Choreography of Lipid Yield and Productivity in Chlorella Sorokiniana Strain BV12 under the Influence of Variable Cultivation Conditions

Quantification of biomass, along with lipid yield and productivity, is essential for utilizing microalgae as an oleaginous feedstock. Several strategies have been evaluated for their effects on lipid accumulation in different microalgal taxa, with UV exposure and nutrient stress identified as key variables. The Chlorella sorokiniana strain BV12 demonstrates sufficient robustness to tolerate 15 minutes of UV exposure, resuming growth within 12 days. The UV exposure temporarily stimulated lipid accumulation pathways, resulting in a 49.10% increase compared to the control. In comparison, nutrient deprivation led to a 51.18% increase in lipid yield, proving to be a more effective method for lipid enhancement in this strain. The increase in lipid yield was attributed to the accumulation of additional lipid droplets, leading to a 40.28% and 50.59% enhancement in gravimetric lipid yield and neutral lipid productivity, respectively. This accumulation also resulted in an increase in cell size. Furthermore, this strain is scalable, as only a 12.18% loss in performance was observed when growing the culture in a 40 L medium compared to flask-level production under outdoor conditions. Notably, the shading effect was negligible, as increasing the depth of the medium had an insignificant impact on total biomass and lipid yield. Fed-batch cultivation with lactose supplementation altered the production profile, increasing lipid and biomass production by 70.64% and 11.48%, respectively, indicating the positive effect of this disaccharide.