• Genetic engineering
• Basidiomycete
• Single Cell Oil
• Lipogenesis
• Cell Factory
• Oleaginous yeast
• Cutaneotrichosporon oleaginosus

The route to a sustainable bioeconomy requires the development of robust biobased processes, which enable an efficient transformation of complex low-cost biomasses into added-value bioproducts. One of the main biobased products is the microbial oil from oleaginous yeast species, which have long been recognised as an alternative resource for biodiesel production. However, the costs associated to the production of microbial lipids starting from high-quality carbon sources remain prohibitively high for the process scale-up and commercialization. For this reason, the use of low-cost substrates represents one key issue to make microbial lipids production sustainable.
Microbial lipids, also known as single cell oils (SCO), can be produced from a number of renewable resources. Oleaginous microorganisms can convert biomass sugars into lipids up to more than 20% of their dry mass. The lipogenesis process is triggered by specific culture conditions, namely nitrogen, phosphate or sulphate limitations.
The aim of this thesis is to analyze the metabolic features of Cutaneotrichosporon oleaginosus, an oleaginous yeast with several favourable qualities: it is fast growing, it accumulates high amounts of lipid and has a very broad substrate spectrum. Its resistance to hydrolysis by-products and genetic accessibility make it a promising Cell Factory for custom tailored microbial oils. C. oleaginosus can accumulate up to 60% of its biomass as lipids, and several studies in the literature have optimized fermentation conditions to accumulate over 70% of its biomass as lipids.
This work focused on the state of the art about innovative and sustainable biorefinery schemes involving the promising yeast C. oleaginosus. This species is able to grow by using as a substrate several compounds such as acetic acid, biodiesel-derived glycerol, aromatic compounds, N-acetylglucosamine (a by-product from the fish sector), cheese whey permeate, amino-rich wastes, agro-industrial waste, wastepaper and activated sludge. Finally, the main engineering techniques of C. oleaginosus were reported as further improvement of the strain to produce microbial lipids. To conclude, this work highlights the great metabolic capacities of this yeast and the possible engineering processes as a further step towards an increasingly sustainable production of a new generation oil.