| 1. |
- Albers, Eva, 1966, et al.
(författare)
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Cellular response in fresh water microalgae to polluting compounds of flue gas when used as carbon source
- 2012
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Ingår i: 15th Workshop of International Study Group for Systems Biology (ISGSB), September 25-28, Ameland, The Netherlands.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Attention has lately been given to the use of microalgae as provider of valuable biomass or as production organism. To be able to use algae in industrial production, especially of biofuels, the cultivation procedures need to be improved in terms of efficiency and minimization of production costs. To reach these goals understanding of both process conditions as well as biological response to such conditions is needed for optimization of algal cultivation. Carbon dioxide, the carbon source during phototrophic growth, should be provided at high levels to result in the high biomass concentrations needed for a feasible production. Suitable high-level sources of CO2 are flue gases from industrial activities, which when used for algal cultivation will be a way of carbon capture reducing CO2 emissions. However, flue gases contain additional components that may affect cellular activity negatively. The aim of this research is to understand the physiological behavior of microalgae in industrial conditions to be able to optimize cellular performance. This initial project was launched to provide basic information about response of several types of microalgae that could grow in fresh water conditions to the main gaseous pollutants in flue gas, NO and SO2. This knowledge would guide the selection for a deeper characterization of effect-response relations and control of metabolism in algae in response to industrial conditions. Ten strains of fresh water species and one marine were selected based on reported fast growth and interesting composition such as high levels of lipids. The algae were screened for growth and cellular composition in cultivations with fresh water mineral medium. Artificially produced flue gas, mimicking effluents of pulp mills, consisting of 15% CO2 with 100 ppm NO and 10 ppm SO2 included for the last period of the cultivations was bubbled into the cultures. All strains tested were able to grow and two Scenedesmus strains, an isolated strain from a nearby lake, Chorella protothecoides and Chlamydomonas reinhardtii exhibited the highest specific growth rates. The highest levels of cellular macromolecules were found in Chlorella emersonii (45% carbohydrates), Nannochloropsis salina and the local isolate (65% proteins), and Botrycoccus braunii (57% lipids). It can be concluded that all strains tested were able to grow in cultures with flue gas as carbon source, also the marine species Nannochloropsis salina, and that the gaseous components decrease pH which needs to be monitored carefully to avoid that large drops in pH inhibit algal growth.
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| 2. |
- Albers, Eva, 1966, et al.
(författare)
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Influence of flue gas mimicking effluents of paper mills on growth and cellular composition of fresh water species of microalgae
- 2012
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Ingår i: 9th European Workshop on Biotechnology of Microalgae, 4-5 June, Nuthetal, Germany.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To be able to use algae in industrial production, especially of biofuels, the cultivation procedures need to be improved in terms of efficiency and minimization of production costs. One important factor is to reach as high biomass concentrations as possible e.g. by using high levels of carbon dioxide provided by flue gas. The aim of this project was to study the influence of flue gas simulated to mimic effluents of pulp mills on growth and cellular composition of microalgae. Ten strains of fresh water species and one marine were selected based on reported fast growth and interesting composition such as high levels of lipids. The algae were screened in cultivations with fresh water mineral medium and artificially produced flue gas bubbled into the cultures consisting of 15% CO2 with 100 ppm NO and 10 ppm SO2 included for the last period of the cultivations. All strains tested were able to grow and two Scenedesmus strains, an isolated strain from a nearby lake, Chorella protothecoides and Chlamydomonas reinhardtii exhibited the highest specific growth rates. The highest levels of cellular macromolecules were found in Chlorella emersonii (45% of carbohydrates), Nannochloropsis salina and the local isolate (65% of proteins), and Botrycoccus braunii (57% of lipids). It can be concluded that all strains tested were able to grow in cultures with flue gas as carbon source, also the marine species Nannochloropsis salina, and that the gaseous components decrease pH which needs to be monitored carefully to avoid that large drops in pH inhibit algal growth.
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| 3. |
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| 4. |
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| 5. |
- Cheregi, Otilia, et al.
