Brown Seaweed Saccharina Japonica Research Articles

Epimicrobiome Shifts With Bleaching Disease Progression in the Brown Seaweed Saccharina japonica

Recent bacterial induced bleaching disease events of the commercially farmed brown seaweed Saccharina japonica has resulted in significant reduction in healthy sporeling supply. However, to date the host associated epimicrobial community shifts with the disease progression have not been characterized. We investigated the dynamic shifts in the composition of the epibacterial communities of S. japonica with disease progression using 16S rRNA gene amplicon sequencing. We found that the alpha diversity was significantly higher in the control group than in the infected group over disease progression (P < 0.01). There was a significant shift in the composition and predicted functions of the epibacterial communities in both control and infected groups. Indicator species, belonging to Stenotrophomonas, Pseudomonas and Sphingomona were significantly higher in the control group than infected group, suggesting that these taxa are associated with healthy S. japonica. In contrast, Vibrio, Pseudoalteromonas and Colwellia were keystone taxa in the infected group at 24 h, and thus maybe considered to be the secondary opportunistic pathogens. Our study describes the changes of epibacterial communities associated with the progression of bleaching disease in S. japonica. This new information not only extends our baseline knowledge of the S. japonica epimicrobiome, but also paves the way for developing measures to mitigate disease outbreaks for the sustainable aquaculture of S. japonica.

Role of alginate in the mechanism by which brown seaweed Saccharina japonica intake alleviates an increase in blood pressure in 2-kidney, 1-clip renovascular hypertensive rats

ABSTRACT Background The intake of Saccharina japonica (SJ), a widely consumed brown seaweed, has been reported to decrease blood pressure (BP) in hypertensive rats. It has been suggested that this effect is related to an increase in fecal sodium excretion (SE) by alginate (Alg) to the gastrointestinal tract; however, the mechanism is still unclear. This study investigated how different seaweeds with different amounts of Alg suppressed BP increase and enhanced fecal SE in 2-kidney, 1-clip renovascular hypertensive (2K1C) rats given SJ diet. Methods Rats with 2K1C or sham operation were fed a normal-/high-salt diet with some kinds of seaweeds (5.0%, w/w) or SJ extract with different Alg contents for 6 weeks. We measured systolic BP every week and mean arterial pressure at the end, and measured the total and molecular weights of Alg in each seaweed. Then, we evaluated the relationship of the Alg amount in each seaweed with the suppression of BP increase in 2K1C rats. Finally, urinary and fecal SE for 24 h was measured. Results The intake of SJ, SJ extract, Saccharina ochotensis (SO) blades and SO roots suppressed BP increase in 2K1C rats, but the strength was not proportional to the amounts of Alg contained in the seaweeds. Although SJ intake increased fecal SE in 2K1C rats fed a high-salt diet, the fecal SE was much less than urinary SE. Conclusion The sodium excretion in feces by Alg in SJ may not be one of the major mechanisms by which SJ intake attenuates hypertension in 2K1C rats.

Isolation and identification of a pathogenic bacterium, Exiguobacterium oxidotolerans XP-2, from the abnormal diseased mature sporophytes of a commercially cultivated brown seaweed Saccharina japonica

Diseases of the commercially cultivated brown seaweed Saccharina japonica have been noticed since the 1960s in China. However, the usually opportunistic nature of the pathogenic bacteria of seaweeds is still a main obstacle for isolating and identifying pathogenic bacteria responsible for causing diseases of the cultivated S. japonica. In this study, a Gram-positive bacterium XP-2 was isolated from the abnormal diseased mature sporophytes of S. japonica. Pathogenicity test indicated that XP-2 could cause green-rotten disease in healthy juvenile sporophytes and significant algal ultrastructural changes were observed after S. japonica was infected by XP-2. The cells shrank, and the thylakoids of the chloroplasts became blurred after 12 h of re-infection. At 24 h slight deformation was observed in the structure of the mitochondria, chloroplasts, and nucleus. There also were many vacuoles in the infected cells. After 31 h of re-infection, mitochondrial structure and thylakoids became more indistinct. SEM and TEM observations indicated that XP-2 was rod-shaped with no flagella. Analysis of the full length 16S rRNA gene sequence and physiological and chemical characteristics indicated that XP-2 was closely related to Exiguobacterium oxidotolerans 12280 T. Based on these results, XP-2 was designated Exiguobacterium oxidotolerans XP-2. The pathogenicity of E. oxidotolerans XP-2 was identified by Koch’s Postulate under laboratory conditions. These results enrich the growing list of pathogenic bacteria in commercially cultivated seaweeds and also provide a foundation for investigating the virulence mechanisms of pathogenic bacteria of commercially cultivated seaweeds in the near future.

