Aquaculture Production of the Brown Seaweeds Laminaria digitata and Macrocystis pyrifera: Applications in Food and Pharmaceuticals

Mass spectrometric characterization of aminophospholipids containing N-(2-hydroxyethyl)glycine in kombu algae extracts

RATIONALE

1,2-Diacyl-sn-glycero-3-phospho-O-[N-(2-hydroxyethyl)glycines] (PHEGs) are a class of rare aminophospholipids found specifically in brown algae, including kombu seaweed. Despite their potential importance in algal physiology, a comprehensive mass spectrometry (MS) characterization, useful to understand their biological behaviour, is still lacking.

METHODS

To establish the structural regiochemical features of PHEGs, we employed hydrophilic interaction liquid chromatography (HILIC). Following separation, the isolated band of PHEGs was analyzed using MS techniques. This included multistage tandem MS experiments, performed in both positive and negative electrospray ionization modes at low and high resolution.

RESULTS

By comparing MS/MS and MS3 spectra acquired in negative ion mode, the regiochemical rules for PHEG identification were established. The most abundant PHEG species in kombu seaweed, from both Laminaria ochroleuca (European Atlantic) and Laminaria longissima (Japan), was identified as PHEG 20:4/20:4. Less abundant species included PHEG 20:4/20:5 and hydroxylated forms of both PHEG 20:4/20:4 (i.e. 40:8;O) and 20:4/20:5 (40:9;O). The presence of a lyso PHEG 20:4 was consistently detected but at very low levels.

CONCLUSIONS

This study employed MS analysis to elucidate the regiochemical patterns of PHEGs in kombu seaweed. We identified PHEG 20:4/20:4 as the dominant species, along with several less abundant variants, including hydroxylated forms. These findings provide valuable insights into the potential roles and metabolism of PHEGs in brown algae, paving the way for further investigation into their biological functions.

Algae-based approaches for Holistic wastewater management: A low-cost paradigm

Aquatic algal communities demonstrated their appeal for diverse industrial applications due to their vast availability, ease of harvest, lower production costs, and ability to biosynthesize valuable molecules. Algal biomass is promising because it can multiply in water and on land. Integrated algal systems have a significant advantage in wastewater treatment due to their ability to use phosphorus and nitrogen, simultaneously accumulating heavy metals and toxic substances. Several species of microalgae have adapted to thrive in these harsh environmental circumstances. The potential of algal communities contributes to achieving the United Nations' sustainable development goals in improving aquaculture, combating climate change, reducing carbon dioxide (CO2) emissions, and providing biomass as a biofuel feedstock. Algal-based biomass processing technology facilitates the development of a circular bio-economy that is both commercially and ecologically viable. An integrated bio-refinery process featuring zero waste discharge could be a sustainable solution. In the current review, we will highlight wastewater management by algal species. In addition, designing and optimizing algal bioreactors for wastewater treatment have also been incorporated.

New Perspective for Macroalgae-Based Animal Feeding in the Context of Challenging Sustainable Food Production

Food production is facing challenging times due to the pandemic, and climate change. With production expected to double by 2050, there is a need for a new paradigm in sustainable animal feed supply. Seaweeds offer a highly valuable opportunity in this regard. Seaweeds are classified into three categories: brown (Phaeophyceae), red (Rhodophyceae), and green (Chlorophyceae). While they have traditionally been used in aquafeed, their demand in the feed market is growing, parallelly increasing according to the food demand. Additionally, seaweeds are being promoted for their nutritional benefits, which contribute to the health, growth, and performance of animals intended for human consumption. Moreover, seaweeds contain biologically active compounds such as polyunsaturated fatty acids, antioxidants (polyphenols), and pigments (chlorophylls and carotenoids), which possess beneficial properties, including antibacterial, antifungal, antiviral, antioxidant, and anti-inflammatory effects and act as prebiotics. This review offers a new perspective on the valorization of macroalgae biomass due to their nutritional profile and bioactive components, which have the potential to play a crucial role in animal growth and making possible new sources of healthy food ingredients.