(författare)
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Marine microalgae for outdoor biomass production - a laboratory study simulating seasonal light and temperature for the west coast of Sweden
- 2021
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Ingår i: Physiologia plantarum. - : Wiley. - 1399-3054 .- 0031-9317. ; 173:2, s. 543-554
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Tidskriftsartikel (refereegranskat)abstract
- At Nordic latitudes, year-round outdoor cultivation of microalgae is debatable due to seasonal variations in productivity. Shall the same species/strains be used throughout the year, or shall seasonal-adapted ones be used? To elucidate this, a laboratory study was performed where two out of 167 marine microalgal strains were selected for intended cultivation at the west coast of Sweden. The two local strains belong to Nannochloropsis granulata (Ng) and Skeletonema marinoi (Sm142). They were cultivated in photobioreactors and compared in conditions simulating variations in light and temperature of a year divided into three growth seasons (spring, summer and winter). The strains grew similarly well in summer (and also in spring), but Ng produced more biomass (0.225 versus 0.066 g DW L-1 d-1 ) which was more energy rich (25.0 versus 16.6 MJ kg-1 DW). In winter, Sm142 grew faster and produced more biomass (0.017 versus 0.007 g DW L-1 d-1 ), having similar energy to the other seasons. The higher energy of the Ng biomass is attributed to a higher lipid content (40 versus 16% in summer). The biomass of both strains was richest in proteins (65%) in spring. In all seasons, Sm142 was more effective in removing phosphorus from the cultivation medium (6.58 versus 4.14 mg L-1 d-1 in summer), whereas Ng was more effective in removing nitrogen only in summer (55.0 versus 30.8 mg L-1 d-1 ). Our results suggesting that, depending on the purpose, either the same or different local species can be cultivated are relevant when designing outdoor pilot studies. This article is protected by copyright. All rights reserved.
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| 6. |
- Cheregi, Otilia, et al.
(författare)
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Microalgae biotechnology in Nordic countries - the potential of local strains.
- 2019
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Ingår i: Physiologia plantarum. - : Wiley. - 1399-3054 .- 0031-9317. ; 166:1, s. 438-450
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Forskningsöversikt (refereegranskat)abstract
- Climate change, energy use and food security are the main challenges that our society is facing nowadays. Biofuels and feedstock from microalgae can be part of the solution if high and continuous production is to be ensured. This could be attained in year-round, low cost, outdoor cultivation systems using strains that are not only champion producers of desired compounds but also have robust growth in a dynamic climate. Using microalgae strains adapted to the local conditions may be advantageous particularly in Nordic countries. Here, we review the current status of laboratory and outdoor-scale cultivation in Nordic conditions of local strains for biofuel, high-value compounds and water remediation. Strains suitable for biotechnological purposes were identified from the large and diverse pool represented by saline (NE Atlantic Ocean), brackish (Baltic Sea) and fresh water (lakes and rivers) sources. Energy-efficient annual rotation for cultivation of strains well adapted to Nordic climate has the potential to provide high biomass yields for biotechnological purposes.
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| 7. |
- Cheregi, Otilia, et al.
(författare)
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Transcriptome analysis reveals insights into adaptive responses of two marine microalgae species to Nordic seasons
- 2023
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Ingår i: Algal Research. - 2211-9264. ; 74
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Tidskriftsartikel (refereegranskat)abstract
- There is an increasing interest in algae-based biomass produced outdoors in natural and industrial settings for biotechnological applications. To predict the yield and biochemical composition of the biomass, it is important to understand how the transcriptome of species and strains of interest is affected by seasonal changes. Here we studied the effects of Nordic winter and summer on the transcriptome of two phytoplankton species, namely the diatom Skeletonema marinoi (Sm) and the eustigmatophyte Nannochloropsis granulata (Ng), recently identified as potentially important for biomass production on the west coast of Sweden. Cultures were grown in photobioreactors in simulated Nordic summer and winter, and the gene expression in two phases was quantified by Illumina RNA-sequencing. Five paired comparisons were made among the four conditions. Sm was overall more responsive to seasons since 70 % of the total transcriptome (14,783 genes) showed differential expression in at least one comparison as compared to 1.6 % (1403 genes) for Ng. For both species, we observed larger differences between the seasons than between the phases of the same season. In summer phase 1, Sm cells focused on photosynthesis and polysaccharide biosynthesis. Nitrate assimilation and recycling of intracellular nitrogen for protein biosynthesis were more active in summer phase 2 and throughout winter. Lipid catabolism was upregulated in winter relative to summer to supply carbon for respiration. Ng favored lipid accumulation in summer, while in winter activated different lipid remodeling pathways as compared to Sm. To cope with winter, Ng upregulated breakdown and transport of carbohydrates for energy production. Taken together, our transcriptome data reveal insights into adaptive seasonal responses of Sm and Ng important for biotechnological applications on the west coast of Sweden, but more work is required to decipher the molecular mechanisms behind these responses.
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| 9. |
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| 10. |
- Ekendahl, Susanne, 1965, et al.