Protective Effect of a Fucose-Rich Fucoidan Isolated from Saccharina japonica against Ultraviolet B-Induced Photodamage In Vitro in Human Keratinocytes and In Vivo in Zebrafish.

A fucose-rich fucoidan was purified from brown seaweed Saccharina japonica, of which the UVB protective effect was investigated in vitro in keratinocytes of HaCaT cells and in vivo in zebrafish. The intracellular reactive oxygen species levels and the viability of UVB-irradiated HaCaT cells were determined. The results indicate that the purified fucoidan significantly reduced the intracellular reactive oxygen species levels and improved the viability of UVB-irradiated HaCaT cells. Furthermore, the purified fucoidan remarkably decreased the apoptosis by regulating the expressions of Bax/Bcl-xL and cleaved caspase-3 in UVB-irradiated HaCaT cells in a dose-dependent manner. In addition, the in vivo UV protective effect of the purified fucoidan was investigated using a zebrafish model. It significantly reduced the intracellular reactive oxygen species level, the cell death, the NO production, and the lipid peroxidation in UVB-irradiated zebrafish in a dose-dependent manner. These results suggest that purified fucoidan has a great potential to be developed as a natural anti-UVB agent applied in the cosmetic industry.

Transcriptome sequencing of Saccharina japonica sporophytes during whole developmental periods reveals regulatory networks underlying alginate and mannitol biosynthesis

BackgroundAlginate is an important cell wall component and mannitol is a soluble storage carbon substance in the brown seaweed Saccharina japonica. Their contents vary with kelp developmental periods and harvesting time. Alginate and mannitol regulatory networks and molecular mechanisms are largely unknown.ResultsWith WGCNA and trend analysis of 20,940 known genes and 4264 new genes produced from transcriptome sequencing of 30 kelp samples from different stages and tissues, we deduced that ribosomal proteins, light harvesting complex proteins and “imm upregulated 3” gene family are closely associated with the meristematic growth and kelp maturity. Moreover, 134 and 6 genes directly involved in the alginate and mannitol metabolism were identified, respectively. Mannose-6-phosphate isomerase (MPI2), phosphomannomutase (PMM1), GDP-mannose 6-dehydrogenase (GMD3) and mannuronate C5-epimerase (MC5E70 and MC5E122) are closely related with the high content of alginate in the distal blade. Mannitol accumulation in the basal blade might be ascribed to high expression of mannitol-1-phosphate dehydrogenase (M1PDH1) and mannitol-1-phosphatase (M1Pase) (in biosynthesis direction) and low expression of mannitol-2-dehydrogenase (M2DH) and Fructokinase (FK) (in degradation direction). Oxidative phosphorylation and photosynthesis provide ATP and NADH for mannitol metabolism whereas glycosylated cycle and tricarboxylic acid (TCA) cycle produce GTP for alginate biosynthesis. RNA/protein synthesis and transportation might affect alginate complex polymerization and secretion processes. Cryptochrome (CRY-DASH), xanthophyll cycle, photosynthesis and carbon fixation influence the production of intermediate metabolite of fructose-6-phosphate, contributing to high content of mannitol in the basal blade.ConclusionsThe network of co-responsive DNA synthesis, repair and proteolysis are presumed to be involved in alginate polymerization and secretion, while upstream light-responsive reactions are important for mannitol accumulation in meristem of kelp. Our transcriptome analysis provides new insights into the transcriptional regulatory networks underlying the biosynthesis of alginate and mannitol during S. japonica developments.