Integrated multi-trophic aquaculture with sugar kelp and oysters in a shallow coastal salt pond and open estuary site

Sustainable aquaculture includes the aquaculture of non-fed crops that provide ecosystem services including nutrient extraction and water quality improvement. While shellfish are the most farmed sustainable aquaculture crops in the USA, shellfish farmers in the northeastern US have an interest in diversifying their crops and incorporating seaweeds into their farms. In this study, we worked with oyster farmers to investigate the potential for farming sugar kelp, Saccharina latissima, across different environmental regimes in coastal Rhode Island USA. Kelp seed spools were outplanted at two time points in the fall/winter of 2017 and 2018 at four sites and cultivated until harvest the following spring. Kelp performance (length, width, yield), tissue content, and nutrient extraction were determined for each line in each year; oyster growth was also measured monthly for one year at each site. We found that kelp could successfully grow in both shallow coastal lagoons and estuarine sites, although the timing of planting and placement of sites was important. Lines that were planted earlier (as soon as water temperatures<15°C) grew longer and yielded more biomass at harvest; overall, kelp blade yield ranged from 0.36 ± 0.01 to 11.26 ± 2.18 kg/m long line. We report little variation in the tissue quality (C:N) of kelp among sites, but differences in biomass production led to differences in nutrient extraction, which ranged from 0.28 ± 0.04 to 16.35 ± 4.26 g nitrogen/m long line and 8.93 ± 0.35 to 286.30 ± 74.66 g carbon/m long line. We found extensive variability in kelp growth within and between lines and between years, suggesting that crop consistency is a challenge for kelp farmers in the region. Our results suggest that, as there is a lower barrier in terms of permitting (versus starting a new aquaculture farm), it may be a worthwhile investment to add sugar kelp to existing oyster farms, provided they have suitable conditions. At current market rates of US$0.88-$3.30 per kg, farmers in southern New England have the potential to earn US$2,229 per 60 m longline. While seaweed aquaculture is growing, considerable barriers still exist that prevent wide-scale kelp aquaculture adoption by existing aquafarmers.

Natural variation of Macrocystis pyrifera gametophyte germplasm culture microbiomes and applications for improving yield in offshore farms

With national interest in seaweed-based biofuels as a sustainable alternative to fossil fuels, there is a need for tools that produce high-yield seaweed cultivars and increase the efficiency of offshore farms. Several agricultural studies have demonstrated that the application of microbial inoculants at an early life stage can improve crop yield, and there is an opportunity to use similar techniques in seaweed aquaculture. However, there is a critical knowledge gap regarding host-microbiome associations of macroalgae gametophytes in germplasm cultures. Here, we investigate the microbial community of Macrocystis pyrifera gametophyte germplasm cultures that were used to cultivate an offshore farm in Santa Barbara, California and identify key taxa correlated with increased biomass of mature sporophytes. This work provides a valuable knowledge base for the development of microbial inoculants that produce high-biomass M. pyrifera cultivars to ultimately be used as biofuel feedstocks.

Brown Seaweed (Padina australis) Extract can Promote Performance, Innate Immune Responses, Digestive Enzyme Activities, Intestinal Gene Expression and Resistance against Aeromonas hydrophila in Common Carp (Cyprinus carpio)

