-MS analysis showed that the primary end-products were mainly disaccharides to tetrasaccharides. The study of ULA-2 enriches the ulvan lyase library, promotes the development and high-value utilization of Ulva resources, and facilitates further research applications of ulvan lyase in ulva oligosaccharides., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Halomonas elongata 1H9 T is a moderate halophilic strain able to produce poly(3-hydroxybutyrate) (P(3HB)), a biodegradable plastic, and gluconic acid, a valuable organic acid with wide industrial applications. In this work, the green alga Ulva rigida was used as platform to produce cultivation substrates for microbial conversion as well as functional ingredients, targeting its full valorization. The liquor obtained by autohydrolysis presented the highest concentration of oligosaccharides and protein, being an interesting feedstock to produce functional ingredients. The acid and/or enzymatic hydrolysis liquors are adequate as substrates for microbial processes. Shake flask assays with H. elongata revealed that the N-rich liquor produced after acidic treatment was the best suited for cell growth while the N-poor liquor produced by the enzymatic treatment of acid-pretreated algae residues produced the highest P(3HB) titers of 4.4 g/L. These hydrolysates were used in fed-batch cultivations as carbon and protein sources for the co-production of gluconic acid and polymer achieving titers of 123.2 g/L and 7.2 g/L, respectively. Besides gluconic acid, the Krebs cycle intermediate 2-oxoglutaric acid, also called alpha-ketoglutaric acid (KGA), was produced. Therefore, the co-production of P(3HB) and acids may be of considerable interest as an algal biorefinery valorization strategy.

In this study, Ulva lactuca polysaccharide (ULP) antihyperglycemic effect was assessed by monitoring changes in the gut microbiota of aging diabetic mice. The results showed that ULP alleviated type 2 diabetes by improving insulin tolerance, increasing SOD and CAT activities, and thus lowering blood glucose level. Moreover, ULP regulated the expressions of INSR and AMPK concurrent with inhibition the expression of JNK, JAK, STAT3, p16 and p38 to improve glucose metabolism dysfunction. Interestingly, the abundance of Alloprevotella and Pediococcus change might the key factor for ULP antihyperglycemic effectiveness in aging-related diabetes. These results suggest that ULP can exert a mechanism of blood glucose regulation by improving intestinal diversity composition asides from direct insulin mimetic actions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Although the use of airborne molecules as infochemicals is common in terrestrial plants, it has not been shown to occur in an ecologically relevant context in marine seaweeds. Like terrestrial plants, intertidal plants spend part of their lives emersed at low tide and release volatile organic compounds (VOCs) into the air when they are grazed or physiologically stressed. We hypothesized seaweeds could use airborne VOCs as infochemicals and respond to them by upregulating a keystone defensive metabolite, dimethylsulfoniopropionate (DMSP). We conducted laboratory and field experiments in which Ulva fenestrata was exposed to airborne dimethyl sulfide (DMS), a volatile antiherbivore and antioxidant metabolite released when the seaweed is grazed or physiologically stressed. In the laboratory, U. fenestrata exposed to DMS had 43-48% higher DMSP concentrations, relative to controls, 6-9 days after exposure. In the field, U. fenestrata 1 m downwind of DMS emitters had 19% higher DMSP concentrations than upwind seaweeds after 11 days. To our knowledge, this is the first demonstration of a marine plant using an airborne molecule released when damaged to elicit defensive responses. Our study suggests that the ability to detect airborne compounds has evolved multiple times or before the divergence of terrestrial plants and green algae., (© 2023. The Author(s).)

In the present study, Ulva prolifera, an edible alga, was used to prepare angiotensin-I converting enzyme (ACE) inhibitory peptide. The algae protein was isolated and later hydrolyzed by five commercial enzymes (alcalase, papain, pepsin, trypsin, neutral protease), either individually or in combination. Hydrolysate, with the highest in vitro ACE inhibitory activity, was processed using the Sephadex-G100, ultrafiltration, HPLC-Q-TOF-MS, ADMET screening and molecular docking, respectively. The ACE inhibitory peptide DIGGL with a IC 50 value of 10.32 ± 0.96 μM was then identified. The peptide against ACE by a non-competitive mode and mainly attributable to the three Conventional Hydrogen Bonds. It could activate Endothelial nitric oxide synthase activity in NO generation and reduce Endothelin-1 secretion induced by Angiotensin II in Human umbilical vein endothelial cells. Meanwhile, DIGGL could promote mice splenocytes proliferation, which was also effective when co-incubated with Con A or LPS, respectively. Besides, the anti-ACE peptide could remain active during the digestion of gastrointestinal proteases (pepsin-trypsin) in vitro., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The marine green macroalga Ulva (Chlorophyta, Ulvales), also known as sea lettuce, coexists with a diverse microbiome. Many Ulva species proliferate in nature and form green algal blooms ("green tides"), which can occur when nutrient-rich wastewater from agricultural or densely populated areas is flushed into the sea. Bacteria are necessary for the adhesion of Ulva to its substrate, its growth, and the development of its blade morphology. In the absence of certain bacteria, Ulva mutabilis develops into a callus-like morphotype. However, with the addition of the necessary marine bacteria, the entire morphogenesis can be restored. Surprisingly, just two bacteria isolated from U. mutabilis are sufficient for inducing morphogenesis and establishing the reductionist system of a tripartite community. While one bacterial strain causes algal blade cell division, another causes the differentiation of basal cells into a rhizoid and supports cell wall formation because of a low concentration of the morphogen thallusin (below 10 -10 mol/L). This review focuses on the research conducted on this topic since 2015, discusses how U. mutabilis has developed into a model organism in chemical ecology, and explores the questions that have already been addressed and the perspectives that a reductionist model system allows. In particular, the field of systems biology will achieve a comprehensive, quantitative understanding of the dynamic interactions between Ulva and its associated bacteria to better predict the behavior of the system as a whole. The reductionist approach has enabled the study of the bacteria-induced morphogenesis of Ulva. Specific questions regarding the optimization of cultivation conditions as well as the yield of raw materials for the food and animal feed industries can be answered in the laboratory and through applied science. Genome sequencing, the improvement of genetic engineering tools, and the first promising attempts to leverage macroalgae-microbe interactions in aquaculture make this model organism, which has a comparatively short parthenogenetic life cycle, attractive for both fundamental and applied research. The reviewed research paves the way for the synthetic biology of macroalgae-associated microbiomes in sustainable aquacultures., Competing Interests: Declaration of interest None., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The annual outbreak of green tides since 2007 has destroyed coastal waters' ecological environment and caused substantial economic losses. Ulva prolifera, known as the dominant species of green tides, is influenced by temperatures. Omics-based technology was used to analyze U. prolifera under 12 h of treatment at 30 °C in the work. High temperature has the following advantages, e.g., activating the abscisic acid signaling pathway, improving the heat tolerance of U. prolifera, up-regulating metabolites such as glycolipids, glyceroyl, and glutamic acid to maintain the stability and fluidity of cells, and reducing the stimulatory effect of external stress on cells. The key genes and proteins of the tricarboxylic acid cycle, glycolysis, and pentose phosphorylation pathways were inhibited; however, the key enzyme pyruvate phospho-dikinase of the C4 pathway was up-regulated. The C4 pathway was activated in U. prolifera in response to high-temperature stress and may play a key role in photosynthesis. Besides, U. prolifera metabolizing amino acids was active. High temperature inhibited genes and proteins related to DNA replication and cell cycle in the transcriptome and proteome as well as the growth and reproduction of U. prolifera., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Chemical mediators are key compounds for controlling symbiotic interactions in the environment. Here, we disclose a fully stereoselective total synthesis of the algae differentiation factor (-)-thallusin that utilizes sophisticated 6-endo-cyclization chemistry and effective late-stage sp 2 -sp 2 -couplings using non-toxic reagents. An EC 50 of 4.8 pM was determined by quantitative phenotype profiling in the green seaweed Ulva mutabilis (Chlorophyte), underscoring this potent mediator's enormous, pan-species bioactivity produced by symbiotic bacteria. SAR investigations indicate that (-)-thallusin triggers at least two different pathways in Ulva that may be separated by chemical editing of the mediator compound structure., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Marine heatwaves (MHWs) are affecting the survival of macroalgae. However, little is known regarding how the impacts of MHWs are regulated by nitrogen availability. In this study, we investigated the physiological and genetic responses of a green-tide macroalga Ulva intestinalis Linnaeus and a commercially cultivated macroalga Gracilariopsis lemaneiformis (Bory) E.Y. Dawson, Acleto & Foldvik under different nitrate conditions to simulated MHWs. Under nitrogen limited conditions (LN), heatwaves did not significantly affect biomass or Fv/Fm of U. intestinalis although it led to an earlier biomass decline due to more reproduction events, and meanwhile an upregulation in genes related to TCA cycle and oxidative phosphorylation was detected, supporting sporulation. Under nitrogen replete conditions (HN), heatwaves did not change biomass, Fv/Fm or photosynthetic pigments but reduced reproduction rate along with insignificant change of oxidative phosphorylation and TCA cycle related genes. Meanwhile, genes related to photosynthesis and glutathione metabolism were upregulated. Regarding G. lemaneiformis, heatwaves reduced its Fv/Fm and photosynthetic pigments content, leading to bleaching and death, and photosynthesis-related genes were also downregulated at LN. Fv/Fm was improved and photosynthesis-related genes were up-regulated by the combination of nitrogen enrichment and heatwaves, whereas G. lemaneiformis remained bleached and died by day 12. Therefore, U. intestinalis could survive heatwaves through shifting to micropropagules at LN and protecting its photosynthesis at HN. In contrast, G. lemaneiformis died of bleaching when suffering heatwaves regardless of nitrogen availability. These findings suggest that in future oceans with eutrophication and MHWs, the harmful alga U. intestinalis may have more advantages over the economic alga G. lemaneiformis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

