| 1. |
- Adler, Sven
(författare)
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Effects of counting variances on water quality assessments: implications from four benthic diatom samples, each counted by 40 diatomists
- 2016
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 28, s. 2287-2297
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Tidskriftsartikel (refereegranskat)abstract
- The European Water Framework Directive (EU WFD) aims to improve and maintain the water quality of lakes and rivers. Diatoms play an important role for implementing the EU WFD as they are widely used to assess water quality. To asses and use diatom-based evaluations in practice, it is essential to know and to minimize the analyst-dependent variability of the primary diatom results. We compare the counting results of benthic diatoms from two river and two lake samples as identified by 40 participants of the first German benthic diatom intercalibration exercise. Differences among participants and auditors are calculated with the Bray-Curtis distance, and similarities are graphically displayed by detrended correspondence analyses. Additionally, this study identifies the effects of counting variances on the ecological water assessment with the German PHYLIB method for implementing the EU WFD using the above dataset. Counting result differences among participants may have a significant impact on the assessed water quality. Some taxonomically problematic taxa do not have indicator values (no impact), sometimes, several taxonomic mistakes counterbalance each other during assessment (no or minor impact), and sometimes, taxonomic differences greatly influence the assessment due to highly deviating taxon abundances and/or strongly differing indicator values between mistaken taxa. Intercalibration exercises promote discussion about taxonomy, identify problematic taxa, and harmonize taxonomic concepts among diatomists. Thus, the shown analyst-induced variability of diatom counts may be reduced with an intercalibration exercise, thereby further refining the accuracy of water quality assessments.
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| 2. |
- Allahgholi, Leila, et al.
(författare)
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Composition analysis and minimal treatments to solubilize polysaccharides from the brown seaweed Laminaria digitata for microbial growth of thermophiles
- 2020
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 32:3, s. 1933-1947
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Tidskriftsartikel (refereegranskat)abstract
- Brown macroalgae (Phaeophyta) hold high potential as feedstock for biorefineries due to high biomass productivity and carbohydrate content. They are, however, a challenging, unconventional feedstock for microbial refining and several processing problems need to be solved to make them a viable option. Pre-treatment is necessary to enhance accessibility and solubility of the biomass components but should be minimal and mild to assure sustainable and cost-effective processing. Here, two routes to pre-treatLaminaria digitata to release polysaccharides were investigated: hot water pre-treatment by autoclaving (121 °C, 20 min or 60 min) and a two-step extraction with mild acid (0.1 M HCl) followed by alkaline treatment. Hot water pre-treatment resulted in partial extraction of a mixture of polysaccharides consisting of alginate, fucoidan and laminarin. After mild acid pre-treatment, alginate was found in the remaining insoluble residues and was extracted in a second step via alkaline treatment using Na2CO3 (0.15 M) at 80 °C and CaCl2 (10%) for the precipitation. In addition to carbohydrates, a fraction of other components such as proteins, phenolic compounds, minerals and trace elements was detected in the extracts. Cultivation of the thermophilic bacterial strains Rhodothermus marinus DSM 16675 and Bacillus methanolicus MGA3 (ATCC 53907) in media supplemented with the respective extracts resulted in growth of both strains, indicating that they were able to utilize the available carbon source for growth. R. marinus displayed the highest cell density in the medium containing the extract from acid pre-treatment, whereas B. methanolicus growth was highest with the extract from hot water pre-treatment.
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| 3. |
- Bigler, Christian, et al.