Eight-week oral administration of Padina australis ethyl acetate extract at 100, 200, and 400 mg/kg diets was assessed on the growth performance, tight junction proteins, intestinal immunity, and disease resistance to Aeromonas hydrophila in common carp (Cyprinus carpio). A total of 300 healthy common carp weighing around 14.8 ± 0.03 g were randomly assigned into four equal groups within 12 glass aquariums, each in three replicates (25 fish/tank), for the feeding trial experiment. The first group served as the control group and was fed an un-supplemented diet, whilst the other three groups were offered diets containing graded amounts of Padina australis ethyl acetate extract at 100, 200, and 400 mg/kg, respectively. The growth indices, including final weight, length, weight gain rate, specific growth rate, and feed conversion ratio, were meaningfully improved in fish fed with the algae at 200 and 400 mg/kg compared to the control fish (p < 0.05). Similarly, digestive enzyme activities and serum immune parameters were significantly higher in all treatments, especially 200 and 400 mg/kg fed groups, compared to the control (p < 0.05). In parallel, significant upregulation of genes related to integrity and the immune system was shown in the intestine of these treatment groups compared to control fish (p < 0.05). When fish were challenged with A. hydrophila, the cumulative survival percentages were 53.3% (p = 0.215), 70.0 % (p = 0.009), and 76.7% (p = 0.002) in fish fed 100, 200, and 400 mg/kg diets, respectively, compared to 36.7% survival in control fish (p = 0.134). These data show that the eight-week dietary administration of P. australis extract to common carp can enhance growth performance, digestive enzyme activity, immune response, and disease resistance to A. hydrophila infection.

A Bioactive Substance Derived from Brown Seaweeds: Phlorotannins

Phlorotannins are a type of natural active substance extracted from brown algae, which belong to a type of important plant polyphenol. Phloroglucinol is the basic unit in its structure. Phlorotannins have a wide range of biological activities, such as antioxidant, antibacterial, antiviral, anti-tumor, anti-hypertensive, hypoglycemic, whitening, anti-allergic and anti-inflammatory, etc. Phlorotannins are mainly used in the fields of medicine, food and cosmetics. This paper reviews the research progress of extraction, separation technology and biological activity of phlorotannins, which will help the scientific community investigate the greater biological significance of phlorotannins.

Novel Active Food Packaging Films Based on Gelatin-Sodium Alginate Containing Beetroot Peel Extract

Currently, the exploration of natural colorants from vegetal waste has gained particular attention. Furthermore, incorporation of these natural sources into biopolymers is an encouraging environmentally friendly approach to establishing active films with biological activities for food packaging. The present study developed bioactive antioxidant films based on gelatin-sodium alginate (NaAlg) incorporated with aqueous beetroot peel extract (BPE). Firstly, the effects of combining gelatin-NaAlg and BPE at 0.25, 0.5, and 1% on the mechanical, physical, antioxidant, and antibacterial properties of the films were analyzed. With increasing BPE, mechanico-physical properties and antioxidant and anti-foodborne pathogen capacities were enhanced. Likewise, when added to gelatin-NaAlg films, BPE remarkably increased the instrumental color properties. Moreover, during 14 days of storage at 4 °C, the impact of gelatin-NaAlg coating impregnated with BPE on microbial and chemical oxidation and on the sensory characteristics of beef meat samples was periodically assessed. Interestingly, by the end of the storage, BPE at 1% limited the microbial deterioration, enhanced the instrumental color, delayed chemical oxidation, and improved sensory traits. By practicing chemometrics tools (principal component analysis and heat maps), all data provided valuable information for categorizing all samples regarding microbiological and oxidative properties, sensory features, and instrumental color. Our findings revealed the ability of gelatin-NaAlg with BPE as an antioxidant to be employed as food packaging for meat preservation.

