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Green seaweeds exhibit a wide range of morphologies and occupy various ecological niches, spanning from freshwater to marine and terrestrial habitats. These organisms, which predominantly belong to the class Ulvophyceae, showcase a remarkable instance of parallel evolution toward complex multicellularity and macroscopic thalli in the Viridiplantae lineage. Within the green seaweeds, several Ulva species ("sea lettuce") are model organisms for studying carbon assimilation, interactions with bacteria, life cycle progression, and morphogenesis. Ulva species are also notorious for their fast growth and capacity to dominate nutrient‐rich, anthropogenically disturbed coastal ecosystems during "green tide" blooms. From an economic perspective, Ulva has garnered increasing attention as a promising feedstock for the production of food, feed, and biobased products, also as a means of removing excess nutrients from the environment. We propose that Ulva is poised to further develop as a model in green seaweed research. In this perspective, we focus explicitly on Ulva mutabilis/compressa as a model species and highlight the molecular data and tools that are currently available or in development. We discuss several areas that will benefit from future research or where exciting new developments have been reported in other Ulva species. [ABSTRACT FROM AUTHOR]

Background: Macroalgal epiphytic microbial communities constitute a rich resource for novel enzymes and compounds, but studies so far largely focused on tag-based microbial diversity analyses or limited metagenome sequencing of single macroalgal species. Results: We sampled epiphytic bacteria from specimens of Ulva sp. (green algae), Saccharina sp. (brown algae), Grateloupia sp. and Gelidium sp. (both red algae) together with seawater and sediment controls from a coastal reef in Weihai, China, during all seasons. Using 16S rRNA amplicon sequencing, we identified 14 core genera (consistently present on all macroalgae), and 14 dominant genera (consistently present on three of the macroalgae). Core genera represented ~ 0.7% of all genera, yet accounted for on average 51.1% of the bacterial abundances. Plate cultivation from all samples yielded 5,527 strains (macroalgae: 4,426) representing 1,235 species (685 potentially novel). Sequencing of selected strains yielded 820 non-redundant draft genomes (506 potentially novel), and sequencing of 23 sampled metagenomes yielded 1,619 metagenome-assembled genomes (MAGs), representing further 1,183 non-redundant genomes. 230 isolates and 153 genomes were obtained from the 28 core/dominant genera. We analyzed the genomic potential of phycosphere bacteria to degrade algal polysaccharides and to produce bioactive secondary metabolites. We predicted 4,451 polysaccharide utilization loci (PULs) and 8,810 biosynthetic gene clusters (BGCs). These were particularly prevalent in core/dominant genera. Conclusions: Our metabolic annotations and analyses of MAGs and genomes provide new insights into novel species of phycosphere bacteria and their ecological niches for an improved understanding of the macroalgal phycosphere microbiome. DnRc39z963CYrL7RdN5UNd Video Abstract [ABSTRACT FROM AUTHOR]

Ulva sp. is green macroalgae with a high potential for nutrient-dense food production. This species is found on a coastline in the intertidal zone of Indonesia's waters. There has been research on this species starting from post-harvest handling, nutrition, probiotics, and its ulvaran, however, information on the effect of temperature storage on Ulva lactuca freshness is still lacking. This study was undergone to evaluate the freshness quality of U. lactuca by sensory changes in different temperatures short-term storage. In order to evaluate the effect of the different storage circumstances, the fresh U. lactuca was collected from its natural habitat (intertidal zone of Sepanjang Coast, Yogyakarta Indonesia). It was rinsed from debris and epiphyte, stored in a transparent polyethylene bag, and stored at 4 °C, 15-20 °C, and room temperature for five days. Color, pH, ash, moisture, crude protein, chlorophyll, Total Plate Count, and sensory analysis was undergone during the storage period. The sensory evaluation score of U. lactuca in 4 °C was more than 6, and better than other storages. The crude protein (U. lactuca stored in 4 °C) decreased significantly on day 4 by 5.53%, it was lower than others. The TPC of all samples varied from 147x103in 0 days of storage to 2,462.5x103 CFU/ml on the last day of storage. In summary, the sensory scores of U. lactuca are more consistent and higher at 4 °C than in other storage conditions, despite a slight decline in nutrient content. [ABSTRACT FROM AUTHOR]

The genus Ulva L. (Sea lettuce), one of the most valuable marine macroalgae, is found in shallow coastal areas and in brackish and fresh water around the world. Ulva species have nutritional and medicinal values in addition to other applications, and contain various compounds such as lipids, proteins and carotenoids. These species have high phenotypic plasticity and varied in response to different environmental conditions. In this study, 38 populations of 10 species of Ulva from the coastal areas of the Persian Gulf and Oman Sea, from different areas of Bushehr, Hormozgan and Sistan and Baluchestan provinces, were studied and identified on the basis of morphological and anatomical traits. Different populations showed variations in characteristics such as height, shape and color of thallus, number of pyrenoids and cell dimensions. Metabolites such as total protein, total oil, chlorophyll a, b and carotenoids contents were measured and compared among the different populations. The results should that the percentage of protein was highest in U. prolifera of Shif Island from Bushehr province as compared with the Ulva species studied, with about 26.5% of dry weight, and the percentage of total oil was lowest in U. flexuosa of Hakhamanesh region from Hormozgan province as compared with the species studied, with about 4.8% of dry weight. These results show that different environmental conditions affect the morphological and anatomical structure of species and the content of their metabolites. Due to the high-protein and low-calorie content of the Ulva genus and the importance of finding new and sustainable resources for food and pharmaceutical industries, the species of this genus have valuable potentials.

Crude and α- and β-cellulose yields were estimated in six macroalgal species belonging to various groups growing in the Mediterranean coast, Egypt. The extracted cellulose yield varied between 11.70% dry weight (DW) for Colpomenia sinuosa and 1.38% DW for Jania rubens. The results revealed that α-cellulose represented the major proportion “43%” to “74%” of cellulose, while β–cellulose represented the minor proportion “2.3%” to “12%”. Cellulose nanofibers (CNFs) were prepared from crude cellulose via acid hydrolysis, and the yield was calculated as “47.74%” to “9.13%”. The seaweed cellulose and CNFs of the maximum-producing species were morphologically characterized via scanning electron microscopy (SEM). The shapes of the extracted cellulose ranged from filaments and plates to web-like structures according to the seaweed species and cellulose fractions. The CNFs exhibited nanosphere shapes, with the average size ranging from 14.94 to 30.82 nm. Chemical analysis of the prepared cellulose performed via Fourier-transform infrared spectrometry (FTIR) demonstrated the similarity between crude and α- and β-cellulose. The CNFs were investigated via Ultraviolet–visible spectroscopy and surface plasmon resonance (SPR) bands, which confirmed the spherical shape of the prepared CNFs. In conclusion, the selected seaweeds can be used as a renewable source of dietary fibers and CNFs with economic applications. Further studies are required to screen numerous species of seaweeds for large-scale production of cellulose.

