Red Algae Research Articles

Super-slippery silicone-based gel coating with a regenerative oil layer for long-term prevention of surface contamination

Polymer-based gel-type coatings, in which oil molecules are absorbed within polymer networks, have drawn attention as functional coatings to address fouling problems. However, surface drought caused by lubricant depletion limits the longevity of conventional gel-type coatings. In this study, a super-slippery long-chain entangled polydimethylsiloxane (LEP) gel that can self-regenerate its low-viscosity oil layer is proposed to enhance its long-term anti-fouling performance in both indoor and marine habitats. The proposed LEP gel coating can effectively prevent contamination from numerous liquids and protect aluminum surfaces from corrosion in seawater. Even when it was incubated with Porphyridium purpureum, marine red algae that readily stick to the surface, no biofilm was formed on the coated samples for 37 weeks. In field tests, no biological adhesion was observed on the coating surface which was applied to port structures and left for two summer months. This enhanced anti-contamination performance is mainly attributed to the dual protective barrier comprising the underlying polymer layer and regenerative oil layer. Due to special property of continuous self-regeneration of oil layer, the proposed LEP gel surface demonstrates much enhanced sustainability, compared to conventional gel-type coatings. Consequently, the long-term anti-contamination performance of the super-slippery LEP gel coating would pave the way for novel approach to its practical applications.

The Free-Running Circasemilunar Period Is Determined by Counting Circadian Clock Cycles in the Marine Midge Clunio Marinus.

Semilunar rhythms are found in numerous marine organisms, but the molecular mechanism and functional principles of endogenous circasemilunar clocks remain elusive. Here, we explore the connection between the free-running circasemilunar clock and the circadian clock in the marine midge Clunio marinus with three different chronobiological assays. First, we found that the free-running circasemilunar period of the adult emergence rhythm in C. marinus changes linearly with diel T-cycle length, supporting a day-counting mechanism. Second, under LD 6:6, periods of circasemilunar and circadian emergence were comparable to those under LD 12:12, indicating that the circasemilunar counter in C. marinus relies on endogenous circadian oscillations rather than external T-cycles. Finally, when desynchronizing the circadian clock with constant light, the free-running circasemilunar emergence rhythm disappeared as well, suggesting that it requires a synchronized circadian clock. These results oppose the long-held view that C. marinus' free-running circasemilunar clock operates independently of the circadian clock. In a broader evolutionary context, our results strengthen the idea that the circasemilunar clocks of dipterous insects are based on different functional principles compared to the circasemilunar or circalunar clocks of marine annelids and algae. These divergent clock principles may indicate multiple evolutionary origins of circasemilunar and circalunar clocks.

Enhancing marine algae composites with cellulose nanofibrils for sustainable nutrient management

Enhancing marine algae composites with cellulose nanofibrils for sustainable nutrient management

Report on <i>Phaeophila dendroides</i> (Crouan) Batters Endophytic in <i>Rosenvingea intricata</i> (J. Ag.) Boergs.

Phaeophila dendroides (Crouan) Batters is reported here for the first time from North India from Chilka Lake. While the species is known as an endophyte in several marine algae belonging to Chlorophyta and Rhodophyta and a few marine Spermatophyta, it is reported here for the first time in a Phaeophyta in Roservingea intricata (J. Ag.) Boergs. The endophyte from Chilka Lake is described in some detail.

Extraction, Purification, Structural Characteristics, and Biological Activities of Seaweed Polysaccharides: A Review

AbstractThis paper presents a thorough review of the extraction, purification, structural characterization, and biological activities of polysaccharides obtained from seaweed. The focus is on the polysaccharide compositions of green algae, brown algae, and red algae, which are systematically compared and analyzed. It has been discovered that while there are similarities in the extraction and purification processes of seaweed polysaccharides, there are also significant differences and unique features in their structural characteristics and biological activities. These differences are not only reflected in the chemical composition of the polysaccharides but are also closely related to their sources and extraction methods. The relationship between the structure and activity of seaweed polysaccharides will aid in comprehending the biological activity mechanism of marine organisms. This review provides a theoretical basis and practical guidance for the development of new types of marine drugs or functional foods.

Metabolic changes of the red marine alga Gracilariopsis tenuifrons elicited by high PAR in laboratory

Metabolic changes of the red marine alga Gracilariopsis tenuifrons elicited by high PAR in laboratory

Recent advances in in vitro and in vivo studies on Kappaphycus alvarezii and its derivatives.

