Effects of macro and micronutrients on neutral lipid accumulation in oleaginous microalgae

In this study, effects of key macro and micronutrients on neutral lipid accumulation of six oleaginous microalgae species were investigated. For each nutrient, three different concentrations (0.5×, 1×, and 2×) were tested individually and compared to the most commonly utilized growth medium recipes. Neutral lipid accumulation was quantified using specific nonpolar dyes with long-wavelength absorption and fluorescence. Tested microalgae species showed different lipid accumulation responses to changes in nutrient concentrations. Optimum concentrations of nutrients were selected for each species based on either the most lipid productive case or no significant difference to the lipid contents. Selected optimal conditions were also validated where Chlorella sorokiniana, Chlorella vulgaris, Dunaliella tertiolecta, and Tetraselmis suecica showed 4, 10, 34, and 39% higher lipid productivities per unit volume, respectively. Botryococcus sudeticus and Ettlia oleoabundans did not show improved lipid productivities. Extensive optimization of macro and micronutrient concentrations offers several benefits of decreased material inputs and waste generation, improved biomass productivity, and overall cost savings.