Development of a microbial platform for the production of Monoethylene glycol from biorenewable sources

• Grant number: 22/01696-8
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Effective date (Start): May 01, 2023
• Effective date (End): March 31, 2027
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Leandro Vieira dos Santos
• Grantee: Ícaro Fier
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

The exploration of lignocellulosic biomass (2G) as an alternative energy source for the production of high value-added bioproducts, and the mitigation of greenhouse gases derived from fossil fuels is a global consensus. However, for the production of bioproducts from 2G sources, a robust microbial platform capable of surviving the extreme conditions present in hydrolysates is essential. The yeast Saccharomyces cerevisiae is widely used in industrial environments, due to its greater resistance to these conditions. However, in addition to consuming glucose (C6), it is necessary for the yeast to be able to metabolize xylose (C5) efficiently. Currently, there are modified strains of S. cerevisiae capable of metabolizing xylose with yields close to the theoretical maximum. However, the amount of xylose is still a bottleneck, due to the canonical preference and higher affinity for glucose. It is necessary to develop modified xylose transporters to enable the efficient co-assimilation of these two sugars aiming at the conversion into bioproducts. Monoethylene glycol (MEG) is an important chemical for the industry, due to its physicochemical characteristics that make it versatile, mainly as a raw material for the production of PET. Currently, the production of MEG is done via fossil derivatives, making its production from biorenewable materials of scientific and industrial interest. To date, three biosynthetic routes have stood out for the production of MEG in the literature. However, MEG production by S. cerevisiae still reaches low levels, reaching a maximum titer of 4 g/L. Therefore, this project will be divided into two main stages aiming at the construction of an efficient microbial platform in the conversion of agro-industrial residues into MEG: (a) development of new specific transporters, through adaptive evolution and directed evolution approaches, for the creation of a microbial platform capable of co-assimilating glucose and xylose simultaneously uncoupling cell growth (C6 pathway) and MEG production (C5 pathway), and (b) optimizing Monoethylene glycol (MEG) production by S. cerevisiae, through optimization of heterologous biosynthetic pathways using iterative approaches of metabolic engineering and rational design, such as building a Genomic Scale Metabolic Model for MEG production; the construction of combinatorial expression libraries to fine-tune the expression of each gene; the development of a genetically modified biosensor and high-throughput screening of MEG overproducing strains; metabolomics analyzes to identify bottlenecks in metabolic flow; and production of MEG in the sugar mixture and in 2G hydrolyzate. In this way, it is expected that the final grade of MEG produced after the engineering of the strain will be competitive and allow the creation of a robust and efficient microbial platform in the conversion of agro-industrial residues into renewable, sustainable bioproduct with high added value. (AU)