Organic wastes/by-products as alternative to CO₂ for producing mixotrophic microalgae enhancing lipid production

In this work, white wine lees (WWL), cheese whey (CW), and glycerol (GLY) were used as carbon (C) sources to mixotrophically support the production of the microalga Nannochloropsis salina, replacing CO₂ supply. In doing so, the alga was allowed to grow on C sources dosed at 2 g L^-1, 3 g L^-1, and 4 g L^-1 of C, in the presence and absence of CO₂ supply. WWL and CW were not able to support the algal growth due to a fungal contamination that was genomically identified, while GLY gave interesting results in particular with 3 g L^-1 of C. GLY-C was able to replace CO₂-C completely when the latter was omitted, showing an algal biomass production similar to those obtained in autotrophy. If CO₂-C was provided jointly with GLY-C, biomass production and lipid contents increased more than 30% and 23%, respectively, compared to autotrophy.