Reduced acetaldehyde production by genome shuffling of an industrial brewing yeast strain

Abstract

High levels of acetaldehyde produced by yeast during fermentation can be of concern to product quality. A novel approach, based on genome shuffling, was applied to reduce the production of acetaldehyde by industrial brewing strain YS86. Four isolates with different impacts of acetaldehyde concentration were obtained from populations generated by ultraviolet irradiation and nitrosoguanidine mutagenesis. These yeast strains were then subjected to recursive pool‐wise protoplast fusion. A strain library that was likely to yield positive colonies was created by fusing the lethal protoplasts obtained from both UV irradiation and heat treatments. After two rounds of genome shuffling, a recombinant YSF2–9 strain produced less acetaldehyde than wild‐type strain YS86, by 64.5 and 66.2% in laboratory and pilot plant fermentations, respectively. The shuffled yeast strain YSF2–9 was genetically stable and may have a potential application in brewing industry for managing acetaldehyde in beer. Copyright © 2017 The Institute of Brewing & Distilling

Yeast Metabolism and Its Exploitation in Emerging Winemaking Trends: From Sulfite Tolerance to Sulfite Reduction

“…A mutant strain, obtained by inhibiting the activity of alcohol dehydrogenase 2 (ADH2) through UV mutagenesis and using a competitive ADH2 inhibitor (4-Methylpyrazole) as a selection marker, produced about 10 mg/L of acetaldehyde [89]. Yin et al [90] obtained an isolate producing 3.9 mg/L of acetaldehyde by using a genome shuffling protocol. Recently, a reverse engineering strategy was used to modify the redox state of the cell (NADH/NAD+), resulting in a strain with 45% lower acetaldehyde production than that of the parental strain [91].…”