Ulva lactuca is a seaweed with antinutritional cell wall for monogastrics. Carbohydrate-Active enZymes (CAZymes) supplementation can potentially cause its disruption. This study evaluates four diets: Ctrl—control diet; UL—control + 7% U. lactuca (wild caught, powdered form); ULR—UL + 0.005% Rovabio® Excel AP; ULU—UL + 0.01% ulvan lyase on piglets' haematologic and serologic profiles, hepatic lipids and minerals. White blood cells and lymphocytes reached the highest values in piglets fed UL compared to control, and to control and ULR; respectively (P < 0.05). IgG levels were boosted by seaweed incorporation compared to control (P = 0.015). The glycaemic homeostasis was assured by the seaweed inclusion. Dietary seaweed decreased serum lipids (P < 0.001), with the exception of ULU, due to HDL-cholesterol increase (P < 0.001). Cortisol was decreased in ULR and ULU (P < 0.001). No systemic inflammation was observed (P > 0.05). While hepatic n-3 PUFA increased in piglets fed with seaweed diets due to increment of beneficial 22:5n-3 and 22:6n-3 fatty acids (P < 0.05), the opposite occurred for n-6 PUFA, PUFA/SFA and n-6/n-3 ratios (P < 0.05). Hepatic pigments were unchanged (P > 0.05). ULR reduced α-tocopherol levels (P = 0.036) and increased serum potassium levels (P < 0.001) compared to control. Seaweed contributed to overcome piglets' weaning stress, with some benefits of including CAZyme supplementation. [ABSTRACT FROM AUTHOR]

Introduction: Vibrio is an important bacterial genus containing many pathogenic species. Although more and more Vibrio phages were isolated, the genome, ecology and evolution of Vibrio phages and their roles in bacteriophage therapy, have not been fully revealed. Methods: Novel Vibrio phage vB_ValR_NF infecting Vibrio alginolyticus was isolated from the coastal waters of Qingdao during the Ulva prolifera blooms, Characterization and genomic feature of phage vB_ValR_NF has been analysed using phage isolation, sequencing and metagenome method. Results and Discussion: Phage vB_ValR_NF has a siphoviral morphology (icosahedral head 114±1 nm in diameter; a tail length of 231±1 nm), a short latent period (30 minutes) and a large burst size (113 virions per cell), and the thermal/pH stability study showed that phage vB_ValR_NF was highly tolerant to a range of pHs (4-12) and temperatures (-20 - 45 °C), respectively. Host range analysis suggests that phage vB_ValR_NF not only has a high inhibitory ability against the host strain V. alginolyticus, but also can infect 7 other Vibrio strains. In addition, the phage vB_ValR_NF has a double-stranded 44, 507 bp DNA genome, with 43.10 % GC content and 75 open reading frames. Three auxiliary metabolic genes associated with aldehyde dehydrogenase, serine/threonine protein phosphatase and calcineurin-like phosphoesterase were predicted, might help the host V. alginolyticus occupy the survival advantage, thus improving the survival chance of phage vB_ValR_NF under harsh conditions. This point can be supported by the higher abundance of phage vB_ValR_NF during the U. prolifera blooms than in other marine environments. Further phylogenetic and genomic analysis shows that the viral group represented by Vibrio phage vB_ValR_NF is different from other well-defined reference viruses, and can be classified into a new family, named Ruirongviridae. In general, as a new marine phage infecting V. alginolyticus, phage vB_ValR_NF provides basic information for further molecular research on phage-host interactions and evolution, and may unravel a novel insight into changes in the community structure of organisms during the U. prolifera blooms. At the same time, its high tolerance to extreme conditions and excellent bactericidal ability will become important reference factors when evaluating the potential of phage vB_ValR_NF in bacteriophage therapy in the future. [ABSTRACT FROM AUTHOR]

To understand the evolutionary driving forces of chloroplast (or plastid) genomes (plastomes) in the green macroalgal genus Ulva (Ulvophyceae, Chlorophyta), in this study, we sequenced and constructed seven complete chloroplast genomes from five Ulva species, and conducted comparative genomic analysis of Ulva plastomes in Ulvophyceae. Ulva plastome evolution reflects the strong selection pressure driving the compactness of genome organization and the decrease of overall GC composition. The overall plastome sequences including canonical genes, introns, derived foreign sequences and non-coding regions show a synergetic decrease in GC content at varying degrees. Fast degeneration of plastome sequences including non-core genes (minD and trnR3), derived foreign sequences, and noncoding spacer regions was accompanied by the marked decrease of their GC composition. Plastome introns preferentially resided in conserved housekeeping genes with high GC content and long length, as might be related to high GC content of target site sequences recognized by intronencoded proteins (IEPs), and to more target sites contained by long GC-rich genes. Many foreign DNA sequences integrated into different intergenic regions contain some homologous specific orfs with high similarity, indicating that they could have been derived from the same origin. The invasion of foreign sequences seems to be an important driving force for plastome rearrangement in these IRlacking Ulva cpDNAs. Gene partitioning pattern has changed and distribution range of gene clusters has expanded after the loss of IR, indicating that genome rearrangement was more extensive and more frequent in Ulva plastomes, which was markedly different from that in IR-containing ulvophycean plastomes. These new insights greatly enhance our understanding of plastome evolution in ecologically important Ulva seaweeds. [ABSTRACT FROM AUTHOR]

One of the main bioactive compounds of interest from the Ulva species is the sulfated polysaccharide ulvan, which has recently attracted attention for its anticancer properties. This study investigated the cytotoxic activity of ulvan polysaccharides obtained from Ulva rigida in the following scenarios: (i) in vitro against healthy and carcinogenic cell lines (1064sk (human fibroblasts), HACAT (immortalized human keratinocytes), U-937 (a human leukemia cell line), G-361 (a human malignant melanoma), and HCT-116 (a colon cancer cell line)) and (ii) in vivo against zebrafish embryos. Ulvan exhibited cytotoxic effects on the three human cancer cell lines tested. However, only HCT-116 demonstrated sufficient sensitivity to this ulvan to make it relevant as a potential anticancer treatment, presenting an LC50 of 0.1 mg mL−1. The in vivo assay on the zebrafish embryos showed a linear relationship between the polysaccharide concentration and growth retardation at 7.8 hpf mL mg−1, with an LC50 of about 5.2 mg mL−1 at 48 hpf. At concentrations near the LC50, toxic effects, such as pericardial edema or chorion lysis, could be found in the experimental larvae. Our in vitro study supports the potential use of polysaccharides extracted from U. rigida as candidates for treating human colon cancer. However, the in vivo assay on zebrafish indicated that the potential use of ulvan as a promising, safe compound should be limited to specific concentrations below 0.001 mg mL−1 since it revealed side effects on the embryonic growth rate and osmolar balance. [ABSTRACT FROM AUTHOR]

