The world energy matrix is based on the use of fossil fuels such as coal, gas and oil. However, in the last decades the worldwide community has expressed intense concern about the consequences caused by the use of these compounds, such as the increase of greenhouse gases emission. The second-generation ethanol (2G) from lignocellulosic biomass appears with a great potential of alternative energy production from a cleaner and renewable matrix. One of the major challenges in implementing this technology is the development of a robust microorganism capable to convert sugars from lignocellulosic materials into ethanol. Recently, our group developed a modified S. cerevisiae strain with high capacity to ferment the five-carbon sugar xylose, present in abundance in the lignocellulosic biomass. However, a major technological bottleneck in the 2G fermentation is the extensive time to consume xylose compared to glucose. Xylose is only assimilated after the majority consumption of glucose by the microorganism, caused by a competition of the sugar molecules to the yeast transporters, which have a higher affinity for glucose. There are few studies that covers this issue and no efficient transporter has been developed to solve this technological challenge. The principle of this project is the development of a strain with efficient co-fermentation on xylose and glucose, reducing the total time of 2G fermentation. For strain development, we will use the CRISPR-Cas9 methodology to delete three genes that encode hexokinases genes in two xylose fermenter strains developed by our group. The strains will be submitted to an adaptive evolution process in order to promote and identify mutations in sequences of sugar transporters and other genetic features that increase the affinity and transport xylose even in the presence of glucose, allowing the co-fermentation and decreasing the time of fermentation process.
News published in Agência FAPESP Newsletter about the scholarship: