Laminaria Japonica Research Articles

Laminaria japonica polysaccharide prevents high-fat-diet-induced insulin resistance in mice via regulating gut microbiota.

Insulin resistance has become a worldwide nutrition and metabolic health problem due to the lack of effective protective agents. Laminaria japonica is a well-known marine vegetable. Purified Laminaria japonica polysaccharide (LJP61A) can inhibit atherosclerosis in high-fat-diet (HFD)-fed mice via ameliorating insulin resistance. In this study, we aimed to clarify the mechanism by which LJP61A ameliorates HFD-induced insulin resistance. The results indicated that HFD-induced insulin resistance, obesity, systematic inflammation, metabolic endotoxemia, and gut permeability in mice could be reduced by LJP61A. Gut microbiota analysis showed that the gut microbiota dysbiosis of HFD-fed mice, especially the reduction in mucin-degrading Akkermansia, could be reversed by LJP61A. Additionally, the reduction in mucin-producing goblet cells in HFD-fed mice could also be reversed by LJP61A. Moreover, insulin resistance, obesity, systematic inflammation, metabolic endotoxemia, and gut microbiota dysbiosis in HFD-fed mice could also be alleviated by faecal transplant from LJP61A-treated mice. Overall, LJP61A might be used as a prebiotic to ameliorate HFD-induced insulin resistance and associated metabolic disorders via regulating gut microbiota, especially Akkermansia.

Разработка функциональных композиций сухих концентратов морепродуктов и исследование их свойств

Introduction. Nutrition has a significant impact on human health, performance, well-being, and lifespan. The research objective was to develop formulations for functional compositions of seafood cryoconcentrates.
 Study objects and methods. The study featured concentrates obtained by cryotechnology from carcasses of Pacific squid (Todarodes pacificus), muscular shell of cucumaria (Cucumaria japonica), scallop mantle (Mizuhopecten yessoensis), octopus skin (Octopus dofleini), milt of Pacific herring (Pacific herring), and Japanese kelp (Laminaria japonica), as well as their multicomponent mixes. The content of biologically active substances was determined by the spectrophotometric method. The safety and biological value were biotested on Tetrahymena pyriformis.
 Results and discussion. The dry seafood concentrates had a high content of protein, minerals, and biologically active components, i.e. hexosamines, triterpene glycosides, carotenoids, nucleic acids, etc. The seafood cryoconcentrate mixes were divided into fortifying, restoring, immunomodulating, and mineral. Their chemical composition varied greatly, depending on the functional aim of the mix. For instance, the protein content varied from 28.8 to 57.6%, lipids – from 3.1 to 6.9%, carbohydrates – from 15.0 to 35.9%, minerals – from 10.9 to 22.9%, and hexosamines – from 2.2 to 5.6%. The experiments made it possible to substantiate the composition of the dry mixes. The compilation principle was based on the chemical profile of the raw material, as well as on the choice of biologically active substances. All the dry seafood concentrates showed a high relative biological value. However, the values differed, depending on the type of raw material: from 65.5% for the scallop mantle sample to 86.3% for the octopus skin sample. The difference could be explained by the chemical composition of the cryopowders and their availability to ciliate enzymes. 
 Conclusion. The research resulted in formulations and functional mixes of dry seafood concentrates obtained by cryotechnology. The dry seafood concentrates can be used both independently and as functional compositions. The developed mixes demonstrated rather high content of animal proteins, minerals, and biologically active substance, e.g. hexosamines, triterpene glycosides, carotenoids, nucleic acids, etc. Their functional compositions proved to have excellent sensory properties; they are biologically safe for human consumption and have a high relative biological value.

