This study aimed to determine the ethanol, by-product such as acetic acid and propionic acid during alcoholic fermentation in S. cerevisiae yeast strain FY73 by GC. Furthermore, genes related to acetic acid stress response were also studied by real-time quantitative PCR. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get original essay 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 (proton release leads to essential metabolic functions (Krebs et al. 1983), inhibition of glycolysis (Pearce, Booth, and Brown 2001), and reduction of the cellular ability to generate ATP (P. Piper et al. 1998). S. cerevisiae has been used to study many cellular stress responses. Many genes have been shown to play a role in stress adaptation, including PDR12 which encodes the ABC transporter, which is important for the adaptation of yeast cells to growth in 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 longer-chain acids, such as sorbic, propionic acid. and levulinic (Nygård et al. 2014). CTT1 has been correlated with reduced ROS levels and increased specific growth rates in the presence of high lactic acid concentrations (Abbott et al. 2009). Get a custom paper from our expert writers now. Get Custom Essay Lignocellulosic biomass present in abundance around agricultural areas is rapidly becoming a major source of bioethanol because it is abundant, renewable and non-competitive with food resources. However, many inhibitors that are toxic to the growth of microorganisms, such as acetic acid, formic acid and furfural, are usually generated after pretreatment (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 use of bioethanol increases every year as it is a sustainable and environmentally friendly energy. While fossil fuels cause many problems such as environmental pollution and global warming. This led to the discovery of inexpensive raw materials for bioethanol production (Mohd Azhar et al. 2017).