Gamero-Sandemetrio Esther, Gómez-Pastor Rocío, Matallana Emilia
Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, CSIC, Valencia, Spain.
Biotechnol J. 2014 Aug;9(8):1055-64. doi: 10.1002/biot.201300448. Epub 2014 May 27.
The production of active dried yeast (ADY) is a common practice in industry for the maintenance of yeast starters and as a means of long term storage. The process, however, causes multiple cell injuries, with oxidative damage being one of the most important stresses. Consequentially, dehydration tolerance is a highly appreciated property in yeast for ADY production. In this study we analyzed the cellular redox environment in three Saccharomyces cerevisiae wine strains, which show markedly different fermentative capacities after dehydration. To measure/quantify the effect of dehydration on the S. cerevisiae strains, we used: (i) fluorescent probes; (ii) antioxidant enzyme activities; (ii) intracellular damage; (iii) antioxidant metabolites; and (iv) gene expression, to select a minimal set of biochemical parameters capable of predicting desiccation tolerance in wine yeasts. Our results show that naturally enhanced antioxidant defenses prevent oxidative damage after wine yeast biomass dehydration and improve fermentative capacity. Based on these results we chose four easily assayable parameters/biomarkers for the selection of industrial yeast strains of interest for ADY production: trehalose and glutathione levels, and glutathione reductase and catalase enzymatic activities. Yeast strains selected in accordance with this process display high levels of trehalose, low levels of oxidized glutathione, a high induction of glutathione reductase activity, as well as a high basal level and sufficient induction of catalase activity, which are properties inherent in superior ADY strains.
活性干酵母（ADY）的生产是工业上维持酵母发酵剂以及作为长期储存手段的常见做法。然而，该过程会导致多种细胞损伤，氧化损伤是其中最重要的应激之一。因此，脱水耐受性是酵母用于生产ADY时备受重视的特性。在本研究中，我们分析了三种酿酒酵母葡萄酒菌株的细胞氧化还原环境，这些菌株在脱水后表现出明显不同的发酵能力。为了测量/量化脱水对酿酒酵母菌株的影响，我们使用了：（i）荧光探针；（ii）抗氧化酶活性；（ii）细胞内损伤；（iii）抗氧化代谢物；以及（iv）基因表达，以选择一组能够预测葡萄酒酵母脱水耐受性的最小生化参数集。我们的结果表明，天然增强的抗氧化防御可防止葡萄酒酵母生物量脱水后的氧化损伤并提高发酵能力。基于这些结果，我们选择了四个易于测定的参数/生物标志物，用于选择用于ADY生产的工业酵母菌株：海藻糖和谷胱甘肽水平，以及谷胱甘肽还原酶和过氧化氢酶的酶活性。按照此过程选择的酵母菌株表现出海藻糖水平高、氧化型谷胱甘肽水平低、谷胱甘肽还原酶活性高度诱导，以及过氧化氢酶活性的高基础水平和充分诱导，这些都是优质ADY菌株所固有的特性。