Application of near-infrared spectroscopy and chemometrics for the rapid quality assessment of Sargassum fusiforme

Abstract Edible marine algae, often referred to as sea vegetables, have attracted considerable attention as potential sources of nutrients and health-benefitting components. Quality assessment of sea vegetables is important for identifying commodity grades and ensuring nutritional and health effects. However, the conventional analytical methods to assess the quality of food are costly, time consuming, laborious, and destructive. Thus, in the present study, a simple, fast, and eco-friendly methodology of near-infrared (NIR) spectroscopy was investigated for its ability in the quality evaluation of a sea vegetable, namely, Sargassum fusiforme. To determine the contents of quality parameters (viz. mannitol, polysaccharide, fucosterol, and fucoxanthin) in S. fusiforme, a potential combined CARS-SVM model based on competitive adaptive reweighted sampling (CARS) and support vector machine (SVM) was proposed. The comparison between CARS-SVM and other partial least squares (PLS) models indicated that the wavelength selection method (CARS) and nonlinear regression tool (SVM) could significantly enhance model performance. Among the three types of calibration models (Full-PLS, CARS-PLS, CARS-SVM), CARS-SVM models obtained the best results in prediction of an independent test set. The coefficient of determination (Rp2) and root mean square error (RMSEP) for the prediction set were 0.81 and 3.87 g kg−1 for mannitol, 0.86 and 15.94 g kg−1 for polysaccharide, 0.84 and 0.14 g kg−1 for fucosterol, and 0.78 and 1.76 × 10−2 g kg−1 for fucoxanthin. Overall, NIR spectroscopy coupled with CARS-SVM model was demonstrated to be a potential alternative to the quality assessment of S. fusiforme. These results could provide a valuable reference for the quality assessment of other sea vegetables, such as Porphyratenera, Undariapinnatifida, and Laminaria japonica.

Fucoidan mitigated diabetic nephropathy through the downregulation of PKC and modulation of NF-κB signaling pathway: in vitro and in vivo investigations.

The persistence of hyperglycemia and oxidative stress in diabetic patients ultimately leads to diabetic nephropathy (DN). In this study, we investigated the effect of sulfated polysaccharides (SPS) extracted from Laminaria japonica in relieving DN symptoms. To induce the diabetic model, normal rats were kept on a high-sugar, high-fat diet, then they were injected with streptozocin. Groups of these rats were later treated with SPS and/or protein kinase C (PKC) inhibitor. The analyses performed herein demonstrate that although diabetes significantly decreases the body weights of rats, SPS and inhibitor treatments increase these weights, as well as the ratios of renal to total body weight. Serum biochemical analyses indicate that blood urea nitrogen and serum creatinine levels gradually decrease in the SPS group. In addition, DN symptoms are substantially relieved by SPS and/or inhibitor treatments, as evidenced by histopathological analyses. Changes in the expressions of PKC-α, PKC-β, P-selectin, nuclear factor kappa B (NF-κB), and p65, detected by immunohistochemistry and western blot assessments, show that SPS regulates diabetic nephropathy via the PKC/NF-κB pathway.

Laminaria japonica as a part of feed mixtures for broilers of Arbor Aykres cross

Laminaria japonica as a part of feed mixtures for broilers of Arbor Aykres cross

Effects of dietary n‐3 LC‐PUFA on the growth performance, gonad development, fatty acid profile, transcription of related genes and intestinal microflora in adult sea urchin ( Strongylocentrotus intermedius )

