Barbosa Catarina, García-Martínez José, Pérez-Ortín José E, Mendes-Ferreira Ana
Centre of Agricultural Genomics and Biotechnology (CGBA) Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal; Universitat de Valência, Departamento de Bioquímica y Biología Molecular y E.R.I. Biotecmed, València, Spain.
Universitat de Valência, Departamento de Genética y E.R.I. Biotecmed, València, Spain.
PLoS One. 2015 Apr 17;10(4):e0122709. doi: 10.1371/journal.pone.0122709. eCollection 2015.
Nitrogen levels in grape-juices are of major importance in winemaking ensuring adequate yeast growth and fermentation performance. Here we used a comparative transcriptome analysis to uncover wine yeasts responses to nitrogen availability during fermentation. Gene expression was assessed in three genetically and phenotypically divergent commercial wine strains (CEG, VL1 and QA23), under low (67 mg/L) and high nitrogen (670 mg/L) regimes, at three time points during fermentation (12 h, 24 h and 96 h). Two-way ANOVA analysis of each fermentation condition led to the identification of genes whose expression was dependent on strain, fermentation stage and on the interaction of both factors. The high fermenter yeast strain QA23 was more clearly distinct from the other two strains, by differential expression of genes involved in flocculation, mitochondrial functions, energy generation and protein folding and stabilization. For all strains, higher transcriptional variability due to fermentation stage was seen in the high nitrogen fermentations. A positive correlation between maximum fermentation rate and the expression of genes involved in stress response was observed. The finding of common genes correlated with both fermentation activity and nitrogen up-take underlies the role of nitrogen on yeast fermentative fitness. The comparative analysis of genes differentially expressed between both fermentation conditions at 12 h, where the main difference was the level of nitrogen available, showed the highest variability amongst strains revealing strain-specific responses. Nevertheless, we were able to identify a small set of genes whose expression profiles can quantitatively assess the common response of the yeast strains to varying nitrogen conditions. The use of three contrasting yeast strains in gene expression analysis prompts the identification of more reliable, accurate and reproducible biomarkers that will facilitate the diagnosis of deficiency of this nutrient in the grape-musts and the development of strategies to optimize yeast performance in industrial fermentations.
葡萄汁中的氮含量在酿酒过程中至关重要,它能确保酵母充分生长并具有良好的发酵性能。在此,我们通过比较转录组分析来揭示葡萄酒酵母在发酵过程中对氮供应的反应。在低氮(67毫克/升)和高氮(670毫克/升)条件下,于发酵的三个时间点(12小时、24小时和96小时),对三种遗传和表型不同的商业葡萄酒酵母菌株(CEG、VL1和QA23)的基因表达进行了评估。对每种发酵条件进行双向方差分析,从而鉴定出那些表达依赖于菌株、发酵阶段以及这两个因素相互作用的基因。高发酵罐酵母菌株QA23与其他两种菌株的差异更为明显,这体现在参与絮凝、线粒体功能、能量产生以及蛋白质折叠和稳定的基因表达存在差异。对于所有菌株而言,在高氮发酵中,因发酵阶段导致的转录变异性更高。观察到最大发酵速率与参与应激反应的基因表达之间存在正相关。与发酵活性和氮吸收均相关的共同基因的发现,揭示了氮对酵母发酵适应性的作用。对12小时时两种发酵条件下差异表达基因的比较分析(此时主要差异在于可用氮水平)显示,菌株间的变异性最高,这揭示了菌株特异性反应。然而,我们能够鉴定出一小部分基因,其表达谱可定量评估酵母菌株对不同氮条件的共同反应。在基因表达分析中使用三种对比鲜明的酵母菌株,促使我们鉴定出更可靠、准确和可重复的生物标志物,这将有助于诊断葡萄汁中这种营养素的缺乏情况,并有助于制定优化工业发酵中酵母性能的策略。