Marine algae are considered a source of different bioactive constituents including protein, oil, fiber, vitamins, pigments and dietary minerals. To evaluate the fine chemical and biochemical properties of the marine microalga Nannochloropsis oculata and macroalga Ulva lactuca, the present study was carried out. The cultivated N. oculate and the collected U. lactuca were washed, oven-dried, ground and subjected to analysis of moisture, protein, fats, carbohydrates and ash. In addition, macro and micro-nutrients, amino acids profile, fatty acids methyl ester and pigments were assessed. The moisture content of U. lactuca was higher (13.25 %) than N. oculata (3.5 %). Protein, oil and fiber contents were significantly higher (P<0.05) in N. oculata than in U. lactuca and ranged between 32.19 % and 20.44 %, 10.29 % and 0.65 %, 11.91 % and 8.61 %, respectively, based on dry weight. Total phytochemical chlorophyll in U. lactuca (5.97µg/ml) was more than in N. oculata (1.18µg/ml). The dominant dietary element in N. oculata was P (24000 mg/kg), while Ca (48300 mg/kg) was dominant in U. lactuca. The trace dietary minerals (Fe, Mn and Cu) were significantly higher in U. lactuca than in N. oculata. Both algae proteins had 17 (N. oculata) and 16 (U. lactuca) amino acids, seven of them being non-essential amino acids, which accounted for 40.01 and 48.75 g/100g, respectively. Saturated and unsaturated fatty acids represented 45.13 and 54.87%; 68.95 and 31.05% of the fat of N. oculata and U. lactuca, respectively. Polyunsaturated fatty acids were more evident in N. oculata (31.36%) than in U. lactuca (3.81%). [ABSTRACT FROM AUTHOR]

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Detecting non-native species can be challenging, particularly in the case of taxa such as seaweeds, which can be difficult to distinguish based on morphology and often require molecular-assisted taxonomy for reliable identification. The sub-Antarctic island of South Georgia supports unique and important marine biodiversity, including a rich seaweed flora, but despite its isolation, its inshore ecosystems are susceptible to the introduction of potentially invasive non-native species. Here, we provide the first report of a non-native seaweed in South Georgia, Ulva fenestrata Postels & Ruprecht (Ulvophyceae, Chlorophyta), and confirm its widespread presence in the Falkland Islands via molecular-assisted taxonomy. Phylogenetic analyses of tufA and rbcL-3P genetic markers enabled the identification of a specimen collected from Grytviken, South Georgia in November 2021 as U. fenestrata. In terms of tufA sequence, this sample was identical to specimens collected from four sites spanning West and East Falkland in 2013 and 2018. This study represents the second Southern Hemisphere record of U. fenestrata, which is generally regarded as a Northern Hemisphere species. Our findings provide a foundation for monitoring this potentially invasive species in South Georgia, and for determining its likely source and mode of arrival, while emphasising the importance of robust biosecurity measures. [ABSTRACT FROM AUTHOR]

The marine algal biomass of Ulva lactuca was utilized for the extraction of cellulose and the development of cellulose nanocrystals/graphene oxide film. Cellulose nanocrystals with 50–150 nm were produced by H2SO4 hydrolysis of the algal cellulose. The adsorption efficiency of the nanocomposite film for Fe(II) and Fe(III) ions was successfully evaluated using Box-Behnken design. The maximum removal for Fe(II) (64.15%) could be attained at pH 5.13, adsorbent dosage 7.93 g L−1 and Fe(II) concentration 15.39 mg L−1, while the biosorption of Fe(III) was 69.92% at pH 5.0, adsorbent dosage 2 g L−1, and Fe(III) concentration 15.0 mg L−1. However, in the binary system, the removal efficiency of Fe(II) was enhanced to 95.48% at Fe(II):Fe(III) ratio of 1:1, while the Fe(III) removal was increased to 79.17% at ratio 1:2. The pseudo-second-order kinetics exhibited better fitting to the experimental results of Fe(II) and Fe(III) adsorption in both single and binary systems. The intra-particle diffusion was prominent during the biosorption, but the effect of the external mass transfer was significant. The Langmuir, Freundlich, Langmuir–Freundlich, Temkin, and Dubinin-Radushkevich isotherms showed satisfactory fitting to the experimental data, but they differ in priority based on iron state and pH. The adsorption of Fe(II) in the presence of Fe(III) in a mixture was best represented by the extended Langmuir model, while the extended Langmuir–Freundlich model best fitted the adsorption of Fe(III). The FT-IR analysis indicated that physisorption through electrostatic interaction/complexation is the predominant mechanism for the adsorption of iron using the nanocomposite film. [ABSTRACT FROM AUTHOR]

Various antibiotics are available, including gentamicin, chloramphenicol, ampicillin, amoxicillin, and streptomycin, but they have some restrictions. Many microorganisms are resistant to these medications. A new antimicrobial source must be found or developed to solve this issue. Inhere, extract from seaweeds Ulva lactuca was investigated for its antibacterial activity using a well diffusion assay against Klebsiella pneumoniae, and a promising inhibition zone diameter was recorded to be 14.04 mm. The biochemical structure of the antibacterial compound was determined via GC-MS and FTIR analysis. Also, a micro-dilution assay was used to calculate the minimum concentration that makes inhibition (MIC) to be 1.25 mg/ml from U. extract reliable to prevent the visibility of any bacterial growth, this was followed by examining the antibacterial effect of U. Lactuca methanolic extract alone and the synergetic effect of U. Lactuca methanolic extract in combination with two different antibiotics (gentamicin and chloramphenicol). This was assayed by the agar well diffusion method to achieve promising and strong inhibiting power against K. pneumoniae. It was deduced that the maximum synergism could be achieved by adding 2.5 mg/ml of Ulva methanolic extract to gentamicin (4 µg/ml), and the results were illustrated obviously via transmission electron microscope in which severe morphological deteriorations were experienced by the treated cells. From this study, we can conclude that U. lactucae extract has the power to aid antibiotics in reducing the growth of pathogenic K. pneumoniae. [ABSTRACT FROM AUTHOR]

SUMMARY: The subtidal brown algal species Sporochnus dotyi Brostoff (Sporochnales, Phaeophyceae), which has been regarded as a Hawaiian endemic, is reported from Kushimoto, Kii Peninsula, Pacific coast of central Honshu, Japan, for the first time outside Hawai'i. The species grew on subtidal rocks ca. 5–20 m deep attached by a small conical holdfast. The erect thalli were 5–30 cm high, terete, robust and alternately branched in 1–2 orders. When mature, pedicellate receptacles developed on the branches, and formed elliptical sori 1 mm long with a pedicel 3–5 mm long. The apical parts of the thalli and the receptacles were terminated with a tuft of simple assimilatory filaments of up to 4 mm long and showed prominent green to yellow underwater iridescence. Reproductive filaments (paraphyses) were densely packed, simple, up to 200 μm long and bore 4–6 mostly unilateral unilocular zoidangia 20–22 μm long and 5–6 m in diameter. In the genetic analyses, the Sporochnus alga from Kushimoto had partial rbcL sequence identical to S. dotyi from Hawai'i. The cox3 phylogeny revealed that this alga formed a fully supported clade with S. dotyi. Therefore, we identified the alga from Kushimoto as S. dotyi. This finding of S. dotyi from Japan, together with the recent reports of the mesophotic macroalgae Ryuguphycus kuaweuweu (=Umbraulva kuaweuweu), Ulva iliohaha and Newhousia imbricata from various localities in the Pacific Ocean including Japan, suggest closer biogeographical connections of subtidal/mesophotic macroalgae in the Pacific than previously recognized. [ABSTRACT FROM AUTHOR]