To explore the spatial and temporal distributions of dissolved organic matter (DOM) affected by Ulva prolifera bloom and the regulation of DOM released by the addition of nitrate (NO 3 -N) nutrients, the variation in DOM was analyzed by three cruises in the coastal waters of the southern Yellow Sea (SYS) off Qingdao during a 2018 U. prolifera bloom. A mesocosm experiment was conducted during the decay of U. prolifera. The U. prolifera bloom resulted in higher concentrations of the bulk DOM except for total dissolved amino acids (TDAA), compared with levels recorded during non-bloom periods. Three different fluorescent substances of chromophoric dissolved organic matter (CDOM) were identified, which were also affected by the bloom. Concentrations of total dissolved carbohydrates (TCHO), monosaccharides (MCHO), and polysaccharides (PCHO) peaked during the late bloom, with average levels of 49.78 ± 9.73, 14.23 ± 3.32, and 35.55 ± 9.19 μmol C L -1 , respectively, accompanied by an increase of DOC, indicating release of DOM with U. prolifera decay. In contrast, the concentrations of CDOM and TDAA declined during the late bloom, with averages of 0.10 ± 0.10 m -1 and 1.16 ± 0.82 μmol L -1 , suggesting that the yields of CDOM and TDAA were regulated by the U. prolifera bloom and other mechanism. These findings were confirmed by the mesocosm experiment. DOM production was obviously improved by NO 3 -N addition except for TDAA and CDOM. The release of protein-like CDOM was primarily regulated by NO 3 -N nutrients, however, it was not obvious with humic-like CDOM. Our findings provide evidence supporting the role of U. prolifera blooms in the coastal DOM pool and its significant effect on the marine carbon cycle., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Potential toxic chemicals, specifically, polycyclic aromatic hydrocarbons (PAHs), are major sediment contaminants. Herein, green seaweed (Ulva lactuca) was used as a feedstock and pyrolyzed at temperature in the range between 300 and 900 °C. The metal-free carbocatalyst (GSBC) for peroxymonosulfate (PMS) activation to degrade PAHs contaminated sediments was studied. The effects of GSBC‒PMS treatment on microbial community abundance was studied as well. The pyrolysis temperature of GSBC preparation affected the PMS activation performance. Results show that GSBC700 exhibited remarkable catalytic characteristics in PAHs degradation by effective activation of PMS. The results also demonstrated that the sulfate radical-carbon-driven advanced oxidation processes (SR-CAOP) reaction achieved 87% and apparent rate constant (k obs ) of 6.3 × 10 -2 h -1 of total PAHs degradation in 24 h at 3.3 g/L of GSBC, PMS dose of 1 × 10 -4  M, and pH 3.0. The degradation of 2-, 3-, 4-, 5-, and 6-ring PAHs was 84, 83, 83, 80, and 89%, respectively. The synergetic effect established between GSBC and PMS enhanced the formation of ROSs, namely, SO 4 - , HO, and 1 O 2 , which were major species contributing to PAHs degradation. The synergistic effect of π‒π stacking structure and graphitization of GSBC formed electron shuttle, which contributed to PAHs degradation performance. Microbial community structure analyses in the GSBC‒PMS treated sediments showed that the relative abundance of Lactobacillus_rhamnosus species, most of which belonged to the Lactobacillus genus and Firmicutes phylum, which aided in continuing PAHs biodegradation post GSBC‒PMS treatment. Therefore, GSBC can be a promising carbocatalyst produced via biomass-to-biochar conversion as biowaste-to-energy source used in the SR-CAOP-mediated process for sediment remediation., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Ethnopharmacology Relevance: Enteromorpha has long been recorded in traditional Chinese medicine, with cholesterol-lowering, anti-cancer, anti-inflammatory and antibacterial effects. Recently, we extracted the polyphenol-enriched fraction from Enteromorpha clathrata (E. clathrata) by ethyl acetate (ECPs), and isolated six individual polyphenols from ECPs via high-speed counter-current chromatography (HSCCC) with high-performance liquid chromatography (HPLC)., Aim of the Study: In this study, we explored the anti-inflammatory activity and underlying mechanism of ECPs in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages., Materials and Methods: ECPs and the six polyphenols were used for nitric oxide (NO) assay to identify the components with potent inflammation inhibitory effect. Enzyme-linked immunosorbent assay (ELISA), quantitative real-time PCR (qPCR), flow cytometry, and Western blot analysis were applied to further investigate their anti-inflammatory effects and underlying mechanism in LPS-stimulated RAW264.7 cells., Results: ECPs and the three individual polyphenols, including (-)-epicatechin, epigallocatechin-3-O-gallate and (-)-epicatechin-3-O-gallate, showed in vitro immunosuppressive activity by altering the cell biology at the gene, protein and functional levels in a dose- and species-dependent manner. Their anti-inflammatory effects were achieved by inhibiting LPS-induced production of nitric oxide and its upstream enzyme inducible nitric oxide synthase (iNOS), the pro-inflammatory cytokines including interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), as well as the phagocytotic capacity, without cytotoxicity. The mechanism study further revealed that these anti-inflammatory properties were, at least partly, attributed to the suppressed activation of nuclear factor-κB (NF-κB) and p38 mitogen-activated protein kinase (MAPK) signaling pathways., Conclusions: These findings indicated for the first time the correlation between the anti-inflammatory activity of ECPs and NF-κB and MAPK signaling pathways, suggesting that polyphenol-enriched organic fraction of E. clathrata could be potential candidate as therapeutic agent for treating inflammatory diseases., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The Yellow Sea green tide (YSGT) is the world's largest transregional macroalgal blooms, and the causative species Ulva prolifera ( U. prolifera ) suffers from ultraviolet-b radiation (UVBR) during the floating migration process. Previous study confirmed that U. prolifera displayed a wide variety of physiological responses characterized as acclimation to UVBR, while the response mechanisms against low-dose and short-term radiation (LDSTR) are not clear. A study with photosynthetically active radiation (PAR) and UVBR was designed: normal light (NL: 72 μmol photons m -2 s -1 ), NL+0.3 (UVBR: 0.3 W·m -2 ), and NL+1.6 (UVBR: 1.6 W·m -2 ). The results showed that high-dose UVBR inhibited photosynthesis in thalli, especially under long-term exposure, while a variety of physiological responses were observed under LDSTR. The inhibition of photosynthesis appeared to be ameliorated by the algae under LDSTR. Further analysis showed that U. prolifera achieved balancing damage by means of non-photochemical quenching (NPQ), accumulation of phenolic compounds coupled with the ASA-GSH cycle involved in the antioxidant process and enhanced photorespiratory metabolism under LDSTR. This study provides new insights into the balancing damage mechanisms of U. prolifera under LDSTR, enabling the thalli to adapt to the light conditions during the long duration and distance involved in floating migration.

