| 1. |
- Olofsson, Martin, et al.
(author)
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Are algal oil yield estimations dependent on seasonal variation?
- 2011
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In: Algae: The sustainable biomass for the future. Perspectives from the submariner project algae cooperation event Trelleborg, Sweden - September 28-29, 2011. - Berlin, Germany : s.Pro-sustainable projects GmbH. ; , s. 44-45
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Conference paper (pop. science, debate, etc.)
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| 2. |
- Olofsson, Martin, 1975-, et al.
(author)
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Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata
- 2014
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In: Marine Drugs. - Basel, Switzerland : MDPI AG. - 1660-3397 .- 1660-3397. ; 12:4, s. 1891-1910
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Journal article (peer-reviewed)abstract
- Instead of sole nutrient starvation to boost algal lipid production, we addressed nutrient limitation at two different seasons (autumn and spring) during outdoor cultivation in flat panel photobioreactors. Lipid accumulation, biomass and lipid productivity and changes in fatty acid composition of Nannochloropsis oculata were investigated under nitrogen (N) limitation (nitrate:phosphate N:P 5, N:P 2.5 molar ratio). N. oculata was able to maintain a high biomass productivity under N-limitation compared to N-sufficiency (N:P 20) at both seasons, which in spring resulted in nearly double lipid productivity under N-limited conditions (0.21 g L−1 day−1) compared to N-sufficiency (0.11 g L−1 day−1). Saturated and monounsaturated fatty acids increased from 76% to nearly 90% of total fatty acids in N-limited cultures. Higher biomass and lipid productivity in spring could, partly, be explained by higher irradiance, partly by greater harvesting rate (~30%). Our results indicate the potential for the production of algal high value products (i.e., polyunsaturated fatty acids) during both N-sufficiency and N-limitation. To meet the sustainability challenges of algal biomass production, we propose a dual-system process: Closed photobioreactors producing biomass for high value products and inoculum for larger raceway ponds recycling waste/exhaust streams to produce bulk chemicals for fuel, feed and industrial material.
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| 3. |
- Olofsson, Martin, 1975-, et al.
(author)
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Seasonal variation of lipids and fatty acids of the microalgae Nannochloropsis oculata grown in outdoor large-scale photobioreactors
- 2012
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In: Energies. - : MDPI AG. - 1996-1073. ; 5:5, s. 1577-1592
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Journal article (peer-reviewed)abstract
- While focus in oil-producing microalgae is normally on nutrient deficiency, weaddressed the seasonal variations of lipid content and composition in large-scalecultivation. Lipid content, fatty acid profiles and mono- di- and triglycerides (MAGs,DAGs, and TAGs) were analyzed during May 2007–May 2009 in Nannochloropsis oculatagrown outdoors in closed vertical flat panels photobioreactors. Total lipids (TL) rangedfrom 11% of dry weight (DW) in winter to 30% of DW in autumn. 50% of the variation inTL could be explained by light and temperature. As the highest lipid content was recordedduring autumn indicating an optimal, non-linear, response to light and temperature wehypothesize that enhanced thylakoid stacking under reduced light conditions resulted inmore structural lipids, concomitantly with the increase in glycerides due to releasedphoto-oxidative stress. The relative amount of monounsaturated fatty acids (MUFA)increased during autumn. This suggested a synthesis, either of structural fatty acids asMUFA, or a relative increase of C16:1 incorporated into TAGs and DAGs. Our resultsemphasize the significant role of environmental conditions governing lipid content and composition in microalgae that have to be considered for correct estimation of algal oilyields in biodiesel production.
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