Red Alga Gracilaria Research Articles

Combined extraction methodology for simultaneous recovery of phycobiliproteins and agar from the red alga Gracilaria chilensis C. J. Bird, McLachlan & E. C. Oliveira

The red alga Gracilaria chilensis C. J. Bird, McLachlan & E. C. Oliveira ( Agarophyton chilense Gurgel, J.N. Norris & Fredericq) is one of the few algae commercially farmed in Chile, where this alga is commonly named “Pelillo”. G. chilensis main by-product is agar, a gelling agent used in the food and pharmaceutical industries. This alga is also a valuable feedstock for the biorefinery of phycobiliproteins (PBPs), colored and fluorescent water-soluble proteins with industrial applications. This work aimed to valorize G. chilensis by sequentially extracting PBPs and agar. After freeze-thaw treatment, we successfully extracted two PBPs from alga: R-phycoerythrin (R-PE) and R-phycocyanin (R-PC). After two purification steps, we recovered 45 % of both PBPs (R-PE = 0.20 mg g −1 DW and R-PC = 0.23 mg·g −1 DW). After PBPs extraction, we successfully recovered agar from the residual algal matter. There were no significant differences between the physical parameters of agars obtained after PBP extraction and those from agars directly extracted from G. chilensis (melting and gelling temperature, and agar deformation). The agar yield after PBPs extraction was 24.9 ± 1.0 % and showed a gel strength of 726 ± 182.9 g·cm −2 , whereas agar directly extracted from alga yielded 23.1 ± 2.0 % with a gel strength of 730.5 ± 96.9 g·cm −2 . The agar obtained after PBPs extraction showed no inhibitory effects on microbial growth and allowed the effective separation of nucleic acids without agarose purification. Thereby, the method proposed in this work allowed the simultaneous extraction of PBPs and agar from G. chilensis . • The red seaweed Gracilaria chilensis ( Agarophyton chilense ) is a good source of phycobiliproteins and agar. • Phycobiliproteins are purified by salting-out and anion-exchange chromatography. • Purified phycobiliproteins (R-PE and R-PC) may be used in the food industry. • High-quality agar was successfully recovered from the residual algal matter after phycobiliproteins' extraction. • Agar extracted after phycobiliproteins' purification was useful for microbial growth and nucleic acid separation.

Agar content of estuarine seaweed Gracilaria using different cultivation methods

Red algae Gracilaria is one of the most cultivated seaweeds and a major source of agar in the world. Gracilaria demonstrates easy propagation, high growth rates, and tolerance to a broad range of salinities. Agar usage is related to thermo-reversible gels formation at low concentrations in water with wide applications in food, pharmaceutical, medical, engineering, agricultural and other fields. In this work, we analyzed and compared agar content of the estuarine seaweed Gracilaria sp. grown in two distinct cultivation methods: (1) inshore tank cultivation technique and (2) indoor cultivation technique using different mediums (seawater and brackish water) to get a better understanding about the best medium for large scale sustainable cultivation in the future; wild Gracilaria sp. samples were used as control. Inshore tank cultivation exhibited the highest agar extraction yield (20.67±0.27%) when compared with the control (16.67±2.72%); indoor cultivation using brackish water medium (13.8 ± 1.5%) and seawater medium (11.64±2.38%) revealed lower values than the control, but still promising for large scale cultivation and agar exploitation.

Biochemical and spectroscopic analysis of the effect of UV on the pigmentation of the red algae Gracilaria dentata, Hypnea musciformis and Centroceras clavulatum

Biochemical and spectroscopic analysis of the effect of UV on the pigmentation of the red algae Gracilaria dentata, Hypnea musciformis and Centroceras clavulatum

Pollinators of the sea: A discovery of animal-mediated fertilization in seaweed.

The long-held belief that animal-mediated pollination is absent in the sea has recently been contradicted in seagrasses, motivating investigations of other marine phyla. This is particularly relevant in red algae, in which female gametes are not liberated and male gametes are not flagellated. Using experiments with the isopod Idotea balthica and the red alga Gracilaria gracilis, we demonstrate that biotic interactions dramatically increase the fertilization success of the alga through animal transport of spermatia on their body. This discovery suggests that animal-mediated fertilization could have evolved independently in terrestrial and marine environments and raises the possibility of its emergence in the sea before plants moved ashore.

Purification and Identification of an ACE-Inhibitory Peptide from Gracilaria tenuistipitata Protein Hydrolysates

Edible marine species are valuable sources of bioactive peptides. This study investigated the ACE-inhibitory activity of protein hydrolysates from the red algae Gracilaria tenuistipitata. Fifteen groups of protein hydrolysates were prepared by a two-step enzymatic hydrolysis of G. tenuistipitata: initial hydrolysis with several glycolytic enzymes, followed by three separate proteolytic reactions (Alcalase, Neutrase and Flavourzyme) for 2–10 h. Results showed that the hydrolysate GTN4H had the highest ACE-inhibitory activity in vitro. Furthermore, oral administration of GTN4H significantly reduced systolic blood pressure in spontaneously hypertensive rats. Fraction A derived from GTN4H displayed the highest ACE-inhibitory activity among fractions. Further purification of fraction A by RP-HPLC obtained a purified peptide (MW: 1776 Da) with 17 amino acids and 95.4% ACE-inhibitory activity.

Arsenic and Nutrient Composition Across Different Edible Seaweeds From Hawaii

ObjectivesSeaweed is used for various cultural, culinary, and medicinal purposes in Hawaii and has been consumed for generations around the world (i.e., the Pacific, Asia, and parts of Europe). In the US, seaweed is gaining popularity because of its reputation for being highly nutritional. However, some types of seaweed are known to accumulate heavy metals, including inorganic arsenic (iAs) species. While some seaweed species have been studied, there is still limited species-specific compositional data. The purpose of this study was to quantify arsenic and nutrient (i.e., macronutrient and mineral) levels in edible seaweeds.MethodsBrown algae (Sargassum aquifolium and Sargassum spp.), red algae (Gracilaria parvispora, Halymenia formosa, and Halymenia hawaiiana, and green algae (Ulva ohnoi) were analyzed using HPLC-ICP-MS for arsenic speciation. Proximate (protein, dietary fiber, ash, moisture, carbohydrate, crude fat, and crude protein) and mineral (P, K, Ca, Mg, Na, Fe, Mn, Zn, Cu, B) analyses were conducted. Values were expressed per freeze-dried weight (FDW) or fresh weight serving (FW) of seaweed.ResultsBrown algae had the highest concentration of total and iAs compared to all others. Statistical differences amongst macronutrients and minerals existed across seaweed species, with G. parvispora having higher Mn (∼510 µg/g FDW) and K (∼4.6 g/100g FDW) levels compared to all other samples (P < 0.05). Based on recommended nutritional daily values, G. parvispora (∼80 g FW) was high in Mn, H. formosa (∼100 g FW) was high in Fe, U. ohnoi (∼100 g FW) was high in Mg, and H. hawaiiana (∼100 g FW) was high in Mg, Fe, and Zn.ConclusionsOverall, these findings indicate significant differences in composition across seaweed species. As some seaweeds were excellent sources of essential nutrients while others were high in iAs, it is critical to continually expand compositional data to assess both nutritional adequacy and safety of diets.Funding SourcesUSDA-ARS, FDA.

Non-native red alga Gracilaria vermiculophylla compensates for seagrass loss as blue crab nursery habitat in the emerging Chesapeake Bay ecosystem.

