The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
Pauli Snoeijs - One of the best experts on this subject based on the ideXlab platform.
-
Long-term changes of macroalgal vegetation in the Skagerrak area
Hydrobiologia, 1998Co-Authors: G. Johansson, B. K. Eriksson, M. Pedersén, Pauli SnoeijsAbstract:The algal vegetation at three rocky-shore localities on the Swedish Skagerrak coast with different environmental conditions was studied in 1960–1961 by SCUBA diving. The same localities were revisited in the summer of 1997, using the same methods for recording the vegetation. Detailed descriptions of the vegetation profiles are presented to allow the recording of future changes in these profiles, and extensive ecological herbaria are kept of both the 1960–1961 and the 1997 investigations. The abundance and depth distribution of 78 macroalgal species were recorded in 1997 and community composition was compared with that of the early 1960's. Increases of perennial red algae with delicate foliaceous thalli (Delesseria sanguinea, Phycodrys rubens) were conspicuous at the two localities most exposed to wave action, whereas perennial red algae with tougher foliaceous thalli (Phyllophora truncata and Phyllophora pseudoceranoides) prevailed at the more sheltered locality with most sedimentation. It is hypothesised that increased abundances of delicate species with a large growth potential are caused by eutrophication, but that this effect may be counteracted when eutrophication results in a high load of sedimentation. Tougher species are designed better to withstand a heavy load of sediment. Other perennial red algae with tougher thalli (Chondrus crispus, Furcellaria lumbricalis) also decreased at the exposed sites, but not at the site with most sedimentation, possibly because of lack of competition from D. sanguinea and P. rubens. The abundance of filamentous algae had increased since the early 1960's at all three localities, which may be attributed to eutrophication as well, but no changes were observed in the large perennial brown algae. Decaying loose-lying algae occurred at all localities, but algal mat formation was only abundant at the most sheltered locality. The observed changes in the attached algal vegetation of the exposed sites may be an indication of a general large-scale eutrophication of the Skagerrak.
-
Long-term changes in the sublittoral zonation of brown algae in the southern Bothnian Sea
European Journal of Phycology, 1998Co-Authors: Britas Klemens Eriksson, Gustav Johansson, Pauli SnoeijsAbstract:The algal vegetation of five diving profiles situated at exposed sites of the outer Oregrund archipelago, southern Bothnian Sea, Sweden, was investigated by SCUBA diving in 1996. The vegetation of the same profiles had been described earlier in 1943-4 and 1984. In the present study, special attention was paid to the occurrence of the structurally important belt-forming brown algae Fucus vesiculosus and Sphacelaria arctica in comparison with the situation 52-53 and 12 years earlier. Prominent differences between the 1940s and 1996 were found. The weighted average depth of the F. vesiculosus belt in 1996 was about 1.7 m shallower than in the 1940s, and the lower distribution limit of this species was about 2.5 m shallower. At its lower end the Fucus belt was replaced by epilithic red algae, mainly Furcellaria lumbricalis, Rhodomela confervoides and Polysiphonia fucoides. These results were similar to those of the 1984 study and show neither an improvement nor a deterioration of the belt during the past 12 years. In four of the five diving profiles, a conspicuous belt of S. arctica occurred in the lower sublittoral, similar to that observed in the 1940s, but in one of the five profiles the S. arctica belt was heavily impoverished. These results contrast with the 1984 study which reported that S. arctica had practically disappeared from all profiles. The epiphytic cover of annual filamentous algae, dominated by Pilayella littoralis and Ceramium gobii, was higher in 1996 than in 1943-4. The results of this comparative study are discussed in relation to the general eutrophication of the Baltic Sea.
