Ulva Biomass Research Articles

Correction to: Harnessing green tide Ulva biomass for carbon dioxide sequestration

Correction to: Harnessing green tide Ulva biomass for carbon dioxide sequestration

Light Spectra, a Promising Tool to Modulate Ulva lacinulata Productivity and Composition.

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 O2•- 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.

Harnessing green tide Ulva biomass for carbon dioxide sequestration

Harnessing green tide Ulva biomass for carbon dioxide sequestration

Nano iron loaded algal biomass: For better yield, amino acid and iron content in rice – A ‘nano-phycofertilizer’

The iron nano particles (INPs) loaded algal biomass can stimulate plant growth, leading to improved crop yields and quality. In this article, we have explored the efficacy of INPs-loaded biomass of Ulva intestinalis as ‘Nano-Phyco-Fertilizer (NPF)’ for rice cultivation. In situ INPs synthesis by Ulva biomass was spontaneous, turning the green thallus to brown due to the deposition of a large amount of intracellular INP within 24 h in dark conditions. The synthesized INPs was characterized as spindle-shaped with ferromagnetic properties by TEM analysis. The INPs-loaded algal biomass was dried, dusted, and applied to soil as NPF. Additionally, algal biomass without iron and free INPs were also tested separately and compared to NPF. The synergistic combination of algae and INPs in fertilizer formulations is a novel work and it offers several advantages over conventional fertilizers. As a result, after the application of NPF, the heights and grain yield of rice plants increased by 40 % and 2.5 times respectively. Moreover, the essential amino acid and iron content in rice grains showed a significant increase by 20–40 % and 45 % respectively upon NPF application, as compared to that of rice crops with conventional agricultural practice. The integration of algal and INP-based fertilizers represents a sustainable and innovative approach to meet the growing demands of global agriculture. As a result, it can be concluded that NPF shows significant enhancement in the growth and productivity of rice plant cultivation and holds immense promise in ensuring food security and mitigating the environmental impacts associated with conventional fertilization malpractices.

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

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

Dilute nitric acid pretreatment of Ulva biomass for production of fermentable sugars and its validation using Design of Experiments (DoE)

Dilute nitric acid pretreatment of Ulva biomass for production of fermentable sugars and its validation using Design of Experiments (DoE)

Short term decreases in salinity, combined with the right choice of species, can allow for a more nutritious sea lettuce lipid profile

The sea lettuce Ulva spp is becoming an increasingly important macroalgae for aquaculture. Sea lettuce can be grown on- and off-shore, displays high growth rates, and its biomass possesses attractive nutritional benefits. Among those are their fatty acids (FA) and lipid profiles, rich in omega 3 Polyunsaturated Fatty Acids (PUFAs) as well as bioactive lipids. In order to tailor those properties for food applications, we explored the use of a short-term (seven days) low salinity treatment to modulate the lipid profile of two species of Ulva. We found large quantitative differences between species, and while a low-salinity treatment negatively affected growth, Ulva australis’ lipid profile was positively impacted. Total FA particularly ɷ-3 PUFAs, increased three-fold, as well as most polar lipid species including known bioactive compounds. This study highlights profound differences between species and describes a simple method to increase the nutritional properties of Ulva biomass for food applications.

Effects of season, depth and pre-cultivation fertilizing on Ulva growth dynamics offshore the Eastern Mediterranean Sea

Offshore macroalgae production could provide an alternative source of biomass for food, materials and energy. However, the offshore environment in general, specifically the Eastern Mediterranean Sea (EMS) offshore, is a high energy and low nutrients environment, thus challenging for macroalgae farming. In this study, we experimentally investigated the impact of season, depth, and pre-cultivation fertilization duration on the growth rates and chemical composition of offshore Ulva biomass, and developed a predictive model tailored to offshore conditions, capable of estimating both biomass growth rate and nitrogen content. Specifically, we measured Ulva biomass growth rate and internal nitrogen in the nitrogen-poor EMS a few kilometers offshore the Israeli coast at various depths and on-shore pre-cultivation fertilization schedules. Based on these data, we constructed a predictive cultivation model of Ulva offshore growth, which allows for the optimization of fertilization requirements for offshore cultivation. This study provides new insights on the effects of seasonality, depth, and pre-cultivation fertilization duration on growth rates and chemical composition of offshore Ulva sp. biomass production.

