Distributions of metabolic flux and reducing equivalents/ATP in Saccharomyces cerevisiae during redox potential-controlled very-high-gravity ethanol fermentation

在酒精发酵过程中，特别是在非常高的重力(VHG)条件下，保持健康的酵母种群是必需的。我的长期目标是将生物信息学、基因组学、蛋白质组学、代谢流量分析和连续培养与反馈控制算法相结合，开发以目的为导向的发酵过程，以研究受外界干扰的细胞代谢和调节。在这里，我建议研究发酵氧化还原电位对酿酒酵母在超重(VHG)乙醇生产过程中代谢通量、还原当量和ATP的分布的影响，以及潜在的酵母生理。我的短期目标是：*1.开发氧化还原电位控制的VHG乙醇发酵过程；*2.研究不同氧化还原电位水平下VHG乙醇发酵过程中的基因表达谱；*3.在氧化还原电位的影响下重建乙醇发酵特有的基因组和代谢网络；以及*4.在氧化还原电位的影响下构建VHG乙醇发酵特有的蛋白质-蛋白质相互作用网络。*发酵氧化还原电位反映发酵罐中氧化和还原能力之间的瞬时平衡。通过操纵胞外发酵氧化还原电位，可以间接改变胞内还原当量对和ATP，最终导致酵母细胞内代谢通量的重新分配。在VHG乙醇生产过程中，保持发酵罐好氧是必不可少的。然而，过多的氧气会使代谢流转向生物质的形成，从而降低乙醇的产量。*我们建议开发一种氧化还原电位控制的微氧发酵过程，以研究代谢通量、还原当量和三磷酸腺苷在酿酒酵母工业菌株乙醇红®中的分布。该毒株最近已被测序，其基因组信息可用。这些信息将被用于重建基因组规模的代谢模型(GSMM)。结合上述发酵过程和GSMM的实验数据，可以识别在特定条件下被调控的基因，并阐明它们在VHG条件下与乙醇生产有关的代谢功能。这将导致对酵母细胞基因表达的深入了解，然后可以用来设计有效的发酵策略来提高乙醇产量。*拟议的研究目标是在乙醇生产过程中使用酿酒酵母，但这样开发的发酵过程也可以用于生产重要的中间单体，如琥珀酸或1，3-丙二醇，以及其他生物燃料，如生物丁醇。这项研究计划将有助于高素质人才的培养和生物燃料和化学工业的经济增长。

Maintaining a healthy yeast population is required during ethanol fermentation, particularly under very-high-gravity (VHG) conditions. My long-term objective is to integrate bioinformatics, genomics, proteomics, metabolic flux analysis, and continuous cultivation with feedback control algorithms to develop purpose-oriented fermentation processes to investigate cellular metabolism and regulation subject to extraneous perturbations. Herein, I propose to investigate the effect of fermentation redox potential on the distribution of metabolic flux, reducing equivalents, and ATP within Saccharomyces cerevisiae during very-high-gravity (VHG) ethanol production, as well as the underlying yeast physiology. My short-term objectives are to: *** 1. develop a continuous redox potential-controlled VHG ethanol fermentation process;*** 2. investigate gene expression profiles during VHG ethanol fermentation under various redox potential levels;*** 3. reconstruct an integrated genomic and metabolic network specific to ethanol fermentation under the influence of redox potential; and*** 4. construct a protein-protein interaction network specific to VHG ethanol fermentation under the influence of redox potential.***Fermentation redox potential reflects the momentary balance between oxidizing and reducing powers in a fermenter. By manipulating the extracellular fermentation redox potential, the intracellular reducing equivalent pairs and ATP can be indirectly altered, ultimately resulting in the redistribution of metabolic flux inside the yeast cells. keeping fermenter aerobic during VHG ethanol production is essential. However, too much oxygen will re-route metabolic flux towards biomass formation, thereby lowering ethanol yield. *** We propose to develop a redox potential-controlled micro-aerobic fermentation process to study the distribution of metabolic flux, reducing equivalents, and ATP within Ethanol Red®, an industrial S. cerevisiae strain. This strain has recently been sequenced, and its genome information is available. This information will be used to reconstruct a genome-scale metabolic model (GSMM). Combining experimental data collected from the above-mentioned fermentation process and the GSMM, the genes being modulated under specific conditions can be identified and their metabolic functions relating to ethanol production under VHG conditions can be elucidated. This will consequently result in an in-depth understanding of gene expression of yeast cells, which can then be used to design an effective fermentation strategy to increase ethanol productivity. *** The proposed research targets the use of S. cerevisiae during ethanol production, but the fermentation process so developed can also be adapted to produce important intermediate monomers, such as succinic acid or 1,3-propanediol, and other biofuels such as biobutanol. This research program will help in the development of highly qualified personnel and the economic growth of the biofuel and chemical industry.*****