Enabling large-scale production of algal oil in continuous output mode

Stephen P Slocombe; Maria Huete-Ortega; Rahul Vijay Kapoore; Katarzyna Okurowska; Alison Mair; John G Day; Michele S Stanley; Seetharaman Vaidyanathan

doi:10.1016/j.isci.2021.102743

Enabling large-scale production of algal oil in continuous output mode

iScience. 2021 Jun 17;24(7):102743. doi: 10.1016/j.isci.2021.102743. eCollection 2021 Jul 23.

Authors

Stephen P Slocombe¹, Maria Huete-Ortega², Rahul Vijay Kapoore², Katarzyna Okurowska², Alison Mair¹, John G Day¹, Michele S Stanley¹, Seetharaman Vaidyanathan²

Affiliations

¹ The Scottish Association for Marine Science (SAMS), Scottish Marine Institute, Oban, Argyll PA37 1QA, UK.
² Advanced Biomanufacturing Centre, Department of Chemical and Biological Engineering, ChELSI Institute, The University of Sheffield, Sheffield S1 3JD, UK.

Abstract

Large-scale algal oil production requires continuous outputs and a trade-off between growth and oil content. Two unrelated marine algae (Nannochloropsis oceanica [CCAP 849/10] and Chlorella vulgaris [CCAP 211/21A]) that showed high oil production under batch culture were studied under controlled semicontinuous cultivation conditions. Three essential attributes maximized oil productivity: (i) downregulation of cell size to maximize light absorption under N limitation; (ii) low nutrient-depletion thresholds to trigger oil induction; (iii) a means of carbohydrate suppression in favor of oil. N. oceanica responded better to input N/P variations and is more suited to continuous oil production. A low N/P ratio was effective in both suppressing carbohydrate and reducing cell size concomitant with oil production. In C. vulgaris, nutrient starvation thresholds for oil were higher and carbohydrate was preferentially induced, which impeded stress-level optimization for oil. These differences, which impact continuous oil production at scale, are driven by species adaptation to specific marine habitats.

Keywords: Chemical Engineering; Chemical Reaction Engineering; Energy Sustainability; Energy Systems.