Functional characterization of genes required for yeast fitness during fermentation

单细胞酵母酿酒酵母（Saccharomyces cerevisiae， S. cerevisiae）是了解保守细胞过程的模式生物，也是工业食品生产的关键微生物。现代酿酒葡萄球菌基因组已经进化到能够承受恶劣的环境条件的葡萄酒发酵。然而，大多数关于酿酒酵母基因功能的研究都是在相对良性的实验室条件下进行的，因此，15%的酵母基因仍然没有已知的功能。细胞代谢的变化，使酵母菌在发酵期间的生存也知之甚少。我的实验室已经评估了葡萄汁发酵过程中所有非必需酿酒葡萄球菌基因的生长情况。我们已经发现，自噬（字面意思是“自噬”）是细胞吞噬自身细胞质并回收不需要的细胞器以重复使用必需营养物质的过程，对发酵过程中的细胞适应性很重要。在发酵条件下，许多其他基因或积极或消极地影响细胞存活，包括超过50个以前不知道细胞功能的基因。本研究为了解酵母如何适应发酵提供了一个框架，并提出了提高商品酵母菌株承受发酵过程能力的可能方法。我的NSERC发现基金建议了解自噬在发酵过程中是如何诱导的机制细节，并为在发酵过程中改变适应性的未表征基因提供功能。该建议的未来意义包括开发具有提高发酵能力的抗逆性葡萄酒酵母菌株。了解酵母的抗逆性途径可以提高葡萄酒酵母的抗逆性，提高工业性能，降低加拿大酿酒厂发酵不完全（缓慢或停滞）的成本。

The unicellular yeast Saccharomyces cerevisiae (S. cerevisiae) is a model organism for understanding conserved cellular processes and is also a key microorganism for industrial food production. The modern S. cerevisiae genome has evolved to withstand the harsh environmental conditions of wine fermentation. However, most studies of S. cerevisiae gene function are performed in relatively benign laboratory conditions and as a result, 15% of yeast genes still have no known function. The changes to cellular metabolism that enable survival of yeast during fermentation are also poorly understood. My lab has assessed the growth of all nonessential S. cerevisiae genes during grape juice fermentation. We have discovered that autophagy (literally, "self-eating"), a process whereby cells engulf their own cytoplasm and recycle unwanted organelles for reuse of essential nutrients, is important for cellular fitness during fermentation. A number of other genes either positively or negatively affect cell survival under fermentation conditions, including over fifty genes with no previously known cellular function. This study provides a framework for understanding how yeast are adapted to fermentation and suggests possible means to improve the ability of commercial yeast strains to withstand the fermentation process. My NSERC Discovery Grant proposes to understand the mechanistic details of how autophagy is induced during fermentation and to provide a function for uncharacterized genes that have altered fitness during fermentation. Future implications of this proposal include developing stress resistant wine yeast strains with improved fermentation capability. Understanding stress resistance pathways in yeast creates potential to increase stress resistance in wine yeast, improve industrial performance and reduce the cost to Canadian wineries of incomplete (sluggish or stuck) fermentations.