Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Instituto Superior Técnico, Technical University of Lisbon, Lisboa, Portugal.
PLoS One. 2013;8(2):e55439. doi: 10.1371/journal.pone.0055439. Epub 2013 Feb 8.
A metabolomic analysis using high resolution 1H NMR spectroscopy coupled with multivariate statistical analysis was used to characterize the alterations in the endo- and exo-metabolome of S. cerevisiae BY4741 during the exponential phase of growth in minimal medium supplemented with different ethanol concentrations (0, 2, 4 and 6% v/v). This study provides evidence that supports the notion that ethanol stress induces reductive stress in yeast cells, which, in turn, appears to be counteracted by the increase in the rate of NAD+ regenerating bioreactions. Metabolomics data also shows increased intra- and extra-cellular accumulation of most amino acids and TCA cycle intermediates in yeast cells growing under ethanol stress suggesting a state of overflow metabolism in turn of the pyruvate branch-point. Given its previous implication in ethanol stress resistance in yeast, this study also focused on the effect of the expression of the aquaglyceroporin encoded by FPS1 in the yeast metabolome, in the absence or presence of ethanol stress. The metabolomics data collected herein shows that the deletion of the FPS1 gene in the absence of ethanol stress partially mimics the effect of ethanol stress in the parental strain. Moreover, the results obtained suggest that the reported action of Fps1 in mediating the passive diffusion of glycerol is a key factor in the maintenance of redox balance, an important feature for ethanol stress resistance, and may interfere with the ability of the yeast cell to accumulate trehalose. Overall, the obtained results corroborate the idea that metabolomic approaches may be crucial tools to understand the function and/or the effect of membrane transporters/porins, such as Fps1, and may be an important tool for the clear-cut design of improved process conditions and more robust yeast strains aiming to optimize industrial fermentation performance.
采用高分辨 1H NMR 光谱结合多元统计分析的代谢组学分析，用于表征在补充不同乙醇浓度（0、2、4 和 6%v/v）的最小培养基中生长的酿酒酵母 BY4741 指数生长期的内代谢物和外代谢物的变化。这项研究提供的证据支持了这样一种观点，即乙醇胁迫会诱导酵母细胞产生还原性应激，而这种应激似乎又被 NAD+再生生物反应速率的增加所抵消。代谢组学数据还表明，在乙醇胁迫下生长的酵母细胞中，大多数氨基酸和 TCA 循环中间产物的细胞内和细胞外积累增加，表明在丙酮酸分支点处出现了溢出代谢的状态。鉴于其先前在酵母乙醇胁迫抗性中的作用，本研究还重点研究了在不存在或存在乙醇胁迫的情况下，由 FPS1 编码的 aquaglyceroporin 的表达对酵母代谢组的影响。本文收集的代谢组学数据表明，在不存在乙醇胁迫的情况下，FPS1 基因的缺失部分模拟了亲本菌株中乙醇胁迫的作用。此外，研究结果表明，报道的 Fps1 在介导甘油的被动扩散中的作用是维持氧化还原平衡的关键因素，氧化还原平衡是乙醇胁迫抗性的一个重要特征，并且可能干扰酵母细胞积累海藻糖的能力。总的来说，获得的结果证实了这样一种观点，即代谢组学方法可能是理解膜转运体/孔蛋白（如 Fps1）功能和/或作用的关键工具，并且可能是设计改进的工艺条件和更稳健的酵母菌株的重要工具，旨在优化工业发酵性能。
