Departamento de Bioquímica y Biología Molecular, Universitat de València, Valencia, Spain.
Int J Food Microbiol. 2010 Jan 1;136(3):295-303. doi: 10.1016/j.ijfoodmicro.2009.10.018. Epub 2009 Oct 28.
The tolerance of the yeast Saccharomyces cerevisiae to desiccation is important for the use of this microorganism in the wine industry, since active dry wine yeast is routinely used as starter for must fermentations. Many studies have shown the complexity of the cellular effects caused by water loss, including oxidative injuries on macromolecular components. However the technological interest of yeast drying was not addressed in those studies, and the dehydration conditions were far from the industrial practice. In the present study a molecular approach was used to characterize the relevant injuring conditions during pilot plant dehydration under two different drying temperatures (i.e., 35 and 41 degrees C). We have analyzed expression changes for several stress gene markers and we have determined two biochemical redox indicators (glutathione and lipid peroxidation levels) during pilot plant dehydration to produce active dry biomass, according to the standard practice in industry. The main gene expression response involves the induction of genes TRR1 and GRX5, corresponding to the two main redox balance systems, thioredoxins and glutathione/glutaredoxins. Elevated glutathione content and significant lipid peroxidation damage indicate the physiological impact of the oxidative stress on cellular components. The comparison between commercial stocks and pilot plant samples demonstrate the suitability of the molecular approach at the pilot plant scale to study physiological traits of industrial yeast products.
酵母酿酒酵母对干燥的耐受性对该微生物在葡萄酒行业中的应用很重要，因为活性干酵母通常用作发酵的起始剂。许多研究表明，水分流失引起的细胞效应的复杂性，包括对大分子成分的氧化损伤。然而，这些研究并没有涉及到酵母干燥的技术意义，而且脱水条件远非工业实践。在本研究中，采用分子方法在两个不同的干燥温度（即 35 和 41°C）下对中试工厂脱水过程中的相关损伤条件进行了表征。我们分析了几个应激基因标记的表达变化，并在中试工厂脱水过程中根据工业标准实践测定了两个生化氧化还原指标（谷胱甘肽和脂质过氧化水平），以生产活性干生物量。主要基因表达反应涉及 TRR1 和 GRX5 基因的诱导，这两个基因对应于两个主要的氧化还原平衡系统，硫氧还蛋白和谷胱甘肽/谷胱甘肽还原酶。谷胱甘肽含量升高和脂质过氧化损伤显著表明氧化应激对细胞成分的生理影响。商业库存和中试工厂样本之间的比较表明，该分子方法在中试工厂规模上适用于研究工业酵母产品的生理特性。
