FTIR characterization of stress response to acetic acid in Saccharomyces cerevisiae cells. Role of MCR1 to counteract the oxidative stress

Abstract

Saccharomyces cerevisiae cells are widely employed as microbial factories for the production of bioethanol through the alcoholic fermentation. One of the main bottlenecks of the process is the formation of toxic metabolites, such as acetic acid, that can inhibit the production pathway. In order to increase the final yield, the biotechnology industry is looking for the optimal conditions to carry out the fermentation process. In this project, we studied the infrared response of S. cerevisiae cells exposed to acetic acid. In particular, we investigated whether the overexpression of MCR1 - a gene involved in the response to oxidative stress - makes the cells more resistant to the acetic acid. We found that in the exponential phase of growth cells engineered with the MCR1 seem to counteract the effects of acetic acid by decreasing membrane fluidity, mainly through the dramatic reduction of phosphatidylcholine and the increase of ergosterol. However, interestingly, in the stationary phase of growth the MCR1 gene seemed to be mainly involved in the prevention of oxidative stress due to aging.