-
Long-term changes of macroalgal vegetation in the Skagerrak area. Hydrobiologia 385
1998Co-Authors: G. Johansson, B. K. Eriksson, M. Pedersén, Pauli SnoeijsAbstract:The algal vegetation at three rocky-shore localities on the Swedish Skagerrak coast with different environmental conditions was studied in 1960–1961 by SCUBA diving. The same localities were revisited in the summer of 1997, using the same methods for recording the vegetation. Detailed descriptions of the vegetation profiles are presented to allow the recording of future changes in these profiles, and extensive ecological herbaria are kept of both the 1960–1961 and the 1997 investigations. The abundance and depth distribution of 78 macroalgal species were recorded in 1997 and community composition was compared with that of the early 1960’s. Increases of perennial red algae with delicate foliaceous thalli (Delesseria sanguinea, Phycodrys rubens) were conspicuous at the two localities most exposed to wave action, whereas perennial red algae with tougher foliaceous thalli (Phyllophora truncata and Phyllophora pseudoceranoides) prevailed at the more sheltered locality with most sedimentation. It is hypothesised that increased abundances of delicate species with a large growth potential are caused by eutrophication, but that this effect may be counteracted when eutrophication results in a high load of sedimentation. Tougher species are designed better to withstand a heavy load of sediment. Other perennial red algae with tougher thalli (Chondrus crispus, Furcellaria lumbricalis) also decreased at the exposed sites, but not at the site with most sedimentation, possibly because of lack of competition from D. sanguinea and P. rubens.Th
Rando Tuvikene - One of the best experts on this subject based on the ideXlab platform.
-
spatial variation and structural characteristics of phycobiliproteins from the red algae Furcellaria lumbricalis and coccotylus truncatus
Algal Research-Biomass Biofuels and Bioproducts, 2020Co-Authors: Mihkel Saluri, Tiina Paalme, Margit Kaldmae, Mihkel Rospu, Hannes Sirkel, Michael Landreh, Rando TuvikeneAbstract:Abstract Phycobiliproteins, red phycoerythrins and blue (allo)phycocyanins, are one of the most highly valued components extracted from cyanobacteria and red algae. In the given study, 95 Furcellaria lumbricalis and 92 Coccotylus truncatus samples were collected from different locations and depths from Kassari Bay, Estonia. Firstly, a strong, positive exponential correlation between the R-phycoerythrin and allophycocyanin concentrations and the collection depth (R > 0.75 and R > 0.61, respectively) was found. Secondly, a preparative scale purification was performed, and the proteins were further characterised by spectrophotometry, fluorimetry and native mass spectrometry. The obtained purity indices (A566/A280) for the R-phycoerythrins were 1.6 for F. lumbricalis and 2.6 for C. truncatus, thus making them suitable for cosmetics and food industries. Purified R-phycoerythrins from the two algal species had subtle differences in absorption and fluorescence maxima. Based on their slightly different absorption characteristics, R-phycoerythrin from F. lumbricalis would categorise as type III (RIII-PE) and R-phycoerythrin from C. truncatus, alongside with the Sigma 52412 standard, as type II (RII-PE). The native mass spectrometry analysis supported the results by showing different intact complexes with distinct γ-subunits for the R-phycoerythrin types. The R-phycoerythrin hexamers linked to various γ-subunits, which are in turn coupled to different chromophores, could explain the similarities (analytical standard and C. truncatus) and differences (F. lumbricalis) in absorption and fluorescence characteristics among the tested species.
-
extraction and quantification of phycobiliproteins from the red alga Furcellaria lumbricalis
Algal Research-Biomass Biofuels and Bioproducts, 2019Co-Authors: Mihkel Saluri, Margit Kaldmae, Rando TuvikeneAbstract:Abstract Phycobiliproteins are natural additives in food industry and essential fluorescent probes in biotechnology. Various algal species may be suitable for their extraction, therefore, it is important to study different seaweeds to determine the highest-yielding species. Furcellaria lumbricalis, a red algal species primarily harvested from Canadian, Danish and Estonian waters, has been utilized for merely furcellaran extraction in Estonia on a commercial scale for over 50 years. To further valorize the bioresource it is vital to study whether additional products, such as phycobiliproteins, can be extracted. In the given study, optimal phycobiliprotein extraction conditions from F. lumbricalis were determined for the first time. For quantification, a novel high-pressure liquid chromatography method with fluorescence and photodiode array detection was developed. Considering R-phycoerythrin, citrate pH 6 buffer gave the highest yields (0.13% using fluorescence detector and 0.43% using photodiode array detector) after an extraction for 24 h at 20 °C. Different enzymes (cellulases, xylanases, galactosidases) and their combinations, lowering the extraction temperature or ultrasonication increased the yield further. In addition, red-coloured low-molecular fraction (with similar absorption characteristics to R-phycoerythrin) was separated. For allophycocyanin phosphate pH 6 buffer gave slightly higher yield (0.09% using fluorescence detector and 0.12% using photodiode array detector), compared to citrate or acetate buffer at the same pH. However, the tested enzyme combination, temperature variation and ultrasonication were not so advantageous for allophyocyanin recovery. The phycocyanin concentration from the red algae was below the limit of detection.
