Improving second-generation biofuel production: exploiting the natural diversity of S. stipitis

Human activity is driving a global climate crisis and fossil fuels need to be replaced with renewable energy. Second generation biofuels, generated from forestry and agriculture waste, have great potential to replace petroleum-based fuels.

This is because biomass is a renewable resource and have, after combustion, a theoretical net null CO2 emission. However, production of second-generation biofuels is still inefficient and faces important challenges as Saccharomyces cerevisiae, the most heavily used organism for ethanol production, cannot ferment pentose sugars (i.e. xylose) found in large concentration in agriculture and forestry waste. This PhD project focuses one of the most promising second generation bioethanol producer: the yeast Scheffersomyces stipitis. Contrary to S. cerevisiae, S. stipitis ferments both pentose and exose sugars. To date, only few S. stipitis strains have been tested for bioethanol production and it is clear that the use of these stains is not suited to large industrial production as their performance is suboptimal.

Our hypothesis is that novel yet uncharacterised S. stipitis natural isolates possess characteristics that can be exploited for bioethanol production. To test this hypothesis we have collected S. stipitis natural strains sampled from different geographical locations. In this cross-disciplinary project the PhD student will combine Microbiology, Biotechnology, Robotics, Genetics, Genomics and Bioinformatics to identify novel S. stipitis natural isolates that are superior bioethanol producers (Objective 1 in Collaboration with Singer Instruments) and to determine the genetic drivers leading to improved bioethanol production (Objective 2 in Collaboration with NIAB-EMR). Outcomes: This project will lead to the identification of S. stipitis strains that are superior bioethanol producers. These isolates are ideal candidates for industrial implementation.