Non-native species can become deleterious or potentially beneficial as components of novel ecosystems. The non-native red macroalga Gracilaria vermiculophylla may provide nursery habitat where eelgrass Zostera marina has been extirpated in Chesapeake Bay. A mensurative experiment was conducted monthly May–October 2013 and 2014 in the York River, Chesapeake Bay, to evaluate hypotheses that Gracilaria (1) can compensate for the loss of seagrass nurseries by colonizing habitats where seagrass has been eliminated by environmental stress, and (2) is utilized by juvenile blue crabs (Callinectes sapidus) as nursery habitat. We quantified Gracilaria presence, percent cover, and biomass as a function of region (upriver, midriver, and downriver) and seagrass presence or absence using stratified random sampling, 20-m transects, and 0.0625-m2 quadrats. Gracilaria volume was measured and converted to dry weight. Effects of the factors and covariates temperature, salinity, dissolved oxygen, month, and year were analyzed using generalized linear models. Juvenile blue crab density was quantified in summer 2013 using suction sampling in Gracilaria and seagrass. A model with the collective effect of region and seagrass presence or absence (downriver seagrass, downriver unvegetated bottom, midriver unvegetated bottom) best predicted Gracilaria abundance. Gracilaria presence, percent cover, and biomass were highest in downriver seagrass, followed by downriver unvegetated bottom, and then midriver unvegetated bottom, where seagrass has been extirpated, supporting hypothesis (1). Gracilaria did not occur upriver, likely due to a lack of recruitment. Seagrass and Gracilaria housed similar densities of juvenile blue crabs, supporting hypothesis (2). We estimated that a single 40-ha cove system with Gracilaria could house 200,000 juvenile crabs as would a single 2.4-ha seagrass bed. Consequently, the numerous midriver and downriver cove systems in the York River could support millions of young juvenile blue crabs and thereby compensate for the loss of seagrass in the river and in other areas of Chesapeake Bay. At present, Gracilaria has no widespread negative impacts on seagrass in the York River or most regions of Chesapeake Bay, likely because percent cover and biomass are not excessively high at present. We posit that Gracilaria has become an important alternative nursery habitat for the blue crab in Chesapeake Bay and can potentially mitigate impacts of climate change on seagrass nursery habitats.

High density cultivation and CO2 uptake by panel arrays of the macrophytic red alga Gracilaria vermiculophylla in a 100 L raceway pond

New approaches are needed for land-based cultivation of macrophytic red algae that reduce costly aeration requirements for biomass suspension and enable high-density cultivation. The goal of this study was to demonstrate the high-density cultivation of the carbohydrate-rich macrophytic red alga Gracilaria vermiculophylla on vertical arrays of panels deployed in an open channel raceway configuration similar to those developed for mass cultivation of microalgae. A clonal culture of G. vermiculophylla, consisting of branched, cylindrical thallus tissues of 8–10 cm length, was mechanically blended using a Waring blender into 2–3 cm fragments and then fluidically injected onto a 3 mm polypropylene mesh support. Immobilized G. vermiculophylla mesh panels were spaced 6.5 cm apart and aligned parallel to flowing seawater medium at nominal bulk velocity of 20 cm s−1 in a 100 L raceway pond of 20 cm liquid depth. This raceway was equipped with real-time measurement of CO2 concentration in the inlet and outlet gas for determination of CO2 uptake dynamics. Specific rates for CO2 uptake became saturated at 8000 ppm CO2. To match CO2 demand by the biomass under nutrient-replete conditions at 21 °C, the inlet gas CO2 was increased from 1000 to 4000 ppm (day 7–14), and then to 8000 ppm (day 14–23) at 0.010 L gas L−1 liquid min−1 gas flow. Over the 23 day cultivation, biomass on the panel increased by a factor of 48, with final biomass loading exceeding 10 kg FW m−2 panel area, and cumulative CO2 capture of 65%. The cumulative average areal productivity within the panel zone of the raceway exceeded 60 g AFDW m−2 day−1, and final biomass density nearing 7.2 g AFDW L−1 (47 g FW L−1) was achieved after 23 days. Overall, these outcomes demonstrate the potential for land-based raceway cultivation of clonal red macroalgae of present and future commercial significance.