Highly crystalline cellulose from brown seaweed Saccharina japonica: isolation, characterization and microcrystallization

Highly crystalline cellulose was isolated from kelp (Saccharina japonica) and used to prepare microcrystalline cellulose (MCC) via an optimized chemical–mechanical approach. The purity of the cellulose reached 99.9% (dry basis) according to HPLC and FT-IR analysis, with extraction yield reaching 9.9% on a dry kelp basis. The kelp cellulose (KC) had a degree of polymerization (DP) of 695, and featured natively highly crystalline structure with a crystallinity index (CrI) as high as 90.9% according to X-ray powder diffraction analysis. The KC was subjected to successive hydrochloric acid treatment and ball-milling to obtain MCC having a DP of 235 and a CrI of 88.6%. The kelp MCC exhibited comparable quality attributes to commercially available MCC. Polymorphic analysis based on peak deconvolution of the diffractograms revealed that the crystalline region of the kelp cellulose featured one-chain triclinic (Iα) rich polymorph, in contrast to two-chain monoclinic (Iβ) dominant structure found in higher-plant cellulose.

Ionic liquid-assisted subcritical water enhances the extraction of phenolics from brown seaweed and its antioxidant activity

Natural phenolic substances have recently been recovered from brown seaweeds using various techniques. Particularly, subcritical water extraction (SWE) has been developed to replace conventional processes because of its sustainable properties. In addition, ionic liquids (IL) have recently been proved to have potential capabilities in extracting bioactive compounds from natural resources. This study explores the power of the IL-assisted SWE method (SWE + IL) in obtaining different phenolic compounds from the brown seaweed Saccharina japonica. The imidazolium-based IL 1-butyl-3-methylimidazolium tetrafluoroborate [C4C1im][BF4] was provided as a catalyst in the SWE system at different temperatures (100–250 °C) and concentrations (0.25–1.00 M) to examine its thermal and quantitative effects. Solid–liquid extraction (SLE) and SWE were additionally provided as references for the considered method. High-performance liquid chromatography analysis of the SWE and SWE + IL extracts showed high contents of gallic, chlorogenic, gentisic, protocatechuic, p-hydroxybenzoic, and caffeic acids along with minor amounts of vanillic and syringic acids. The highest total content of phenolics was determined at 175 °C in two SWE techniques; however, in conventional SLE, phenolic compounds were poorly detected. Various antioxidant-determining assays such as 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assay, total antioxidant capacity assay, and ferric reducing antioxidant power assay indicated the high antioxidant activity of extracting samples from SWE and SWE + IL; however, limited capacity was observed from conventional SLE. Correlation testing and principal component analysis indicated a strong connection between phenolic content and antioxidant activity, thereby demonstrating the high quality of phenolic bioactive extracts from brown seaweeds.

The positive effects of fucoidans extracted from the brown seaweed Saccharina japonica on protection against CCl4-induced liver injury

Fucoidan is a sulphated polysaccharide derived from brown algae that contains a variety of bioactive compounds. The brown alga Saccharina japonica is an abundant bioresource for the commercialization of fucoidan, which has been aquacultured on a large scale in China. To explore the hepatoprotective effect of fucoidans from S. japonica, the seaweeds were extracted using an enzymolysis protocol, and a crude extract (F) was obtained by ethanol precipitation. Then, F was subjected to diethylaminoethyl (DEAE) column chromatography, and three fractions (F1, F2, and F3) were collected. The fundamental characteristics, including the monosaccharide composition and the structural features of F1–F3, were investigated using high-performance liquid chromatography (HPLC), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopy. F1 and F2 were rich in galactose and mannuronic acid, respectively, in addition to containing fucose. F3 mainly consisted of sulphated fucopyranose. All three fractions showed in vitro antioxidative activity against the hydroxyl radical. The hepatoprotective activities of F1–F3 were evaluated. Mice were orally administered fucoidans for 1 week and then intraperitoneally injected with CCl4. Four hepatoprotective indicators were analysed to evaluate the efficacy of the three preparations. A high dose of F3 (300–500 mg kg−1 day−1) caused a significant difference in all four indicators compared to the control without fucoidan; this result was confirmed by histological examination of the mouse liver tissues. These results suggest that fucoidans from S. japonica had potential as ingredients for functional foods or pharmaceuticals to prevent liver injury.

