Chapter 33 – Lipids, sterols, and fatty acids production in algal bioreactors

A microalgae biorefinery is an outstanding sustainable alternative that integrates diverse technologies for producing important chemicals. The most important strategy for modulating microalgae metabolites is associated with the upstream process, which is basically related to culture modifications. Culture systems can be performed in multiple ways, including heterotrophic, photoheterotrophic, mixotrophic, and photoautotrophic. In terms of commercial value, microalgae lipid extracts bring a new spectrum of novel bio-based materials and are one of the most important fractions to be studied. Depending on the fatty acid profile, microalgae oil can be converted into several applications, such as biofuels or important compounds targeted by the pharmaceutical industry, including omega fatty acids, linoleic acid, eicosapentaenoic acid, and docosahexaenoic acid. Additionally, there are other secondary metabolites important to be studied in the lipid fraction, such as sterols, which have drawn attention due to their diverse applications, including cosmetics, agriculture, and in drug development. In this chapter, we will discuss modifications in the upstream process, address different bioreactors, and also the optimization of culture conditions considering abiotic nutritional stress, light intensities, photoperiods, temperature, pH, and other factors affecting the production of these important high-value lipidic molecules in microalgae and cyanobacteria.