Effects of UV–visible radiation on growth, photosynthesis, pigment accumulation and UV-absorbing compounds in the red macroalga Gracilaria cornea (Gracilariales, Rhodophyta)

Radiation induces different processes in photosynthetic organisms through photosynthetic pigments and photoreceptors. This study evaluated the performance of the red alga Gracilaria cornea cultivated under different radiation treatments. The objective was to identify responses associated with the treatments and mediated by photoreceptors. For this, G. cornea was exposed for 15 days to low fluence radiation of the ultraviolet (UV)-visible spectrum (red, green and blue light, and UV-A and UV-B radiation) combined with a high fluence radiation provided by a low-pressure sodium lamp (SOX), in order to saturate the photosynthesis. We measure the growth rate and other variables, such as photosynthesis estimated as chlorophyll a fluorescence, chlorophyll a, phycobiliproteins, carotenoids, mycosporine-like amino acids (MAAs), phenolic compounds, antioxidant capacity soluble proteins, and internal carbon and nitrogen content. The results showed that the UV radiation influenced the growth rates, as well as the accumulation of internal compounds (carotenoids: violaxanthin, antheraxanthin and zeaxanthin; MAA palythine; and phenolic compounds). As the treatments with UV radiation also had a peak of blue light, the presence of photoreceptors sensitive to these qualities of radiation (UV-A, UV-B and blue light) is suggested. In general, UV-A appears to induce some compounds without affecting growth, while UV-B seems to cause the accumulation of compounds at the expense of growth. The effect of light quality on growth and metabolism in G. cornea is compared to that in other species following similar experimental design.

Native tube-building polychaete prefers to anchor non-native alga over other macrophytes.

Novel facultative mutualisms that develop between native and non-native ecosystem engineers can lead to the retention of the non-native partner. In some cases, behavior plays an additional, but less understood, role in the development and persistence of mutualisms. In soft-sediment marine habitats along the western Atlantic, the native decorator worm Diopatra cuprea anchors the non-native red alga Gracilaria vermiculophylla to its tube cap in a mutualism. To understand whether the worm's usage of G. vermiculophylla could represent a preference, we first surveyed the species composition of macrophytes affixed to worm tube caps at three sites in coastal Virginia, USA using transect and quadrat sampling. These unmanipulated field surveys supported previous work revealing variable, but often high frequencies (31-98%) of D. cuprea decoration with G. vermiculophylla. We next used field manipulations and controlled laboratory experiments to test the consistency of individual D. cuprea decoration with G. vermiculophylla versus three common macrophytes (Ulva sp., Agardhiella sp., and Spartina alterniflora) found in our field surveys. Twenty-four hours after removing the worm's tube cap in the field, D. cuprea decoration was dominated by both G. vermiculophylla (39.6%) and S. alterniflora (25.9%). When provided a choice of macrophytes in the laboratory, individual D. cuprea consistently decorated with G. vermiculophylla (58.7%) over the other macrophytes, showing a preference for the non-native macrophyte. Our study suggests that preference can drive strong and steadfast interactions between native and non-native organisms, facilitating the latter's persistence and spread, change available habitat, and alter community interactions.

Cholinesterase inhibitory activities of neuroprotective fraction derived from red alga Gracilaria manilaensis

Anti-cholinesterase (ChE)s are commonly prescribed as the symptomatic treatment of Alzheimer’s disease. They are applied to prevent the breakdown of neurotransmitter acetylcholine (ACh) that bind to muscarinic and nicotinic receptors in the synaptic cleft. Seaweeds are one of the richest sources of bioactive compounds for both nutraceuticals and pharmacognosy applications. This study aimed to determine the anti-ChEs activity of Gracilaria manilaensis, one of the red seaweeds notables for its economic importance as food and raw materials for agar production. Methanol extracts (GMM) of G. manilaensis were prepared through maceration, and further purified with column chromatography into a semi-pure fraction. Ellman assay was carried out to determine the anti-acetylcholinesterase (AChE) and anti-butyrylcholinesterase (BuChE) activities of extracts and fractions. Lineweaver-Burk plot analysis was carried out to determine the inhibition kinetic of potent extract and fraction. Major compound(s) from the most potent fraction was determined by liquid chromatography-mass spectrometry (LCMS). GMM and fraction G (GMMG) showed significant inhibitory activity AChE with EC50 of 2.6 mg/mL and 2.3 mg/mL respectively. GMM and GMMG exhibit mixed-inhibition and uncompetitive inhibition respectively against AChE. GMMG possesses neuroprotective compounds such as cynerine A, graveolinine, militarinone A, eplerenone and curumenol. These findings showed a promising insight of G. manilaensis to be served as a nutraceutical for neuronal health care in the future.

The Feasibility of Using Agarophyte Processing Waste

When agarophytes are processed, 16-89% algal waste (AW) is formed. Due to the high content of minerals in this waste and the presence of proteins that are resistant to the action of proteolytic enzymes, such AW is mainly used in the production of feed for farm animals. The significant content of polysaccharides in dry AW indicates that it could be used as a raw material for the production of dietary fiber (DF). Due to the difference in the chemical composition of AW depending on the type of red algae, different approaches for its deproteinization have been used. Thus, a 3% alkali solution should be used for the deproteinization of algal waste from the red algae Gracilaria, a 0.5% alkali solution for GelidiumAW, and a 1% sodium carbonate solution for A. plicataAW.The duration of the deproteinization process is 30 min at a temperature of 97±2 ∘C for all types of AW. In this study, functional and technological solutions of DF from AW were developed. The results showed that their water binding capacity was 6-22 g of water per 1 g of the preparation, the fat binding capacity was 1.6-3.3 g of fat per 1 g of the preparation, and the swelling capacity was 46-312% depending on the type of red algae.The obtained DF was used in the production of minced fish food products of the ‘fish sticks’ type, based on minced fish and consisting of cod and pink salmon. The study of the chemical composition and calorie content of the developed food product showed the possibility of its use in dietary nutrition.&#x0D; Keywords: red algae, algal waste, deproteinization, dietary fiber

Chemical characterization of a new sulfated polysaccharide from Gracilaria chouae and its activation effects on RAW264.7 macrophages.

This study aimed to characterize the chemical composition of a new sulfated polysaccharide from the red alga Gracilaria chouae and evaluate its activation effects on RAW264.7 macrophages. It showed that the obtained G. chouae polysaccharide (GCP-3A) was a sulfated acidic polysaccharide with a molecular weight of 11.87 kDa. GCP-3A was composed of xylose, galactose, glucose, and mannose with a molar ratio of 3.00:29.28:0.63:0.45, and it contained α,β‍-glycosidic linkages. Scanning electron microscopy (SEM) and a Congo red test showed that it was a heterogeneous polysaccharide with irregular interwoven sheets and rods, and did not have a triple-helix conform‍ation. Furthermore, GCP-3A significantly promoted the proliferation of RAW264.7 macrophages and the secretion of nitric oxide (NO) in tests of 3-‍(4,‍5-dimethylthiahiazo-2-yl)‍-2,‍5-diphenytetrazoliumromide(MTT) and NO.

Agar Extraction, Physical Properties, FTIR Analysis and Biochemical Composition of Three Edible Species of Red Seaweeds Gracilaria corticata (J. Agardh), Gracilaria dentata (J. Agardh) and Gracilariopsis longissima (S. G. Gmelin)........

