Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, CSIC, Apartado de Correos, 73 Burjassot (Valencia), E-46100, Spain.
Microb Cell Fact. 2010 Feb 12;9:9. doi: 10.1186/1475-2859-9-9.
Wine Saccharomyces cerevisiae strains, adapted to anaerobic must fermentations, suffer oxidative stress when they are grown under aerobic conditions for biomass propagation in the industrial process of active dry yeast production. Oxidative metabolism of sugars favors high biomass yields but also causes increased oxidation damage of cell components. The overexpression of the TRX2 gene, coding for a thioredoxin, enhances oxidative stress resistance in a wine yeast strain model. The thioredoxin and also the glutathione/glutaredoxin system constitute the most important defense against oxidation. Trx2p is also involved in the regulation of Yap1p-driven transcriptional response against some reactive oxygen species.
Laboratory scale simulations of the industrial active dry biomass production process demonstrate that TRX2 overexpression increases the wine yeast final biomass yield and also its fermentative capacity both after the batch and fed-batch phases. Microvinifications carried out with the modified strain show a fast start phenotype derived from its enhanced fermentative capacity and also increased content of beneficial aroma compounds. The modified strain displays an increased transcriptional response of Yap1p regulated genes and other oxidative stress related genes. Activities of antioxidant enzymes like Sod1p, Sod2p and catalase are also enhanced. Consequently, diminished oxidation of lipids and proteins is observed in the modified strain, which can explain the improved performance of the thioredoxin overexpressing strain.
We report several beneficial effects of overexpressing the thioredoxin gene TRX2 in a wine yeast strain. We show that this strain presents an enhanced redox defense. Increased yield of biomass production process in TRX2 overexpressing strain can be of special interest for several industrial applications.
适应厌氧葡萄汁发酵的葡萄酒酿酒酵母菌株，在工业生产活性干酵母过程中，为了生物量繁殖，在有氧条件下生长时，会遭受氧化应激。糖的氧化代谢有利于获得较高的生物量，但也会导致细胞成分的氧化损伤增加。TRX2 基因（编码硫氧还蛋白）的过表达增强了葡萄酒酵母模型的氧化应激抗性。硫氧还蛋白和谷胱甘肽/谷氧还蛋白系统是对抗氧化的最重要防御机制。Trx2p 还参与了 Yap1p 驱动的转录反应对一些活性氧的调节。
工业活性干生物量生产过程的实验室规模模拟表明，TRX2 过表达不仅提高了葡萄酒酵母的最终生物量产量，而且提高了分批和补料分批阶段后的发酵能力。用改良菌株进行的微型发酵显示出快速启动表型，这源自其增强的发酵能力和有益香气化合物含量的增加。改良菌株的 Yap1p 调控基因和其他与氧化应激相关基因的转录反应增加。抗氧化酶如 Sod1p、Sod2p 和过氧化氢酶的活性也增强。因此，在改良菌株中观察到脂质和蛋白质的氧化减少，这可以解释硫氧还蛋白过表达菌株性能的提高。
我们报告了在葡萄酒酵母菌株中过表达硫氧还蛋白基因 TRX2 的几种有益效果。我们表明，该菌株具有增强的氧化还原防御能力。TRX2 过表达菌株在生物量生产过程中的产量增加可能对几种工业应用具有特殊意义。