Melanogenesis involves a synthesis of melanin pigment and is regulated by tyrosinase. The addition of whitening agents with tyrosinase-inhibiting properties in cosmetics is becoming increasingly important. In this study, the ethanolic extracts from twelve seaweeds were assessed for tyrosinase-inhibiting activity using mushroom tyrosinase and melanin synthesis in B16F10 melanoma cells. The highest mushroom tyrosinase inhibition (IC50) was observed with Lobophora challengeriae (0.15 ± 0.01 mg mL−1); treatment was more effective than kojic acid (IC50 = 0.35 ± 0.05 mg mL−1), a well-known tyrosinase inhibitor. Three seaweeds, Caulerpa racemosa, Ulva intestinalis, and L. challengeriae, were further investigated for their ability to reduce melanogenesis in B16F10 cells. The ethanolic extracts of C. racemosa, U. intestinalis, and L. challengeriae showed inhibitory effects by reducing melanin and intracellular tyrosinase levels in B16F10 cells treated with α-melanocyte stimulating hormone in a dose-dependent manner. C. racemosa (33.71%) and L. challengeriae (36.14%) at 25 µg mL−1 reduced melanin production comparable to that of kojic acid (36.18%). L. challengeriae showed a stronger inhibition of intracellular tyrosinase (decreased from 165.23% to 46.30%) than kojic acid (to 72.50%). Thus, ethanolic extracts from C. racemosa, U. intestinalis, and L. challengeriae can be good sources of natural tyrosinase inhibitors and therapeutic or cosmetic agents in the future. [ABSTRACT FROM AUTHOR]

Plant-based protein has been increasingly demanded as a sustainable protein source. Sea lettuce (Ulva lactuca) is one of the potential sources as plant protein due to its high protein content. During processing, the sea lettuce is exposed to heat which might affect its nutrition, particularly the protein quality. This study aimed to evaluate two different cooking processes on the nutritional quality of the sea lettuce based on the proximate and protein quality analyses. The samples were raw, roasted, and boiled-roasted sea lettuce. All treatment using temperature 100°C. The protein quality was assessed by in-vitro protein digestibility, solubility, and amino acid profiles. The result showed that boiling treatment followed by roasting treatment had significantly higher protein content, amino acid score and essential amino acid index, and predicted-protein efficiency ratio compared with the value of roasting treatment only. It resulted in protein content of 18.87% (dry basis), amino acid score of 37.96%, essential amino acid index of 79.41% and predicted-protein efficiency ratio of 2.58. Therefore, boiling followed with roasting process is recommended to maintain the nutrition quality of sea lettuce. [ABSTRACT FROM AUTHOR]

Pollution by heavy metals is one of the most serious issues in the world, and the principal sources are manufacturing, fertilizers, mining, pesticides, transport, and wastewater discharge. In this study, the presence of macroelements (Nitrogen (N) and Phosphorus (P)) and heavy metals (Chromium (Cr), Nickel (Ni), Cadmium (Cd), Iron (Fe), Zinc (Zn), Lead (Pb), Cooper (Cu), and Manganese (Mn)) in the green tide caused by the green seaweed Ulva lactuca from Marchica lagoon (NE-Morocco, Mediterranean) was evaluated. The mean values of P and N in the algae were 1773.33 mg·kg −1 and 44.4 g·kg −1, respectively. The heavy metals have mean values following this descending sequence: Fe > Mn > Zn > Cu > Ni > Pb > Cr > Cd. This finding has suggested that Ulva has the strongest affinity to Fe and Mn among the metals examined. Mn, Fe, and Pb recorded the highest bioconcentration factors (BCFs), which were 1687, 1656, and 1643, respectively. Regarding their contribution to the Recommended Dietary Allowance (RDA), Fe showed a contribution of 13.58% to the RDA, while that of Mn varied between 4.42 % and 28.42%. The health risk assessment did not indicate any hazard related to the ingestion of Ulva lactuca. Therefore, this study suggests that Ulva lactuca in the Nador lagoon has the potential to bioaccumulate heavy metals and mitigate eutrophication. [ABSTRACT FROM AUTHOR]

The current study compared between marine ulva lactuca seaweed and freshwater azolla filiculoides macroalgae to evaluate the productivity and characteristics of lipids and biodiesels. Using Soxhlet apparatus, 7.6 ± 0.10% and 12.52 ± 0.23% of lipids were extracted from ulva lactuca and azolla filiculoides , respectively. Besides, a second-order kinetic model and Eyring equations were used to conduct the study of kinetics and thermodynamics of oil extraction from both species. The activation energies were estimated to be 53.93 kJ/mol & 85.79 kJ/mol for ulva lactuca and azolla filiculoides , respectively. Analyses of thermodynamic properties of the Soxhlet extraction for both species revealed that the extraction was exothermal and temperature-dependent process. However, they are different in the Gibbs free energy of activation (ΔG) analysis where it revealed spontaneous extraction process for ulva lactuca and unspontaneous process for azolla filiculoides. The extracted oils from both species were subjected to optimized base-catalyzed transesterification in order to synthesize biodiesel fuel. Four independent varying variables were optimized using response surface methodology (RSM) which were oil to methanol molar ratio (1:3–1:12), NaOH catalyst ratio (1–2% w/w), temperature (55–70 °C), and time (1–2.5 h). The maximum biodiesel yield was from ulva lactuca lipids 88.77% obtained at 1:12, 1.5%, 63 °C, and 1.7 h. In contrast, 82.85% of biodiesel was yielded from azolla filiculoides lipids at optimal values 1:10, 1%, 60 °C, and 2 h for oil to methanol molar ratio, catalyst ratio, temperature, and time, respectively, for both species. Characteristics of both biodiesels revealed almost close compliance with ASTM D6751 and EN14214 standards. Apart from comparisons, it can be concluded that marine ulva lactuca seaweeds and freshwater azolla filiculoides macroalgae are obtainable, affordable, and potential feedstock toward sustainable biodiesel production. [Display omitted] [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The aqueous extract of Ulva lactuca , obtained from algae waste, has been used both as precursor for nanobiochar and source of phycocolloids, for obtaining of ZnO@C composites by hydrothermal method, through two synthesis routes, and capped ZnO nanopowders. The nanomaterials were characterized by XRD, SEM, thermal analysis, UV–vis, PL and FTIR spectroscopy. The presence of ZnO with hexagonal wurtzite structure was confirmed by XRD, while the presence of biochar and capping molecules was confirmed by FTIR spectroscopy and thermal analysis correlated with the total organic carbon determination. The band gap energy was calculated from diffuse reflectance spectra. The photocatalytic properties were tested in the degradation of Congo red azo dye under UV and visible light irradiations, the prepared zinc oxide-biochair nanocomposites demonstrating a good photocatalytic activity, superior to the pristine ZnO nanopowders obtained in similar conditions. The results confirmed a good fit with the Langmuir–Hinshelwood kinetic model. A correlation between photoluminescent and photocatalytic properties of nanomaterials was done. The properties of ZnO@C nanocomposites depended on the synthesis route were compared with those of capped and pristine ZnO samples. [ABSTRACT FROM AUTHOR]