The organization of bacteria in biofilms is one of the adaptive resistance mechanisms providing increased protection against conventional treatments. Thus, the search for new antibiofilm agents for medical purposes, especially of natural origin, is currently the object of much attention. The objective of the study presented here was to explore the potential of extracts derived from three seaweeds: the green Ulva lactuca , the brown Stypocaulon scoparium , and the red Pterocladiella capillacea , in terms of their antibiofilm activity against P. aeruginosa . After preparation of extracts by successive maceration in various solvents, their antibiofilm activity was evaluated on biofilm formation and on mature biofilms. Their inhibition and eradication abilities were determined using two complementary methods: crystal violet staining and quantification of adherent bacteria. The effect of active extracts on biofilm morphology was also investigated by epifluorescence microscopy. Results revealed a promising antibiofilm activity of two extracts (cyclohexane and ethyl acetate) derived from the green alga by exhibiting a distinct mechanism of action, which was supported by microscopic analyses. The ethyl acetate extract was further explored for its interaction with tobramycin and colistin. Interestingly, this extract showed a promising synergistic effect with tobramycin. First analyses of the chemical composition of extracts by GC-MS allowed for the identification of several molecules. Their implication in the interesting antibiofilm activity is discussed. These findings suggest the ability of the green alga U. lactuca to offer a promising source of bioactive candidates that could have both a preventive and a curative effect in the treatment of biofilms.

Ulvans from Ulva ohnoi, Ulva tepida and Ulva prolifera were extracted under mild acidic conditions, isolated and their composition and structure determined. The ulvans contained mostly rhamnose (31.6-46.7 mol%) and glucuronic acid (26.6-37.5 mol%), with smaller amounts of xylose (3.4-10.4 mol%) and iduronic acid (3.1-7.6 mol%). In addition, the ulvan samples also contained galactose (4.4-26.0 mol%). Glycosyl linkage analysis showed that ulvan from U. ohnoi contained mostly →4)-GlcpA-(1→ and →3,4)-Rhap-(1→. Preparation of partially methylated alditol acetate standards of idose showed that U. ohnoi contained →4)-IdopA-(1→. In addition to these residues, glycosyl linkage analysis of U. tepida and U. prolifera showed the presence of →2,3,4)-Rhap-(1→, →4)-Xylp-(1→, →2,4)-GlcpA-(1→ and →3,4)-GlcpA-(1→. These two species also contained galactose linkages. These data, together with nuclear magnetic resonance (NMR) spectroscopy indicated that U. ohnoi comprised mostly of type A 3S ulvanobiuronic acid repeats [→4)-β-D-GlcpA-(1→4)-α-L-Rhap3S-(1→], together with smaller amounts of type B 3S ulvanobiuronic acid repeats [→4)-α-L-IdopA-(1→4)-α-L-Rhap3S-(1→] and ulvanobiose (U 3S [→4)-β-D-Xylp-(1→4)-α-L-Rhap3S-(1→]). NMR spectra of U. tepida and U. prolifera showed resonances not detected in U. ohnoi, highlighting the complexity of the ulvans from these species. Regardless of the structural diversity of the ulvan samples there was very little antioxidant or inhibitory activity detected on enzymatic processes investigated., (Copyright © 2021. Published by Elsevier B.V.)

Ulvans from green algae are promising compounds for plant protection because they are environmentally friendly and induce plant defense responses. We analyzed the structure-function relationship of ulvan polymers and oligomers for their elicitor activity in suspension-cultured cells of three dicot species. The polysaccharide from Ulva fasciata was characterized regarding its monosaccharide composition, degree of sulfation, and molecular mass. The polymer was partially depolymerized using acid hydrolysis, and the oligomers were separated using size exclusion chromatography. The oligomeric fractions were analyzed revealing mostly sulfated and de-sulfated ulvan dimers. Both the polymer and the oligomer fractions induced an NADPH oxidase-dependent oxidative burst in plant cells. The elicitor activity of the ulvan dimers did not require sulfation. By identifying the smallest elicitor-active unit, HexA-Rha, we took an important next step to understand how the structure influences ulvan elicitor responses. The desulfated ulvan dimer is discussed as a promising agro-biologic for sustainable agriculture., (Copyright © 2021. Published by Elsevier Ltd.)

In order to analyze the mechanisms involved in copper accumulation in Ulva compressa , algae were collected at control sites of central and northern Chile, and at two copper-polluted sites of northern Chile. The level of intracellular copper, reduced glutathione (GSH), phytochelatins (PCs), PC2 and PC4, and transcripts encoding metallothioneins (MTs) of U. compressa , UcMT1 , UcMT2 and UcMT3 , were determined. Algae of control sites contained around 20 μg of copper g -1 of dry tissue (DT) whereas algae of copper-polluted sites contained 260 and 272 μg of copper g -1 of DT. Algae of control sites and copper-polluted sites did not show detectable amounts of GSH, the level of PC2 did not change among sites whereas PC4 was increased in one of the copper-polluted sites. The level of transcripts of UcMT1 and UcMT2 were increased in algae of copper-polluted sites, but the level of UcMT3 did not change. Algae of a control site and a copper-polluted site were visualized by transmission electron microscopy (TEM) and the existence of copper in electrodense particles was analyzed using energy dispersive x-ray spectroscopy (EDXS). Algae of copper-polluted sites showed electrodense nanoparticles containing copper in the chloroplasts, whereas algae of control sites did not. Algae of a control site, Cachagua, were cultivated without copper (control) and with 10 μM copper for 5 days and they were analyzed by TEM-EDXS. Algae cultivated with copper showed copper-containing nanoparticles in the chloroplast whereas control algae did not. Thus, U. compressa from copper-polluted sites exhibits intracellular copper accumulation, an increase in the level of PC4 and expression of UcMTs , and the accumulation of copper-containing particles in chloroplasts.

Seaweed is a promising sustainable source of vegan protein as its farming does not require arable land, pesticides/insecticides, nor freshwater supply. However, to be explored as a novel protein source the content and nutritional quality of protein in seaweed need to be improved. We assessed the influence of pH-shift processing on protein degree of hydrolysis (%DH), protein/peptide size distribution, accessibility, and cell bioavailability of Ulva fenestrata proteins after in vitro gastrointestinal digestion. pH-shift processing of Ulva, which concentrated its proteins 3.5-times, significantly improved the %DH from 27.7±2.6% to 35.7±2.1% and the amino acid accessibility from 56.9±4.1% to 72.7±0.6%. Due to the higher amino acid accessibility, the amount of most amino acids transported across the cell monolayers was higher in the protein extracts. Regarding bioavailability, both Ulva and protein extracts were as bioavailable as casein. The protein/peptide molecular size distribution after digestion did not disclose a clear association with bioavailability., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Enhancing the cholesterol turnover in the brain via activation of liver x receptors can restore memory in a mouse model for Alzheimer's disease. The edible Asian brown alga Sargassum fusiforme (Hijiki) contains high amounts of oxysterols such as (3β, 24ξ)-stigmasta-5, 28-dien-3, 24-diol (24[R, S]-saringosterol) that are a potent liver x receptor agonists. We aimed to find native European seaweed species with contents of 24(R, S)-saringosterol that are comparable to those found in Sargassum fusiforme. Additionally, we hypothesize that seasonal variations modify the amount of 24(R, S)-saringosterol in seaweeds. Sterols and oxysterols were extracted with chloroform/methanol from various seaweed species harvested in the Eastern Scheldt in different seasons between October 2016 and September 2017. Identification and quantification of the lipids was performed by gas chromatography- mass spectrometry and gas chromatography- flame ionization detection. We confirmed that brown algae Undaria pinnatifida harvested in February and Sargassum muticum harvested in October contained the highest amounts of 24(R, S)-saringosterol (32.4 ± 15.25 μg/g, mean ± S.D. and 32.95 ± 2.91 μg/g, respectively) and its precursor fucosterol (1.48 ± 0.11 mg/g), higher than Sargassum fusiforme (20.94 ± 3.00 μg/g, mean ± S.D.), while Ascophyllum nodosum and Fucus vesiculosus and Fucus serratus contained amounts of 24(R, S)-saringosterol (22.09 ± 3.45 μg/g, 18.04 ± 0.52 μg/g and 19.47 ± 9.01 μg/g, mean ± S.D., respectively) comparable to Sargassum fusiforme. In other algae only minor amounts of these sterols were observed. The green algae Ulva lactuca contained only 0.29 mg/g fucosterol and 10.3 μg/g 24 (R, S)-saringosterol, while all investigated red algae did not contain any 24(R, S)-saringosterol or fucosterol. In the Eastern Scheldt algae harvested in September/October delivered the highest yield for 24(R, S)-saringosterol, with the exception of Undaria pinnatifida that showed the highest levels in February. We showed that exposure of lipid extracts of Ulva lactuca to sunlight at room temperature or in the presence of oxygen to UV-C light lead to the quantitative conversion of fucosterol into 24(R, S)-saringosterol. Exposing pure fucosterol to UV-light did not convert any fucosterol into 24(R, S)-saringosterol underscoring the requirement of seaweed constituents in the conversion of fucosterol into 24(R, S)-saringosterol. In conclusion, we showed that brown seaweeds harvested from the Eastern Scheldt contain amounts of 24(R, S)-saringosterol comparable to Sargassum fusiforme, varying per season and showing the highest amounts in spring. In accordance with these observations the amount of 24(R, S)-saringosterol in the brown seaweeds can be modulated by light., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Multi-scale macroalgae growth models are required for the efficient design of sustainable, economically viable, and environmentally safe farms. Here, we develop a multi-scale model for Ulva sp. macroalgae growth and nitrogen sequestration in an intensive cultivation farm, regulated by temperature, light, and nutrients. The model incorporates a range of scales by incorporating spatial effects in two steps: light extinction at the reactor scale (1 m) and nutrient absorption at the farm scale (1 km). The model was validated on real data from an experimental reactor installed in the sea. Biomass production rates, chemical compositions, and nitrogen removal were simulated under different seasons, levels of dilution in the environment and water-exchange rate in the reactor. This multi-scale model provides an important tool for environmental authorities and seaweed farmers who desire to upscale to large bioremediation and/or macroalgae biomass production farms, thus promoting the marine sustainable development and the macroalgae-based bioeconomy.

Extracellular matrix (ECM) provides structural support for cell growth, attachments and proliferation, which greatly impact cell fate. Marine macroalgae species Ulva sp. and Cladophora sp. were selected for their structural variations, porous and fibrous respectively, and evaluated as alternative ECM candidates. Decellularization-recellularization approach was used to fabricate seaweed cellulose-based scaffolds for in-vitro mammalian cell growth. Both scaffolds were confirmed nontoxic to fibroblasts, indicated by high viability for up to 40 days in culture. Each seaweed cellulose structure demonstrated distinct impact on cell behavior and proliferation rates. The Cladophora sp. scaffold promoted elongated cells spreading along its fibers' axis, and a gradual linear cell growth, while the Ulva sp. porous surface, facilitated rapid cell growth in all directions, reaching saturation at week 3. As such, seaweed-cellulose is an environmentally, biocompatible novel biomaterial, with structural variations that hold a great potential for diverse biomedical applications, while promoting aquaculture and ecological agenda.

Rare earth elements (REEs) are gaining growing attention in environmental and ecotoxicological studies due to their economic relevance, wide range of applications and increasing environmental concentrations. Among REEs, special consideration should be given to Gadolinium (Gd), whose wide exploitation as a magnetic resonance imaging (MRI) contrast agent is enhancing the risk of its occurrence in aquatic environments and impacts on aquatic organisms. A promising approach for water decontamination from REEs is sorption, namely through the use of macroalgae and in particular Ulva lactuca that already proved to be an efficient biosorbent for several chemical elements. Therefore, the present study aimed to evaluate the toxicity of Gd, comparing the biochemical effects induced by this element in the presence or absence of algae. Using the bivalve species Mytilus galloprovincialis, Gd toxicity was evaluated by assessing changes on mussels' metabolic capacity and oxidative status. Results clearly showed the toxicity of Gd but further revealed the capacity of U. lactuca to prevent injuries to M. galloprovincialis, mainly reducing the levels of Gd in water and thus the bioaccumulation and toxicity of this element by the mussels. The results will advance the state of the art not only regarding the effects of REEs but also with regard to the role of algae in accumulation of metals and protection of aquatic organisms, generating new insights on water safety towards aquatic wildlife and highlighting the possibility for resources recovery., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

