Study of gene expression of hsp26 and yhr087w and its relation to temperature and ethanol tolerance in strains of Saccharomyces cerevisiae isolated during the production of ethanol

• Grant number: 13/15097-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2013
• End date: December 31, 2014
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Anderson Ferreira da Cunha
• Grantee: Érica Lima Marçal
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

For environmental reasons and mainly due to a possible shortage of fossil fuels, many countries have invested in renewable energy sources that can replace this energy matrix in a sustainable way. In this sense, Brazil is investing effort in the production of ethanol. Production of this fuel is made through the fermentation of must (sugar cane syrup or molasses diluted) by yeast Saccharomyces cerevisiae species. During this process, these microorganisms are commonly subjected to several stresses such as high temperatures and high concentrations of ethanol. The yeast currently used in the production of ethanol does not exhibit significant resistance to these stress factors. Then temperature and concentration of ethanol need to be controlled. The identification of the genes which promote resistance is crucial for increasing the efficiency of the process. Using yeast able of act under high temperatures and high concentrations of ethanol would be possible to start the process with higher sugar concentration and higher temperatures. This contributes, consequently, to increase the production of ethanol and decrease the contamination inside the vat. This project aims to determine genetic hypotheses able to reduce such stress and promote improvements in ethanol production. Genes that were found in the literature with interesting characteristics for this study were HSP26 and YHR087W. The first is responsible for encoding heat shock proteins (HSPs) which has chaperone activity, i.e., their role is to prevent important proteins denature and lose their functions. The second gene expression is induced in high glucose concentrations, and other studies suggest that this gene can be activated in oxidative stress, osmotic and thermal shock. The expression of these genes is studied in selected strains, which shows characteristics as ethanol resistance as well heat resistance, in order to relate its expression to these stressors. In case of a positive correlation, these genes are used in overexpression experiments on strains sensitive to these conditions and have adapted to industrial fermentation process is to identify those strains become resistant to these factors. The results of this study will lead to a better understanding of the relationship between the expression of these genes with ethanol resistance and thermotolerance, assisting in the development of yeast that can increase the fermentation process, contributing to the establish a extremely strategic area for Brazil. (AU)