• lignin
• yeasts
• enzymatic hydrolysis
• fermentation
• biodiesel
• biomass
• catalysis
• green chemistry

The transition from a fossil-based economy to a bio-based economy is a current global goal in order to contrast some important issues, such as climate change and environmental pollution, and to reduce the dependency on fossil sources as well. Thus, the replacement of fossil-based fuels and materials with biofuels and bioproducts is a key solution.
Among biofuels, biodiesel represents one of the most promising renewable energy sources since it does not require new technology and engines for its use. Traditional biodiesel is produced on the industrial scale starting from vegetable oils obtained from oleaginous crops. However, most of the oleaginous plant species are food crops, thus determining the ethical debate on the right use of these renewable resources and the competition between the energy industry and food chain.
In this context, an innovative and promising solution is represented by new generation biodiesel, produced from microbial oil or single cell oil. Some oleaginous yeasts can accumulate lipids over 20% of their dry cell weight and the typical lipids profile of SCOs is very similar to that of the main vegetable oils such as palm, rapeseed and sunflower oil.
The main aim of this thesis was the investigation and the optimisation of synergistic combinations of chemical and biological catalytic approaches, in order to develop a sustainable biorefinery model based on the Green Chemistry principles and characterised by a potential industrial application. In particular, the implemented catalytic strategies aimed to maximise the valorisation of each fraction of the starting biomass, which requires tailored reaction conditions in terms of temperature, reaction time, biomass concentration and catalyst amount.