Effects of sulfated polysaccharides from Laminaria japonica on regularating the gut microbiotan and alleviating intestinal inflammation in obese mice

Due to their known health-enhancing properties, Laminaria japonica polysaccharides (LJP) may alleviate obesity via unknown mechanisms. This study aimed to investigate beneficial LJP effects and mechanism(s) of action using an animal obesity model (ICR mice fed a high-fat diet). First, LJP were confirmed to consist of sulfated polysaccharides via infrared spectroscopy. Next, LJP administration to mice was found to induce weight loss, reduce liver fat accumulation, and support healthy obesity-related blood serum indicator levels. Notably, LJP treatment significantly reduced TC and LDL levels and significantly increased HDL, LPL, UCP-2, and PPAR-α levels. Furthermore, examinations of tissues of LJP-treated mice revealed significantly reduced intestinal tissue inflammation as compared to corresponding results obtained for untreated obese controls. Additionally, LJP treatment relieved colonic shortening and reduced colonic levels of inflammatory factors TNF-α and IL-6. Further exploration of LJP treatment effects on mouse gut microbiota conducted via fecal 16S rRNA gene sequence-based gut microbiome profiling analysis revealed that LJP treatment increased the Bacteroidetes/Firmicutes ratio and increased gut abundances of probiotics Bacteroides acidifaciens, s_Lactobacillus intestinalis, and s_Lactobacillus murinus. In conclusion, these results collectively suggest that LJP use as a food supplement may alleviate obesity and related gut microbiota dysbiosis and intestinal inflammatory disorders.

Research Progress on the Protective Effect of Brown Algae-Derived Polysaccharides on Metabolic Diseases and Intestinal Barrier Injury

In the human body, the intestine is the largest digestive and immune organ, where nutrients are digested and absorbed, and this organ plays a key role in host immunity. In recent years, intestinal health issues have gained attention and many studies have shown that oxidative stress, inflammation, intestinal barrier damage, and an imbalance of intestinal microbiota may cause a range of intestinal diseases, as well as other problems. Brown algae polysaccharides, mainly including alginate, fucoidan, and laminaran, are food-derived natural products that have received wide attention from scholars owing to their good biological activity and low toxic side effects. It has been found that brown algae polysaccharides can repair intestinal physical, chemical, immune and biological barrier damage. Principally, this review describes the protective effects and mechanisms of brown algae-derived polysaccharides on intestinal health, as indicated by the ability of polysaccharides to maintain intestinal barrier integrity, inhibit lipid peroxidation-associated damage, and suppress inflammatory cytokines. Furthermore, our review aims to provide new ideas on the prevention and treatment of intestinal diseases and act as a reference for the development of fucoidan as a functional product for intestinal protection.

The potential mechanisms of Macrocystis pyrifera polysaccharides mitigating type 2 diabetes in rats

Our previous studies have proved that the anti-digestive polysaccharide from Macrocystis pyrifera possesses potential hypoglycemic and lipid-lowering activities; however, its potential mechanisms for improving diabetes have not been elucidated. The current study was aimed to determine the anti-diabetic effects and possible mechanisms of Macrocystis pyrifera polysaccharides (MPP) in diabetic rats. After 8-week MPP treatment, the serum profiles, gut bacteria composition and relative gene expressions of rats were determined. MPP administration effectively ameliorated the diabetic symptoms, dyslipidemia, liver and kidney damage, oxidative stress and chronic inflammation in diabetic rats. In addition, MPP treatment could also notably improve the microbial dysbiosis by increasing the beneficial bacteria and decreasing a bacterial pathogen in the diabetic rats. The RT-qPCR analysis indicated that MPP intervention significantly up-regulated the IRS/PI3K/AKT signaling pathway and down-regulated the relative expressions of glucose-6-phosphatase (G-6-Pase), phosphoenolpyruvate carboxykinase (PEPCK), acetyl-CoA carboxylase (ACC), hydroxymethylglutaryl CoA reductase (HMGCR) and sterol regulatory element binding protein 1c (SREBP-1c) in diabetic rats. These results demonstrated that MPP had the potential to be exploited as functional foods or pharmaceutical supplements for preventing and treating diabetes.