A study was conducted to investigate the effects of dietary n-3 LC-PUFA on the growth performance, fatty acid profile, transcription of related genes and intestinal microflora in adult sea urchin (Strongylocentrotus intermedius). Kelp (Laminaria japonica) and four formulated feeds with graded levels of n-3 LC-PUFA (0%, 0.5%, 0.8% and 1.0% dry diet) were prepared as the experimental diets. Each diet was randomly allocated to ten adult sea urchin individuals. The feeding period lasted for 90 days. Results showed that gonadosomatic index (GSI) of adult S. intermedius fed formulated feeds was significantly higher than that fed kelp (p < 0.05), while weight gain rate (WGR) showed no significance between kelp and feed groups (p > 0.05). Neither WGR nor GSI showed significant differences among the four feed treatments (p > 0.05). Notably, ARA and EPA in the gonads of S. intermedius fed the feeds devoid of n-3 LC-PUFA were comparable to that fed the feeds with 0.5% n-3 LC-PUFA (p > 0.05). Transcription of Elovl4 and Δ5-desaturase in the intestine and gonad significantly decreased as dietary n-3 LC-PUFA increased (p < 0.05). Proteobacteria and Bacteroidetes (phylum level) and Psychromonas and Sulfurimonas (genus level) were the most abundant bacteria species in the intestine of S. intermedius. The abundance of Sulfurimonas was comparable in the S. intermedius fed kelp and the feed with 0% n-3 LC-PUFA, which was significantly higher than that fed the other formulated feeds (p < 0.05). These results indicated that S. intermedius seems to have a low requirement for n-3 LC-PUFA to sustain its normal growth and gonad development. The increased transcription of rate-limiting enzymes (Elovl4 and Δ5-desaturase) could be responsible for the considerable amounts of EPA and ARA in the gonads of S. intermedius when fed feeds without LC-PUFA. The intestinal microflora were affected to a certain extent by the die categories and the n-3 LC-PUFA in the formulated feeds. It is speculated that some unknown bacteria in the genus of Sulfurimonas could participate in the synthesis of LC-PUFA.

Physical Stress Induced Reduction of Proliferating Cells and Differentiated Neuroblasts Is Ameliorated by Fermented Laminaria japonica Extract Treatment.

Laminaria japonica is widely cultivated in East Asia, including South Korea. Fucoidan, a main component of L. japonica, protects neurons from neurological disorders such as ischemia and traumatic brain injury. In the present study, we examined the effects of extract from fermented L. japonica on the reduction of proliferating cells and neuroblasts in mice that were physically (with electric food shock) or psychologically (with visual, auditory and olfactory sensation) stressed with the help of a communication box. Vehicle (distilled water) or fermented L. japonica extract (50 mg/kg) were orally administered to the mice once a day for 21 days. On the 19th day of the treatment, physical and psychological stress was induced by foot shock using a communication box and thereafter for three days. Plasma corticosterone levels were significantly increased after exposure to physical stress and decreased Ki67 positive proliferating cells and doublecortin immunoreactive neuroblasts. In addition, western blot analysis demonstrated that physical stress as well as psychological stress decreased the expression levels of brain-derived neurotrophic factor (BDNF) and the number of phosphorylated cAMP response element binding protein (pCREB) positive nuclei in the dentate gyrus. Fermentation of L. japonica extract significantly increased the contents of reduced sugar and phenolic compounds. Supplementation with fermented L. japonica extract significantly ameliorated the increases of plasma corticosterone revels and decline in the proliferating cells, neuroblasts, and expression of BDNF and pCREB in the physically stressed mice. These results indicate that fermented L. japonica extract has positive effects in ameliorating the physical stress induced reduction in neurogenesis by modulating BDNF and pCREB expression in the dentate gyrus.

Brown Algal Model Organisms.

Model organisms are extensively used in research as accessible and convenient systems for studying a particular area or question in biology. Traditionally, only a limited number of organisms have been studied in detail, but modern genomic tools are enabling researchers to extend beyond the set of classical model organisms to include novel species from less-studied phylogenetic groups. This review focuses on model species for an important group of multicellular organisms, the brown algae. The development of genetic and genomic tools for the filamentous brown alga Ectocarpus has led to it emerging as a general model system for this group, but additional models, such as Fucus or Dictyota dichotoma, remain of interest for specific biological questions. In addition, Saccharina japonica has emerged as a model system to directly address applied questions related to algal aquaculture. We discuss the past, present, and future of brown algal model organisms in relation to the opportunities and challenges in brown algal research.

