title: Two-stage cultivation of Nannochloropsis oculata for lipid production using reversible alkaline flocculation.
abstract: Two-stage cultivation for microalgae biomass is a promising strategy to boost lipid accumulation and productivity. Most of the currently described processes use energy-intensive centrifugation for cell separation after the first cultivation stage. This laboratory study evaluated alkaline flocculation as low-cost alternative separation method to harvest Nannochloropsis oculata prior to cultivation in the second nutrient-depleted cultivation stage. Biomass concentration over time and the maximum quantum yield of photosystem II expressed as Fv:Fm ratio showed identical patterns for both harvesting methods in both stages. The composition of total lipids, carbohydrates, and protein was similar for biomass harvested via alkaline flocculation or centrifugation. Likewise, both harvest methods yielded the same increase in total lipid content, to 40% within the first 2days of the nutrient-depleted stage, with an enrichment in C16 fatty acid methyl esters. Centrifugation can therefore be replaced with alkaline flocculation to harvest Nannochloropsis oculata after the first cultivation stage.
authors.affiliation: Tecnologico de Monterrey, Campus Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. 64849, Mexico.
authors.forename: Gibran Sidney
authors.initials: GS
authors.lastname: Aléman-Nava
authors.affiliation: KU Leuven Campus Kulak, Laboratory for Aquatic Biology, E. Sabbelaan 53, 8500 Kortrijk, Belgium.
authors.forename: Koenraad
authors.initials: K
authors.lastname: Muylaert
authors.affiliation: KU Leuven Campus Kulak, Laboratory for Aquatic Biology, E. Sabbelaan 53, 8500 Kortrijk, Belgium.
authors.forename: Sara Paulina
authors.initials: SP
authors.lastname: Cuellar Bermudez
authors.affiliation: KU Leuven Campus Kulak, Laboratory for Aquatic Biology, E. Sabbelaan 53, 8500 Kortrijk, Belgium.
authors.forename: Orily
authors.initials: O
authors.lastname: Depraetere
authors.affiliation: Tecnologico de Monterrey, Campus Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. 64849, Mexico; Biodesign Swette Center for Environmental Biotechnology, Arizona State University, PO Box 875701, Tempe, AZ 85287-5701, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Rittmann
authors.affiliation: Tecnologico de Monterrey, Campus Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. 64849, Mexico.
authors.forename: Roberto
authors.initials: R
authors.lastname: Parra-Saldívar
authors.affiliation: KU Leuven Campus Kulak, Laboratory for Aquatic Biology, E. Sabbelaan 53, 8500 Kortrijk, Belgium. Electronic address: Dries.Vandamme@kuleuven.be.
authors.forename: Dries
authors.initials: D
authors.lastname: Vandamme
mesh_terms: D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D002498:Centrifugation; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism; D005427:Flocculation; D008055:Lipids / Q000096:biosynthesis* / Q000737:chemistry; D058086:Microalgae / Q000254:growth & development / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D058009:Stramenopiles / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005227:Fatty Acids; D008055:Lipids; D045332:Photosystem II Protein Complex
keywords: Algae; Flocculation; Lipids; Nutrient starvation; Separation