Cultivation modes for microbial oil production using oleaginous yeasts – A review

Microbial oil has been a valuable alternative oil source with applications in the food, cosmetics and biofuels sectors. As concerns for the environment grow, microbially-synthesized oil has emerged as a potential contributor for sustainable production of biodiesel. However, the high costs of its production hinder its large-scale application. Main bottleneck to industrial lipid production is the cost of the fermentation stage. Therefore, it is imperative to design cultivations with little operating requirements and high yields, adjusted to an oleaginous system. This paper provides an overview of the latest advances in oleaginous yeast cultivation in bioreactors. Focus is given to oleaginous yeasts and de novo lipid accumulation due to their high lipid accumulating ability, robustness and versatility across a range of substrates. The advantages and disadvantages of different cultivation modes, feeding patterns and impact on biomass and lipid yield are critically reviewed. The role of biochemical engineering in facilitating understanding of the lipid accumulation kinetics, lipid productivity and its importance as predictive scale up tool is highlighted through a review of existing equations. Perspectives for further bioprocess improvement through kinetic modelling, and valorisation through utilisation of by-products are also discussed.