A multiomic-based analysis of Rhodosporidium fluviale LM-2 yeast for lignin biocatalytic valorization

Author(s)

Nathalia Vilela

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2022-05-13

Examining board members

Fabio Marcio Squina; João Ricardo Moreira de Almeida; Thiago Olitta Basso; Elizabeth Bilsland; Marcelo Mendes Brandão

• Advisor: Fabio Marcio Squina; André Ricardo de Lima Damásio

Abstract

Currently, the search for renewable sources of energy and raw material is constant, due to recurrent environmental, economic, and social problems resulting from the continuous use of fossil fuels. The use of lignocellulosic biomass, in turn, presents itself as a sustainable opportunity, aiming at the production of biofuels through the fermentation of cellulose and hemicellulose and the possible valorization of lignin to produce compounds with high added value. However, the use of lignin is still limited, and it is usually burned for energy. Lignin is a polymer with a complex structure composed of several aromatic compounds, such as ferulic acid. Some microorganisms have ligninolytic enzymes responsible for the depolymerization of lignin, as well as the assimilation and conversion of aromatic compounds. Discovering new ligninolytic strains and understanding their enzyme system is essential to improve lignin valorization. In this sense, this work characterized a yeast isolated from a microbial consortium cultured with lignin fragments. This yeast, called Rhodosporidium fluviale LM-2, has a genome of 50.7 Mb with 17,942 genes. Among the protein-coding genes, there is the presence and overexpression of ligninolytic enzymes, such as peroxidases and beta-etherase, as well as enzymes related to the metabolism of aromatic compounds, such as phenolic acid decarboxylase (PDC). This enzyme converts ferulic acid into 4-vinyl guaiacol (4-VG), a high value-added compound used in the food industry. Thus, aiming at a biotechnological application, two genes (Rf_PDC_A and Rf_PDC_B) from R. fluviale LM-2 that encode the PDC enzyme were selected for expression in the yeast model Saccharomyces cerevisiae. The recombinant strain S. cerevisiae Ethanol Red™ expressing the Rf_PDC_B gene increased 4-VG production compared to the parental strain when cultivated in rich medium containing ferulic acid and in minimal medium containing lignocellulosic biomass hydrolyzate. In summary, a combination of omics strategies described important enzymatic pathways for lignin degradation, one of which was applied to the production of bioproducts from agro-industrial residues (AU)

• FAPESP's process: 17/08166-6 - Genetic engineering of yeast for conversion lignocellulosic material to ferulic acid
• Grantee: Nathália Vilela
• Support Opportunities: Scholarships in Brazil - Doctorate