In recent years, algae blooms have caused severe problems, such as environmental pollution, the disruption of tourism, and shore-based activities, in many coastal areas worldwide. To reduce these problems, algae biomass (Ulva ohnoi) was used to develop a fully transparent regenerated cellulose-based composite film for food packaging. Cellulose was extracted from U. ohnoi using chemical treatments and characterized using scanning electron microscopy, nuclear magnetic resonance, and Fourier transform infrared spectroscopy. The extracted cellulose was activated, dissolved in dimethylacetamide/lithium chloride, and regenerated in ethanol to prepare a flexible transparent cellulose film. The mechanical strength, UV–visible light transmittance, and oxygen barrier properties of the regenerated cellulose film were characterized. The tensile strength, elongation at break, Young modulus, T660, and oxygen permeability at 50% relative humidity of the regenerated cellulose film were 69.21 ± 9.20 MPa, 13.43 ± 2.43%, 4016.2 ± 623.4 MPa, 90.71%, and 1898.4 ± 195.2 cc·µm/(m2·day·atm), respectively. The regenerated cellulose was mixed with zinc oxide nanoparticles and curcumin to prepare antibacterial and antioxidant functional composite films. These functional composite films displayed strong antibacterial activities against various Gram-negative and Gram-positive bacteria. [ABSTRACT FROM AUTHOR]

The use of algae as alternative feeds has long time attracted interest. However, due to excessive accumulation and variation in some of its components, difficulty in harvesting, and the need for some processes (cleaning, rinsing, drying, etc.) before final use, it causes hesitations about their use as feed. The feed values of Ulva lactuca and Cladophora glomerata collected from the same region in two different years (2020–2021) were investigated. The comparison of Ulva lactuca and Clodophora glomerata in two successive yearsyielded significant differences (P < 0.05) for crude protein% (22.23–10.78 and 18.38–12.85), crude ash% (19.28–34.10 and 40.67–35.51), ADF% (13.41–12.39 and 19.61–22.13), NDF% (39.18–36.35 and 29.36–35.74), calcium% (11.75–1.49 and 38.47–1.35), magnesium% (1.02–13.54 and 1.76–8.61), potassium% (0.53–6.17 and 1.50–17.86), sulphur% (4.76–2.41 and 3.41–1.80), and nickel ppm (9.50–87.5 and 20.25–105.3). Significant differences were also detected between other nutrients, minerals, energy, and digestibility values (P < 0.05). It has been determined that some heavy metal and mineral amounts are at restrictive levels at the point of use as feed. Aluminum (4982.7–7459.3 ppm) and silicon (8882.3–1449.3 ppm) were found in Ulva lactuca and Cladophora glomerata, respectively (P < 0.05). Sulphur, aluminum, silicon, and nickel amounts are above the tolarable feed criteria limits. Cadmium and lead were determined to be above the limits allowed in the legal legislation. Their biosorbent properties cause them to be affected by the ecosystem, and undesirable accumulations appear as a restrictive situation. Therefore, it is necessary to systematically determine their contents and variations. It was concluded that they are important in terms of potential feed value but should be used in a controlled manner. [ABSTRACT FROM AUTHOR]

A biofloc system is rich in nutrients, which favors the cultivation of macroalgae, but the influence of the system on the performance of macroalgae is unknown. The objective of this study was to analyze the feasibility of introducing the macroalgae Ulva lactuca into the culture of Litopenaeus vannamei in a biofloc system. The first experiment evaluated the influence of 400 mg L−1 and 30 mg L−1 solids concentration of the system in biofloc and von Stosch culture medium on macroalgae growth. In the second experiment, the densities of 1, 2, and 3 g L−1 of U. lactuca were cultivated in an integrated system with shrimp and monoculture treatment. Both experiments had 35 days of cultivation. There was no significant difference in macroalgae growth between the treatments with biofloc and von Stosch culture medium. In the integrated culture, the density of 1 g L−1 showed better nutrient absorption. Shrimp performance was not affected by macroalgae cultivation. In conclusion, the solids did not affect the growth of the macroalgae, and it could be cultivated in a biofloc system for nitrate uptake in integrated culture with shrimp. [ABSTRACT FROM AUTHOR]

Penicillium digitatum causes severe damage to postharvest and stored citrus fruits, making it necessary to seek acceptable solutions limiting environmental and sanitary impacts. The seaweed liquid extracts (SLEs) obtained from the green macroalgae Ulva lactuca have previously shown anti-fungal activities towards postharvest green mold due to P. digitatum. Moreover, treatment with aqueous and ethanolic extracts had an influence on disease incidence and lesion severity on wounded oranges "Valentia late". Therefore, we studied the abilities of the U. lactuca extracts and chlorophyll a (as a standard) to activate defense mechanisms in oranges. The analyses showed modifications in the protein concentrations and activities of β-1,3-glucanase and peroxidase in orange tissues, with a maximum activity level reached at 72 h after treatments. It appears that the SLEs were able to fight P. digitatum infections in the absence of direct contact with the pathogen, reflecting that the induction of host resistance is also a probable mode of action. Ulva lactuca fractions are rich in chlorophyll a, polyphenols, organic acids and ulvans, which might be the key molecules involved in the defense mechanism of oranges' albedo. The use of these natural substances could be an alternative way to control postharvest citrus rot. [ABSTRACT FROM AUTHOR]

The runoff of textile dye effluents into public water bodies is a major environmental and health problem. Color removal, in particular, has recently become of substantial scientific interest, as revealed by the multitude of related research reports. The present study focused on measuring the efficiency of two marine algae, Ulva fasciata and Pterocladia capillacea, in bio-removal of four synthetic dyes (RY2, RR195, RB19, and RB5) based on the fresh and dried biomass of the tested algal species. According to the highest removal efficiencies of the dyes, two algal species were chosen from among nine different algae. Bio-removal efficiency was examined under the effects of salinity and contact time. The results of this experiment revealed that algae achieved high bio-removal efficiency of the examined dyes in both fresh and saline water, but the removal percentages were higher in saline water compared to fresh conditions. The highest removal percentage recorded after 8 h by fresh U. fasciata in saline water reached 82.75 and 83.23% for RY2 and RR195 dyes, respectively. Contact time has the highest impact on dye removal in both algal species. The highest removal values were obtained in the case of dried U. fasciata, which achieved impressive removal percentages that reached 100% for RB195 and RB5 and fresh P. capillacea which had high removal percentages of 91.11, 94.85 and 97.13% for RR195, RB19, and RB5 dyes, respectively, after 8 h. Our results revealed that the used algal species were highly significant in the biosorption of most used dyes. [ABSTRACT FROM AUTHOR]

Ulva is a commercially important marine macroalga. It hosts both epiphytes and endophytes. The latter are assumed to protect Ulva through secondary metabolites. Previously, we demonstrated bioactive endophytes from macroalgae with great potential to control diseases of aquaculture. In this study, we introduced a bioactive bacterial endophyte back into its original host (Ulva sp.) and demonstrated its survival over time in fresh and freeze-dried Ulva sp. We visualized the endophyte’s location and survival in the seaweed using a Green Fluorescent Protein (GFP) reporter gene. The isolate colonized the intercellular space and survived for at least 5 months in fresh, and 12 months in freeze-dried algae, while maintaining its bioactivity against the aquaculture pathogen Streptococcus iniae. We studied the influence of the endophyte on the bacterial community in the Ulva sp. We found that once introduced, the endophyte significantly changed algal microbiota diversity and abundance. Two of Ulva’s associated bacterial species were quantified over time, suggesting different trends in absolute abundance of these bacteria between treatments. To the best of our knowledge, this is the first report of the successful introduction of an endophytic microorganism into macroalgal tissue. These findings may be useful in applied research for the potential management of aquaculture diseases.

