Biomass and lipid characterization of microalgae genera Botryococcus, Chlorella, and Desmodesmus aiming high-value fatty acid production

Microalgae have been largely considered for biofuel production; however, further research focusing on its wide potential also in food, cosmetic, and pharmaceutical industries is still scarce. It is a promising raw material for several bioproducts, due to high growth rate, CO2 biofixation, and nutrient assimilation from wastewater and does not require large areas for cultivation compared to conventional crops. This study characterized six microalgae (Chlorella sp., C. vulgaris, Desmodesmus sp., D. brasiliensis, Botryococcus braunii, and B. terribilis) regarding growth parameters, total protein, carbohydrate, lipid, ash, and chlorophyll contents. The focus was lipid composition; thus, detailed results of fatty acid profile and polar lipid identification in total lipids are presented. The highest biomass productivity (42.6 mg L-1 day(-1)) and third highest lipid content (21.9%) were achieved by C. vulgaris, with 23.0% alpha -linolenic and 5.6% gamma -linolenic in total fatty acids. Both are of interest for food and pharmaceutical industries and a vegan alternative to currently consumed fish oil. B. braunii showed higher lipid accumulation, oleic acid as the major fatty acid, but significantly low growth rate. B. terribilis presented intense lipid accumulation, at intra- and extracellular levels, but a high percentage of lipids should be hydrocarbons. Lipid and biomass characterization identified different bioproducts and high-value food additives that could be explored to establish a multi-product biorefinery instead of focusing exclusively on biodiesel production, which has been extensively studied but is not economic competitive in the current market.