Microbial oils production by yeast from glycerol using an Air-Lift and Bubble-Column bioreactors

Abstract

The renewable fuels productions are a strategically important sector for developing countries like Brazil. Currently, biofuels such as biodiesel and bio-jet fuels are obtained from vegetable oils. However, the use of vegetable oils for this purpose presents a disadvantage as the seasonal nature of agricultural production and the competition with food crops. An alternative to vegetable oils refers to the use of oils produced by microorganisms. The microbial oils can be obtained by autotrophic microorganisms, such as microalgae and cyanobacteria, or heterotrophic microorganisms, such as fungi and yeasts. When compared to autotrophic cultures, heterotrophic microorganisms allow obtain high concentrations of cells and lipids, in bioreactors with high volume per unit of surface area, resulting in higher productivity those autotrophic cultures. In this context, this project aims to develop technologies related to the production of microbial oils under heterotrophic conditions using glycerol as the main substrate. In a first step will be developed studies aiming to selection of lipid-producing yeast and the optimization of culture conditions as nutritional composition of the fermentation medium and the oxygen supply in order to improve microbial oils production. In a next step will be carried out studies in pneumatic bioreactors, such as column of bubbles and airlift in order to optimize oxygen transfer conditions and verify the influence of this parameter on the production of microbial oils. At this step, the hydrodynamic parameters of the bioreactor are also determined. This project is relevant in the technological and environmental point of view, since it promotes the development of processes for the production of lipids from glycerol, a renewable source and a byproduct of biodiesel production, contributing to the generation of technologies necessary for the development of lipid-based biorefinery. (AU)