Coccolithophores, a green technology for mitigation of carbon emissions
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1
Faculdade de Ciências, Universidade de Lisboa, MARE - Centro de Ciências do Mar e do Ambiente, Portugal
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2
Faculdade de Ciências, Universidade de Lisboa, Departamento de Biologia Vegetal, Portugal
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3
Faculdade de Ciências, Universidade de Lisboa, IDL - Instituto D. Luís, Portugal
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4
ALLMICROALGAE, Natural Products S.A., Portugal
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5
Faculdade de Ciências, Universidade de Lisboa, BioISI – Biosystems & Integrative Sciences Institute, Portugal
One of the present-day concerns for humanity is the observed increase in global warming as a consequence of anthropogenic emissions of green-house gases, such as carbon dioxide (CO2). All IPCC (Intergovernmental Panel on Climate Change) scenarios urge for innovative mitigation options that may contribute to limit warming below 2°C, relative to pre-industrial levels, by the end of the century.
Microalgae remove CO2 from the atmosphere through photosynthesis and their efficient industrial production may represent a sustainable technology for carbon sequestration. Within marine phytoplankton, coccolithophores are useful candidates for capture and storage of CO2 since they not only photosynthesize but also produce an exoskeleton made of calcite scales (coccoliths) with potential multiple uses (Jakob et al. 2017, 2018).
Coccolithophores have a haplodiplontic life cycle with morphological distinct life cycle stages. The two life-cycle stages differ in the nature of the coccoliths and the haplontic stage is motile, with two flagella.
In the present work, cocolithophores from Portuguese coastal waters were isolated and domesticated under laboratory conditions with the objective of providing strains with high CO2 sequestration capacity for the microalgae industry. Several new strains of Emiliania huxleyi and Coccolithus braarudi were successfully established in culture and are now kept at the algae culture collection of the University of Lisbon (ALISU).
The photophysiology of C. braarudi, both haplontic and diplontic stage, was investigated using pulse amplitude modulated fluorometry (PAM). The growth characteristics (exponential growth rate and cell yield) of the haplontic flagellated stage was studied in batch cultures using standard laboratory medium (Guillard f/2) and industrial medium (IM) mimicking conditions on an industrial unit. Studies on the influence of silica (1.06 x 10-4 M) on growth were also performed for the distinct media. Before all experiments cells were pre-acclimated for several generations to the culturing conditions.
Culture growth was monitored by cell counts, using a haemocytometer, in vivo fluorescence (Fo), and flow cytometry. The latter approach allowed the characterization of cell size, chlorophyll contents and cell complexity.
Results indicate that growth rates in f/2 medium are significantly higher than in IM. The addition of Si in IM had little effect on growth rate and cell yield, while in f/2 medium, Si allowed a higher cell yield, despite very similar exponential growth rates.
In cultures grown with IM, results from cell counts and flow cytometry indicate a reduction in cell size and cellular chlorophyll concentrations, in comparison with cells grown in f/2 medium. These observations explain the discrepancy recorded between cell concentrations and Fo for the distinct media: for equivalent cell concentrations Fo was significantly higher in f/2 medium.
Further research on the biochemistry and nutritional profile of the studied species will be performed, considering not only their potential for carbon sequestration but also for the production of high value products, such as fatty acids and pigments.
Acknowledgements
The authors would like to acknowledge project AlgaCO2, 16/SI/2016 number 23310 co-financed by COMPETE 2020, and Strategic Project MARE - UID/MAR/04292/2013. HD acknowledges FCT funding SFRH/BPD/121365/2016.
References
Jakob, I., Chairopolus, M.A., Vucak, M, Posten, C., Teipel, U. 2017. Biogenic calcite particles from microalgae - Coccoliths as a potential raw material. Engineering in Life Sciences 17, 605–612
Jakob, I, Weggenmann, F., Posten, C. 2018. Cultivation of Emiliania huxleyi for coccolith production. Algal Research, 31: 47-59.
Keywords:
Carbon Sequestration,
Coccolithus braarudi,
Emiliania huxleyi,
Microalgae isolation,
calcite scales,
CO2 mitigation,
Coccolithophores cultivation
Conference:
IMMR'18 | International Meeting on Marine Research 2018, Peniche, Portugal, 5 Jul - 6 Jul, 2018.
Presentation Type:
Poster Presentation
Topic:
Blue Biotech
Citation:
Vicente
B,
Cachão
M,
David
H,
Silva
JL,
Tenreiro
A and
Amorim
A
(2019). Coccolithophores, a green technology for mitigation of carbon emissions.
Front. Mar. Sci.
Conference Abstract:
IMMR'18 | International Meeting on Marine Research 2018.
doi: 10.3389/conf.FMARS.2018.06.00034
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Received:
27 Apr 2018;
Published Online:
07 Jan 2019.
*
Correspondence:
PhD. Ana Amorim, Faculdade de Ciências, Universidade de Lisboa, MARE - Centro de Ciências do Mar e do Ambiente, Lisbon, 1749-016 Lisboa, Portugal, aaferreira@fc.ul.pt