(författare)
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Characterisation of Yeasts isolated from deep igneous rock aquifers of the fennoscandian shield
- 2003
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Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 0095-3628 .- 1432-184X. ; 46:4, s. 416-428
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Tidskriftsartikel (refereegranskat)abstract
- The diversity of prokaryotes in the groundwater deep below the surface of the Baltic Sea at the Aspo Hard Rock Laboratory (HRL) in southeast Sweden is well documented. In addition, there is some evidence that eukaryotes, too, are present in the deep groundwater at this site, although their origins are uncertain. To extend the knowledge of eukaryotic life in this environment, five yeast, three yeastlike, and 17 mold strains were isolated from Aspo HRL groundwater between 201 and 444 m below sea level. Phenotypic testing and phylogenetic analysis of 18S rDNA sequences of the five yeast isolates revealed their relationships to Rhodotorula minuta and Cryptococcus spp. Scanning and transmission electron microscopy demonstrated that the strains possessed morphological characteristics typical for yeast, although they were relatively small, with an average length of 3 mum. Enumeration through direct counting and most probable number methods showed low numbers of fungi, between 0.01 and 1 cells mL(-1), at some sites. Five of the strains were characterized physiologically to determine whether they were adapted to life in the deep biosphere. These studies revealed that the strains grew within a pH range of 4-10, between temperatures of 4degreesC and 25-30degreesC, and in NaCl concentrations from 0 to 70 g L-1. These growth parameters suggest a degree of adaptation to the groundwater at Aspo HRL. Despite the fact that these eukaryotic microorganisms may be transient members of the deep biosphere microbial community, many of the observations of this study suggest that they are capable of growing in this extreme environment.
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| 11. |
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| 12. |
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| 13. |
- Ekendahl, Susanne, 1965, et al.
(författare)
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Energieffektiv odling av marina mikroalger vid den svenska västkusten - potentiella applikationer : RISE Rapport 2020: 72
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- An energy-efficient cultivation method for microalgae has been further developed for the Nordic climate, specifically for the Swedish west coast. The principle for the cultivation process has earlier been developed by RISE for freshwater microalgae. In this project, we have used marine species, and thereby also seawater, in the cultivation. Utilization of natural seawater lowers the environmental impact since, during some circumstances, freshwater may become limiting even in Sweden. The aim of the study was to investigate if selected marine species could be rotated during the year to achieve a longer cultivation season and increased production of energy-rich algal biomass. Winter, spring and summer at the Swedish west coast were simulated in cultivation experiments in laboratory bioreactors with the species Skeletonema marinoi, usually thriving and blooming on the west coast in winter and spring, and Nannochloropsis granulata, which blooms in summer and produces high amounts of lipids. Nannochloropsis was shown to be more suitable for cultivation during spring and summer, when it comes to production of biomass and energy, while Skeletonema grew better during winter and displayed a higher uptake of phosphate than Nannochloropsis. The productivity of Nannochloropsis was in the same range as that of a previously studied freshwater microalgal species, Tetradesmus obliquus. We have shown the principle for a rotational cultivation strategy and that species adapted for a cold climate can give higher productivity during the cold season. Nevertheless, the selected species (Skeletonema) generally showed too low productivity when cultivated during winter to be energy efficient. More species need to be studied to identify those with a high productivity during winter conditions. Even if cold-adapted species are less productive than the summer-adapted ones, considering the available sunlight, they could still be used to prolong the growth season. The cultivation process of Nannochloropsis could also be optimized in an outdoor environment to prolong the season in different ways, since it was tolerant to cold conditions. In practice, the work-related consequences of a rotational cultivation should be weighed against its benefits for each application. Possible applications mainly include cleaning of air and seawater, production of energy, biomass and biomaterials for the industry.
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| 14. |
- Ekendahl, Susanne, et al.