Marine macroalgae (seaweeds) are important primary global producers, with a wide distribution in oceans around the world from polar to tropical regions. Most of these species are exposed to variable environmental conditions, such as abiotic (e.g., light irradiance, temperature variations, nutrient availability, salinity levels) and biotic factors (e.g., grazing and pathogen exposure). As a result, macroalgae developed numerous important strategies to increase their adaptability, including synthesizing secondary metabolites, which have promising biotechnological applications, such as UV-absorbing Mycosporine-Like Amino Acid (MAAs). MAAs are small, water-soluble, UV-absorbing compounds that are commonly found in many marine organisms and are characterized by promising antioxidative, anti-inflammatory and photoprotective properties. However, the widespread use of MAAs by humans is often restricted by their limited bioavailability, limited success in heterologous expression systems, and low quantities recovered from the natural environment. In contrast, bloom-forming macroalgal species from all three major macroalgal clades (Chlorophyta, Phaeophyceae, and Rhodophyta) occasionally form algal blooms, resulting in a rapid increase in algal abundance and high biomass production. This review focuses on the bloom-forming species capable of producing pharmacologically important compounds, including MAAs, and the application of proteomics in facilitating macroalgal use in overcoming current environmental and biotechnological challenges.

The article, titled "Being Algae. Transformations in Water, Plants. Critical Plant Studies," explores the deep connection that many people have with algae. The book, "Being Algae," takes a humanist and arts perspective on algae, while also incorporating new science and terminology. The editors, who have diverse backgrounds, cover a wide range of topics including the historical uses of algae, the role of algae in the environment, and the potential benefits of algae in various industries. The article emphasizes the need for humans to reconcile their lives with algae and to recognize the importance of algae in the natural world. [Extracted from the article]

One of the most prevalent chronic infectious disorders is tooth decay. Acids produced when plaque bacteria break down sugar in the mouth cause tooth decay. Streptococcus mutans and Lactobacillus acidophilus are the most prominent species related to dental caries. Innovative biocidal agents that integrate with a biomaterial to prevent bacterial colonization have shown remarkable promise as a result of the rapid advancement of nanoscience and nanotechnology. In this study, Ulva lactuca was used as a cellulose source and reducing agent to synthesize nanocellulose and Ulva/Ag/cellulose/nanocomposites. The characterizations of nanocellulose and Ulva/Ag/cellulose/nanocomposites were tested for FT-IR, TEM, SEM, EDS, XRD, and zeta potential. Ulva/Ag/cellulose/nanocomposites and Ulva/nanocellulose, both blended with fluoride, were tested as an antibacterial against S. mutans ATCC 25175 and L. acidophilus CH-2. The results of the SEM proved that nanocellulose is filament-shaped, and FT-IR proved that the functional groups of Ulva/nanocellulose and Ulva/Ag/cellulose/nanocomposites and cellulose are relatively similar but present some small diffusion in peaks. The TEM image demonstrated that the more piratical size distribution of Ulva/Ag/cellulose/nanocomposites ranged from 15 to 20 nm, and Ulva/nanocellulose ranged from 10 to 15 nm. Ulva/Ag/cellulose/nanocomposites have higher negativity than Ulva/nanocellulose. Ulva/Ag/cellulose/nanocomposites and Ulva/nanocellulose possess antibacterial activity against S. mutans ATCC 25175 and L. acidophilus CH-2, but Ulva/Ag/cellulose/nanocomposites are more effective, followed by that blended with fluoride. It is possible to use Ulva/Ag/cellulose/nanocomposites as an antimicrobial agent when added to toothpaste. It is promising to discover an economic and safe nanocomposite product from a natural source with an antimicrobial agent that might be used against tooth bacteria. [ABSTRACT FROM AUTHOR]

In this study, we utilized pomegranate peel and marine algae Ulva lactuca (U. lactuca) as rich and sustained sources of bioactive compounds to combat tomato-black spot disease. n-Hexane extracts from the peel of pomegranate (Punica granatum) (PPE) and the marine algal biomass U. lactuca (ULE) were used alone and in combinations to verify their impact against Alternaria alternata (A. alternata). The applied extracts exhibited severe destructive effects on both fungal growth and structure such as mycelia malformation, underdeveloped conidia, cell wall deformation, and shrinkage. Moreover, increased deformations and protrusions, and notch-like structures, were noticed in A. alternata mycelia treated with mixed extracts (PPE and ULE) compared to all other treatments. The protein and reduced sugar contents in tomato fruits were significantly increased in the infected fruits with A. alternata. The highest enzyme activities of pectinase, cellulase, catalase (CAT), and ascorbate peroxidase (APX) were recorded in infected tomatoes in comparison with the healthy ones. Molecular docking studies showed that each extract is rich with bioactive compounds that have a promising inhibition effect on A. alternata cellulases. Pomegranate and Ulva extract showed promising antifungal activity against A. alternata which revealed their feasibility and applicability as biocontrol agents in postharvest disease management and food preservation against fungal pathogens. [ABSTRACT FROM AUTHOR]

The generalized use of molecular identification tools indicated that multispecific green tides are more common than previously thought. Temporal successions between bloom‐forming species on a seasonal basis were also revealed in different cold temperate estuaries, suggesting a key role of photoperiod and temperature controlling bloom development and composition. According to the Intergovernmental Panel on Climate Change, water temperatures are predicted to increase around 4°C by 2100 in Ireland, especially during late spring coinciding with early green tide development. Considering current and predicted temperatures, and photoperiods during bloom development, different eco‐physiological experiments were developed. These experiments indicated that the growth of Ulva lacinulata was controlled by temperature, while U. compressa was unresponsive to the photoperiod and temperatures assayed. Considering a scenario of global warming for Irish waters, an earlier development of bloom is expected in the case of U. lacinulata. This could have significant consequences for biomass balance in Irish estuaries and the maximum accumulated biomass during peak bloom. The observed seasonal patterns and experiments also indicated that U. compressa may facilitate U. lacinulata development. When both species were co‐cultivated, the culture performance showed intermediate responses to experimental treatments in comparison with monospecific cultures of both species. [ABSTRACT FROM AUTHOR]

