The intensive land-based production of the green seaweeds Derbesia tenuissima and Ulva ohnoi: biomass and bioproducts

Abstract

The green seaweeds Derbesia tenuissima and Ulva ohnoi were assessed comparatively for yields of biomass and bioproducts (fatty acids, soluble fibres and amino acids) under controlled land-based culture over 6 months. The intensive cultivation of these seaweeds yielded an average biomass productivity of 15 g dry weight (dw) m⁻² day⁻¹ (56 t dw ha⁻¹ year⁻¹) for D. tenuissima and 38 g dw m⁻² day⁻¹ (138 t dw ha⁻¹ year⁻¹) for U. ohnoi. The production of D. tenuissima was comparatively consistent, ranging between 8 and 20 g dw m⁻² day⁻¹, while that of U. ohnoi was highly variable and stochastic, ranging between 16 and 77 g dw m⁻² day⁻¹. The major bioproducts were lipids (13 % dw) and fatty acids (5 % dw) for D. tenuissima and soluble fibres (ulvan, 12 % dw) for U. ohnoi. These concentrations were consistent over time, irrespective of the variation in environmental conditions and biomass productivity. In addition, D. tenuissima and U. ohnoi are potential bioresources for the extraction of proteins (amino acids). The amino acid content of D. tenuissima (24 % dw) was higher than that of U. ohnoi (13 % dw). However, the annual amino acid productivity of U. ohnoi (18 t ha⁻¹ year⁻¹) was higher than that of D. tenuissima (14 t ha⁻¹ year⁻¹) due to the higher annual productivity of biomass. Notably, both species offer niche opportunities to deliver multiple products through a biorefinery process.