Distribution of Ulva prolifera, the dominant species in green tides along the Jiangsu Province coast in the Southern Yellow Sea, China

Green tides have long occurred in the Yellow Sea for 17 years, with 5S-II Ulva prolifera being the dominant species. Previous studies indicate the Neopyropia aquaculture area in Jiangsu to be the main source of green tides in the Southern Yellow Sea. Little is known regarding the occurrence of this species in coastal dykes in Jiangsu Province. We investigated the species composition, diversity, and biomass of green macroalgae in these dykes during 2022 using internal transcribed spacers and 5S rDNA and identified U. prolifera, Ulva linza, Blidingia spp., Ulva meridionalis, Ulva torta, Ulva flexuosa, Ulva compressa, Ulva aragoensis, Ulva australis, and Ulva simplex. Ulva prolifera occurred in every month of the survey. Species diversity was highest in October, and the Ulva spp. biomass was highest in February. Attached 5S-II U. prolifera occurred in the coastal dykes in February, April, and June 2022. Dyke characteristicsand elevations may affect the biomass and species of Ulva spp. observed. Green tide blooms in the Yellow Sea have enabled 5S-II U. prolifera to colonize the Jiangsu coast dykes.

Self-graphenized biochar with huge pore volume prepared from pre-boiled Ulva lactuca for electrochemical supercapacitor with high energy density

To enhance energy density of water-based electrochemical supercapacitor, a highly self-graphenized bicohar with huge pore volume is pyrolyzed from the biomass Ulva lactuca (UL) pre-boiled in Mg(CH3COO)2 solution. During the pyrolysis process, the MgO converted from the Mg(CH3COO)2 re-crystallized in the biomass UL inhibits the pore shrinkage and helps to inherit the pristine pore system. The resultant biochar HUB-2.0 exhibits high specific surface area (SSA) of 2296.7 m2 g−1 and huge pore volume of 4.59 m3 g−1. It is also featured with moderate self-graphenization and heteroatoms self-doped surface in the connected pore system inherited from the precursor. It achieves a specific capacitance of 445.0 F g−1 at 0.5 A g−1 in the three-electrode system with the electrolyte 1.0 M H2SO4. A superior energy density of 27.17 Wh kg−1 is also calculated at a power density of 222.8 W kg−1 in the two-electrode system with the neutral electrolyte Na2SO4. The work provides a fast and efficient method to prepare the biochar with balanced properties to achieve superior electrochemical supercapacitor performance, especially for high energy density.

Acrylic acid and DMSP lyases in the green algae Ulva

Green macroalgae of the genus Ulva contain dimethylsulfoniopropionate (DMSP) produced from methionine through a transamination pathway. DMSP is converted by DMSP lyase enzymes (DLs) into acrylic acid (AA), a high-value compound with a vast market as its esters have applications in the production of plastic additives, textiles, sealants, adhesives and surface coatings. The levels of AA produced by Ulva species, and the processes to extract it from this biomass, are currently poorly understood. In this study an analytical method was implemented for the simultaneous measurement of AA, DMSP and the pathway intermediates (4-methylthio-2-oxobutyrate, 4-methylthio-2-hydroxybutyrate, and 4-dimethylsulfonio-2-hydroxybutyrate) in Ulva biomass. The amounts of these compounds – with a focus on AA – were then quantified after processing the macroalgae with different chemical, thermal, and enzymatic treatments. AA was extracted in the range of 0.22–0.45 % of the algal dry weight. Sequential enzyme treatments showed no higher yields compared to individual enzymatic treatments or chemico-physical extractions, an encouraging result for the application of the treatments in industry. Codon-optimised synthetic genes for two candidate DLs from Ulva mutabilis were expressed and purified in E. coli with solubility tags, and the biochemical characteristics of these recombinant lyases were investigated. Both enzymes UM021_MBP and UM030_Halo7 had lower activity than their microalgal counterpart Alma1, with whom they share 33.9 % and 39.7 % similarity at amino acid level respectively. UM030_Halo7 appeared more active than UM021_MBP, with Km and Vm of 7.10 mM and 5.99 mM/min/mg protein respectively. UM030_Halo7 showed a preferred pH of 6.0, an optimal of temperature of 20 °C, was inhibited by NaCl concentration equal or higher than 0.5 M but not by H2O2 up to 50 μM. These results advance our understanding of AA biosynthesis in Ulva at the molecular level, and could be useful to implement processes for extracting AA from Ulva species within a biorefinery framework.

Potential extract of green algae (Ulva luctuca) as antimicrobial in mouthwash: literature review

Green algae as one of the marine natural resources which is included in the main seaweed is found in many coastal areas of In-donesia. The bioactive component that acts as an antibacterial agent in green algae type Ulva lactuca is ulvan polysaccharide extract. Ulvan is a cell wall polysaccharide that accounts for 9-36% dry weight of Ulva biomass and is mainly composed of rhamnose sulfate, uronic acid (glucuronic acid and iduronic acid) and xylose. Polysaccharide ulvan extracted from Ulva lactuca can be one of the antimicrobial materials used in mouthwash in dentistry.

Applications of Ulva Biomass and Strategies to Improve Its Yield and Composition: A Perspective for Ulva Aquaculture.

Sea lettuce (Ulva spp.), with its worldwide distribution and remarkable ability to grow rapidly under various conditions, represents an important natural resource that is still under-exploited. Its biomass can be used for a wide range of applications in the food/feed, pharmaceutical, nutraceutical, biofuel, and bioremediation industries. However, knowledge of the factors affecting Ulva biomass yield and composition is far from complete. Indeed, the respective contributions of the microbiome, natural genetic variation in Ulva species, environmental conditions and importantly, the interactions between these three factors on the Ulva biomass, have been only partially elucidated. Further investigation is important for the implementation of large-scale Ulva aquaculture, which requires stable and controlled biomass composition and yields. In this review, we document Ulva biomass composition, describe the uses of Ulva biomass and we propose different strategies for developing a sustainable and profitable Ulva aquaculture industry.

Insight into the mechanisms involved in the removal of toxic, rare earth, and platinum elements from complex mixtures by Ulva sp.

Hazardous leachate/effluent from fluorescent lamps contains potentially toxic elements such as Hg and Pb, and critical raw materials such as rare earth elements (REEs). This work evaluated the ability of the live macroalgae Ulva sp. to remediate a simulated lamp industry wastewater consisting of a complex mixture of elements (Y, Eu, La, Ce, Tb, Gd, Hg, Pb, Zn, Cu, Co, Cd, and Pt), with particular emphasis on the investigation of the sorption mechanisms. Experiments were performed with 3.0 g/L (fresh weight) of Ulva sp., salinity 25, and an initial concentration of 100 µg/L for each element. Hierarchical cluster analysis highlighted two main groups according to removal: Pt and Cd as the less removed, and all others with removals > 76 %, underlining Hg and Ce with the fastest kinetics (up to 92 %). Apart from Co, Zn and Cd, all mathematical models described sorption kinetics well, with Akaike Information Criteria identifying the Elovich model as the best for describing REEs sorption. FTIR analysis identified the sulphated polysaccharide Ulvan as intervening in binding elements to Ulva biomass. Extraction with EDTA 0.001 mol/L showed that most elements were mainly localized in the outer fraction (surface), except for Hg, which was entirely in the inner part. SEM analysis supported the EDTA analysis and showed a clean surface after washing. The results are an important contribution to the understanding of sorption mechanisms in macroalgae and demonstrate the feasibility of macroalgae-based biotechnologies with reduced costs and high efficiency for water decontamination, in complex saline mixtures.

Evidence from preliminary experiments revealed drifted Ulva biomass has seedling and aquaculture potential

Evidence from preliminary experiments revealed drifted Ulva biomass has seedling and aquaculture potential

Modeling the growth and sporulation dynamics of the macroalga <i>Ulva</i> in mixed-age populations in cultivation and the formation of green tides

Abstract. Ulva is a widespread green algal genus with important ecological roles and promising potential as a seagriculture crop. One of the major challenges when cultivating Ulva is sudden biomass disappearance, likely caused by uncontrolled and unpredicted massive sporulation. However, the dynamics of this process are still poorly understood. In this study, we propose a mathematical model describing the biomass accumulation and degradation of Ulva, considering the potential impact of sporulation inhibitors. We developed a differential equation model describing the time evolution of Ulva biomass. Our model simulates biomass in compartments of different Ulva “age” classes, with varying growth and sporulation rates. Coupled with these classes is a differential equation describing the presence of a sporulation inhibitor, produced and secreted by the algae. Our model mimics observed Ulva dynamics. We present Ulva's biomass accumulation under different initial algae population, age distributions and sporulation rates. Furthermore, we simulate water replacement, effectively depleting the sporulation inhibitor, and examine its effects on Ulva's biomass accumulation. The model developed in this work is the first step towards understanding the dynamics of Ulva growth and degradation. Future work refining and expanding our results should prove beneficial to the ecological research and industrial growth of Ulva.

