Fine regulation of genes involved in important phenotypes in S. cerevisiae for second generation ethanol production

Abstract

Agro-industrial residues rich in lignocellulosic material are an attractive alternative to increase the yield on bioethanol production from biomass, while decreasing the carbon footprint of the fuel production chain. Saccharomyces cerevisiae yeast is the microorganism of choice for cellulosic ethanol production due to its industrial robustness and fermentative power, although it does not naturally metabolize pentoses. Metabolic engineering has traditionally been used to give S. cerevisiae the ability to convert xylose into ethanol efficiently. Despite the efforts, there is still room for improvement of productivity in the strains used, which has motivated a range of scientific research. Among the possibilities of genetic improvement, the alteration of metabolic flow in the xylose consumption route and reverse engineering to improve the response to industrial stresses are options explored in S. cerevisiae. In this sense, the project proposed here aims at regulating target genes important for the second generation (2G) industry, which are: i) XKS1, involved in the Pentose Phosphate pathway and essential for metabolization of xylose; and ii) PKC1, participant of the Cell Wall Integrity pathway, and described as a regulator of thermotolerance - phenotype required for commercial strains. Different promoters will be tested to regulate the expression of XKS1, motivated by transcriptome performed on yeast used in the 2G industrial process; while different mutations in PKC1 will be validated for their relationship with response to thermal stress. Together, the genotypes studied contribute to the viability of a non-fossil fuel industry.(AU)