The marine red algae Kappaphycus alvarezii (KA), commonly known as cottonii, is a valuable resource with diverse applications. Research has primarily focused on its primary metabolites such as amino acids, proteins, plant hormones etc. Additionally, KA also produces secondary metabolites under stress, some of which exhibit antioxidant and antibacterial properties. This review provides a comprehensive overview of recent in vitro and in vivo research on KA, delving into their therapeutic effects and potential pharmaceutical applications. The study followed a through literature survey in three databases. From the obtained literature, the studies fitting the criteria were reviewed. The study explores the underlying mechanisms behind the algae's diverse characteristics. The results show that KA is a valuable resource for potential therapeutic applications, but a deeper exploration of its various metabolites and rigorous research are necessary for a thorough understanding of its capabilities.

First report of antioxidant potential of peptide fraction derived from Colaconema formosanum (Rhodophyta) protein hydrolysates

Foods that contain natural antioxidants can improve people's health and performance and make them more resistant to environmental stressors like diseases, lousy living conditions, and heat stress. Marine algae are well known for their function as an antioxidant. Colaconema formosanum is a new rhodophyte discovered in Taiwan and its bioactive activities are rarely studied. This work aims to prepare the protein hydrolysate fraction with antioxidant properties in C. formosanum using single enzyme or complex enzyme hydrolysis. Afterward, a 3 kDa molecular weight cut-off (MWCO) was used for centrifugation, and then fractionation was carried out using Strong Cation Exchange (SCX) Chromatography. The quantification of antioxidant activity was performed using the DPPH test. The results showed that the thermolysin hydrolysate (IC50 1.48 ± 0.92 mg/mL) and the combination of trypsin-thermolysin hydrolysates (IC50 1.37 ± 0.84 mg/mL) had the highest antioxidant activity. The fractionation procedure with strong cation exchange (SCX) yielded fraction C from thermolysin hydrolysates, which exhibited the most significant antioxidant activity with an IC50 value of 0.47 ± 0.02 mg/mL. The fraction 4 derived from trypsin-thermolysin hydrolysates exhibited the most potent antioxidant activity (IC50: 0.34 ± 0.002 mg/mL). No previous reports have been made about the antioxidant properties of the hydrolysate fractions derived from C. formosanum proteins. Consequently, these findings could serve as a foundation for exploring peptides that have potential therapeutic sources for reducing oxidative stress.

Effects of dietary seaweed on obesity-related metabolic status: a systematic review and meta-analysis of randomized controlled trials.

Seaweed is a promising source of anti-obesity agents, including polysaccharides, proteins, polyphenols, carotenoids, and n-3 long-chain polyunsaturated fatty acids. The anti-obesity effects of such compounds may be due to several mechanisms, including inhibition of lipid absorption and metabolism, effect on satiety, and inhibition of adipocyte differentiation. The aim of this study was to assess the evidence from human randomized controlled trials for the effects of seaweed on body-weight status as well as lipid and nonlipid parameters in adults with overweight and obesity. Four databases-Medline, Scopus, Web of Science, and Cochrane Library-were searched from December 2022 to June 2023 using the following key words: Seaweed OR fucoxanthin OR alginates OR fucoidans OR phlorotannin's OR macroalgae OR marine algae AND obesity OR overweight OR BMI OR body mass index. Eleven interventional studies (10 parallel and 1 crossover) were extracted. Meta-analysis showed a significant effect, favoring the intervention group for BMI (body mass index) (standardized mean difference [SMD]: -0.40; 95% CI: -0.65 to -0.16 kg/m2; P = 0.0013) and percentage of fat mass (SMD: -1.48; 95% CI: -2.66% to -0.30%, P = 0.0138). The results were seen when refined or extracted brown seaweed (BMI) or only refined brown seaweed (% fat mass) were administered to participants for at least 8 weeks. Moreover, a significant overall effect of seaweed supplementation on total cholesterol (SMD: -7.72; 95% CI: -12.49 to -2.95 mg/dL; P = 0.0015) and low-density-lipoprotein cholesterol (SMD: -7.33; 95% CI: -11.64 to -3.02 mg/dL; P < 0.001) was noted. Any significant effects of seaweed on glucose metabolism were not shown. Edible seaweed supplementation shows potential for managing obesity and disorders of the blood lipid profile when administered to participants for at least 8 weeks. PROSPERO registration no. CRD42022378484 (www.crd.york.ac.uk/PROSPERO).

