Production of quality seaweed biomass through nutrient optimization for the sustainable land-based cultivation

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The Ulva fasciata Delile is a rapidly growing intertidal green marine macroalga and is a potential source of numerous value-added products such as mineral salts, ulvan, cellulose, and proteins. It is among the edible seaweeds that can bring down the pressure on to the terrestrial crop farming. The cultivation of such economically valuable species presents two major advantages: their higher photosynthetic efficiency that leads to the higher level of atmospheric CO2 sequestration and the biomass produced can effectively be employed in food formulations to combat the food security issues. In this study, the optimum concentration of nutrients namely, nitrate and phosphate were estimated to maximize the biomass production to achieve higher growth rates with the best biochemical contents. The optimization of nutrient regimes resulted in the modulation of algal cell-cycle as evidenced by the highly varying growth rates (ranging from 6% to 56%) as well as dynamic nutrient uptake kinetics. The biochemical analysis of biomass grown in optimized nutrient combination (N2: 60 μM nitrate; 6 μM phosphate) contained proteins 9.3 ± 0.32%, carbohydrates 20.2 ± 2.51% and lipids 6.28 ± 0.84% on dry weight basis. Further, the cultures with the optimized nutrient combination were found to have healthy green leaf-like thallus with reduced or no incidence of deterioration of biomass. The findings reported in this study would be useful for the sustainable production of Ulva in land-based systems.