Three species of red algae Gracilaria corticata (J. Agardh), Gracilaria dentata (J. Agardh) and Gracilariopsis longissima (S.G. Gmelin), Steentoft, L. M; Irvine and Farnham (formerly Gracilaria verrucosa (Hudson) were collected from four different sites (Buleji, Hawks Bay, Manora and Paradise Point) of Karachi coast. The G. corticata was the dominant species and the highest yield of agar was compared to other studied species. The physical properties such as gel temperature, melting temperature, density, viscosity and gel strength showed large variations. Interestingly, the gel temperature, melting temperature, density, and gel strength had the highest value in G. corticata samples collected, while gel viscosity recorded the highest value in G. dentata samples. Intensive spectroscopic FTIR analysis was determined in all three species of G. corticata, G. dentata and G. longissima. The bands at 414.7/cm to 3917.2/cm represents stretching and bending vibrations of alcohol O-H, amine N-H, alkane C-H, alkyne C=C, nitriles C=N, carboxyl C=O, nitro aromatic N=O, alkane C-C, nitro methane C-N, aliphatic amines C-N, sulfoxides S=O, alkene C-H alkyl halide C-Cl, C-I groups. The ash content of all studied species (G. corticata, G. dentata and G. longissima) was in the range of 20-30%, while the carbohydrate content was in the range of 22-24%. The results of this study suggested the utilization of our natural resources present in Karachi coast. This could be achieved by determining the quantity and quality of agar in the edible species of Gracilaria/Gracilariopsis.&#x0D;

Pengaruh Perlakuan pH dan Suhu terhadap Stabilitas Ekstrak Alga Merah (Gracilaria sp.) sebagai Pewarna Alami

Phycoerytrin is a red pigment found in red algae. Red algae Gracilaria sp. potential to be a source of natural dye because it contains phycoerythrin. Phycoerythrin is unstable to light, pH, and temperature. The purpose of this study was to determine the effect of pH and temperature on the stability of the dye extract from the red algae Gracilaria sp. and determine the pH and temperature that best maintain the constancy of the red algae Gracilaria sp. extract during storage. The design in this study used a completely randomized design with two factors, namely pH and temperature. First factor was the pH treatment which consist of three levels namely pH 4, pH 7 and pH 10 and second factor was initial temperature consist of two levels, namely 4±2?C and 28±2?C. The results showed that pH had a very significant effect (P&lt;0.01) on the total phycoerythrin, brightness (L*), redness (a*) and yellowness (b*) at weeks 2, 3, 4. Temperature treatment has a very significant effect on the total phycoerythrin and brightness (L*) at weeks 3 and 4, as well the level redness (a*) and the level yellowness (b*) at weeks 2, 3 and 4. At pH 4 and cold temperature (4±2?C) were the best treatments to maintain the stability of the red algae Gracilaria sp. extract during storage. They had the lowest decrease in phycoerythrin levels and redness (a*), and had the smallest increase in brightness (L*) and yellowness (b*). Extract that were stored for 4 weeks with pH 4 and temperature 4±2?C treatment had decrease in total phycoerythrin, increase in brightness (L*), decrease in redness (a*), and increase in yellowness (b*) successively was 13.04%, 0.47%, 6.58%, dan 3.50%. &#x0D; Keywords : Gracilaria sp. extract, phycoeriythrin, pH, temperature, stability

Apical, sub-apical, and basal explants of industrially exploited marine red alga Gracilaria salicornia exhibited differential response to commercial seaweed-derived plant bio-stimulants

Apical, sub-apical, and basal explants of industrially exploited marine red alga Gracilaria salicornia exhibited differential response to commercial seaweed-derived plant bio-stimulants

Potency of Local Gracilaria sp. Extract as an Antibacterial against Skin Disease Pathogen

Skin disease is one of the most common diseases in tropical countries such as Indonesia, which might be caused by infection of pathogens like Staphylococcus aureus and Pseudomonas aeruginosa. Red algae Gracilaria sp. originated from Wediombo Beach, Yogyakarta, Indonesia has not been widely used for medicinal purpose, especially as an antimicrobial for skin diseases in human. Therefore, this research aimed to study about the potency of local Gracilaria sp. extract as an antibacterial against skin disease pathogen. Red algae extraction was carried out using maceration method in ethanol solvent. Identification of phytochemical groups was determined using basic biochemistry analysis and Thin Layer Chromatography (TLC), while active phytochemical compounds were identified using Gas Chromatography-Mass Spectrophotometry (GC-MS). Antibacterial tests were performed by minimum inhibition concentration (MIC) using MTT indicator and inhibition assay using paper disc method. Alkaloids and saponins were identified in phytochemical based on biochemical tests. Compound separation by TLC using chloroform and methanol solvents with a ratio of 90:10 resulted in seven color spots with ninhydrin spray and six color spots with anisaldehyde spray. The GC-MS results showed that there were 38 compounds identified in the crude extract, which 8 of these 38 compounds are known to have anti-bacterial activity. Anti-bacterial assay of Gracilaria sp. extract on concentration of 100% showed medium strength to inhibit Staphylococcus aureus and strong strength to inhibit Pseudomonas aeruginosa. Crude extract of local Gracilaria sp. is potential to be used as antimicrobials against Staphylococcus aureus and Pseudomonas aeruginosa common agents for skin disease.