Study of Antioxidant, Antimicrobial and Cytotoxic Activities of Ag-Co Bimetallic Nanoparticles Biosynthesized from Red Alga (Amphiroa sp.)

Study of Antioxidant, Antimicrobial and Cytotoxic Activities of Ag-Co Bimetallic Nanoparticles Biosynthesized from Red Alga (Amphiroa sp.)

Red Algae Compounds: Potential Neuroprotective Agents for Neurodegenerative Disorders

This review explores the potential of compounds derived from red algae (Rhodophyta) as promising neuroprotective agents for treating neurodegenerative disorders. Red algae, abundant in marine environments, contain bioactive compounds with diverse chemical structures and functionalities. Sulfated polysaccharides, primarily agar and carrageenans, stand out as the predominant and widely utilized compounds derived from red algae. Additionally, red algae harbor a spectrum of potential molecules such as essential fatty acids, phycobiliproteins, vitamins, minerals, and secondary metabolites. Extensive research has highlighted the diverse biological activities exhibited by these compounds, including anti-oxidative and anti-inflammatory properties. These compounds show various biological activities that have garnered interest in their therapeutic potential for neurodegenerative diseases. This comprehensive review aims to summarize the current knowledge regarding the extraction, characterization, mechanisms of action, and therapeutic applications of Rhodophyta-derived compounds in the context of neuroprotection and treatment of neurodegenerative disorders.

Exploring the Bioactive Potential of Marine Algae: Insights from Phytochemical Analysis, GC-MS Profiling, and Antioxidant Evaluation

Exploring the Bioactive Potential of Marine Algae: Insights from Phytochemical Analysis, GC-MS Profiling, and Antioxidant Evaluation

Marine algae oils from Phaeodactylum tricornutum and Laminaria japonica alleviate obesity, insulin resistance, and gut microbiota dysbiosis in high-fat diet-fed mice

The present study was aimed to investigate the effects of Phaeodactylum tricornutum oil (PO) and Laminaria japonica oil (LO) against obesity and other metabolic disorders in a high-fat diet (HFD) induced obese mouse model. The results revealed that PO or LO supplementation significantly reduced HFD-induced body weight gain, hyperlipemia, and fat accumulation in mice. PO or LO supplementation also inhibited SREBP-1-mediated de novo lipogenesis and PPARγ-mediated adipogenesis, as well as enhanced PPARα-mediated fatty acid β-oxidation in the WAT and liver of HFD-fed mice. Moreover, PO or LO supplementation attenuated low-grade chronic inflammation, hyperglycemia and insulin resistance in obese mice. Furthermore, Dietary PO or LO also modulated HFD-induced gut microbiota dysbiosis and increased the SCFAs production. More importantly, our results also manifested that the ameliorative effect of PO and LO against HFD-induced obesity, IR and gut microbiota dysbiosis was comparable, but was superior than that of krill oil and fish oil.

Phenology and the response of photosynthesis to irradiance and temperature gradient in the herbal drug red alga, Chondria armata (Rhodomelaceae, Ceramiales) from Kagoshima, Japan

AbstractSeasonal changes in the size of the herbal drug red alga Chondria armata (Rhodomelaceae, Ceramiales) were investigated in Kagoshima, Japan, which is near the northern distributional limit in the western Pacific. Additionally, its photosynthetic response to irradiance and temperature was examined using dissolved oxygen sensors and a pulse amplitude modulation (PAM)-chlorophyll fluorometer. This alga was observed in tidepools throughout the year; its height and weight were greatest in December and the lowest in April and May. The net photosynthesis of the photosynthesis–irradiance (P–E) curve determined at 28°C quickly saturated at 113 µmol photons m-2 s-1, with minimal inhibition even at 1000 µmol photons m-2 s-1. The gross photosynthesis of the photosynthesis–temperature (P–T) curved over 8 to 40°C, measured at 500 µmol photons m-2 s-1, peaked at 30.1°C and decreased rapidly below 20°C and above 36°C, respectively. Similarly, the effective quantum yield (ΔF/Fm') after a 3-day culture during 4–40°C at 50 µmol photons m-2 s-1 remained stable between 16°C and 32°C but decreased outside of this range. The combined effect of irradiance (200 [low] and 1000 [high] µmol photons m-2 s-1) and temperature (28, 22, and 16°C) revealed that ΔF/Fm' declined during exposure to high irradiance at all temperature treatments. However, it mostly recovered after a subsequent 12-hour period of dim-light acclimation at 28°C and 22°C. In contrast, those at 16°C could not recover, indicating the occurrence of low-temperature light stress. This alga appears to be well-adapted to the irradiance and temperature environment at the study site. However, the winter temperature appears to approach its threshold level, and the occurrence of strong light during the winter might adversely affect the abundance of this alga near its northern distributional limit.