Combined protective effects of oligo-fucoidan, fucoxanthin, and L-carnitine on the kidneys of chronic kidney disease mice

Chronic kidney disease (CKD) is a common global progressive disease, but there are no ideal drugs for the treatment. Fucoidan and fucoxanthin, and L-carnitine are one of the very few natural products that have a therapeutic effect on CKD in animal experiments. However, the combined effects of these compounds on CKD are unknown. We established a mouse CKD model by right nephrectomy with transient ischemic injury to the left kidney. Oligo-fucoidan and fucoidan were extracted from Laminaria japonica. We fed CKD mice with the two compounds and L-carnitine to evaluate the combined effects on CKD. Oligo-fucoidan and fucoidan inhibited renal fibrosis and reduced serum creatine in CKD mice to a greater extent than any single compound. L-carnitine had no measurable effect on renal fibrosis but promoted the protective effect of the mixture of oligo-fucoidan and fucoidan on renal function in CKD mice. In the two-month safety test, the combined mixture further improved renal function and did not elevate serum aspartate aminotransferase and alanine aminotransferase levels in CKD mice. Furthermore, the weights of CKD mice treated with the combination increased to the normal level. We also found that all oligo-fucoidan, fucoxanthin, and L-carnitine inhibit H2O2-induced apoptosis and activated Akt in rat renal tubular cells. Our results confirm that oligo-fucoidan, fucoxanthin, and L-carnitine have a combined protective effect on the kidneys. The combined mixture may be beneficial for CKD patients.

Low Molecular Weight Fucoidan from Saccharina Japonica Ameliorates the Antioxidant Capacity and Reduces Plaque Areas in Aorta in Apoe-Deficient Mice with Atherosclerosis

Low molecular weight fucoidan (LMWF) extracted from Saccharina japonica exhibits many biological activities including immune regulation and inhibition of tumor angiogenesis, but little research has been done for its antioxidant effect in atherosclerosis (AS). In this study, AS modeling was successfully conducted in ApoE-/- mice by feeding atherogenic diet to animals. The antioxidant activity of LMWF was verified by determining its superoxide anion radical scavenging ability and hydroxyl radical scavenging ability. LMWF significantly increased the antioxidant capacity of AS mice, this conclusion being confirmed by total antioxidant capacity (T-AOC) assay. Test results confirmed that LMWF can enhance T-AOC by reducing reactive oxygen species (ROS) and oxidized low density lipoprotein (ox-LDL) levels and increasing glutathione peroxidase (GSH-Px) level in myocardium and liver tissues of AS mice. The results showed that LMWF and probucol had comparable antioxidant effects on AS, and when combined, no further antioxidant effect was achieved.

Production of polyhydroxyalkanoates and carotenoids through cultivation of different bacterial strains using brown algae hydrolysate as a carbon source

Abstract Laminaria japonica biomass was investigated as an untapped carbon source for polyhydroxyalkanoates (PHA) accumulation via batch and fed-batch cultivation of three different bacterial strains including Cupriavidus necator NCIMB 11599, Paracoccus sp. LL1, and Bacillus megaterium ALA2. Algal biomass (10% (w/v)) was treated with different sulfuric and hydrochloric acid concentrations (0.1, 0.15, 0.2, and 0.3 N). Increasing acid concentration led to a significant increase in reducing sugar production, giving rise to a maximum production of 6.1 and 5.9 g/L for H2SO4 and HCl pretreatment, respectively. Shake flask culture revealed that C. necator, Paracoccus sp. LL1, and B. megaterium ALA2 were able to produce PHA up to 19–32% of their dry cell weight (DCW) under 2% of reducing sugar supplementation. Overall, C. necator showed the highest level of PHA accumulation (1.58 g/L, 32% of DCW). By batch and fed-batch culture, PHA content was enhanced to 44 and 49%, respectively. Along with PHA, Paracoccus sp. LL1 was able to produce 0.9 mg/L of carotenoids after 96 h of cultivation in flask culture. Carotenoid production was enhanced by batch and fed-batch culture to 1.45 and 2.3 mg/L, respectively. Based on Fourier transform infrared spectroscopy, gas chromatography, and 1H nuclear magnetic resonance spectroscopy, the produced PHA polymers were identified as poly(3-hydroxybutyrate) or poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

Cellulose nanocrystal effects on the biodegradability with alginate and crude seaweed extract nanocomposite films

Degradability of alginate and crude seaweed extract bionanocomposite films were used to study the effect of cellulose nanocrystals (CNC) on biodegradation. CNC were successfully isolated from brown seaweeds, kombu (Laminaria japonica) and sargassum (Sargassum natans). Degradability was measured using weight loss with an indoor soil burial and lake water immersion tests for 35 days each. With the addition of CNC, alginate nanocomposite films showed lower weight lost than pure alginate films with 13.6% in soil burial and 19.9% in lake water immersion which indicated higher stability. In the case of kombu and sargassum films, stability of films increased 9.3 and 11.9% in soil burial and lake water immersion with CNC, respectively. Morphological observations with scanning electron microscopy showed wrinkles, pores, and cracks of the films after soil burial and lake water immersion. Chemical structure analysis showed that the molecular interactions in the polymer matrix diminished after the degradation tests. Thermogravimetric analysis was used to determine the thermal stabilities of nanocomposite films. The study showed that the alginate and crude seaweed extract bionanocomposite films reinforced with CNC can increase the polymer matrix interactions which led to higher stability in soil burial and lake water immersion tests.

Galactofucan from Laminaria japonica is not degraded by the human digestive system but inhibits pancreatic lipase and modifies the intestinal microbiota

The effects of galactofucan from Laminaria japonica on the digestion and intestinal microbiota of human were investigated in the present study. Crude fraction of the sulfated polysaccharide from L. japonica (CF) and its molecular-weight homogeneous fraction (CGF-3) were prepared and characterized. In the simulated digestion model for the human saliva and gastrointestinal tract, no obvious changes in the molecular weight or the reducing sugar content of CGF-3 were observed, indicating CGF-3 is resistant to the human digestive system. Then CGF-3 did not affect the α-amylase activity while it dose-dependently inhibited the activity of pancreatic lipase partly depending on its sulfate groups. In the in vitro fermentation with the human fecal microbiota, CF did not change the total carbohydrate, reducing sugar and short chain fatty acids contents, which indicated CF was not utilized by the microbiota. However, the microbiota composition was modulated greatly by CF intervention. These findings shed a light on the better understanding of the impacts of dietary galactofucan on the digestion and intestinal microbiota.

Ecofriendly conversion of algal waste into valuable plant growth-promoting rhizobacteria (PGPR) biomass

With the development of marine biorefinery concept, utilisation of algal waste during industrial processing as well as some “green tide” waste biomass has become an important research topic. In this work, a single-step microwave process was used to hydrolyse Laminaria japonica processing waste (LJW) and Enteromorpha prolifera (EP), producing a growth medium suitable for microbial cultivation. The medium contained a range of mono- and polysaccharides as well as macro- and micronutrients that could be used by the microbes. The cultivation behavior of three plant growth-promoting rhizobacteria (PGPR) strains (Bacillus subtilis strain Tpb55, Bacillus amyloliquefaciens strain Cas02, and Burkholderia pyrrocinia strain Lyc2) in the two media were investigated. LJW hydrolysate from 180 °C and EP hydrolysate from 150 °C performed better cultivation efficiency than those hydrolysates from other microwave conditions. Saccharide analysis showed that microbes metabolized some monosaccharide such as glucose, mannose during cultivation, leaving polysaccharide unused in the medium. Furthermore, hydrolysate-strain cultivation mixtures were applied to pepper growth. The EP hydrolysate-Cas02 broth showed better plant growth-promoting effect compared to other treatments, which might be attributed to the higher indole-3-acetic acid (IAA) production of Cas02 in the EP hydrolysate. This work shed lights on the conversion of algal waste to PGPR biomass as well as the co-application of algal hydrolysates- strains cultivation broth for a better plant growth promotion.

The effects of temperature and irradiance on the photosynthesis of two heteromorphic life history stages of Saccharina japonica (Laminariales) from Japan

This study examined the effects of temperature and irradiance on photosynthetic characteristics of the macroscopic sporophyte (SPO) and microscopic gametophyte (GAM) stages of a subarctic brown alga, Saccharina japonica var. japonica (Laminariales) from Hokkaido, Japan. In vitro measurements under short- and long-term exposures were carried out by using optical dissolved oxygen sensors and the pulse amplitude modulation (PAM)-chlorophyll fluorometer, respectively. The heteromorphic life history stages of S. japonica showed photosynthetic optima at 23–23.3 °C, derived from the gross photosynthesis–temperature model. Maximum quantum yields (Fv/Fm) of SPO and GAM after 72 h of temperature exposures in the dark were reduced to near zero above 24 °C, indicating PSII inactivation. Such similarity in their temperature characteristics suggests the co-occurrence of both generations in the habitat despite the seasonal growth and reproduction of the species. Net photosynthesis–irradiance experiments in the two life history stages at 8, 16, and 24 °C revealed similarity in their light-saturated photosynthetic rates (NPmax = 3.02–4.41 μg O2 gww−1 min−1, SPO; 2.87–3.73 μg O2 gww−1 min−1, GAM), but saturation irradiances of SPO (Ek = 81–102 μmol photons m−2 s−1) were higher than those of GAM (48–69 μmol photons m−2 s−1). A slight decrease in net photosynthetic rates of GAM above 500 μmol photons m−2 s−1 was likewise observed. This difference may be related to the light regime of their natural habitat, suggesting the low irradiance adaptation of the microscopic stage that settles on rock crevices beneath algal canopies.

미세먼지로 유도된 기관지염증에 다시마가 함유된 복합물의 효과

미세먼지로 유도된 기관지염증에 다시마가 함유된 복합물의 효과

Laminaria japonica Suppresses the Atopic Dermatitis-Like Responses in NC/Nga Mice and Inflamed HaCaT Keratinocytes via the Downregulation of STAT1.

Atopic dermatitis (AD) is a skin allergy accompanied by acute and chronic dermal inflammation. In traditional oriental medicine, Laminaria japonica has been used to treat various diseases, including inflammatory diseases. Therefore, to determine the therapeutic potential of L. japonica against AD, we investigated the inhibitory effects of L. japonica water extract (LJWE) on the inflammatory mediators and AD-like skin lesions. We determined the cell viability of LJWE-treated HaCaT cells using the cell counting kit-8 assay and the levels of inflammatory cytokines using cytometric bead array kits. Additionally, we analyzed the modulatory effects of LJWE on the signaling pathways in tumor necrosis factor-α/interferon-γ-stimulated HaCaT cells via Western blotting. Furthermore, we determined the in vivo effect of LJWE on NC/Nga mice and found that LJWE remarkably improved the skin moisture, reduced dermatitis severity, and inhibited the overproduction of inflammatory mediators in 2,4-dinitrochlorobenzene-sensitized NC/Nga mice. We also observed that LJWE inhibits the expression of inflammatory chemokines in human keratinocytes by downregulating the p38 mitogen-activated protein kinase signaling pathway and activating the signal transducer and activator of transcription 1. In conclusion, LJWE has the therapeutic potential against AD by healing AD-like skin lesions, and suppressing inflammatory mediators and major signaling molecules.

Plants as the basis for the development of environmentally friendly highly functional bioadditives for animals (review)

Presently, the use of plant components with antimicrobial, antiviral, antioxidant, anti-inflammatory, hepatoprotective and immunomodulatory effects is of particular interest for the preparation of biologically active additives in animal husbandry. Of great biological value as components of herbal supplements are Japanese kelp (Laminaria japonica) and spotted milk thistle (Silybum marianum (L). Gaertn), a wide range of biological action of which is due to the rich chemical composition. The uniqueness of spotted milk thistle lies in the content of silymarin − flavolignan with pronounced hepatoprotective properties, used throughout the world for the manufacture of medicines with a pronounced hepatoprotective effect. Another feature of milk thistle is its rich macro- and microelement composition, which, among other things, includes such a rare essential element as selenium (22.90 mg per 1 g of seeds), the deficiency of which in food and feed leads to the development of endemic microelementoses in humans and animals. The biological feature of Japanese laminaria is the presence in its composition of alginic acid, its salts, mannitol, laminarin and fucoidan, which have immunomodulating, antimicrobial, antacid, antiallergic and hemostatic activity, as well as a large number of minerals (26.6-32.9 % by weight of dry matter) and vitamins. Laminaria japonica thallus are rich in organic iodine, the content of which in the extracts amounts to 5.4 mg/g, which is important in the conditions of iodine deficiency, which is present at the most territory of Russia and the world. At the same time, the problem of the use of these plants as dietary supplements for animals is still under study. There is very little data on the effect of each plant on the productivity of farm animals and the quality of their products, and no information about their joint use has been obtained yet.