The ubiquitous and species rich genus Ulva comprises entities of green macroalgae with variable morphologies. Ulva species are important from ecological and economic perspectives, but their identification is often problematic. Current knowledge on Ulva diversity has focused mainly on foliose individuals of temperate regions, but genetic and morphological data on tubular species are often insufficient and the species richness is ambiguous due to the lack of molecularly identified type vouchers. Together with a previous study, our study demonstrates that due to the crypticity of tubular entities of the genus Ulva present in the Atlantic-Baltic Sea transect, certain species remained undetected until recently whereas molecular evidence of other historically identified species is missing. An entity which appears to be a relatively frequent species in the Atlantic-Baltic Sea transect and which was probably mis-identified with other species in the past is here described as Ulva capillata sp. nov.. The description is based on molecular identification using tufA and rbcL sequences, and by comparing the species´ phylogenetic relationships, distribution and range margins in the Atlantic-Baltic Sea transect, as well as on morpho-anatomical characters, and early ontogenetic development. By comparisons with closely related and potentially morphologically overlapping species concepts we were able to identify the uniqueness of U. capillata. Therefore, the description of U. capillata as a new species within the genus Ulva is supported by a combination of molecular, morphological, and ontogentic evidence which confirm their uniqueness in comparison to other species concepts. Furthermore, our results strongly emphasize the importance and necessity to molecularly investigate especially tubular historic type vouchers within the genus Ulva to facilitate a clear species identification to omit continuing with taxonomic confusion and ongoing misapplication of names of e.g. cryptic species concepts within this important green algal genus. [ABSTRACT FROM AUTHOR]

The exploration of bioactive phytochemical quantities of two underutilized Sri Lankan seaweeds Ulva lactuca (UL) and Ulva fasciata (UF) revealed significant phenolic, flavonoid, ulvan, carotenoid, chlorophyll, tannin, saponin, alkaloid contents, and DPPH radical scavenging activities. To evaluate their application in developing seaweed incorporated cereal-based functional snacks, wheat crackers were formulated using 0% (control), 2%, and 4% seaweed powder as a flour replacement. Developed seaweed incorporated crackers had elevated sensory acceptability, protein, and ash contents and DPPH radical scavenging activities, confirming the capacity of UL and UF seaweed utilization in producing potentially functional snacks with improved sensory and nutritional attributes. [ABSTRACT FROM AUTHOR]

The production of lactic acid and value-added chemicals (such as hydroxypropanone, glycolic acid, and formic acid) directly from Ulva prolifera via one-step catalytic process was studied. The effect of different amounts of YCl3-derived catalysts on the hydrothermal conversion of carbohydrates in Ulva prolifera was explored, and the reaction conditions were optimized. In this catalytic system, rhamnose could be extracted from Ulva prolifera and converted in situ into lactic acid and hydroxypropanone at 160 °C, while all the glucose, xylose, and rhamnose were fractionated and completely converted to lactic acid at 220 °C or at a higher temperature, via several consecutive and/or parallel catalytic processes. The highest yield of lactic acid obtained was 31.4 wt% under the optimized conditions. The hydrothermal conversion of Ulva prolifera occurred rapidly (within 10 min) and showed promise to valorize Ulva prolifera. [ABSTRACT FROM AUTHOR]

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. • The macroalga Ulva mutabilis was established as a model system in chemical ecology. • Cross-kingdom interactions foster symbiosis between Ulva and associated bacteria. • Bacteria provide Ulva with algal growth and morphogenesis promoting factors. • The morphogen thallusin induces rhizoid and cell wall formation in Ulva. • Microbiome leveraging and engineering are useful for aquaculture maintenance and optimization. [ABSTRACT FROM AUTHOR]

Acidification of seawater resulting from absorption of excessive carbon dioxide from the atmosphere is posing a serious threat to marine ecosystem. In this study, we hypothesized that acidified seawater attenuates allelopathic effects of macroalgae on red tide algae because the increase of dissolved carbon dioxide benefits algal growth, and investigated the allelopathic effects of Ulva pertusa on Karenia mikimotoi in response to seawater acidification by determining cell density, photosynthetic pigment content, chlorophyll fluorescence parameters, and chloroplast structure of K. mikimotoi under U. pertusa stress in original (pH=8.2) and acidified (pH=7.8) seawater. U. pertusa inhibited the growth of K. mikimotoi in the original and acidizing seawater, and the inhibition rate was positively correlated with treatment time and concentration of U. pertusa. However, acidizing condition significantly weakened the inhibition degree of U. pertusa on K. mikimotoi (P < 0.05), with the inhibition rates decreased from 51.85 to 43.16% at 10 gFW/L U. pertusa for 96 h. U. pertusa reduced contents of chlorophyll a, chlorophyll c, and carotenoid, maximum photochemical quantum yield (Fv/Fm), actual quantum yield, maximum relative electron transfer efficiency (rETRmax) of PSII, real-time fluorescence value (F), and maximum fluorescence value (Fm′) of PSII of K. mikimotoi under original and acidified conditions. And, the inhibition degree of U. pertusa under acidizing condition was significantly lower than that of original seawater group. Furthermore, the damage degree of chloroplast structure of K. mikimotoi under U. pertusa stress was more serious under original seawater condition. These results indicate that acidification of seawater attenuates the allelopathic effects of U. pertusa on K. mikimotoi. [ABSTRACT FROM AUTHOR]

Microwave-assisted hydrothermal processing was proposed to recover high valuable compounds with antioxidant and gelling features from Ulva spp. green seaweed. The influence of the extraction conditions on the solubles, ulvan fraction and residual solid phase was studied to achieve a global valorization of the seaweed. A particular emphasis was placed on the selective coagulation of ulvan stimulated by a bio-ionic liquid during the extraction process. The achieved outcomes indicated that the selected microwave treatment exhibited a notable impact on the phytochemical properties of the soluble extracts, with the highest values of sulfate and protein content at 160 °C, and the highest antioxidant features at 200 °C. The most prominent molecular weight distributions were also identified for systems hydrothermal treated at 160 °C. The ulvan analyses showed that those extracted after microwave treatment at 160 °C showed the highest yields, molecular weight and the strongest gel features from the rheological point of view. The presence of the chloride chlorine during the extraction process favored the ulvan performance and the enhancement of the corresponding viscoelastic properties. [ABSTRACT FROM AUTHOR]

SUMMARY: Species diversity of Ulva in Vietnam was investigated using three commonly used genetic markers, the nuclear encoded rDNA ITS region and the plastid encoded rbcL and tufA genes. Single locus species delimitation methods, complemented with morphological and ecological information resulted in the delimitation of 19 species. This diversity is largely incongruent with the traditional understanding of Ulva diversity in Vietnam. Only four species identified in this study, U. lactuca, U. reticulata, U. spinulosa, and U. flexuosa, have been previously reported, and seven species, U. ohnoi, U. tepida, U. chaugulii, U. kraftiorum, U. meridionalis, U. limnetica, and U. aragoënsis, are recorded for the first time from Vietnam. Seven genetic clusters could not be associated with species names with certainty. A new species, U. vietnamensis, is described from marine to brackish coastal areas from southern Vietnam based on its morphological and molecular distinctiveness from the currently known Ulva species. A comparison with recent molecular‐based studies of Ulva diversity showed that species composition in Vietnam is similar to that of adjacent countries, including Japan, China, as well as Australia. Our study emphasizes the importance of molecular data in the assessment of Ulva diversity, and indicates that a lot of diversity may still remain to be discovered, especially in tropical regions. [ABSTRACT FROM AUTHOR]