(författare)
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Numerical simulations suggest that counting sums and taxonomic resolution of diatom analyses to determine IPS pollution and ACID acidity indices can be reduced
- 2010
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 22:5, s. 541-548
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Tidskriftsartikel (refereegranskat)abstract
- Implementation of the European Union Water Framework Directive and associated national guidelines has emphasized the value of using biota, such as epilithic diatoms in streams, as indicators of water quality. However, guidelines for evaluating diatom samples have been established without explicitly evaluating their statistical robustness. We used epilithic diatom samples from 73 streams in northern Sweden and simulated the effects of variations in the counting sum size and taxonomic resolution of classifications for two indices indicating pollution (Indice de Polluo-sensibilité Spécifique, IPS) and acidity (acidity index for diatoms, ACID). Instead of the stipulated 400, we found that a count sum of 40 diatom valves for 50 streams, and 80 valves for 60 streams, would have been sufficient to obtain the same IPS index classification. The ACID index is more sensitive to count sum reductions, since the same classification would only have been obtained for 12 streams with 40 counted diatom valves or 24 streams with a count of 80 valves. Excluding rare taxa had negligible effects on the IPS and ACID indices. Excluding taxa occurring with less than 1.0% frequency affected the IPS classification of only one stream, and excluding taxa with less than 2.5% and 5.0% frequencies affected those of just one and no streams, respectively. The ACID index was affected for none, five, and 12 streams, respectively. At least in relatively unpolluted regions such as northern Sweden, our simulations suggest that a simplified methodological approach with site-specific counting sum sizes and reduced taxonomical resolution could be adopted, taking into account the way sites are classified in relation to established class boundaries. The simplified method is a step forward in improving the cost efficiency for stream monitoring, as costs of diatom analysis to obtain identical IPS and ACID classifications of our streams could be reduced considerably. Before the simplified method can be widely adopted, further simulations including regions with a higher proportion of polluted streams are required.
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| 4. |
- Cardoso, Isabel, et al.
(författare)
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Salinity as a tool for strain selection in recirculating land-based production of Ulva spp. from germlings to adults
- 2023
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Ingår i: Journal of Applied Phycology. - 0921-8971.
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Tidskriftsartikel (refereegranskat)abstract
- The genus Ulva is globally distributed and has been thoroughly studied because of its functional biochemical composition, rapid growth rates and opportunistic features, and interest in Ulva cultivation is growing worldwide. In Europe, mostly near- and on-shore flow-through cultivation systems are used, and land-based recirculating aquaculture systems (RAS) using fresh water or artificial seawater have not been developed for Ulva. While RAS provides quality control and can be located inland, maintenance costs are high. Using selected strains adapted to low-salinity could reduce seawater production costs and improve the economic feasibility. Therefore, our study assessed how salinity can be used as a tool for strain selection and optimization of functional traits. Growth rates and antioxidant activity of three species (four strains) of tubular and foliose Ulva from the NE-Atlantic and Mediterranean (foliose: Ulva lacinulata – two geographical strains, tubular: Ulva linza and Ulva flexuosa) were followed for three weeks at salinities ranging from 10 to 30 PSU. The tubular strains achieved optimal growth at a lower salinity than U. lacinulata. However, growth rates of both foliose strains were higher than of tubular strains, even at sub-optimal salinity. Therefore, U. lacinulata is a good candidate for RAS with artificial seawater, and the cost of salt can be reduced by up to 33.3% (20 PSU) without significantly reducing the growth rate of U. lacinulata. Higher antioxidant activity was achieved by reducing the salinity to 10 PSU for 10 days, suggesting that the functional traits of cultivated Ulva lacinulata can be optimized prior to harvest.
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| 5. |
- Chow, Fungyi, et al.
(författare)
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Modulation of nitrate reductase activity by photosynthetic electron transport chain and nitric oxide balance in the red macroalga Gracilaria chilensis (Gracilariales, Rhodophyta)
- 2013
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 25:6, s. 1847-1853
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Tidskriftsartikel (refereegranskat)abstract
- Nitrate reductase (NR), a key enzyme in nitrogen metabolism, has been implicated in the production of nitric oxide (NO) in plants. The effect of photosynthetic electron transport chain inhibitors and NO scavengers or donors on NR activity of Gracilaria chilensis was studied under experimental laboratory conditions. Effective quantum yield (I broken vertical bar (PSII)) and NR activity were significantly diminished by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, two photosynthetic electron flux inhibitors of photosystem (PS) II and PSI, respectively, but not by diphenyleneiodonium, a NADPH oxidase inhibitor, indicating a direct dependence of NR activity on the PSII and PSI electron flux. Nitrate reductase activity was sensitive to a decrease or increase of NO levels when NO scavenger (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) and NO donor (sodium nitroprusside) were added. Moreover, the addition of 8Br-cGMP, a secondary signal molecule, stimulated NR activity. These results evidence a modulation of the photosynthetic electron transport chain and NO balance on G. chilensis NR activity. This association could be linked to the crucial tight modulation of nitrogen assimilation and carbon metabolism to guarantee nitrite incorporation into organic compounds and to avoid toxicity by nitrite, reactive oxygen species, or nitric oxide in the cells. Nitric oxide showed to be an important signaling molecule regulating NR activity and cGMP could participate as secondary messenger on this regulation by phosphorylation and desphosphorylation processes.
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| 6. |
- Collen, Pi Nyvall, et al.
(författare)
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Analysis of expressed sequence tags from the agarophyte Gracilaria tenuistipitata (Rhodophyta)
- 2012
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 24:4, s. 641-647
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Tidskriftsartikel (refereegranskat)abstract
- A total of 3,631 expressed sequence tags (ESTs) were established from two size-selected cDNA libraries made from the tetrasporophytic phase of the agarophytic red alga Gracilaria tenuistipitata. The average sizes of the inserts in the two libraries were 1,600 bp and 600 bp, with an average length of the edited sequences of 850 bp. Clustering gave 2,387 assembled sequences with a redundancy of 53%. Of the ESTs, 65% had significant matches to sequences deposited in public databases, 11% to proteins without known function, and 35% were novel. The most represented ESTs were a Na/K-transporting ATPase, a hedgehog-like protein, a glycine dehydrogenase and an actin. Most of the identified genes were involved in primary metabolism and housekeeping. The largest functional group was thus genes involved in metabolism with 14% of the ESTs; other large functional categories included energy, transcription, and protein synthesis and destination. The codon usage was examined using a subset of the data, and the codon bias was found to be limited with all codon combinations used.
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| 7. |
- Danilov, Roman, et al.
(författare)
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Influence of chlorophyll concentrations on the reliability of measurements with an oxygen electrode when studying photosynthetic efficiency in bioassays using microalgae
- 2000
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Ingår i: Journal of Applied Phycology. - 0921-8971 .- 1573-5176. ; 12:1, s. 63-67
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Tidskriftsartikel (refereegranskat)abstract
- Euglena gracilis and Chlamydomonas reinhardtii were used as model organisms to establish the best conditions for studying photosynthetic efficiency using the Light Pipetteexperimental system, which enables sensitive detection of changes in oxygen evolution/consumption and an easy collection and digitalisation of data. Chlorophyll concentrations of 0.005, 0.025, 0.050 and 0.075 mg mL-1 were investigated using different light regimes. Cultures of E. gracilis at the same chlorophyll concentration absorbed more light (measured at 580 μmol m-2 s-1) than those of C. reinhardtii. Cell density had a considerable effect on the reliability of measurements. Chlorophyll concentrations between 0.025 mg(Chl) ml-1 and 0.050 mg(Chl) ml-1 can be recommended when applying the Light Pipette system in bioassays using microalgae.
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| 8. |
- Danilov, Roman, et al.
(författare)
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Influence of waste water from the paper industry and UV-B radiation on the photosynthetic efficiency of Euglena gracilis
- 1999
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Ingår i: Journal of Applied Phycology. - 0921-8971 .- 1573-5176. ; 11, s. 157-163
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Tidskriftsartikel (refereegranskat)abstract
- The green flagellate Euglena gracilis has been used as a model organism to elucidate the possible large-scale and short-term effects of waste substances from the pulp and paper industry on photosynthetic efficiency (PE). Different concentrations of waste substances before and after treatment in a cleaning system were studied. The uncleaned sample at concentrations up to 1:10 and the cleaned sample at concentrations up to 1:5 showed stimulating effects on the PE after 7 days of incubation compared to the control. The effects of waste substances on the PE of E. gracilis were also studied in combination with short-term studies (20 and 40 min) of ultraviolet-B radiation (UV-B, 280–320 nm). It was shown that increasing concentrations of the uncleaned sample had continuously stimulating effects on the PE and worked protectively against UV-B radiation. The cleaned sample exhibited no effects, or negative effects, on the PE of E. gracilis together with UV-B radiation compared to the experiments with only UV-B radiation. At the concentration 1:1 of the cleaned sample an increase in the PE was detected due to the high concentration of the coloured substances and a decrease in the UV-B penetration. PE revealed itself to be highly sensitive for detecting toxic effects on E. gracilis and is thus very promising for use in regular toxicity tests of waste water from pulp and paper industry.
