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

氧化还原电位控制超重力乙醇发酵过程中酿酒酵母代谢通量和还原当量/ATP的分布

• 批准号: RGPIN-2019-07035
• 负责人: Lin, YenHan
• 金额: $ 2.04万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739272
• 关键词: Distributions; metabolic; flux; reducing; equivalents

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 Redr, 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.

在乙醇发酵过程中，特别是在非常高重力（VHG）条件下，需要保持健康的酵母群。我的长期目标是将生物信息学、基因组学、蛋白质组学、代谢通量分析和持续培养与反馈控制算法相结合，开发目标导向的发酵过程，以研究受外来扰动影响的细胞代谢和调节。在此，我建议研究发酵氧化还原电位对very-high-gravity （VHG）乙醇生产过程中酿酒酵母代谢通量、还原当量和ATP分布的影响，以及潜在的酵母生理学。我的短期目标是：1.开发一种连续氧化还原电位控制的VHG乙醇发酵工艺；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，重建乙醇发酵的基因组和代谢网络；和4。构建氧化还原电位影响下VHG乙醇发酵的蛋白质-蛋白质相互作用网络。发酵氧化还原电位反映了发酵罐中氧化力和还原力之间的瞬间平衡。通过调控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好氧发酵是必不可少的。然而，过多的氧气会将代谢通量重新导向生物质形成，从而降低乙醇产量。我们建议开发一种氧化还原电位控制的微好氧发酵工艺，以研究乙醇Redr（一种工业酿酒酵母）内代谢通量、还原当量和ATP的分布。该菌株最近已被测序，其基因组信息是可用的。这些信息将用于重建基因组尺度的代谢模型（GSMM）。结合上述发酵过程的实验数据和GSMM，可以鉴定在特定条件下被调节的基因，并阐明其在VHG条件下与乙醇生产相关的代谢功能。这将导致深入了解酵母细胞的基因表达，然后可以用来设计一个有效的发酵策略，以提高乙醇产量。拟议的研究目标是在乙醇生产中使用酿酒酵母，但如此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。该研究项目将有助于培养高素质人才，促进生物燃料和化学工业的经济增长。