Fermented Gracilaria lemaneiformis polysaccharides alleviate food allergy by regulating Treg cells and gut microbiota

Food allergy has a significant impact on the health and well-being of individuals, affecting both their physical and mental states. Research on natural bioactive compounds, such as polysaccharides extracted from seaweeds, holds great promise in the treatment of food allergies. In this study, fermented Gracilaria lemaneiformis polysaccharides (F-GLSP) were prepared using probiotic fermentation. Probiotic fermentation of Gracilaria lemaneiformis reduces the particle size of polysaccharides. To compare the anti-allergic activity of F-GLSP with unfermented Gracilaria lemaneiformis polysaccharides (UF-GLSP), an OVA-induced mouse food allergy model was established. F-GLSP exhibited a significant reduction in OVA-specific IgE and mMCP levels in allergic mice. Moreover, it significantly inhibited Th2 differentiation and IL-4 production and significantly promoted Treg differentiation and IL-10 production in allergic mice. In contrast, UF-GLSP only reduced OVA-specific IgE and mMCP in the serum of allergic mice. Furthermore, F-GLSP demonstrated a more pronounced regulation of intestinal flora abundance compared to UF-GLSP, significantly influencing the populations of Firmicutes, Bacteroidetes, Lactobacillus, and Clostridiales in the intestines of mice with food allergy. These findings suggest that F-GLSP may regulate food allergies in mice through multiple pathways. In summary, this study has promoted further development of functional foods with anti-allergic properties based on red algae polysaccharides.

Metabolic relationships between marine red algae and algae-associated bacteria

AbstractMutualistic interactions between marine phototrophs and associated bacteria are an important strategy for their successful survival in the ocean, but little is known about their metabolic relationships. Here, bacterial communities in the algal sphere (AS) and bulk solution (BS) of nine marine red algal cultures were analyzed, and Roseibium and Phycisphaera were identified significantly more abundantly in AS than in BS. The metabolic features of Roseibium RMAR6-6 (isolated and genome-sequenced), Phycisphaera MAG 12 (obtained by metagenomic sequencing), and a marine red alga, Porphyridium purpureum CCMP1328 (from GenBank), were analyzed bioinformatically. RMAR6-6 has the genetic capability to fix nitrogen and produce B vitamins (B1, B2, B5, B6, B9, and B12), bacterioferritin, dimethylsulfoniopropionate (DMSP), and phenylacetate that may enhance algal growth, whereas MAG 12 may have a limited metabolic capability, not producing vitamins B9 and B12, DMSP, phenylacetate, and siderophores, but with the ability to produce bacitracin, possibly modulating algal microbiome. P. purpureum CCMP1328 lacks the genetic capability to fix nitrogen and produce vitamin B12, DMSP, phenylacetate, and siderophore. It was shown that the nitrogen-fixing ability of RMAR6-6 promoted the growth of P. purpureum, and DMSP reduced the oxidative stress of P. purpureum. The metabolic interactions between strain RMAR6-6 and P. purpureum CCMP1328 were also investigated by the transcriptomic analyses of their monoculture and co-culture. Taken together, potential metabolic relationships between Roseibium and P. purpureum were proposed. This study provides a better understanding of the metabolic relationships between marine algae and algae-associated bacteria for successful growth.

Study of Ultrasound Effect on Macrophyte Fouling of Artificial Substrates as a Way to Control Bio-Damage in NPP Water Supply Systems

The results of the study of ultrasound influence on the formation of macrophytoperiphyton on steel and concrete substrates in field conditions (sea water area) are presented. On the example of macroalgae in the conditions of full-scale experiment the ability of ultrasound to complicate, but not completely inhibit the development of plant colonizers is shown. The greatest sensitivity to the impact of ultrasound is shown by red algae. It is recommended to expand the experiments with the use of ultrasound installation of higher power in order to assess the effect of ultrasound on different groups of algae during the operation of NPP.