Ulva green macroalgae or sea lettuce are rich sources of protein with nutritional benefits that promote health as a future plant-based functional ingredient in the food industry. Alkaline pretreatment improved ultrasonic-assisted protein extraction from Ulva rigida biomass. Parameters affecting ultrasonic-assisted extraction of protein were type of solvent, biomass-solvent ratio, biomass preparation and extraction cycle. In vitro digestibility was evaluated from oven- and freeze-dried biomass. Results showed highest concentration and extraction yield of protein from U. rigida using alkaline rather than acid and distilled water. A high biomass–solvent ratio at 1:10 or 0.1 g mL−1 increased protein extraction. Higher alkaline concentration increased protein extraction. Highest protein extractability was 8.5% dry matter from freeze-dried U. rigida biomass, with highest protein extraction and antioxidant activity from extraction of U. rigida macroalgae at high alkaline concentrations. U. rigida macroalgae oven-dried biomass presented suitable human digestibility. Efficient pretreatment of U. rigida maximized protein hydrolysate and bioactive peptide production for wide-ranging applications. [ABSTRACT FROM AUTHOR]

The high-sulfated derivative of Ulva pertusa polysaccharide (HU), with unclear structure, has better anti-hyperlipidmia activity than U pertusa polysaccharide ulvan (U). In this study, we explore the main structure of HU and its therapeutic effect against nonalcoholic fatty liver disease (NAFLD). The main structure of HU was elucidated using FT-IR and NMR (13C, 1H, COSY, HSQC, HMBC). The anti-NAFLD activity of HU was explored using the high-fat diet mouse model to detect indicators of blood lipid and liver function and observe the pathologic changes in epididymal fat and the liver. Results showed that HU had these main structural fragments: →4)-β-D-Glcp(1→4)-α-L-Rhap2,3S(1→; →4)-α-L-Rhap3S(1→4)-β-D-Xylp2,3S(1→; →4)-α-L-Rhap3S(1→4)-β-D-Xylp(1→; →4)-α-L-IdopA3S(1→4)-α-L-Rhap3S(1→; →4)-β-D-GlcpA(1→3)-α-L-Rhap(1→; →4)-α-L-IdopA3S(1→4)-β-D-Glcp3Me(1→; →4)-β-D-Xylp2,3S(1→4)-α-L-IdopA3S(1→; and →4)-β-D-Xylp(1→4)-α-L-IdopA3S(1→. Treatment results indicated that HU markedly decreased levels of TC, LDL-C, TG, and AST. Furthermore, lipid droplets in the liver were reduced, and the abnormal enlargement of epididymal fat cells was suppressed. Thus, HU appears to have a protective effect on the development of NAFLD. [ABSTRACT FROM AUTHOR]

The green tide caused by Ulva prolifera (U. prolifera) is becoming more severe as climate change and human activity accelerate, endangering tourism, aquaculture, and urban landscapes in coastal cities. In order to understand the spatio-temporal distribution of U. prolifera in response to the green tide disaster, this study used the Haiyang-1C (HY-1C) satellite accompanied by the Sentinel-2 and GaoFen-1 (GF-1) satellites to systematically monitor U. prolifera between 2020 and 2022. The consistency of U. prolifera distribution between the HY-1C and Sentinel-2 satellites, as well as the HY-1C and GF-1 satellites, was first investigated and the determination coefficients (R2) were 0.966 and 0.991, respectively, which supports the feasibility of China's first ocean water color operational satellite, HY-1C, for U. prolifera monitoring. Therefore, the spatio-temporal distribution of U. prolifera is studied herein, along with the influence range, influence area, and drift paths. From 2020 to 2022, U. prolifera appeared in late May and lasted for 61, 88, and 73 days. Additionally, the in influence area continuously decreased in 2020 and 2022, while it generally increased and then decreased in 2021. It is an interesting phenomenon that when the maximum influence area occurred at the early stage of U. prolifera in both 2020 and 2022, the drift paths tended to move southward after traveling northward. The overall trend of the drift path in 2021 was to head northward. Thus, the study of the dynamic evolution, influence range, influence area, and drift paths of U. prolifera is helpful to promote the systematic development of emergency response mechanisms for U. prolifera. [ABSTRACT FROM AUTHOR]

Sex-specific nutritional requirements, mating behavior, and parental care can potentially affect food selection and consumption in animals. However, relatively little is known about how sex and reproduction influence food use by aquatic herbivores. We measure male:female ratios in the field and studied sexual differences in algal food choice and feeding rates for the amphipod Gammarus aequicauda from a desert saline lake, where it is the most abundant mesograzer during the colder months. We also assessed the effects of precopulatory pairing and female egg development on feeding behavior. Males were more numerous than females over two sampling periods and significantly preferred one algal species in each of three pairwise food-choice combinations tested. Females were moderately less selective, expressing a preference in only two of these experiments, but showed significantly higher total consumption and feeding rates than males in most assays. When males and females expressed similar preferences, the magnitude of these preferences (% differences in consumption between the algae offered) was statistically equivalent for both sexes. Patterns of compensatory feeding on less nutritious algae were significant and similar for both sexes. Mated pairs had reduced feeding rates compared to unpaired females, but not unpaired males. In contrast, no short-term differences in feeding rates were detected for males and females separated from precopula or between females at two stages of egg development. Variations in population sex ratios and reproductive cycles can potentially modulate interactions between aquatic consumers and their food sources. [ABSTRACT FROM AUTHOR]

An ulvan was extracted from green seaweed Ulva lactuca by ultrasound-assisted extraction. The extraction conditions were optimized by response surface methodology. The optimal conditions were extraction temperature at 84.75 °C, extraction time of 30.51 min, solvent to material ratio of 60.51 mL/g to achieve the yield of 22.5%. The ulvan is composed of repeated sequences of three disaccharides: →4)-β-D-Glucuronic acid(1→4)α-L-Rhamnose-3-sulfate(1→, →4)α-L-Iduronic acid(1→4)α-L-Rhamnose-3-sulfate(1→, and →4)α-D-Xylose-2-sulfate(1→4)α-L-Rhamnose-3-sulfate(→. The ulvan showed cytotoxic activities against five human cancer cell lines, including human hepatocellular carcinoma, human breast cancer, human cervical cancer, human colorectal adenocarcinoma and human undifferentiated thyroid carcinomas. [ABSTRACT FROM AUTHOR]

Nutrient and toxicant levels as well as their bioavailability in S. latissima and Ulva species (fenestrata, intestinalis, rigida) were reviewed. Nutritional quality was assessed by nutrient contribution to daily reference intake (DRI) per portion (5 g dry weight), nutrient density score NRF21.3, and comparisons to reference foods. Toxicological assessments comprised tolerable daily intake (TDI)-levels. Based on mean %DRI per portion, S. latissima and Ulva species were good sources (%DRI >15) of calcium, magnesium, iron, selenium, and vitamin B12. Mean %DRI was <10% for fiber, sodium, and protein. Toxicological concerns were mainly due to iodine (mean %TDI per portion: 3160% for S. latissima and 41–91% for Ulva species). Mean %TDIs for inorganic arsenic, cadmium, and lead were <20% for S. latissima and 9–97%, 6–15%, and 21–46%, for the selected Ulva species, respectively. Bioavailability data were scarce and is, together with nutritional impact of processing, an important aspect to address in future studies. [ABSTRACT FROM AUTHOR]