Accumulation of Lipids by the Oleaginous Yeast Yarrowia Lipolytica Grown on Carboxylic Acids Simulating Syngas and Carbon Dioxide Fermentation

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Volatile fatty acids (VFAs) can be considered as low-cost carbon substrates for lipid accumulation by oleaginous yeasts. This study demonstrates that a common mixture of VFAs, typically obtained from the anaerobic fermentation of C1-gases by some acetogenic bacteria, can be used in a second aerobic fermentation with the yeast Yarrowia lipolytica to obtain lipids as precursors of biodiesel. In the batch experiments, the preference of Yarrowia lipolytica W29 for acetic acid over butyric and caproic acids was demonstrated, with the highest consumption rate reaching 0.664 g/L·h. In the bioreactor experiments, the amount initial biomass inoculated, as well as the initial acid concentration, were found to have a significant influence on the process. Though the lipid content was relatively low, it can be optimized and further improved. Oleic, linoleic and palmitic acids accounted for about 80 % of the fatty acids in the lipids, which makes them suitable for biodiesel.This research is part of a project funded through the Spanish Ministry of Science and Innovation and European FEDER funds (PID2020-117805RB-I00). Funding for Open access publication provided by Universidade da Coruña-CISUG. The manuscript is based on research related to COST action Yeast4Bio. The authors, belonging to the BIOENGIN group, thank Xunta de Galicia for financial support to Competitive Reference Research Groups (ED431C 2021/55)Xunta de Galicia; ED431C 2021/5

Factors Affecting the Optimisation and Scale-up of Lipid Accumulation in Oleaginous Yeasts for Sustainable Biofuels Production

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The recent unprecedented increase in energy demand has led to a growing interest in emerging alternatives such as the production of microbial lipids with high energy density and environmentally-friendly characteristics. Oleaginous yeasts represent a versatile and attractive tool for the accumulation of such lipids, also known as single cell oils (SCOs), used to manufacture biofuels (e.g., biodiesel, aviation fuel) and bioproducts. This review provides an overview of the most common oleaginous species, analysing the viability of typical feedstocks and their effect on lipid accumulation. The best results in terms of lipid content using glucose, glycerol, lignocellulose, or acetic acid as substrates are 81.4, 70, 68.2 and 73.4% (w/w), respectively. Besides, an analysis of the parameters that can affect lipid production is also presented. For instance, the optimum conditions for lipid accumulation are usually a C/N ratio between 100 and 200, pH between 5 and 6 (being more alkaline if acids are used as substrates) and temperature around 30 °C. Besides, genetic modifications generally allow to increase the lipid yield, even by up to 400%. Finally, some cost analysis is provided for scaling-up, with feedstock costs estimated at 50–80%, followed by fermenter costs, and downstream costs estimated at around 13%.This study was funded by the Spanish Ministry of Science and Innovation and European FEDER funds (PID2020-117805RB-I00). The manuscript is based on research related to COST action Yeast4Bio. RR thanks the Ministry of Science and Innovation for financial support of his doctoral research (E-15-2019-0344365). CFB (ED481A-2020/028) thanks Xunta de Galicia for financing her doctoral research. The authors, belonging to the BIOENGIN group, thank Xunta de Galicia for financial support to Competitive Reference Research Groups (ED431C 2021/55)Xunta de Galicia; ED481A-2020/028Xunta de Galicia; ED431C 2021/5