This study aims at investigating the specific ion effects of Na + and K + on Ulva lactuca (L.) growth. U. lactuca was grown in balanced nutrient solutions with 10, 100, 300 and 600 mM NaCl or KCl. The growth was significantly higher at 300 and 600 mM NaCl compared to KCl, with the highest growth rate at 300 mM NaCl. NaCl-treated alga showed increases in the photosynthetic pigments and Rubisco protein content. However, KCl treatments adversely affected these photosynthetic attributes. U. lactuca needs adjusted, but not high K + /Na + ratio for a proper growth, since the high K + /Na + ratio in KCl-treated alga was associated with growth retardation. The cell wall was more extensible at high concentrations of NaCl compared to KCl. Therefore, the deleterious effect of K + could be mainly on the cell wall and hence inhibiting the growth and perhaps the vitality of the whole cell. The transcript of plasma membrane (PM) H + -ATPase was detected only at 300 and 600 mM NaCl, implying that this gene was specifically induced by high concentrations of Na + but not K + . The transcript of PM-Na + /K + -ATPase-like exhibited no Na + specificity and its induction alone could not improve the growth of KCl-treated U. lactuca. The simultaneous induction of the two PM-ATPases could positively affect the algal growth at high NaCl concentrations by maintaining the proper cellular K + /Na + ratio. Also, both PM-ATPases might contribute to energizing the plasma membrane and thereby promoting the cellular growth of U. lactuca at high Na + , but not K + , concentrations., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Three water-soluble polysaccharides (UPPs 1-3) were obtained from edible green alga Ulva pertusa. The chemico-physical analyses indicated that UPPs 1-3 possessed molecular weights of 376.7 kDa, 57.21 kDa, and 131.13 kDa, with sulfate contents of 26.01 ± 8.13%, 9.86 ± 3.24%, and 13.32 ± 6.56%, respectively, and composed of arabinose, galactose, glucose, xylose, galacturonic acid, glucuronic acid, and mannuronic acid, with different ratios. The in vitro studies revealed that UPP-1 showed significant effects on the proliferation and phagocytic activity of macrophage, release of nitric oxide, and secretion of cytokines (TNF-α and IL-6). The transcript-metabolite analysis of UPP-1 treated macrophage revealed 4747 differential genes (2416 up-regulated and 2331 down-regulated) and 94 differential metabolites (77 up-regulated and 17 down-regulated) that significantly co-mapped a transcript-metabolite correlation network of biosynthesis of amino acids, glycerophospholipid metabolism, and carbon metabolism. Thus, these findings provide a valuable foundation for the potential application of U. pertusa polysaccharides., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This study investigated the effect of seaweed supplementation (Ulva lactuca (UL) or Sargassum hemiphyllum var. chinense (SHC)) on the distribution and metabolites of As in broiler breasts. Broilers fed 5% UL or 5% SHC ingested 1.4- or 78- fold greater total As than birds fed the control diet. The majority of As species were arsenate in the SHC feed and dimethylarsinic acid in breasts from chicks fed the SHC-containing diet. Arsenate and arsenobetaine were the dominant metabolites in the UL-containing feed, and arsenobetaine was the major metabolite in breasts from chicks fed the UL-containing diet. Feeding SHC enhanced hepatic S-adenosyl-methionine and arsenic methyltransferase, whereas feeding UL elevated renal arsenic methyltransferase. Taken together, considerable variation in the profiles of As species and As metabolites existed in broilers fed seaweed. The use of SHC-containing feeds in poultry production should be approached cautiously because of the potential accumulation of inorganic As species in chicken breasts., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In order to analyze whether the marine macroalga Ulva lactuca can absorb and metabolize anthracene (ANT), the alga was cultivated with 5 µM ANT for 0-72 h, and the level of ANT was detected in the culture medium, and in the alga. The level of ANT rapidly decreased in the culture medium reaching a minimal level at 6 h, and rapidly increased in the alga reaching a maximal level at 12 h and then decreased to reach a minimal level at 48 h of culture. In addition, ANT induced an increase in hydrogen peroxide that remained until 72 h and a higher increase in superoxide anions that reach a maximal level at 24 h and remained unchanged until 72 h, indicating that ANT induced an oxidative stress condition. ANT induced an increase in lipoperoxides that reached a maximal level at 24 h and decreased at 48 h indicating that oxidative stress caused membrane damage. The activity of antioxidant enzymes SOD, CAT, AP, GR and GP increased in the alga treated with ANT whereas DHAR remained unchanged. The level of transcripts encoding these antioxidant enzymes increased and those encoding DHAR did not change. Inhibitors of monooxygenases, dioxygenases, polyphenol oxidases, glutathione-S-transferases and sulfotransferases induced an increase in the level of ANT in the alga cultivated for 24 h. These results strongly suggest that ANT is rapidly absorbed and metabolized in U. lactuca and the latter involves Phase I and II metabolizing enzymes.

Symbiosis of marine algae is inevitable in the marine environment, and species may occur interaction on the growth. In this study, the macroalgae Ulva pertusa and marine microalgae Heterosigma akashiwo were selected as target species to study the interaction mechanism between them. After the 8 days of co-cultivation, the inhibition on growth was observed for both of U. pertusa and H. akashiwo. Eight fatty acids in U. pertusa was detected, with the significant decrease in contents of polyunsaturated fatty acids (PUFAs) especially for C18:2, C18:3n-3 and C18:3n-6. Twelve fatty acids in H. akashiwo was detected, with the significant change for PUFAs. PUFA concentrations in the co-culture group were less than those in the mono-culture. Meanwhile the principal component analysis was conducted to insight into the interaction between U. pertusa and H. akashiwo by fatty acids content and carbon stable isotope ratio of fatty acids (δ 13 C FAs ). Fatty acid content could not distinguish mono and co-culture. However, δ 13 C FAs could distinguish not only the culture time of algae, but also the living environment of algae. In addition, this study combined fatty acids content and δ 13 C FAs to explore the release of fatty acids by algae into the seawater. The C18:3n-3 was identified as the allelochemical released by U. pertusa to inhibit the growth of H. akashiwo. The ratio of δ 13 C FAs in seawater decreased. This study provides a theoretical basis for the symbiosis of marine algae, and a new method of compound-specific stable carbon isotopes was used to better explore the metabolism of fatty acids in algae., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Cisplatin is widely used in anticancer therapy, but a substantial percentage of patients who receive the therapeutic dose of cisplatin develop nephrotoxicity. Hepatotoxicity may also develop after a single dose or low repeated doses of cisplatin. Ulva fasciata is an edible seaweed, commonly known as sea lettuces have also been shown various biological activities. In this study, ethanol extract and its solvent fractions (n-hexane and chloroform) of U. fasciata were given (orally) to different groups of rats for 10 days. Injury to the kidney was induced by administrating cisplatin, intraperitoneally (i.p.) to rats at a dose of 7 mg/kg body weight (b.w.) dissolved in 1 mL saline, at 5th day of the experiment. At 10th day rats were sacrificed and kidney parameters (creatinine, urea, and blood urea nitrogen (BUN)) and electrolyte balance (Ca ++ , Mg ++ , K+, and Na + ) in serum were determined, while oxidative stress markers glutathione (GSH), catalase (CAT) and malondialdehyde (MDA), and inflammatory cytokines, tumor necrosis factor (TNF α), and interleukin (IL-6) were determined in kidney tissues. Histological examination of the kidney was also performed to examine the changes in kidney tissues. Cisplatin caused adverse effects on blood parameters, antioxidants, and inflammatory markers with severe renal tubular injury in kidney tissues. Ethanol extract of U. fasciata and its fractions effectively improved these disorders and diminished the renal dysfunction. However, ethanol extract was found more effective in attenuating the adverse effect of cisplatin than its fractions. n-Hexane-soluble fraction that was subjected to GC-FID and GC-MS analysis revealed the presence of several compounds and some of them are new from this source. It could be concluded that the U. fasciata possesses nephroprotective effect and can attenuate cisplatin-induced renal dysfunction. Since U. fasciata is an edible seaweed, it may be used as a diet supplement.

