Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Microalgae - future bioresource of the sea?
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. (MPEA)
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Unicellular microalgae are a renewable bioresource that can meet the challenge forfood and energy in a growing world population. Using sunlight, CO2, nutrients,and water, algal cells produce biomass in the form of sugars, proteins and oils, allof which carry commercial value as food, feed and bioenergy. Flue gas CO2 andwastewater nutrients are inexpensive sources of carbon and fertilizers. Microalgaecan mitigate CO2 emissions and reduce nutrients from waste streams whileproducing valuable biomass.My focus was on some of the challenging aspects of cultivating microalgae ascrop: the response of biomass production and quality to seasonality, nutrients andbiological interactions. Approach spans from laboratory experiments to large-scaleoutdoor cultivation, using single microalgal strains and natural communities insouthern (Portugal) and northern (Sweden) Europe.Half of the seasonal variation in algal oil content was due to changes in light andtemperature in outdoor large-scale cultures of a commercial strain (Nannochloropsisoculata). Seasonal changes also influence algal oil composition with more neutrallipids stored in cells during high light and temperature. Nitrogen (N) stress usuallyenhances lipid storage but suppresses biomass production. Our manipulationshowed that N stress produced more lipids while retaining biomass. Thus,projecting annual biomass and oil yields requires accounting for both seasonalchanges and N stress to optimize lipid production in commercial applications.Baltic Sea microalgae proved to be a potential biological solution to reduce CO2emissions from cement flue gas with valuable biomass production. A multi-speciescultivation approach rather than single-species revealed that natural or constructedcommunities of microalgae can produce equivalent biomass quality. Diversecommunities of microalgae can offer resilience and stability due to more efficientresource utilization with less risk of contamination, less work and cost for culturemaintenance.Stable algal biomass production (annual basis) was achieved in outdoor pilot-scale(1600 L) cultivation of Baltic Sea natural communities using cement flue gas as aCO2 source. Results indicate favorable algal oil content at northern Europeanlatitudes compared to southern European latitudes.My thesis establishes the potential of cultivating microalgae as a bioresource inScandinavia, and using a community approach may be one step towardssustainable algal technology.

Place, publisher, year, edition, pages
Växjö: Linnaeus University Press, 2015.
Series
Linnaeus University Dissertations, 227/2015
Keyword [en]
Microalgae, algal cultivation, bioresource, bioenergy, CO2 mitigation, multi-species community approach, seasonal variation
National Category
Biological Sciences Ecology Industrial Biotechnology
Research subject
Natural Science, Aquatic Ecology; Natural Science, Biotechnology; Environmental Science, Environmental technology
Identifiers
URN: urn:nbn:se:lnu:diva-46512ISBN: 978-91-87925-75-7 (print)OAI: oai:DiVA.org:lnu-46512DiVA: diva2:857090
Public defence
2015-10-16, Hörsalen Fullriggaren, Landgången 4, Kalmar, 09:30 (English)
Opponent
Supervisors
Available from: 2015-09-28 Created: 2015-09-28 Last updated: 2015-09-28Bibliographically approved
List of papers
1. Seasonal variation of lipids and fatty acids of the microalgae Nannochloropsis oculata grown in outdoor large-scale photobioreactors
Open this publication in new window or tab >>Seasonal variation of lipids and fatty acids of the microalgae Nannochloropsis oculata grown in outdoor large-scale photobioreactors
Show others...
2012 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 5, no 5, 1577-1592 p.Article in journal (Refereed) Published
Abstract [en]

While focus in oil-producing microalgae is normally on nutrient deficiency, we

addressed the seasonal variations of lipid content and composition in large-scale

cultivation. Lipid content, fatty acid profiles and mono- di- and triglycerides (MAGs,

DAGs, and TAGs) were analyzed during May 2007–May 2009 in Nannochloropsis oculata

grown outdoors in closed vertical flat panels photobioreactors. Total lipids (TL) ranged

from 11% of dry weight (DW) in winter to 30% of DW in autumn. 50% of the variation in

TL could be explained by light and temperature. As the highest lipid content was recorded

during autumn indicating an optimal, non-linear, response to light and temperature we

hypothesize that enhanced thylakoid stacking under reduced light conditions resulted in

more structural lipids, concomitantly with the increase in glycerides due to released

photo-oxidative stress. The relative amount of monounsaturated fatty acids (MUFA)

increased during autumn. This suggested a synthesis, either of structural fatty acids as

MUFA, or a relative increase of C16:1 incorporated into TAGs and DAGs. Our results

emphasize the significant role of environmental conditions governing lipid content and 

composition in microalgae that have to be considered for correct estimation of algal oil

yields in biodiesel production.

