Prof. Dr. Zeynep Petek Çakar's research group at ITU has been successfully improving resistance of yeast cells to various industrial stress types. For this purpose, the research group has been employing the highly effective inverse metabolic engineering approach known as adaptive laboratory evolution or evolutionary engineering. The stress responses and resistance exhibited by yeast cells during the evolutionary engineering process alter their typical physiological behavior. It is imperative to identify the metabolic and molecular differences between the original and evolved yeast cells to develop microorganisms that exhibit improved characteristics relevant to industrial applications.

In this recent international collaborative study published by the prestigious international journal Frontiers in Microbiology (a Q1 journal according to Scopus index and Web of Science), Prof. Çakar’s group and her collaborators (the research group of Prof. Dr. Jean Marie François, Toulouse Biotechnology Institute, University of Toulouse, France) developed a 2-phenylethanol-resistant Saccharomyces cerevisiae yeast strain by evolutionary engineering and characterized the evolved yeast at the genomic, transcriptomic and metabolic levels. 2-Phenylethanol is a commonly used aromatic compound in the food, cosmetic, and pharmaceutical industries. Microbial fermentation is being explored as a sustainable way to produce this compound, but its high toxicity to the producing microorganism poses a challenge. Thus, yeast strains that can produce and tolerate high levels of 2-phenylethanol are highly desirable. In this study, the evolved S. cerevisiae strain had three-fold improved tolerance to 2-phenylethanol. The results revealed that the evolved strain acquired a physiological state described as the environmental stress response (ESR). This stressful state of the evolved strain may be associated with a mutation found in its HOG1 gene leading to a hyperactive MAPKinase, activating the Msn2/4p transcription factor. Additionally, the transcriptional activation of ALD3 gene encoding a NAD⁺ -dependent aldehyde dehydrogenase that is responsible for the oxidation of 2-phenylacetaldehyde into the less toxic 2-phenylacetate may be the mechanism for reducing the 2-phenylethanol toxicity in yeast.

For further information:

https://doi.org/10.3389/fmicb.2023.1148065

Holyavkin C, Turanlı-Yıldız B, Yılmaz Ü, Alkım C, Arslan M, Topaloğlu A, Kısakesen Hİ, de Billerbeck G, François JM and Çakar ZP (2023). Genomic, transcriptomic, and metabolic characterization of 2-Phenylethanol-resistant Saccharomyces cerevisiae obtained by evolutionary engineering. Front. Microbiol. 14:1148065. doi: 10.3389/fmicb.2023.1148065