Mapeamento de QTL de características relacionadas à robustez fermentativa da linhagem industrial Pedra-2 (Saccharomyces cerevisiae)

Author(s)

Alessandro Luis Venega Coradini

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2019-07-02

Examining board members

Gonçalo Amarante Guimarães Pereira; Thiago Olitta Basso; Marcelo Mendes Brandão; Sandra Regina Ceccato Antonini; Anderson Ferreira da Cunha

• Advisor: Gonçalo Amarante Guimarães Pereira

Abstract

Renewable fuels, such as bioethanol, have attracted a growing attention in recent decades due to their potential as a substitute for fossil fuels. In fact, the rising concerns about environmental consequences arising from the use of fossil based fuels accelerated the necessity of increment renewable fuels production. In this context, industrial yeasts have attracted attention of research groups and biotechnology companies, since are considered excellent backgrounds for development of new bioproducts. Among these industrial yeasts we highlight the industrial strain Pedra-2 (PE-2), widely used in Brazilian ethanol mills due its high productivity and ability to tolerate stress conditions typically found in industry. Although the genomic analysis of PE-2 strain has shed lights about the relation between its genomic structure and its prevalence on fermentation vessels of Brazilian ethanol mills, the genetic basis of its robustness remains unclear and it knowledge may contribute to create more productivity strains. Thus, in this study we use a Quantitative trait loci (QTLs) analysis approach to unravel the genetic basis of JAY270 strain (PE-2 derived) resistance to oxidative and low pH stress typically found during 1G fermentation process. First, we developed high-throughput approaches that allow us to isolate and phenotype a large number of JAY270 segregants on oxidative stress (8mM H2O2) and low pH (pH=2.1) conditions. Then, by using a bulk segregant analysis (BSA) approach the major QTLs associated with each trait were mapped. For oxidative stress condition a genome-wide comparison of single-nucleotide polymorphism (SNP) profiles between two bulks of segregants allowed the identification of three main regions on chromossomes II, IV and XV. At these regions, based on SNP effect and frequency at S. cerevisiae sequenced population, we selected 9 main candidate genes - ADH1, HAL9, DUF1, MDM20, FTH1, YBP1, SNO2, MET8 and KCS1. Interesting, all of these genes have been already related to tolerance of oxidative stress in yeasts, which corroborates with our findings. The same analysis was carried out for low pH tolerance and two regions located on chromosomes X and XIII were identified and 7 genes selected as candidates - SOP4, MNN5, MNN11, GAS1, TGL3, GLC8 and DIA1. By applying the Reciprocal hemizygosity analysis (RHA) we were able to solve the major QTL located on chromosome XIII to gene level and found the GAS1 allele as the main responsible for PE-2 tolerance to low pH. Finally, these results provide important information about the genetic basis of two industrial relevant traits – oxidative stress and low pH tolerance - that could help the development of more productivity strains for biochemical and biofuels production process (AU)

• FAPESP's process: 14/26719-4 - Quantitative trait loci mapping of traits related to robustness in industrial yeast Pedra-2 (Saccharomyces cerevisiae)
• Grantee: Alessandro Luis Venega Coradini
• Support Opportunities: Scholarships in Brazil - Doctorate