The Acetic Acid Stress Response in Yeast Saccharomyces Cerevisiae During Alcoholic Fermentation

This study aimed to determine ethanol, by-product such as acetic acid and propionic acid during alcoholic fermentation in yeast S. cerevisiae FY73 strain by GC. Moreover, genes related to acetic acid stress response were also studied via quantitative realtime-PCR.

Acetic acid is a potent fermentation inhibitor that causes intracellular acidification, growth arrest, and reduced ethanol productivity in S. cerevisiae (Graves et al. 2006). At low pH (

The release of protons leads to essential metabolic functions (Krebs et al. 1983), inhibition of glycolysis (Pearce, Booth, and Brown 2001) and reduction of the cell ability to generate ATP (P. Piper et al. 1998). S. cerevisiae has been used to study many cellular stress responses. Many genes are shown to play roles in stress adaptation, including PDR12 encodes the ABC transporter which important for the adaptation of yeast cells to grow in the presence of lipophilic weak acid preservatives, and pdr12Δ mutants are hypersensitive to lipophilic acids at low pH (Holyoak et al. 1999). Overexpression of PDR12 increased tolerance to acids with longer chain length, such as sorbic, propionic and levulinic acid (Nygård et al. 2014). Overexpression of CTT1 was correlated with decreased levels of ROS and increased specific growth rates in the presence of high lactic acid concentrations (Abbott et al. 2009).

Lignocellulosic biomass present in abundance around agricultural area which rapidly becoming a major source of bioethanol because they are abundant, renewable, and uncompetitive with food resources. However, after pretreatment usually generates many inhibitors that toxicity to microorganism growth, such as acetic acid, formic acid, and furfural (Fernandes et al. 2005). Acids cause energy depletion, inhibition of metabolic enzyme activity, growth arrest and ethanol productivity losses in S. cerevisiae (Geng, Zhang, and Shi 2017). The utilization of bioethanol is increasing every year as it is sustainable energy and environmentally friendly. While fossil fuels cause many problems such as environmental pollution and global warming. These led to the finding of inexpensive raw material for bioethanol production (Mohd Azhar et al. 2017).