Bicarbonate for microalgae cultivation: a case study in a chlorophyte, Tetradesmus wisconsinensis isolated from a Norwegian lake

• Published in: Journal of applied phycology Vol. 33; no. 3; pp. 1341 - 1352
• Main Authors: Umetani, Ikumi, Janka, Eshetu, Sposób, Michal, Hulatt, Chris J., Kleiven, Synne, Bakke, Rune
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.06.2021; Springer Nature B.V
• Subjects: Acid production; Aeration; Algae; Aquatic microorganisms; Bicarbonates; Biodiesel fuels; Biofuels; Biomass; Biomedical and Life Sciences; Carbon dioxide; Carbon sources; Cetane number; Chlorophyll; Chlorophyll a; Dry weight; Ecology; Fatty acids; Fluorescence; Freshwater & Marine Ecology; Growth rate; Inorganic carbon; Lakes; Life Sciences; Linolenic acid; Lipids; Microalgae; Photosynthesis; Photosystem II; Phytoplankton; Plant Physiology; Plant Sciences; Polyunsaturated fatty acids; Sodium bicarbonate; Tetradesmus wisconsinensis; Inorganic carbon source; Chlorophyll; Biomass; fluorescence; Biodiesel fuel properties; Fatty acids
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-021-02420-4

Bicarbonate was evaluated as an alternative carbon source for a green microalga, Tetradesmus wisconsinensis , isolated from Lake Norsjø in Norway. Photosynthesis, growth, and lipid production were studied using four inorganic carbon regimes: (1) aeration only, (2) 20 mM NaHCO 3 , (3) 5% (v/v) CO 2 gas, and (4) combination of 20 mM NaHCO 3 and 5% CO 2 . Variable chlorophyll a fluorescence analysis revealed that the bicarbonate treatment supported effective photosynthesis, while the CO 2 treatment led to inefficient photosynthetic activity with a PSII maximum quantum yield as low as 0.31. Conversely, bicarbonate and CO 2 treatments gave similar biomass and fatty acid production. The maximum growth rate, the final cell dry weight, and total fatty acids under the bicarbonate-only treatment were 0.33 (± 0.06) day −1 , 673 (± 124) mg L −1 and 75 (± 5) mg g −1 dry biomass, respectively. The most abundant fatty acid components were α-linolenic acid and polyunsaturated fatty acids constituting 69% of the total fatty acids. The fatty acid profile eventuated in unsuitable biodiesel fuel properties such as high degree of unsaturation and low cetane number; however, it would be relevant for food and feed applications. We concluded that bicarbonate could give healthy growth and comparative product yields as CO 2 .