Culture of benthic diatom Nitzschia sp. with macroalgae carriers and its application as feed of juveniles Stichopus japonicus

Carrier culture is the combination of suspension culture and adherent culture. Carriers could be used to improve the culture efficiency of large-scale culture of adherent benthic diatom. In order to identify a suitable carrier for mass suspension culture of the benthic diatoms Nitzschia sp. powders of seven macroalgae were used as carriers for diatom attachment including Ulva pertusa, degummed Laminaria japonica, Sargassum muticum, Chaetomorpha valida, Zostera marina, Sargassum fusiforme and Sargassum thunbergii. Diatoms could grow on the surface of the suspended carriers and could effectively utilize the nutrients released by the decomposition of these carriers. Among the seven carriers, Ulva pertusa powder was the most effective for Nitzschia culture when comprehensively considering the nutrition of the harvested diatoms and nutrient utilization of the algae carrier by diatoms. The seaweed powder was dried at 80 °C before used as carrier, this process should meet the sterilization requirements for microalgal culture and is easy to implement in the large-scale cultivation of diatoms. Diatoms cultured with carriers were used to feed juveniles Stichopus japonicus with a wet weight of 5.0 ± 2.0 g, as well as diatoms cultured using conventional methods without carriers, and no significant differences were observed between the two kinds of feed. Compared to sea cucumbers fed with commercial feed, the growth rate of S. japonicus fed with carrier-cultured diatoms was approximately 1.5 times greater, and the activities of non-specific immune enzymes were improved in the coelomic fluid including acidic phosphatase, alkaline phosphatase and superoxide dismutase. Feeding sea cucumber with fresh diatoms could effectively reduce the total nitrogen and total phosphorus in the culture water, improve the water quality, and promote the breeding of sea cucumbers, regardless of whether the carrier culture was adopted.

Environmentally persistent free radicals in biochar derived from Laminaria japonica grown in different habitats

Biomass feedstock plays an important role in the formation of environmentally persistent free radicals (EPFRs) in biochars; however, no investigations have been done on the effects of different plant habitats on the formation of EPFRs, especially for algae. Therefore, Laminaria japonica, a large-scale artificially planted marine economic macroalgae, was collected from six different coastal mariculture zones in tropical, subtropical and north-temperate zones from south to north in China. Biochars were obtained at the pyrolysis temperatures of 200−700 °C, and EPFR signs were recorded by an X-band electron paramagnetic resonance (EPR) spectrometer. Temperatures of 300−500 °C were the appropriate for higher levels of spin concentrations, and lower (200 °C) and higher (600−700 °C) temperatures decreased the biochar-bound EPFRs. The types of EPFRs generally belonged to oxygen-centered radicals for biochars produced at 200 and 300 °C, a mixture of carbon- and oxygen-centered radicals for 400 °C biochar, and carbon-centered radicals for 500−700 °C biochars. Different habitats (growth environments) of L. japonica influenced the levels rather than the types of the resulting biochar-bound EPFRs. Pearson correlation analyses showed that biochar-bound EPFRs were significantly positively correlated with the contents of C (p < 0.01) and weakly correlated with the contents of H, N, O and transition elements (Cu, Fe, Mn, Co, Cr, Ni, and Zn) (p > 0.05). Overall, algae biomass-based biochars have the similar levels and types of EPFRs as lignocellulosic-biomass-based biochars, and the different growing habitats of L. japonica grown influence the formation and characteristics of EPFRs in the resulting biochars.