Prospecting genes in extremo-tolerant organisms for engineering high inhibitor tolerance in Saccharomyces cerevisiae

• Grant number: 23/02589-3
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2024
• End date: January 31, 2026
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Elizabeth Bilsland
• Grantee: Elizabeth Bilsland
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated researchers: Leandro Vieira dos Santos ; Per Sunnerhagen

Abstract

The current global energy matrix continues to rely heavily on fossil fuel-based energy sources, leading to increased impact on climate change. Increase awareness of the problem has led to a major shift towards developing cleaner and renewable technologies. In this context, microbial cellular platforms have been engineered to efficiently produce biofuels and biochemicals from lignocellulosic biomass (second generation - 2G), and have moved from solely focusing on ethanol to the production of a wide variety of biorenewable high value products. However, 2G technologies have come at a cost: a wide variety of Lignocellulosic Hydrolysate (LCH) inhibitors that affect fermentation, decreasing its efficiency. This has pushed the genetic engineering of new strains of Saccharomyces cerevisiae to increase its resistance to LCH, which are a series of chemical compounds released during the pre-treatment of lignocellulosic biomass. The three main classes of LCH are furans, phenolics and organic acids. These inhibitors can induce several stress responses, such as decrease of cellular pH and ATP levels, inhibition of DNA synthesis and repair, inhibition of enzyme synthesis and activity, and others. Engineering higher LCH tolerance has historically been done through adaptive laboratory evolution, which takes time and does not always guarantee favourable results. An alternative approach is the prospecting of genes in extremotolerant organisms and transfer those to S. cerevisiae to increase its resistance and, thus, its fermentation efficiency. Extremo-tolerant organisms are known for their ability to thrive in environments once thought to be uninhabitable. Tardigrades, for example, are micro-animals known for surviving in a wide variety of extreme environments. An extensive array of microorganisms can also thrive in environments with extreme temperature, pH, and toxic chemical compounds. To identify genes that could potentially afford S. cerevisiae resistance to different classes of LCH inhibitors, the focus of this project will be to prospect genes in extreme-tolerant organisms such as tardigrades or microbiomes found in environments with extreme conditions. Creating cDNA libraries of extremophiles for overexpression in yeast, followed by high-throughput screening, we expect to identify novel genes, which encode proteins able to improved tolerance levels, such as DNA damage repair proteins, membrane integrity and stability, and that buffer the host's intracellular pH. The end goal of the project is to identify novel genes and molecular mechanisms associated with improved tolerance in extremo-tolerant organisms and to engineer robust industrial yeast strains that are tolerant to LCH inhibitors. (AU)