Henriques David, Alonso-Del-Real Javier, Querol Amparo, Balsa-Canto Eva
(Bio)process Engineering Group, IIM-CSIC, Vigo, Spain.
Grupo de Biología de Sistemas en Levaduras de Interés Biotecnológico, IATA-CSIC, Valencia, Spain.
Front Microbiol. 2018 Feb 2;9:88. doi: 10.3389/fmicb.2018.00088. eCollection 2018.
Wineries face unprecedented challenges due to new market demands and climate change effects on wine quality. New yeast starters including non-conventional species, such as , may contribute to deal with some of these challenges. The design of new fermentations using non-conventional yeasts requires an improved understanding of the physiology and metabolism of these cells. Dynamic modeling brings the potential of exploring the most relevant mechanisms and designing optimal processes more systematically. In this work we explore mechanisms by means of a model selection, reduction and cross-validation pipeline which enables to dissect the most relevant fermentation features for the species under consideration, T73 and CR85. The pipeline involved the comparison of a collection of models which incorporate several alternative mechanisms with emphasis on the inhibitory effects due to temperature and ethanol. We focused on defining a minimal model with the minimum number of parameters, to maximize the identifiability and the quality of cross-validation. The selected model was then used to highlight differences in behavior between species. The analysis of model parameters would indicate that the specific growth rate and the transport of hexoses at initial times are higher for T73 while CR85 diverts more flux for glycerol production and cellular maintenance. As a result, the fermentations with CR85 are typically slower; produce less ethanol but higher glycerol. Finally, we also explored optimal initial inoculation and process temperature to find the best compromise between final product characteristics and fermentation duration. Results reveal that the production of glycerol is distinctive in CR85, it was not possible to achieve the same production of glycerol with T73 in any of the conditions tested. This result brings the idea that the optimal design of mixed cultures may have an enormous potential for the improvement of final wine quality.
由于新的市场需求以及气候变化对葡萄酒品质的影响，葡萄酒厂面临着前所未有的挑战。包括非传统酵母品种（如……）在内的新型酵母发酵剂可能有助于应对其中一些挑战。使用非传统酵母设计新的发酵过程需要更好地理解这些细胞的生理学和代谢。动态建模带来了更系统地探索最相关机制并设计最佳工艺的潜力。在这项工作中，我们通过模型选择、简化和交叉验证流程来探索机制，该流程能够剖析所考虑的T73和CR85品种最相关的发酵特征。该流程涉及比较一系列包含多种替代机制的模型，重点关注温度和乙醇的抑制作用。我们专注于定义一个参数数量最少的最小模型，以最大化可识别性和交叉验证的质量。然后使用所选模型来突出不同品种之间行为的差异。对模型参数的分析表明，T73在初始阶段的比生长速率和己糖转运更高，而CR85将更多通量用于甘油生产和细胞维持。因此，使用CR85进行的发酵通常较慢；产生的乙醇较少但甘油较多。最后，我们还探索了最佳初始接种量和工艺温度，以在最终产品特性和发酵持续时间之间找到最佳平衡。结果表明，CR85中甘油的产生具有独特性，在任何测试条件下，T73都无法实现与CR85相同的甘油产量。这一结果表明，混合培养的优化设计对于提高最终葡萄酒品质可能具有巨大潜力。