(författare)
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Energy-efficient outdoor cultivation of oleaginous microalgae at northern latitudes using waste heat and flue gas from a pulp and paper mill
- 2018
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Ingår i: Algal Research. - : Elsevier BV. - 2211-9264. ; 31, s. 138-146
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Tidskriftsartikel (refereegranskat)abstract
- Energy efficient cultivation is the major bottleneck for microalgal biomass production on a large scale and considered very difficult to attain at northern latitudes. In this study an unconventional method for industrial microalgae cultivation for bio-oil production using pulp and paper mill waste resources while harvesting only once a year was performed, mainly in order to investigate the energy efficiency of the process. Algae were cultivated for three months in 2014 in covered pond systems with access to flue gas and waste heat from the industry, and the biomass was recovered as thick sediment sludge after dewatering. The cultivation systems, designed to manage the waste resources, reached a promising photosynthetic efficiency of at most 1.1%, a net energy ratio (NER) of 0.25, and a projected year-round energy biomass yield per area 5.2 times higher than corresponding rapeseed production at the location. Thus, microalgae cultivation was, for the first time, proven energy efficient in a cold continental climate. Energy-rich indigenous communities quickly out-competed the oleaginous monocultures used for inoculation. The recovered biomass had higher heating values of 20–23 MJ kg− 1 and contained 14–19% oil dominated by C16 followed by C18 fatty acids. The cultivation season at 59°15′N, 14°18′E was projected to be efficient for 10 months and waste heat drying of the biomass is suggested for two winter months. The technique is proposed for carbon sequestering and energy storage in the form of microalgal sludge or dry matter for later conversion into biochemicals.
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| 15. |
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| 16. |
- Mayers, Joshua, 1988, et al.
(författare)
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Identifying a marine microalgae with high carbohydrate productivities under stress and potential for efficient flocculation
- 2018
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Ingår i: Algal Research. - : Elsevier BV. - 2211-9264. ; 31, s. 430-442
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Tidskriftsartikel (refereegranskat)abstract
- Microalgal biomass represents a potential third generation feedstock that could be utilised as a source of carbohydrates for fermentative production of a range of platform biochemicals. Identifying microalgal strains with high biomass and carbohydrate productivities while also being amenable to downstream processes is key in improving the feasibility of these processes. Utilising marine microalgae capable of growing in seawater will decrease reliance on freshwater resources and improve the sustainability of production. This study screened several marine microalgae believed to accumulate carbohydrates to find new high performing strains. Four strains had high growth rates and accumulated carbohydrates > 35% DW under stress. The strain Chlorella salina demonstrated the highest biomass and carbohydrate productivity, and alkaline autoflocculation (4 mM NaOH) enabled biomass recoveries > 95% efficiency, resulting in an 8–10 × concentration of the culture. Under nutrient replete conditions, biomass productivity reached 0.6 g L −1 d −1 , significantly greater than that of nitrogen starved cultures. However, nitrogen starvation rapidly increased carbohydrate content to > 50% DW in 2 days, resulting in carbohydrate productivities > 0.20 g L −1 d −1 . Chlorella salina partitions the products of photosynthesis preferentially into carbohydrate synthesis under nitrogen starvation. A greater understanding of cellular physiology and carbon partitioning in response to nutrient stress will enable better control and optimisation of the bio-processes. This study has identified a potentially high performance marine microalga for carbohydrate production that is also amenable to low-cost harvesting.
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| 17. |
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| 18. |
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Sárvári Horváth, Ilona, et al.
(författare)
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Förbehandlingsteknikers betydelse för ökat biogasutbyte
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Biologisk nedbrytning av organiskt avfall från hushåll och industri till biogas används redan idag. Tekniken är mycket viktig för att kunna uppnå de miljömål som vårt samhälle ställer för en hållbar utveckling. Att erhålla en ökad mängd biogas ur samma mängd substrat har en avgörande ekonomisk betydelse. Samtidigt är alternativa råvaror för biogasproduktion av stort intresse. Syftet med vår studie var att finna lämpliga förbehandlingsmetoder som öppnar molekylstrukturen hos svårnedbrytbara biopolymerer, och på så sätt göra kolet tillgängligt för mikroorganismer inom efterföljande biologisk nedbrytning och rötning till biogas.
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| 25. |
- Spetea, Cornelia, 1968, et al.
(författare)
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Små alger med stor potential
- 2021
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Ingår i: Havsutsikt. ; :2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Mikroalger är mycket små, encelliga och fascinerande organismer som är oerhört viktiga för hela vår planets atmosfär. De producerar ungefär hälften av allt syre som människor och andra organismer på jorden behöver för att kunna andas. Samtidigt som de frigör syre så växer algerna och bildar bland annat fett, kolhydrater och proteiner från kol, väte, kväve, fosfor och svavel, vilket sammantaget utgör deras biomassa. Mikroalger är basen i havets ekologiska näringskedja och föder bland annat mindre vattenlevande kräftdjur, som i sin tur blir föda för fisk som vi själva äter. Men mikroalger kan också odlas, och lyckas man göra det effektivt och storskaligt kan det få stor betydelse i framtiden.
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| 26. |
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| 27. |
- Vaiciulyte, Sigita, 1988, et al.