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| 9. |
- Ekelund, Nils G. A., et al.
(författare)
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In situ study of relative electron transport rates (ETR) in the marine macroalga Fucus vesiculosus from the Baltic Sea at different depths and times of the year.
- 2008
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 20:5, s. 751-756
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Tidskriftsartikel (refereegranskat)abstract
- The brown alga Fucus vesiculous is one of the few marine species in the Baltic Sea. F. vesiculosus shows high morphological and physiological variability as a response to its environmental conditions. The salinity in the Baltic Sea is 4-5 psu in comparison to 35 psu in the Atlantic. Photosynthesis of algae is usually measured after collection and transportation to constant culture conditions. However, in this study the relative photosynthetic electron transport rate (rETR), calculated from chl a fluorescence parameters were compared for algae from 1 and 4 m depths by SCUBA divers. Measurements of light response curves from the same individuals of F. vesiculosus at different depths and times of the year have to our knowledge never been made before. Measurements were performed at four different occasions during the spring (February 25, April 3 and 29 and May 26 in 2005) in the Baltic Sea, using rapid light curves (RLCs) generated with a Diving PAM. In addition, samples were collected for photoinhibition studies in the laboratory. The light response curves obtained in situ at 1 and 4 m depths for F. vesiculosus showed lower values of light saturation with depth. When algae from 1 and 4 m depths were exposed to high irradiances of PAR (1400 µmol photons m-2 s-1), algae from 1 m depth showed a higher degree of photoinhibition in comparison to algae from the 4 m depth.
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| 10. |
- Ferro, Lorenza, 1989-, et al.
(författare)
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Elucidating the symbiotic interactions between a locally isolated microalga Chlorella vulgaris and its co-occurring bacterium Rhizobium sp. in synthetic municipal wastewater
- 2019
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Ingår i: Journal of Applied Phycology. - : Springer. - 0921-8971 .- 1573-5176. ; 31:4, s. 2299-2310
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Tidskriftsartikel (refereegranskat)abstract
- Co-cultivation of microalgae and bacteria during municipal wastewater treatment can boost carbon and nutrient recovery as a result of their synergistic interactions. The symbiotic relationships between the locally isolated microalga Chlorella vulgaris and the bacterium Rhizobium sp., co-isolated from municipal wastewater, were investigated batchwise under photoautotrophic, heterotrophic, and mixotrophic conditions in a synthetic municipal wastewater medium. During photoautotrophic growth in BG11 medium, photosynthetic algal oxygenation and organic carbon production supported bacterial activity but no significant beneficial effects on microalgal growth were observed. In synthetic wastewater, a twofold higher biomass concentration was achieved in the axenic algal culture compared with the co-culture under heterotrophic conditions, suggesting a competition for nutrients. A comparable carbon removal was observed in all cultures (83–79% TOC), but a faster nitrogen consumption (59% TN) and complete phosphate assimilation (100% TP) was only achieved in the co-culture. A positive synergistic relationship was found under mixotrophic conditions, clearly supported by an in situ O2/CO2 exchange between the microorganisms. This mutualism led to a threefold higher biomass production with a 13-fold higher fatty acid content compared with the axenic algal culture, as well as a superior wastewater treatment performance (+ 58% TOC, + 41% TN and + 44% TP). The co-cultivation of C. vulgaris and Rhizobium is therefore suggested as a potential microbial consortium for a cost-efficient biomass generation during municipal wastewater reclamation, especially under mixotrophic conditions.
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