Background: The effect of different cooking methods (boiling, vacuum and steamed cooking) on the volatile compound content and sensory properties of sea lettuce (Ulva rigida) seaweed was assessed. Sea lettuce was cooked at three different temperatures (50, 70 and 100 °C) for three different lengths of time (5, 10 and 15 min). Various statistical techniques were employed in order to establish any possible changes., Results: The different cooking methods modified significantly both the volatile compound content and the sensory properties of sea lettuce seaweed. In general, the cooked samples had lower concentrations of several volatile compounds than the control sample, mainly aldehydes. Regarding sensory analysis, the cooked samples exhibited lower values for various aroma descriptors such as seaside and seaweed, whereas descriptor scores such as cooked fish, salty dry fish and crustacean increased. No clear statistical differences were found between different cooking lengths of time and temperature levels with regard to both volatile compounds and sensory properties., Conclusions: In the cooking of sea lettuce seaweeds, the main sensory changes and modifications in their volatile content took place during the first minutes of cooking and at medium cooking temperatures. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Anthropogenic changes such as ocean acidification, eutrophication, and the release of hazardous chemicals affect coastal environments and aquatic organisms. We investigated the effects of seawater pH (7.4 and 8.2) isolated and in combination with Irgarol on Ulva lactuca. Stress indicators such as membrane damage, lipid peroxidation, and hydrogen peroxide content were assessed. In addition, chlorophyll fluorescence and antioxidant enzyme activities were measured. The photosynthetic yield was affected by low pH in assays with and without Irgarol. However, the combination of low pH and Irgarol promoted photoinhibition, besides the induction of non-photochemical quenching (NPQ) and changes in photosynthetic pigment contents. The induction of NPQ was directly influenced by low pH. The membrane damage was increased in low pH with and without Irgarol exposure. Total soluble protein and carbohydrate contents decreased in low pH, and in presence of Irgarol. The H 2 O 2 content and lipid peroxidation were not affected by low pH. In contrast, Irgarol exposure strongly increased lipid peroxidation in both pHs, suggesting a possible synergistic effect. To avoid the harmful effects of high H 2 O 2 , U. lactuca increased antioxidant enzyme activities in treatments under low pH and in presence of Irgarol. Our results indicate that U. lactuca is tolerant to low pH by inducing NPQ, changing pigment contents, and increasing antioxidant defenses. In contrast, these protective mechanisms could not avoid the harmful effects of the combination with Irgarol., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Most marine algae preferentially assimilate CO 2 via the Calvin-Benson Cycle (C 3 ) and catalyze HCO 3 - dehydration via carbonic anhydrase (CA) as a CO 2 -compensatory mechanism, but certain species utilize the Hatch-Slack Cycle (C 4 ) to enhance photosynthesis. The occurrence and importance of the C 4 pathway remains uncertain, however. Here, we demonstrate that carbon fixation in Ulva prolifera, a species responsible for massive green tides, involves a combination of C 3 and C 4 pathways , and a CA-supported HCO 3 - mechanism. Analysis of CA and key C 3 and C 4 enzymes, and subsequent analysis of δ 13 C photosynthetic products showed that the species assimilates CO 2 predominately via the C 3 pathway, uses HCO 3 - via the CA mechanism at low CO 2 levels, and takes advantage of high irradiance using the C 4 pathway. This active and multi-faceted carbon acquisition strategy is advantageous for the formation of massive blooms, as thick floating mats are subject to intense surface irradiance and CO 2 limitation.

A large number of industries use heavy metal cations to fix dyes in fabrication processes. Malachite green (MG) is used in many factories and in aquaculture production to treat parasites, and it has genotoxic and carcinogenic effects. Chromium is used to fix the dyes and it is a global toxic heavy metal. Face centered central composite design (FCCCD) has been used to determine the most significant factors for enhanced simultaneous removal of MG and chromium ions from aqueous solutions using marine green alga Enteromorpha intestinalis biomass collected from Jeddah beach. The dry biomass of E. intestinalis samples were also examined using SEM and FTIR before and after MG and chromium biosoptions. The predicted results indicated that 4.3 g/L E. intestinalis biomass was simultaneously removed 99.63% of MG and 93.38% of chromium from aqueous solution using a MG concentration of 7.97 mg/L, the chromium concentration of 192.45 mg/L, pH 9.92, the contact time was 38.5 min with an agitation of 200 rpm. FTIR and SEM proved the change in characteristics of algal biomass after treatments. The dry biomass of E. intestinalis has the capacity to remove MG and chromium from aquatic effluents in a feasible and efficient manner.

Ulva prolifera is a macroalgae that forms massive blooms, negatively impacting natural communities, aquaculture operations and recreation. The effects of the natural products, eugenol, β-myrcene, citral and nonanoic acid on the growth rate, antioxidative defense system and photosynthesis of Ulva prolifera were investigated as a possible control strategy for this harmful taxon. Negative effects on growth were observed with all four chemicals, due to the excessive production of reactive oxygen species and oxidative damage to the thalli. However, the response of U. prolifera under the four chemicals stress was different at the cellular level. β-myrcene, the most effective compound in terms of growth inhibition, induced oxidative stress as shown by the damage of total antioxidant capacity (T-AOC) and the downregulation of the glutathione-ascorbate (GSH-ASA) cycle which inhibited the antioxidative system. This chemical also inhibited photosynthesis and photoprotection mechanisms in U. prolifera, resulting in growth limitation. In contrast, U. prolifera was less affected by the second tested chemical, eugenol, and showed no significant change on photosynthetic efficiency in the presence of the chemical. The inhibition effects of the third and fourth tested chemicals, nonanoic acid and citralon, on growth and on the antioxidant defense system in U. prolifera were inferior. These results provide a potential avenue for controlling green tides in the future., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A novel seawater-based pretreatment process was developed to improve the hydrolysis yield of brown (Laminaria digitata), green (Ulva linza) and red (Porphyra umbilicalis) macroalgae. Pre-treated with 5% sulphuric acid at 121 °C, 15 minutes, L. digitata, U. linza and P. umbilicalis liberated 64.63 ± 0.30%, 69.19 ± 0.11% and 63.03 ± 0.04% sugar in seawater compared with 52.82 ± 0.16%, 45.93 ± 0.37% and 48.60 ± 0.07% in reverse-osmosis water, respectively. Low hydrolysis yields (2.6-11.7%) were observed in alkali and hydrothermal pretreatment of macroalgae, although seawater led to relatively higher yields. SEM images of hydrolyzed macroalgae showed that reverse-osmosis water caused contortions in the remaining cell walls following acid and hydrothermal pre-treatments in the L. digitata and U. linza samples. Fed-batch fermentations using concentrated green seaweed hydrolysates and seawater with marine yeast Wickerhamomyces anomalus M15 produced 48.24 ± 0.01 g/L ethanol with an overall yield of 0.329 g/g available sugars. Overall, using seawater in hydrolysis of seaweed increased sugar hydrolysis yield and subsequent bioethanol production.