(författare)
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Sufficient CO2 concentration is crucial for high biomass formation of marine microalgae
- 2015
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Ingår i: Proceedings of 4th Latin-American Society of Environmental and Algal Biotechnology Congress (SOLABIAA), November 8-13, Brazil.
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Konferensbidrag (refereegranskat)abstract
- The effect of low and high CO2 concentration for the growth of marine green microalgae genera Chlorella and Picochlorum were investigated. Chlorella sp. A, Chlorella sp. B, Chlorella sp. C and Picochlorum sp. strains were grown in a batch culture under 20:4 hours of light:dark photoperiods and with either 0.035 % (ambient air) or 2.0 % of CO2 supply. Picochlorum sp. and Chlorella sp. C achieved the highest maximum growth rate (d-1) 1.06 and 1.05, respectively, when cultured with a high CO2 supply (2.0 %). Cultures supplied with low CO2 (0.035 %), did not enter into exponential growth phase, but formed biomass in a steady linear growth pattern, suggesting significant carbon limitation. Thus, it is clear that the supply of CO2 is critical for high rates of microalgal biomass production, and optimal CO2 ¬supply rate should be identified that also improves carbohydrate formation.
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| 28. |
- Villanova, Valeria, et al.
(författare)
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Mixotrophy in a Local Strain of Nannochloropsis granulata for Renewable High-Value Biomass Production on the West Coast of Sweden
- 2022
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Ingår i: Marine Drugs. - : MDPI. - 1660-3397. ; 20:7
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Tidskriftsartikel (refereegranskat)abstract
- A local strain of Nannochloropsis granulata (Ng) has been reported as the most productive microalgal strain in terms of both biomass yield and lipid content when cultivated in photobioreactors that simulate the light and temperature conditions during the summer on the west coast of Sweden. To further increase the biomass and the biotechnological potential of this strain in these conditions, mixotrophic growth (i.e., the simultaneous use of photosynthesis and respiration) with glycerol as an external carbon source was investigated in this study and compared with phototrophic growth that made use of air enriched with 1–2% CO2 . The addition of either glycerol or CO2-enriched air stimulated the growth of Ng and theproduction of high-value long-chain polyunsaturated fatty acids (EPA) as well as the carotenoid canthaxanthin. Bioassays in human prostate cell lines indicated the highest antitumoral activity for Ng extracts and fractions from mixotrophic conditions. Metabolomics detected betaine lipids specifically in the bioactive fractions, suggesting their involvement in the observed antitumoral effect. Genes related to autophagy were found to be upregulated by the most bioactive fraction, suggesting a possible therapeutic target against prostate cancer progression. Taken together, our results suggest that the local Ng strain can be cultivated mixotrophically in summer conditions on the west coast of Sweden for the production of high-value biomass containing antiproliferative compounds, carotenoids, and EPA. © 2022 by the authors.
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| 29. |
- Villanova, Valeria, et al.
(författare)
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Unveiling the ecological resilience and industrial potential of Skeletonema marinoi through mixotrophic cultivation in Nordic winter condition
- 2024
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Ingår i: Physiologia Plantarum : An International Journal for Plant Biology. - 0031-9317. ; 176:3
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Tidskriftsartikel (refereegranskat)abstract
- Mixotrophy, the concurrent use of inorganic and organic carbon in the presence of light for microalgal growth, holds ecological and industrial significance. However, it is poorly explored in diatoms, especially in ecologically relevant species like Skeletonema marinoi. This study strategically employed mixotrophic metabolism to optimize the growth of a strain of Skeletonema marinoi (Sm142), which was found potentially important for biomass production on the west coast of Sweden in winter conditions. The aim of this study was to discern the most effective organic carbon sources by closely monitoring microalgal growth through the assessment of optical density, chlorophyll a fluorescence, and biomass concentration. The impact of various carbon sources on the physiology of Sm142 was investigated using photosynthetic and respiratory parameters. The findings revealed that glycerol exhibited the highest potential for enhancing the biomass concentration of Sm142 in a multi-cultivator under the specified experimental conditions, thanks to the increase in respiration activity. Furthermore, the stimulatory effect of glycerol was confirmed at a larger scale using environmental photobioreactors simulating the winter conditions on the west coast of Sweden; it was found comparable to the stimulation by CO2-enriched air versus normal air. These results were the first evidence of the ability of Skeletonema marinoi to perform mixotrophic metabolism during the winter and could explain the ecological success of this diatom on the Swedish west coast. These findings also highlight the importance of both organic and inorganic carbon sources for enhancing biomass productivity in harsh winter conditions.
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