241 Immunophysiology and performance of broilers supplemented with macroalgal sulfated polysaccharides during a subclinical necrotic enteritis challenge

Abstract This study evaluated the effects of a sulfate polysaccharide extracted from marine algae product on performance, intestinal lesion scores, and mRNA abundance of various tight junction proteins and immune response genes. A total of 600 one-day old male broilers (Ross 708) were allocated to one of four treatment groups (6 replicate floor pens, 25 birds/pen): negative control (NC) group fed a corn-soybean meal diet; positive control (PC) fed NC + 15 ppm Avilamycin and 125 ppm Amprolium, an additive group (AGS) fed NC + Algoguard added at 0.1% of the diet, and (AGH) fed NC + Algoguard added at 0.2% of the diet. To predispose the birds to NE, birds were orally gavaged with 2,000 Eimeria maxima sporulated oocysts on d 14 followed by a dose of approximately 1×108 CFU/mL of C. perfringens on d 19. On d 21, four birds/pen were necropsied for NE lesions and on d 14, 21, and 42 jejunal samples were collected to assess mRNA abundance. Birds and feed were weighed on d 14, 21, 28, and 42 on a per pen basis. Average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were calculated during each feeding phase and adjusted for daily mortality. The data were analyzed using ANOVA (JMP, Pro 16) and significance (P ≤ 0.05) was determined by the LSD test. During d 14-21, 0-21, 0-28, and 0-42, mortality rate and ADFI were significantly less in AGS, AGH, and PC compared with NC. ADG was greater while FCR was significantly less in PC, AGS, and AGH during d 21-28, 0-28, and 0-42 compared with NC (P ≤ 0.05). Lesion severity was also significantly less in AGS, AGH, and PC compared with NC. On d 14, 21, and 42 there were no toxins present in the tested serum samples. Calprotectin concentration was greater in PC and NC on d 21 and 42 compared with the supplemented groups. C. perfringens toxin was not detected in serum samples of any of the four treatment groups. mRNA abundance of CLDN1, IL1β, IL12B, and IL10 was greater in AGS compared with NC on d 14 and 42. ZO1 was significantly greater on d 21 in PC treatment and was less than both AGS and AGH on d 42 (P ≤ 0.05). Compared with all other treatments, mRNA abundance of OCLDN was greater and those of IFN-γ and ZO2 were less in PC, while that of CLDN3 showing no significant difference among all 4 treatments. To conclude, dietary inclusion of this algal product in broiler diets could be considered as a beneficial alternative to antibiotic growth promoters in the context of this challenge model.

Morphological insights into the three-dimensional complexity of rhodolith beds

The ecological importance of rhodolith beds stems from their role as structurally complex three-dimensional habitat formed by free-living red calcareous algae. Their structural singularity is due to the great variety of complex and branching morphologies exhibited by rhodoliths that create interstitial spaces and increase their surface area. This increases the ecological niches for cryptofauna and provide refuge for a high number of organisms, which is why rhodolith beds are considered biodiversity hotspots. In this work, we studied a rhodolith bed located in the Menorca Channel, formed by several species of red calcareous algae that exhibit a great variety of morphologies and form an extensive and heterogeneous habitat. This study explored the morphological diversity of the rhodolith bed, comparing the ‘Core Habitat’ (within the center of the bed with the highest densities of rhodoliths) with the boundaries or ‘Adjacent Habitat’ where rhodolith density was lower. Our results show that all rhodolith growth forms (branched, pralines and boxwork) in the Core Habitat had higher interstitial space and were larger than the ones from adjacent zones. Moreover, we explored the three-dimensional techniques to study the morphological characteristics that have historically been studied in two dimensions. This study contributes to the knowledge of morphological diversity in well-preserved rhodolith beds from continental shelves in the western Mediterranean Sea and reinforces the use of three-dimensional measurements, specifically the interstitial space of branched rhodoliths, to provide more accurate data on habitat complexity.

First Eocene record of a bangialean rhodophyte (the endolithic microboring Conchocelichnus seilacheri) and coralline red algae from the Pacific Coast of North America

First Eocene record of a bangialean rhodophyte (the endolithic microboring Conchocelichnus seilacheri) and coralline red algae from the Pacific Coast of North America