Male broodstock (Litopenaeus vannamei, 36 ± 7 g, n = 600) reproductive performance, spermatophores and reproductive tract melanization, prostaglandin concentrations and biochemical composition were evaluated after including 3.8% Ulva clathrata meal in the diet (dry base) of a commercial hatchery during 45 days. Males fed Ulva had less melanized spermatophores (120 compared with 233, P < 0.01), less bacteria in the ductus deferens (P < 0.01), more sperm cells in testicles (P < 0.05), and increased courtship activity (839 compared with 689, P < 0.01), with no effect on mortality. Ulva-fed males had more arachidonic acid (20:4n-6) in the spermatophores (P < 0.05) but this did not affect the prostaglandin concentrations in response to diet. Males fed Ulva had more carotenoids in the hepatopancreas (0.08 ± 0.02 compared with 0.01 ± 0.01 mg/g, P < 0.05), and phenolic compounds in hepatopancreas (6.1 ± 0.7 compared with 1.8 ± 0.7 mg eq. phloroglucinol/g, P < 0.05) and muscle (0.4 ± 0.3 compared with 0.2 ± 0.1 mg eq. phloroglucinol/g, P < 0.05). Males fed the Ulva also had a lesser carbohydrate content in the hepatopancreas (P < 0.01) and muscle (P < 0.01). In conclusion, supplementing fresh maturation diets with a small dose of dried Ulva allowed for improvement of reproductive performance and to decrease melanization in spermatophores and the male reproductive tract., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Introduction: Copper oxide nanoparticles (CuO-NPs) are widely used as feed additives for livestock and poultry and implicated in many biomedical applications; however, overload of copper NPs induces various toxicological changes and dysfunction of animal's organs. Thus, this study was designed to evaluate the comparative toxicological effects of biologically and chemically synthesized CuO-NPs on mice., Methods: Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) were used to characterize the sizes, shapes and functional groups of CuO-NPs. Forty-five mice were randomly allocated into three groups. Control group received distilled water. The second group was administered a single dose of biologically synthesized CuO-NPs (500 mg/kg bw) orally. The third group was administered a single dose of chemically synthesized CuO-NPs (500 mg/kg bw) orally., Results: TEM revealed that biologically synthesized NPs were spherical in shape, whereas chemically synthesized NPs were spherical or elongated in shape. XRD showed that the size of biologically synthesized NPs ranged from 4.14 to 12.82 nm and that of chemically synthesized NPs ranged from 4.06 to 26.82 nm. FT-IR spectroscopy indicated that the peaks appeared between 779 cm -1 and 425 cm -1 in biologically synthesized NPs and between 858 cm -1 and 524 cm -1 in chemically synthesized NPs were for Cu-O nanostructure. Four mice died due to administration of biologically synthesized CuO-NPs. Both biologically and chemically synthesized CuO-NPs induced leukocytosis, elevated serum activities of alanine aminotransferase and aspartate aminotransferase and serum levels of urea and creatinine and increased P53 mRNA and caspase-3 protein expressions in hepatic tissues. Moreover, CuO-NPs induced degenerative and necrotized changes in hepatic, renal and splenic tissues. Biochemical, apoptotic and pathological changes were more serious in mice administered with biologically synthesized CuO-NPs., Conclusion: This study indicated that a high dose of biologically and chemically synthesized CuO-NPs induced adverse effects on hepatic, renal and splenic tissues. At the same dose level, the biologically synthesized CuO-NPs evoked more potent toxic effects than the chemically synthesized CuO-NPs., Competing Interests: The authors report no conflicts of interest in this work., (© 2020 El Bialy et al.)

Enteromorpha prolifera blooms considerably affected coastal environments in recent years. However, the effects of E. prolifera on microbial ecology and function remained unknown. In this study, metagenomic sequencing was used to investigate the effect of E. prolifera bloom on the microbial communities and functional genes in an aquaculture environment. Results showed that E. prolifera bloom could significantly alter the microbial composition and abundance, and heterotrophic bacteria comprised the major groups in the E. prolifera bloom pond, which was dominated by Actinomycetales and Flavobacteriales. The study indicated that viruses played an important role in shaping the microbial community and diversity during E. prolifera bloom. These viruses affected various dominant microbial taxa (such as Rhodobacteraceae, Synechococcus, and Prochlorococcus), which produced an obvious impact on potential nutrient transformation. Functional annotation analysis indicated that E. prolifera bloom would considerably shift the metabolism function by altering the structure and abundance of the microbial community. E. prolifera bloom pond had the low ability of potential metabolic capabilities of nitrogen, sulfur, and phosphate, whereas promoted gene abundance of genetic information processing. These changes in the microbial community and function could produce serious effect on aquaculture ecosystem.

The physiological and biochemical changes in the green macroalga Ulva pertusa during the progression of sporulation have been characterized. The transition from the vegetative to the sporulation stage was accompanied by an increase in chlorophyll a (Chl a), chlorophyll b (Chl b), and carotenoid content, as well as an increase in DPPH scavenging and responsiveness to diphenylamine. However, oxygen evolution and maximum electron transport rate decreased. The discrepancy between photosynthetic performance and pigment content might relate to the self-shading of spores within a sporangium. Spore-forming U. pertusa thalli were low-light-adapted, due to an increase in the number of photosynthetic units. Decreased electron transport during sporulation might trigger sporulation, as for some cyanobacteria and other Ulva spp., via oxidization of the plastoquinone pool and cyclic phosphorylation, thus producing ATP to generate carbon and nitrogen skeletons required for spores. It is thus concluded that carotenoids function both in spore initiation and/or maturation and in their photoprotection., (© 2020 Phycological Society of America.)

The wild harvest and aquaculture of Ulva spp. has deserved growing attention in Europe. However, the impact of geographical origin on the biochemical composition of different species and/or strains is yet to be described in detail. Hence, the present study aimed to detect the variability of the lipidome of different species and/or strains of Ulva originating from different geographic locations. We hypothesized that lipidomic signatures can be used to trace the geographic origin post-harvesting of these valuable green seaweeds. Ulva spp. was sampled from eight distinct ecosystems along the Atlantic Iberian coast and Ulva rigida was sourced from an aquaculture farm operating a land-based integrated production site. Results showed significant differences in the lipidomic profile displayed by Ulva spp. originating from different locations, namely, due to different levels of polyunsaturated betaine lipids and galactolipids; saturated betaine lipids and sulfolipids; and some phospholipid species. Overall, a set of 25 site-specific molecular lipid species provide a unique lipidomic signature for authentication and geographic origin certification of Ulva species. Present findings highlight the potential of lipidome plasticity as a proxy to fight fraudulent practices, but also to ensure quality control and prospect biomass for target bioactive compounds., Competing Interests: The authors declare no conflict of interest.