Telomeric localization of the Arabidopsis-type heptamer repeat, (TTTAGGG)n , at the chromosome ends in Saccharina japonica (Phaeophyta).

Telomeres generally consist of short repeats of minisatellite DNA sequences and are useful in chromosome identification and karyotype analysis. To date, telomeres have not been characterized in the economically important brown seaweed Saccharina japonica, thus its full cytogenetic research and genetic breeding potential has not been realized. Herein, the tentative sequence of telomeres in S.japonica was identified by PCR amplification with primers designed based on the Arabidopsis-type telomere sequence (TTTAGGG)n , which was chosen out of three possible telomeric repeat DNA sequences typically present in plants and algae. After PCR optimization and cloning, sequence analysis of the amplified products from S.japonica genomic DNA showed that they were composed of repeat units, (TTTAGGG)n , in which the repeat number ranged from 15 to 63 (n=46). This type of repeat sequence was verified by a Southern blot assay with the Arabidopsis-type telomere sequence as a probe. The digestion of S.japonica genomic DNA with the exonuclease Bal31 illustrated that the target sequence corresponding to the Arabidopsis-type telomere sequence was susceptible to Bal31 digestion, suggesting that the repeat sequence was likely located at the outermost ends of the kelp chromosomes. Fluorescence insitu hybridizations with the aforementioned probe provided the initial cytogenetic evidence that the hybridization signals were principally localized at both ends of S.japonica chromosomes. This study indicates that the telomeric repeat of the kelp chromosomes is (TTTAGGG)n which differs from the previously reported (TTAGGG)n sequence in Ectocarpus siliculosus through genome sequencing, thereby suggesting distinct telomeres in brown seaweeds.

Structural, antioxidant, and emulsifying activities of fucoidan from Saccharina japonica using pressurized liquid extraction

Pressurized liquid extraction (PLE) was utilized to extract sulfated polysaccharides (fucoidan) from brown seaweed Saccharina japonica. Various conditions of temperature (80–200°C), pressure (5–100bar), and solvents (water, 0.1% sodium hydroxide, 0.1% formic acid, 70% ethanol, 50% ethanol, and 25% ethanol) were assessed; the best crude fucoidan (CF) yield was 8.23%, obtained from 140°C and 50bar (sodium hydroxide). Compositional analysis, FT-IR, molecular weight, monosaccharides, TGA, UV–vis, XRD, and elemental analysis confirm that extracted polysaccharides revealed the features of fucoidan. Fucose was the main monosaccharide present in CF obtained by various solvent systems. All CF showed antioxidant activities as measured by DPPH radical and ABTS+ radical scavenging. CF demonstrates good emulsion-stabilizing capacities, especially with vegetable oils. This study demonstrates that PLE is an efficacious method for enhancing the yield of polysaccharides from S. japonica and that it could be a potential source of natural antioxidants and emulsifiers.

Meiobenthos under mariculture conditions of the brown seaweed Saccharina japonica in Rifovaya Bay, Peter the Great Gulf, Sea of Japan

The qualitative and quantitative compositions of free-living marine nematodes were studied in Rifovaya Bay (Peter the Great Gulf, Sea of Japan). It was found that the density distribution of nematode populations in bottom sediments of Rifovaya Bay is nonuniform. In total, 72 nematode species were found, including Oncholaimium paraolium, Viscosia epapilosa, and Monoposthia latiannulata on all types of substrates. The dominant trophic group comprised “predators” (2B) and “scrapers” (2A). It was shown that the species composition of nematodes in Rifovaya Bay is very similar to the species composition of nematodes in the other areas of Peter the Great Gulf.

