Bioprocessing of genetically engineered microalga Nannochloropsis gaditana for lipid production: upstream and downstream operations

Interest in microalgae is steadily increasing due to the variety of compounds they can produce, many of which can be used in the food industry, such as lipids. Additionally, they can utilize carbon dioxide as a carbon source for growth, making them valuable in mitigating greenhouse gas emissions. In this context, TMCI Padovan has designed a new 1000 L photobioreactor (PBR) for microalgae production with the aim of converting CO2, a byproduct of various processes like fermentation, into a high-value product: fatty acids. Genetically modified Nannochloropsis gaditana was chosen to test the PBR at two different light intensities, with a maximum concentration of biomass reaching 0.82 g/L. Subsequently, the obtained biomass was concentrated using a tangential flow filtration system with a polyethersulfone membrane. The goal was to observe the maximum achievable biomass concentration by the filters, which reached 300 g/L in the conducted experiments, while monitoring the level of membrane fouling, consistent with literature values. Filtration tests involved two different capillary diameters, with better performance observed in the smaller diameter, given the same surface area for exchange. The future prospect involves combining the tangential flow filtration system with the PBR to create a complete machine capable of providing biomass at high concentrations. Finally, several methods for cell wall disruption were tested, particularly ultrasound, yielding limited results.