-
The extraction, structure, and gelling properties of hybrid galactan from the red alga Furcellaria lumbricalis (Baltic Sea, Estonia)
Journal of Applied Phycology, 2010Co-Authors: Rando Tuvikene, Kalle Truus, Marju Robal, Olga Volobujeva, Enn Mellikov, Tõnis Pehk, Andres Kollist, Tiiu Kailas, Merike VaherAbstract:The structure and composition of galactan from Furcellaria lumbricalis (furcellaran) were investigated in connection with rheological specificities, gel structure, and extraction conditions. The polysaccharide was characterized by ^13C nuclear magnetic resonance (^13C-NMR) and Fourier transform infrared spectroscopy, inductively coupled plasma-optical emission spectrometry, electrothermal atomization atomic absorption spectrometry, and gel permeation chromatography methods. The microstructure of polymer gels was studied using a cryofixation method in combination with freeze-drying and scanning electron microscopy (SEM) techniques. The undersulfated furcellaran backbone consists mainly of 3,6-anhydro- d -galactose (28.5–30.1%) and galactose residues, the latter being partly sulfated in positions 4 and 6, which give rise to some specific properties of the gel. Also, residues of 6- O -methyl- d -galactose as a minor component are found to be present. The water-extracted furcellaran with the average molecular weight about 290 kDa is rich in nitrogen, calcium, magnesium, and potassium, while the sodium content is rather low. The low sulfur content (5.3%) and ^13C-NMR spectra refer to an undersulfated nature of this galactan. The extraction of seaweeds in low concentration alkaline solutions (instead of water) leads to a significant increase of the minimum size of the galactan particles and the value of gel strength (more than 12 times for Rb-containing gels). The properties of the gel are dependent on specific tentacle-like structure units present in furcellaran gels established by a high-resolution SEM.
Milos Hricovini - One of the best experts on this subject based on the ideXlab platform.
-
extraction and characterization of polysaccharide films prepared from Furcellaria lumbricalis and gigartina skottsbergii seaweeds
Cellulose, 2021Co-Authors: Ivan Simkovic, F Gucmann, Raniero Mendichi, Alberto Giacometti Schieroni, Daniele Piovani, E Dobrocka, Milos HricoviniAbstract:Polysaccharide films prepared using water extraction of red algae represent an important group of environmentally-friendly materials suitable for industrial applications in food processing, medicine or electrical engineering. In this study, we prepared polysaccharide films from Furcellaria lumbricalis (FL) and Gigartina skottsbergii (GS) seaweed extracts and investigated their physical, chemical, and mechanical properties. Following contents of individual isolated fractions were observed by the nuclear magnetic resonance (NMR): ultrasonic water extraction of GS (GSUW) consisted of (1–3)-α-glycan 6-sulfate; ultrasonic carbonate-peroxide extraction (GSUCP) consisted of the same glycan and extra carrageenan hybrids µ-D6S and ν-D2S,6S observed for the first time in this study; extractions of FL and GS in boiling water under reflux (FLW, GSW) contained α-, θ-, λ-, µ-, ν-, and ζ-carrageenans and (1–3)-α-glycan partially sulphated at C6 or the most complex mixture of α-, β-, κ-, ι-, θ-, ζ-carrageenans, and (1–3)-α-glycan partially sulfated at C6, respectively. Spatially-resolved surface morphology and mechanical properties were evaluated by the atomic force microscopy and PeakForce quantitative nanomechanical mapping and correlated to the other investigated films properties. According to X-ray diffraction analysis, we observed no cellulose content or confirm the crystalline form of carrageenans in none of the studied polysaccharide films.
Kalle Truus - One of the best experts on this subject based on the ideXlab platform.
-
The extraction, structure, and gelling properties of hybrid galactan from the red alga Furcellaria lumbricalis (Baltic Sea, Estonia)
Journal of Applied Phycology, 2010Co-Authors: Rando Tuvikene, Kalle Truus, Marju Robal, Olga Volobujeva, Enn Mellikov, Tõnis Pehk, Andres Kollist, Tiiu Kailas, Merike VaherAbstract:The structure and composition of galactan from Furcellaria lumbricalis (furcellaran) were investigated in connection with rheological specificities, gel structure, and extraction conditions. The polysaccharide was characterized by ^13C nuclear magnetic resonance (^13C-NMR) and Fourier transform infrared spectroscopy, inductively coupled plasma-optical emission spectrometry, electrothermal atomization atomic absorption spectrometry, and gel permeation chromatography methods. The microstructure of polymer gels was studied using a cryofixation method in combination with freeze-drying and scanning electron microscopy (SEM) techniques. The undersulfated furcellaran backbone consists mainly of 3,6-anhydro- d -galactose (28.5–30.1%) and galactose residues, the latter being partly sulfated in positions 4 and 6, which give rise to some specific properties of the gel. Also, residues of 6- O -methyl- d -galactose as a minor component are found to be present. The water-extracted furcellaran with the average molecular weight about 290 kDa is rich in nitrogen, calcium, magnesium, and potassium, while the sodium content is rather low. The low sulfur content (5.3%) and ^13C-NMR spectra refer to an undersulfated nature of this galactan. The extraction of seaweeds in low concentration alkaline solutions (instead of water) leads to a significant increase of the minimum size of the galactan particles and the value of gel strength (more than 12 times for Rb-containing gels). The properties of the gel are dependent on specific tentacle-like structure units present in furcellaran gels established by a high-resolution SEM.
-
gelling galactans from the algal community of Furcellaria lumbricalis and coccotylus truncatus the baltic sea estonia a structure property study
International Journal of Biological Macromolecules, 1997Co-Authors: Kalle Truus, M Vaher, A I Usov, T Pehk, A KollistAbstract:Extraction of Furcellaria lumbricalis by potassium hydroxide solution shows that the maximum gel strength of polysaccharides separated is attained by extraction at concentration 0.16 M KOH. Crude extract from this algal species has a complicated monosaccharide composition; a drastic increase of gel strength by alkaline extraction of the polysaccharide mixture cannot be explained through the composition of a major (kappa) fraction described earlier. Alkaline treatment is also suitable for accelerating the extraction of polysaccharides from Coccotylus truncatus overlaid with thick epithelium. Viscous galactans from C. truncatus are more stable to alkali, their composition is simpler and close to iota carrageenan. The formation of mixed kappa and iota carrageenan gels as a result of simultaneous extraction of both seaweeds causes levelling of theological properties of different extraction fractions.
A Kollist - One of the best experts on this subject based on the ideXlab platform.
-
gelling galactans from the algal community of Furcellaria lumbricalis and coccotylus truncatus the baltic sea estonia a structure property study
International Journal of Biological Macromolecules, 1997Co-Authors: Kalle Truus, M Vaher, A I Usov, T Pehk, A KollistAbstract:Extraction of Furcellaria lumbricalis by potassium hydroxide solution shows that the maximum gel strength of polysaccharides separated is attained by extraction at concentration 0.16 M KOH. Crude extract from this algal species has a complicated monosaccharide composition; a drastic increase of gel strength by alkaline extraction of the polysaccharide mixture cannot be explained through the composition of a major (kappa) fraction described earlier. Alkaline treatment is also suitable for accelerating the extraction of polysaccharides from Coccotylus truncatus overlaid with thick epithelium. Viscous galactans from C. truncatus are more stable to alkali, their composition is simpler and close to iota carrageenan. The formation of mixed kappa and iota carrageenan gels as a result of simultaneous extraction of both seaweeds causes levelling of theological properties of different extraction fractions.
