The Impact of Transcriptional Factors Znf1 and Sip4 on Xylose Alcoholic Fermentation in Recombinant Strains of Yeast Sac
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Impact of Transcriptional Factors Znf1 and Sip4 on Xylose Alcoholic Fermentation in Recombinant Strains of Yeast Saccharomyces cerevisiae L. S. Dzanaevaa, J. Ruchalab, A. A. Sibirnya, b, and K. V. Dmytruka, * aInstitute
of Cell Biology, National Academy of Sciences of Ukraine, Lviv, 79005 Ukraine b University of Rzeszow, Rzeszow, 35-601 Poland *e-mail: [email protected]
Received March 10, 2020; revised March 24, 2020; accepted September 18, 2020
Abstract—In recent years, the demand for technical ethanol has increased due to its use in the transport sector. Xylose is the major five-carbon sugar obtained as a result of lignocellulose hydrolysis; however, the industrial producer of alcohol S. cerevisiae yeast ferments exclusively hexoses. Based on a recombinant strain capable of xylose metabolism, the derivatives with increased expression of the ZNF1 gene and deletion of the SIP4 gene encoding transcription factors were constructed. It was found that overexpression of the ZNF1 gene did not affect the fermentation of glucose or xylose. The deletion of the SIP4 gene did not affect the fermentation of glucose but resulted in a 29% decrease in ethanol production during xylose fermentation in comparison with the parental strain. Keywords: transcription factors, S. cerevisiae, gene expression, xylose, alcoholic fermentation DOI: 10.3103/S0095452720050035
INTRODUCTION Plant biomass is the most common renewable resource on the planet and is an alternative to refined products. The product of its biotechnological conversion, ethanol, is used as an additive to gasoline-ethanol mixtures or in pure form in specialized engines. Emissions from combustion engines contain dangerous anthropogenic pollutants causing changes in ecosystems, and CO2 emissions exacerbate the greenhouse effect; therefore, ethanol combustion has advantages for environmental reasons. Analytical calculations indicate that pure ethanol has better antiknock properties and, therefore, it is possible to use it in powerful power plants with a high degree of compression, increasing the efficiency. [1]. Almost all ethanol is now obtained by microbial fermentation involving S. cerevisiae initiating alcoholic fermentation from traditional raw materials, which are hydrolysates of starch and sugar (sucrose), obtained by processing food crops. The production of ethanol from inedible raw material, cellulose-containing waste from the agriculture and wood-processing industries, is obstructed by the complexity of the lignocellulosic structure. It consists of three main components: carbohydrate polymers— cellulose comprising 45%, hemicellulose comprising 30%, and aromatic heteropolymer lignin comprising 25%. Lignocellulose fermentation is carried out in
several technological stages, which include pretreatment, hydrolysis, and fermentation. Xylose is a major five-carbon sugar, which is obtained by hydrolysis and the second largest monosaccharide after glucose. Some organisms have a natural ability to ferment it, but the level of ethanol synthesis is very low [2]. In additio
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