Investigation of catalytic pyrolysis of Azolla filiculoides and Ulva fasciata for bio-oil production

The present study investigates the production of bio-oil by catalytic pyrolysis of macroalgae biomass. The effect of catalyst type and catalyst to feed ratio on the yield of bio-oil production and its qualitative characteristics were investigated. Experimental results showed that the maximum yield of the bio-oil production for Azolla and Ulva biomass were respectively 26.5% and 29.5%, both with HZSM-5 catalyst and with the catalyst to feed ratio of 1:10. The largest obtained higher heat values were 36.73 MJ/kg for Azolla bio-oil and 36.18 MJ/kg for Ulva bio-oil, both with 1:5 Mo/HZSM-5 catalyst. Regarding comparing Azolla and Ulva yield, Ulva bio-oil with efficiency, HHV, energy efficiency, cetane number, iodine value of 26.6%, 34.76 MJ/kg, 75.79%, 73.2, and 116.5, respectively. The results show that the bio-oil produced from the pyrolysis of Azolla and Ulva biomass can be very promising for industrial-scale production.

Intestinal anti-inflammatory activity of Ulva ohnoi oil in DSS-induced experimental mouse model

This study was conducted to examine the physiological activity of Ulva ohnoi, some of which may be used for food or natural products but could disturbing coastal ecosystems due to large scale green-tide, to check values of U. ohnoi oil through experimental results. U. ohnoi oil was extracted from bulk of Ulva biomass to confirm its antioxidant and antibacterial activity, and the efficacy of U. ohnoi oil in the state of inflammation was confirmed through animal experiments. To confirm the anti-inflammatory effect, a mouse model induced with DSS was used. As a result of measuring NO using plasma after induction of inflammation, the amount of NO produced in the U. ohnoi oil group was decreased compared to the control group. Expression of inflammatory cytokines TNF-α, IL-6, and IL-1β was decreased compared to the control group. As a result of observing H&E staining, lower crypt loss and inflammatory cell infiltration were found in the U. ohnoi oil group compared to the control group. Consequently, U. ohnoi oil appears to have great anti-inflammatory properties.

Polar Lipids of Commercial Ulva spp. of Different Origins: Profiling and Relevance for Seaweed Valorization

Macroalgae of the genus Ulva have long been used as human food. Local environmental conditions, among other factors, can have an impact on their nutrient and phytochemical composition, as well as on the value of the seaweed for food and non-food applications. This study is the first to initiate a comparison between commercial Ulva spp. from different European origins, France (FR, wild-harvested Ulva spp.), and Portugal (PT, farm-raised Ulva rigida), in terms of proximate composition, esterified fatty acids (FA), and polar lipids. The ash content was higher in PT samples, while FR samples had higher levels of proteins, lipids, and carbohydrates and other compounds. The profile of esterified FA, as well as FA-containing polar lipids at the class and species levels were also significantly different. The FR samples showed about three-fold higher amount of n-3 polyunsaturated FA, while PT samples showed two-fold higher content of monounsaturated FA. Quantification of glycolipids and phospholipids revealed, respectively, two-fold and three-fold higher levels in PT samples. Despite the differences found, the polar lipids identified in both batches included some lipid species with recognized bioactivity, valuing Ulva biomass with functional properties, increasing their added value, and promoting new applications, namely in nutraceutical and food markets.

A sequencing-free assay for foliose Ulva species identification, hybrid detection and bulk biomass characterisation

Sea Lettuce (Ulva spp. Ulvophyceae, Ulvaceae) has tremendous ecological and industrial impacts, from the negative effects of green tide events to the industrial production of food, feed, and value-added products. Due to the morphological similarities between Ulva species, their identification requires the use of “barcoding”, which relies on the sequencing of short fragments of DNA and the comparison of the obtained sequence to that of sequences present in public repositories. However, Sanger sequencing can be costly when hundreds of samples need to be analysed. In addition, “barcoding”, which uses Sanger sequencing, cannot be applied directly on bulk biomass, and requires independent assessment of the individuals within, which is often not possible in commercial products. Here, we describe a novel “sequencing-free” method for species identification of foliose Ulva species that by-passes the drawbacks associated with Sanger sequencing. The assay uses restriction digestion enzymes which target species-specific Single Nucleotide Polymorphisms (SNPs) present within the ITS1 sequence. Digestion of the ITS1 PCR product with two enzyme mixtures allows for the discrimination of the main foliose Ulva species, as well as U. compressa, which can have a foliose morphotype. Of the species tested, only U. pseudorotundata and U. arasakii show the same digestion pattern. Since those two Ulva species are allopatric, we expect this issue to be of limited impact for the users. In addition to species identification, we demonstrate that the assay can be used for hybrid detection, which can have interests for Ulva breeding and species delimitation. Importantly, the assay can be used to detect at once the different Ulva species present within a bulk of Ulva biomass, which could allow for traceability and characterisation of the purity of Ulva commercial products. This study provides a new quick and cost-effective method for foliose Ulva species identification that could readily be extended to other species.