Bioprocess and Biosystems Engineering, IIM-CSIC, Vigo, Spain.
Applied Mathematics II, University of Vigo, Vigo, Spain.
Microb Biotechnol. 2023 Apr;16(4):847-861. doi: 10.1111/1751-7915.14211. Epub 2023 Feb 1.
Saccharomyces non-cerevisiae yeasts are gaining momentum in wine fermentation due to their potential to reduce ethanol content and achieve attractive aroma profiles. However, the design of the fermentation process for new species requires intensive experimentation. The use of mechanistic models could automate process design, yet to date, most fermentation models have focused on primary metabolism. Therefore, these models do not provide insight into the production of secondary metabolites essential for wine quality, such as aromas. In this work, we formulate a continuous model that accounts for the physiological status of yeast, that is, exponential growth, growth under nitrogen starvation and transition to stationary or decay phases. To do so, we assumed that nitrogen starvation is associated with carbohydrate accumulation and the induction of a set of transcriptional changes associated with the stationary phase. The model accurately described the dynamics of time series data for biomass and primary and secondary metabolites obtained for various yeast species in single culture fermentations. We also used the proposed model to explore different process designs, showing how the addition of nitrogen could affect the aromatic profile of wine. This study underlines the potential of incorporating yeast physiology into batch fermentation modelling and provides a new means of automating process design.
非酿酒酵母在葡萄酒发酵中越来越受到关注，因为它们有可能降低乙醇含量并获得吸引人的香气特征。然而，对于新物种的发酵过程设计需要进行密集的实验。使用机械模型可以实现工艺设计的自动化，但迄今为止，大多数发酵模型都集中在初级代谢上。因此，这些模型无法提供对次级代谢产物（如香气）的生产的深入了解，这些产物对葡萄酒的质量至关重要。在这项工作中，我们制定了一个连续模型，该模型考虑了酵母的生理状态，即指数生长、氮饥饿下的生长以及向静止或衰减阶段的过渡。为此，我们假设氮饥饿与碳水化合物的积累以及与静止阶段相关的一组转录变化的诱导有关。该模型准确地描述了在单一培养发酵中各种酵母物种的生物量和初级和次级代谢物的时间序列数据的动态。我们还使用所提出的模型来探索不同的工艺设计，展示了添加氮如何影响葡萄酒的香气特征。这项研究强调了将酵母生理学纳入分批发酵建模中的潜力，并提供了一种自动化工艺设计的新方法。
