Effect of nitrogen addition timing of an enological yeast strain gene expression

The aim of this study was to evaluate the effect of timing of nitrogen added on a Saccharomyces cerevisiae yeast wine strain. We studied several addition timings and evaluated gene expression at different times after nitrogen addition (30min and 2h). We found that there were no major differences between the two samples after addition. 305 induced genes were common to both addition timings and represented amino acid biosynthetic functions. 147 induced genes were only induced after an addition made at the beginning of the stationary phase and 142 exclusively after an addition made at the end of the stationary phase. These genes represented translation and ribosomal RNA synthesis functions respectively. 150 genes were only repressed after an addition made at the beginning of the stationary phase and represented functions of responses to stress and nutritional deficiencies but also oxidoreductase activity. The repressed genes common to both timings (284) represented the same functions. Finally, the 127 genes only repressed after an addition made close to the end of the fermentation represented functions coding for lipid metabolism and cell wall organization.本研究旨在评估氮素添加时机对酿酒酵母（Saccharomyces cerevisiae）葡萄酒酿造菌株的影响。我们设置了多种氮素添加方案，并在氮素添加后的两个时间节点（30分钟与2小时）检测了基因表达水平。研究结果显示，两组样本间未出现显著差异。共有305个诱导基因为两种添加时机所共有，其功能富集于氨基酸生物合成通路。147个诱导基因仅在稳定期初期添加氮素时被诱导，142个诱导基因仅在稳定期末期添加氮素时被诱导；两类基因的功能分别对应翻译过程与核糖体RNA合成通路。另有150个基因仅在稳定期初期添加氮素时被抑制，其功能涉及应激响应、营养缺乏响应以及氧化还原酶活性调控。两种添加时机共有的抑制基因共284个，其功能与前述仅在稳定期初期添加氮素时被抑制的基因一致。最终，仅在发酵接近结束时添加氮素后被抑制的127个基因，其功能涉及脂质代谢与细胞壁组织构建相关通路。