Intelligent biorefinery design that addresses both the composition of the biomass feedstock as well as fermentation microorganisms could benefit from dedicated tools for computational simulation and computer-assisted optimization. Here we present the BioLego Vn2.0 framework, based on Microsoft Azure Cloud, which supports large-scale simulations of biomass serial fermentation processes by two different organisms. BioLego enables the simultaneous analysis of multiple fermentation scenarios and the comparison of fermentation potential of multiple feedstock compositions. Thanks to the effective use of cloud computing it further allows resource intensive analysis and exploration of media and organism modifications. We use BioLego to obtain biological and validation results, including (1) exploratory search for the optimal utilization of corn biomasses-corn cobs, corn fiber and corn stover-in fermentation biorefineries; (2) analysis of the possible effects of changes in the composition of K. alvarezi biomass on the ethanol production yield in an anaerobic two-step process (S. cerevisiae followed by E. coli); (3) analysis of the impact, on the estimated ethanol production yield, of knocking out single organism reactions either in one or in both organisms in an anaerobic two-step fermentation process of Ulva sp. into ethanol (S. cerevisiae followed by E. coli); and (4) comparison of several experimentally measured ethanol fermentation rates with the predictions of BioLego., Competing Interests: The authors have declared that no competing interests exist.

Background: The marine alga Ulva compressa is the dominant species in copper-polluted coastal areas in northern Chile. It has been shown that the alga tolerates micromolar concentrations of copper and accumulates copper at the intracellular level. Transcriptomic analyses were performed using total RNA of the alga cultivated with 10 μ M copper for 0, 1, 3 and 5 days using RNA-seq in order to identify processes involved in copper tolerance., Results: The levels of transcripts encoding proteins belonging to Light Harvesting Complex II (LHCII), photosystem II (PSII), cytochrome b6f, PSI, LHCI, ATP synthase and proteins involved in repair of PSII and protection of PSI were increased in the alga cultivated with copper. In addition, the level of transcripts encoding proteins of mitochondrial electron transport chain, ATP synthase, and enzymes involved in C, N and S assimilation were also enhanced. The higher percentages of increase in the level of transcripts were mainly observed at days 3 and 5. In contrast, transcripts involved protein synthesis and degradation, signal transduction, and replication and DNA repair, were decreased. In addition, net photosynthesis and respiration increased in the alga cultivated with copper, mainly at days 1 to 3. Furthermore, the activities of enzymes involved in C, N and S assimilation, rubisco, glutamine synthase and cysteine synthase, respectively, were also increased, mainly at days 1 and 3., Conclusions: The marine alga U. compressa tolerates copper excess through a concomitant increase in expression of proteins involved in photosynthesis, respiration, and C, N and S assimilation, which represents an exceptional mechanism of copper tolerance.

Stranded green macroalgae represents an important and renewable biomass that remains under valorized despite the numerous environmental problems generated by their accumulation in coastal regions. This work describes the isolation of a filamentous thermophile fungus identified as Aspergillus terreus JL1 that produces an efficient cellulolytic activity for green macroalgae saccharification. The characterization of the endoglucanase activity obtained after submerged fermentation showed a differential induction depending on the carbon source used with a unique isoform released when Ulva lactuca was used as inducer. The crude extract obtained hydrolyzed efficiently the untreated algal biomass (70.5%) compared to other cellulolytic extracts. The unique endoglucanase released was then purified to homogeneity (Yield: 49.6%; Specific activity: 30.1 U/mg; Purification fold: 4.36) and characterized biochemically. Its peptidic sequence was then determined and showed its belonging to the GH12. The described enzyme represents a promising biotechnological tool for algal biomass conversion.

Seaweeds are considered to be one of the richest bio-reserves, comprising of numerous bioactive compounds with versatile properties and multiple activities. The present study examined the antibacterial activity of two types of seaweeds, Ulva lactuca (green) and Stoechospermum marginatum (brown) collected from Oman Coastal region against five multidrug-resistant bacteria. The aqueous extracts of the seaweeds showed better antibacterial activity compared to methanol extracts. The results of the antibacterial assay revealed the excellent inhibitory effects of U.lactuca with the maximum activity against E.coli(8 mm) followed by K.pneumonia(4 mm) and S.typhi(2 mm). S.marginatum formed a clear zone of inhibition only against E.coli(3 mm).The major phytochemical constituents identified in both the types of seaweeds were Alkaloids, Terpenoids, Saponins, Flavonoids, and Steroids. Fourier transform infrared spectroscopy (FTIR) results confirmed the presence of alcoholic/phenolic groups, and amide groups in the seaweed extracts. Gas chromatography-mass spectrometry (GC-MS) results evidenced the presence of bioactive compounds such as 5-Octadecenal, 1-Tricosanol, Neophytadiene, Lactaropallidin, Phytol, Fenretinide, Lucenin, Vincadifformine in U.lactuca. Additionally, U.lactuca displayed better antioxidant activity (33.05%) in the DPPH free radical scavenging activity test compared to the S.marginatum (21.51%). Thus, the green seaweed U.lactuca could be considered as a potential source of natural antioxidant and antibacterial agents for food and pharmaceutical products., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The present study aimed to evaluate the potential protective and antioxidant effect of polysaccharides (PS) extracted from Ulva lactuca against thiacloprid (THC) induced nephrotoxicity and hepatotoxicity. The antioxidant capacity of PS was tested in vitro using ABTS radical scavenging activity and plasmid DNA cleavage assays andin vivo on adult male rats treated for 30 days. Animals were allocated into four groups: control; THC (22.5 mg/kg); THC (22.5 mg/kg) + PS1 (100 mg/kg diet); and THC (22.5 mg/kg) + PS2 (200 mg/kg diet). The structural features of PS were determined by Fourier transformed infrared (FT-IR), UV absorption peak detection, high performance liquid chromatography (HPLC) and gel permeation chromatography, and also functional properties were investigated. Overall, results indicated that THC increased significantly malondialdehyde, advanced oxidation protein products, glutathione levels, which is correlated with severe histological and plasmatic biochemical injuries in both liver and kidney tissues. However, cotreatment PS induced a significant protective and healing affects against the nephrotoxicity and hepatotoxcity induced by THC., (© 2019 Wiley Periodicals, Inc.)

Edible seaweeds are highly consumed food with a rich chlorophyll profile. Although seaweeds are mainly cooked ingested, the influence of cooking on the chlorophyll bioaccessibility remains unknown. In this research, cooked Nori, Sea Lettuce and Kombu were subjected to an in vitro digestion and following micellarization investigations. The processing of red seaweed does not affect the chlorophyll recovery, while cooking green and brown seaweeds implies an important increase in chlorophyll recovery after in vitro digestion. In this line, while cooking affects negatively the micellarization rate of chlorophyll derivatives in Nori and Kombu, it does not modify the micellarization in Sea Lettuce. Generally, the chlorophyll bioaccessibility of microwaved seaweeds is always higher than that of boiled ones. However, cooking improves the chlorophyll bioaccessibility in brown seaweeds, while decreases in red seaweeds. In conclusion, the characteristics of food matrix are the determinant factor on the chlorophyll bioaccessibility of cooked seaweeds., (Copyright © 2019 Elsevier Ltd. All rights reserved.)