Cyclopentenone and wickerol derivatives from the marine algicolous fungus Trichoderma atroviride A-YMD-9-4

A new cyclopentenone derivative, 4-hydroxyhypocrenone A, and a new naturally-occurring wickerol derivative, 8-acetoxywickerol A, as well as two known compounds, hypocrenone A and wickerol B, were purified from Trichoderma atroviride A-YMD-9-4, an endophytic fungus isolated from the marine red alga Gracilaria verrucosa. The structures and relative configurations of two new isolates were established by a combination of 1 D/2D NMR, IR, and mass spectroscopic methods, and the absolute configuration of 1 was assigned on the basis of ECD data analyzed by quantum chemical calculations. Compounds 1 and 2 exhibited weak inhibition of one or two marine phytoplankton species.

Valorization of the red macroalga Gracilaria corticata by hydrothermal liquefaction: Product yield improvement by optimization of process parameters

Hydrothermal liquefaction (HTL) of the red alga Gracilaria corticata was carried out at 260, 280 and 300 °C for 15 min using H2O as solvent. The bio-oil yield was maximal (5.25 wt%) at 300 °C. Influence of the solvents methanol, ethanol, acetone and ethanol-water on the distribution as well as nature of the resultant HTL products has also been examined. Organic solvents could markedly improve the bio-oil yield to over 16 wt%. Bio-oil and biochar were characterized through FT-IR, GC–MS and 1H NMR studies. Analysis of GC–MS data in conjunction with FT-IR and 1H NMR derived information revealed that the bio-oil mainly consisted of various derivatives of compounds such as aldehydes, ketones, phenols, acids and esters, besides nitrogenous compounds. This research outcome using HTL as a technique for enhancing bio-oil yield, in particular from red macroalgae, would provide a stimulus for further investigations on potential commercial applications of algal bio-oil.

Levels of taurine, hypotaurine and homotaurine, and amino acids profiles in selected commercial seaweeds, microalgae, and algae-enriched food products

Amino acids and sulfonic acid derivatives (Taurine-Tau; Hypotaurine-HypTau; Homotaurine-HTau) of 26 different species of commercial macroalgae, microalgae and 10 algae-enriched food products from the market were quantified in a single chromatographic run. Tau and analogues were predominantly distributed in red species followed by green and brown species. Palmaria palmata, Gracilaria longissima and Porphyra sp. were the species with the highest content of Tau and total sulfonic acid derivatives (TAD). Notwithstanding, relatively high concentrations of HTau were found in green algae Ulva lactuca and G. vermicullophyla as well as in the brown algae Undaria pinnatifida. HTau and HypTau were found at lower concentrations than Tau in all species, except in Ulva lactuca. The samples with the highest protein content were the green species Chlorella vulgaris, Nannochloropsis, and Afanizomenon-flos aquae, followed by the red algae Gracilaria longissima and Gracilaria vermicullophyla.Samples of pasta formulated with algae ingredients contained the highest levels of sulfonic acid derivatives, evidencing that these products can provide levels of TAD comparable to those found in foods of animal origin.This study provides, for the first time, quantitative information regarding the distribution of sulfonic acid derivatives and total amino acids in multiple algae species as well as the nutritional impact of the inclusion of algae ingredients in commercial food matrices.