Keyword
microalgae, Nannochloropsis oculata, large-scale, seasonal variation, light, temperature, biofuels, biodiesel, lipids, fatty acids
National Category
Biological Sciences
Research subject
Environmental Science, Environmental technology; Natural Science, Biotechnology; Natural Science, Aquatic Ecology; Technology (byts ev till Engineering), Bioenergy Technology
Identifiers
urn:nbn:se:lnu:diva-25900 (URN)10.3390/en5051577 (DOI)000304450700017 ()2-s2.0-84861801565 (Scopus ID)
Available from: 2013-05-29 Created: 2013-05-28 Last updated: 2017-12-06Bibliographically approved
2. Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata 
Open this publication in new window or tab >>Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata 
Show others...
2014 (English)In: Marine Drugs, ISSN 1660-3397, E-ISSN 1660-3397, Vol. 12, no 4, 1891-1910 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI AG, 2014
Keyword
microalgae; outdoor; Nannochloropsis; large-scale; lipids; fatty acids; nitrogen manipulation; seasonal changes; biofuels; high value products
National Category
Microbiology Bioenergy Bioprocess Technology Biochemicals
Research subject
Natural Science, Aquatic Ecology; Natural Science, Biotechnology
Identifiers
urn:nbn:se:lnu:diva-33842 (URN)10.3390/md12041891 (DOI)000335759500011 ()2-s2.0-84900453929 (Scopus ID)
Funder
Ecosystem dynamics in the Baltic Sea in a changing climate perspective - ECOCHANGE
Available from: 2014-04-11 Created: 2014-04-11 Last updated: 2017-12-05Bibliographically approved
3. Baltic Sea microalgae transform cement flue gas into valuable biomass
Open this publication in new window or tab >>Baltic Sea microalgae transform cement flue gas into valuable biomass
Show others...
2015 (English)In: Algal Research, ISSN 2211-9264, Vol. 11, 227-233 p.Article in journal (Refereed) Published
Abstract [en]

We show high feasibility of using cement industrial flue gas as CO2 source for microalgal cultivation. The toxicity of cement flue gas (12-15% CO2) on algal biomass production and composition (lipids, proteins, carbohydrates) was tested using monocultures (Tetraselmis sp., green algae, Skeletonema marinoi, diatom) and natural brackish communities. The performance of a natural microalgal community dominated by spring diatoms was compared to a highly productive diatom monoculture S. marinoi fed with flue gas or air-CO2 mixture. Flue gas was not toxic to any of the microalgae tested. Instead we show high quality of microalgal biomass (lipids 20-30% DW, proteins 20-28% DW, carbohydrates 15-30% DW) and high production when cultivated with flue gas addition compared to CO2-air. Brackish Baltic Sea microalgal communities performed equally or better in terms of biomass quality and production than documented monocultures of diatom and green algae, often used in algal research and development. Hence, we conclude that microalgae should be included in biological solutions to transform waste into renewable resources in coastal waters. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Microalgae, Baltic Sea, Flue gas, Biomass composition, Natural communities, Brackish
National Category
Microbiology Bioenergy Bioremediation
Research subject
Ecology, Aquatic Ecology
Identifiers
urn:nbn:se:lnu:diva-45559 (URN)10.1016/j.algal.2015.07.001 (DOI)000363046900029 ()2-s2.0-84943643090 (Scopus ID)
Funder
Knowledge Foundation
Available from: 2015-07-25 Created: 2015-07-25 Last updated: 2017-04-27Bibliographically approved
4. Production stability and biomass quality in microalgal cultivation - contribution of community dynamics
Open this publication in new window or tab >>Production stability and biomass quality in microalgal cultivation - contribution of community dynamics
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The prospect of using constructed communities of microalgae in algal cultivation wasconfirmed in this study. Three constructed communities of diatoms (Diatom), greenalgae (Green) and cyanobacteria (Cyano), were each mixed with a natural communityof microalgae as baseline. The communities were cultivated in batch and semicontinuousmode and fed CO2 or cement flue gas (12-15 % CO2). Diatom had thehighest growth rate but Green had the highest yield. Dynamic changes in thecommunity composition occurred from start through batch to semi-steady state. Greenalgae were the most competitive group during the experiment. Euglenoids wererecruited from scarce species in the natural community and became a large part of thebiomass in semi-steady state in all communities. High temporal and yield stabilitywas demonstrated in all communities during semi-steady state. Biochemicalcomposition (lipids, proteins and carbohydrates) was similar for the threecommunities with lipids ranging 14-26 % of dry weight (DW), proteins (15-28 %DW) and carbohydrates (9-23 % DW). Filamentous cyanobacteria were outcompetedearly in the experiment. However, their minute presence in Cyano associated withhigher lipid and lower carbohydrates compared to Diatom and Green, suggesting theimportance of chemical interactions among microorganisms. Our results indicate thatculture functions (stability, biomass quality) were maintained while dynamic changesoccurred in community composition. We propose that a multi-species communityapproach can aid sustainability in microalgal cultivation, through complementary useof resources and higher culture stability. Local environmental conditions,complementary microalgal traits, and interactions among functional groups (algae,bacteria) should be considered in community design where natural succession andcrop rotation will likely provide stability for commercial-scale algal cultivation.

Keyword
Microalgae, multi-species communities, production stability, algal cultivation, biomass composition, flue gas
National Category
Biological Sciences Ecology
Research subject
Ecology, Aquatic Ecology; Chemistry, Biotechnology; Environmental Science, Environmental technology
Identifiers
urn:nbn:se:lnu:diva-46511 (URN)
Available from: 2015-09-28 Created: 2015-09-28 Last updated: 2016-12-07Bibliographically approved

Open Access in DiVA

fulltext(12604 kB)1567 downloads
File information
File name FULLTEXT01.pdfFile size 12604 kBChecksum SHA-512
9786bc0795842eaf8634ae791b88006af2ec368a1e556ebf76e3964a9cf0f571adfa438785938c2fd83f17cde138b5de946ee8260618019d86e65815e7d61dfe
Type fulltextMimetype application/pdf

Authority records BETA

Olofsson, Martin

Search in DiVA

By author/editor
Olofsson, Martin
By organisation
Department of Biology and Environmental Science
Biological SciencesEcologyIndustrial Biotechnology

Search outside of DiVA

GoogleGoogle Scholar
Total: 1567 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1185 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf