Minimization of glycerol synthesis in industrial ethanol yeast without influencing its fermentation performance
Minimization of glycerol synthesis in industrial ethanol yeast without influencing its fermentation performance
复制标题
最大限度地减少工业乙醇酵母中的甘油合成而不影响其发酵性能
DOI：
10.1016/j.ymben.2010.11.003
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发表时间：
2011-01-01
影响因子：
8.4
通讯作者：
Shi, Gui-yang
中科院分区：
文献类型：
--
作者：
Guo, Zhong-peng;Zhang, Liang;Shi, Gui-yang
为了合成甘油（乙醇厌氧生产过程中的主要副产物），酿酒酵母（Saccharomyces cerevisiae）在典型的工业乙醇工艺中将消耗高达4%的糖原料。本研究致力于在不影响其理想的发酵特性，包括高渗透和乙醇耐受性，工业过程中的天然鲁棒性的情况下，主要降低工业乙醇生产酵母中的甘油产量。在本研究中，GPD 1基因，编码NAD（+）依赖的甘油-3-磷酸脱氢酶的工业乙醇产生菌株的S。cerevisiae，被删除。同时，非磷酸化NADP（+）依赖性甘油醛-3-磷酸脱氢酶（GAPN）从蜡状芽孢杆菌中表达的突变缺失的GPD 1。虽然所得菌株AG 1A（gpd 1 Delta P-PGK-gapN）与野生型菌株相比显示出48.7 +/-0.3%（相对于消耗的底物量）的低甘油产率和7.6 +/-0.1%（相对于消耗的底物量）的高乙醇产率，但其对渗透胁迫敏感并且不能在25%葡萄糖上发酵。然而，当海藻糖合成基因TPS 1和TPS 2在上述重组菌株AG 1A中过量表达时，其高渗胁迫耐受性不仅得到恢复，而且得到提高。此外，这种新的重组酵母菌株在厌氧分批发酵中与野生型相比，在可区分的最大比生长速率（mu（max））和发酵能力方面显示出进一步降低的甘油产率。这项研究提供了一个有前途的策略，以提高乙醇产量最小化甘油生产。(C)2010年爱思唯尔公司All rights reserved.
To synthesize glycerol, a major by-product during anaerobic production of ethanol, the yeast Saccharomyces cerevisiae would consume up to 4% of the sugar feed stock in typical industrial ethanol processes. The present study was dedicated to decreasing the glycerol production mostly in industrial ethanol producing yeast without affecting its desirable fermentation properties including high osmotic and ethanol tolerance, natural robustness in industrial processes. In the present study, the GPD1 gene, encoding NAD(+)-dependent glycerol-3-phosphate dehydrogenase in an industrial ethanol producing strain of S. cerevisiae, was deleted. Simultaneously, anon-phosphorylating NADP(+)-dependent glyceraldehyde-3-phosphate dehydrogenase (GAPN) from Bacillus cereus was expressed in the mutant deletion of GPD1. Although the resultant strain AG1A (gpd1 Delta P-PGK-gapN) exhibited a 48.7 +/- 0.3% (relative to the amount of substrate consumed) lower glycerol yield and a 7.6 +/- 0.1% (relative to the amount of substrate consumed) higher ethanol yield compared to the wild-type strain, it was sensitive to osmotic stress and failed to ferment on 25% glucose. However, when trehalose synthesis genes TPS1 and TPS2 were over-expressed in the above recombinant strain AG1A, its high osmotic stress tolerance was not only restored but also improved. In addition, this new recombinant yeast strain displayed further reduced glycerol yield, in distinguishable maximum specific growth rate (mu(max)) and fermentation ability compared to the wild type in anaerobic batch fermentations. This study provides a promising strategy to improve ethanol yields by minimization of glycerol production. (C) 2010 Elsevier Inc. All rights reserved.