(10b) Continuous Photobioreactor Cultivation of Nannochloropsis oculata to Isolate Cosmetical Grade Phospholipids

Microalgae are a promising source of natural ingredients as their cell mass contains polysaccharides, proteins, lipids, pigments, and vitamins. Phospholipids, in particular, are of interest to the cosmetics industry for various formulations, such as emulsifiers, liposome formers, solubilizers, wetting agents, and bioactive compounds. They are currently extracted from food sources, but this practice raises sustainability questions because of the competition with food. Microalgae can serve as a source of phospholipids on a more sustainable basis. To advance the status of microalgae bioproducts for cosmetics applications, the marine microalga Nannochloropsis oculata was cultivated in a vertical flat panel photobioreactor (VFPPBR) in batch and continuous mode. Batch cultivation was employed to optimize the growth parameters of N. oculata, calculate its maximum specific growth rate (µ_max), and determine its phospholipid productivity. The measured µ_max of 0.015 hr^-1 was then used to select the dilution rate for designing and operating a VFPPBR-based continuous cultivation that is deemed more scalable and productive from a commercialization standpoint. Cell harvesting was followed by organic solvent extraction to solubilize and recover the algal phospholipids. The experimental findings in continuous cultivation of N. oculata, the robustness of the strain, and its polar lipid productivity, bioreactor designs, performance of the strain in batch and continuous reactors, and green pathways for downstream processing to isolate, concentrate and fractionate algal phospholipids were analyzed and discussed.