Bioactive Potential of Brown Algae

Marine-derived natural products are rich source of secondary metabolites with huge potentials including novel therapeutic agents. Marine algae are considered to be a good source of secondary metabolites with versatile bioactivities. During the last few decades, researches related to natural products obtained from brown algae have remarkably escalated as they contain active compounds with varied biologically activities like antimicrobial, anticancer, antioxidant, anti-inflammatory, antidiabetic, and antiparasitic properties. The main bioactive components such as phlorotannin, fucoxanthin, alginic acid, fucoidan, and laminarin have been briefly discussed here, together with their composition and biological activities. In this review, the biological function of extracts and the metabolites of brown algae as well as their pharmacological impacts with the description of the possible mechanism of their action are described and discussed. Also, this study is expected to examine the multifunctional properties of brown algae that facilitate natural algal products, including the ability to integrate these functional properties in a variety of applications.

The interactive effects of exercise training and functional feeds on the cardiovascular performance of rainbow trout (Oncorhynchus mykiss) at high temperatures

The cardiovascular performance of salmonids in aquaculture can be impaired by acute climate warming, posing risks for fish survival. Exercise training and functional feeds have been shown to be cardioprotective in mammals but their action on the fish heart and its upper thermal performance has not been studied. To investigate this, rainbow trout were trained at a moderate water velocity of 1 body length per second (bl s⁻¹) for 6 h per day, either alone or in combination with one of two functional feed-supplements, allicin and fucoidan. After 6 weeks of exercise training and feeding, maximum heart rate and the temperature coefficient of heart rate were significantly higher in the trained fish as compared to untrained ones. There was a slight increase in hematocrit in trained control fish reared on a normal diet (TC group) compared to untrained fish fed with the same diet (CC). This implies that exercise training enhanced oxygen delivery to trout tissues via an increase of cardiac blood flow in warm water. However, cardiac thermal tolerance was not affected by exercise training or feeding, except from the temperature of peak heart rate which was higher in the trained group fed with fucoidan supplement (TF) as compared to the untrained group fed with same diet (CF). Allicin supplement caused a significant reduction in the maximum heart rate and the temperature coefficient of heart rate, especially in trained fish, while fucoidan supplement did not cause any effect on heart rate. No differences were observed in growth performance among groups. However, fish fed with fucoidan-supplemented diet had a slight reduction in feed conversion efficiency. We suggest further investigations to understand the antagonistic effect of allicin supplemental feeding and exercise training on cardiovascular performance. More studies are also required to investigate if other exercise training intensities could increase cardiac thermal tolerance.

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Exercise training at 1 bl s⁻¹ increased the hematocrit values of rainbow trout.

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Exercise training at 1 bl s⁻¹ increased the maximum heart rate and temperature coefficient of rainbow trout.

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Exercise training at 1bl s⁻¹ did not enhance the cardiac thermal tolerance of rainbow trout.

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Functional feeds, allicin and fucoidan, did not improve the cardiovascular system of rainbow trout at high temperatures.

Macrocystis pyrifera Extract Residual as Nutrient Source for the Production of Sophorolipids Compounds by Marine Yeast Rhodotorula rubra

Seaweed processing generates liquid fraction residual that could be used as a low-cost nutrient source for microbial production of metabolites. The Rhodotorula strain is able to produce antimicrobial compounds known as sophorolipids. Our aim was to evaluate sophorolipid production, with antibacterial activity, by marine Rhodotorula rubra using liquid fraction residual (LFR) from the brown seaweed Macrocystis pyrifera as the nutrient source. LFR having a composition of 32% w/w carbohydrate, 1% w/w lipids, 15% w/w protein and 52% w/w ash. The best culture condition for sophorolipid production was LFR 40% v/v, without yeast extract, artificial seawater 80% v/v at 15 °C by 3 growth days, with the antibacterial activity of 24.4 ± 3.1 % on Escherichia coli and 21.1 ± 3.8 % on Staphylococcus aureus. It was possible to identify mono-acetylated acidic and methyl ester acidic sophorolipid. These compounds possess potential as pathogen controllers for application in the food industry.