Effects of hydrozoan colonization on biochemical compositions of the brown seaweed Saccharina japonica

The stoloniferous hydrozoan Obelia geniculata frequently colonizes late harvested blade of the aquacultured brown seaweed Saccharina japonica. To understand harmful effects of the hydrozoans, we measured the tissue viability, proximate compositions, amino acid and fatty acid profiles, and metal contents of healthy blades, colonized blades, and hydrozoans isolated from the seaweed. Hydrozoans contained high amount of zinc (1.7 g/kg dry weight), which is 23% against the provisional tolerable weekly intake, at levels higher than the recommended range in food. In seaweed blades beneath the colony, after the removal of hydrozoans, levels of selenium, iodine, and docosahexaenoic acid increased, while copper, cadmium, nickel, chromium, and erucic acid levels decreased compared to healthy tissues. As evaluated for food or fodder, hydrozoans deteriorate the quality of seaweed, thus the epiphytic hydrozoans must be removed from the seaweed blade prior to its use.

Brown seaweed (Saccharina japonica) as an edible natural delivery matrix for allyl isothiocyanate inhibiting food-borne bacteria

The edible, brown seaweed Saccharina japonica was prepared as powder in the size range 500–900μm for the desorption release of allyl isothiocyanate (AITC). Powders were used as raw (containing lipids) and as de-oiled, where the lipid was removed. In general, de-oiled powders adsorbed larger masses of AITC after vapour or solution contact. Mass adsorbed due to solution contact exceeded vapour contact. Larger particles adsorbed more than smaller particles. No chemical bonding between AITC and the powder surface occurred. Release from vapour deposited particles reached 70–85% available within 72h; solution deposited reached 70–90% available at 192h. The larger amounts of AITC adsorbed via solution deposition resulted in greater vapour-phase concentrations at 72h for antimicrobial activity studies. No loss of activity was detected against Escherichia coli, Salmonella Typhimurium or Bacillus cereus. Only a nominal activity against Staphylococcus aureus was demonstrated. S. japonica powder could be used as an edible, natural vehicle for AITC delivery.

Effect of subcritical water hydrolysate in the brown seaweed Saccharina japonica as a potential antibacterial agent on food-borne pathogens

Seaweeds are rich in bioactive compounds which have well-documented antioxidant properties. They also have antimicrobial activities against food pathogenic microorganisms. This study uses an extract of the brown seaweed, Saccharina (Laminaria) japonica, produced by subcritical water hydrolysis (SWH) for investigating its potential to inhibit bacteria. De-oiled S. japonica was obtained by supercritical carbon dioxide extraction. The reaction temperatures for hydrolysis of raw and de-oiled S. japonica were maintained from 200 to 280 °C. The experiment was done with condition 1.3–6.0 MPa for the reaction pressure and 1:10 (w/v) for the ratio of material to water. The antibacterial activities of raw and de-oiled S. japonica produced by SWH were determined by using the agar diffusion method. Antibacterial activity was tested against two Gram-negative (Escherichia coli and Salmonella typhimurium) and two Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus). The antibacterial activities of hydrolysate water with catalyst at 240 °C showed better bacterial inhibition than the others. Strong antibacterial activity was found using de-oiled material with acetic acid added, with a zone of inhibition of S. typhimurium (14.33 ± 0.06 mm) and E. coli (13.00 ± 0.09 mm). On the other hand, the weakest antibacterial inhibition was found for S. aureus (12.83 ± 0.10 mm) and B. cereus (12.50 ± 0.09 mm).

Localization of a female-specific marker on the chromosomes of the brown seaweed Saccharina japonica using fluorescence in situ hybridization.

BackgroundThere is a heteromorphic alternative life in the brown seaweed, Saccharina japonica (Aresch.) C. E. Lane, C. Mayes et G. W. Saunders ( = Laminaria japonica Aresch.), with macroscopic monoecious sporophytes and microscopic diecious gametophytes. Female gametophytes are genetically different from males. It is very difficult to identify the parent of a sporophyte using only routine cytological techniques due to homomorphic chromosomes. A sex-specific marker is one of the best ways to make this determination.Methodology/Principal FindingsTo obtain clear images, chromosome preparation was improved using maceration enzymes and fluorochrome 4′, 6-diamidino-2-phenylindole (DAPI). The chromosome number of both male and female haploid gametophytes was 31, and there were 62 chromosomes in diploid sporophytes. Although the female chromosomes ranged from 0.77 µm to 2.61 µm in size and were larger than the corresponding ones in the males (from 0.57 µm to 2.16 µm), there was not a very large X chromosome in the females. Based on the known female-related FRML-494 marker, co-electrophoresis and Southern blot profiles demonstrated that it was inheritable and specific to female gametophytes. Using modified fluorescence in situ hybridization (FISH), this marker could be localized on one unique chromosome of the female gametophytes as well as the sporophytes, whereas no hybridization signal was detected in the male gametophytes.Conclusions/SignificanceOur data suggest that this marker was a female chromosome-specific DNA sequence. This is the first report of molecular marker localization on algal chromosomes. This research provides evidence for the benefit of using FISH for identifying molecular markers for sex identification, isolation of specific genes linked to this marker in the females, and sex determination of S. japonica gametophytes in the future.

Sensitivity of spore germination and germ tube elongation of Saccharina japonica to metal exposure.

The sensitivity of early life stages of the brown seaweed Saccharina japonica to six metals (Cd, Cu, Hg, Ni, Pb, Zn) and two waste-water samples were investigated and a new toxicity bioassay developed. The two endpoints used were spore germination and germ tube elongation with an exposure time of 24 h. Optimal test conditions determined for photon irradiance, pH, salinity and temperature were darkness, pH 8, 35‰ and 15°C, respectively. The toxicity ranking of five metals was: Hg (EC(50) of 41 and 42 μg l(-1)) > Cu (120 and 81 μg l(-1)) > Ni (2,009 and 1,360 μg l(-1)) > Zn (3,024 and 3,897 μg l(-1)) > Pb (4,760 and 4,429 μg l(-1)) > Cd (15,052 and 7,541 μg l(-1)) for germination and germ tube elongation, respectively. The sensitivities to Cd, Cu and Ni were greater in germ tube elongation than in germination process. When tested against two different waste-water samples (processed animal and printed circuit board waste-water) values of EC(50) were between 21.29 and 32.02% for germination and between 5.33 and 8.98% for germ tube elongation. Despite differences in their chemical composition, the toxic effects of waste-water samples, as indicated by EC(50) values, did not differ significantly for the same endpoints. The CV range for both germination and germ tube elongation was between 4.61 and 37.69%, indicating high levels of precision of the tests. The results compare favourably with those from more established test procedures employing micro- and macroalgae. The advantages and potential limitations of the bioassay for the assessment of anthropogenic impacts on coastal ecosystems and commercial cultivation areas in near-shore environments are discussed.

00/01635 The development of an ASME performance test code for IGCC plants

Pressurized liquid extraction (PLE) was utilized to extract sulfated polysaccharides (fucoidan) from brown seaweed Saccharina japonica. Various conditions of temperature (80–200 °C), pressure (5–100 bar), and solvents (water, 0.1% sodium hydroxide, 0.1% formic acid, 70% ethanol, 50% ethanol, and 25% ethanol) were assessed; the best crude fucoidan (CF) yield was 8.23%, obtained from 140 °C and 50 bar (sodium hydroxide). Compositional analysis, FT-IR, molecular weight, monosaccharides, TGA, UV–vis, XRD, and elemental analysis confirm that extracted polysaccharides revealed the features of fucoidan. Fucose was the main monosaccharide present in CF obtained by various solvent systems. All CF showed antioxidant activities as measured by DPPH radical and ABTS+ radical scavenging. CF demonstrates good emulsion-stabilizing capacities, especially with vegetable oils. This study demonstrates that PLE is an efficacious method for enhancing the yield of polysaccharides from S. japonica and that it could be a potential source of natural antioxidants and emulsifiers.