Functional characterization of genes required for yeast fitness during fermentation

单细胞酿酒酵母(S.cerevisiae)是理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。现代酿酒酵母基因组已经进化到能够承受葡萄酒发酵的恶劣环境条件。然而，大多数对酿酒酵母基因功能的研究都是在相对温和的实验室条件下进行的，因此，15%的酵母基因仍然具有未知的功能。酵母在发酵过程中能够存活的细胞代谢变化也鲜为人知。我的实验室已经评估了葡萄汁发酵过程中所有非必需的酿酒酵母基因的生长情况。我们已经发现，自噬(字面意思是“自噬”)，即细胞吞噬自己的细胞质并回收不需要的细胞器以重复使用必要的营养物质的过程，对发酵过程中的细胞健康非常重要。其他一些基因对发酵条件下的细胞存活有积极或消极的影响，包括50多个以前未知的细胞功能基因。这项研究为了解酵母如何适应发酵提供了一个框架，并提出了提高商业酵母菌株承受发酵过程的能力的可能方法。我的NSERC发现赠款建议了解发酵过程中如何诱导自噬的机械细节，并为在发酵过程中改变适应度的未定性基因提供功能。这项建议的未来影响包括开发具有更高发酵能力的抗应激葡萄酒酵母菌株。了解酵母中的抗逆性途径可以提高葡萄酒酵母的抗逆性，改善工业性能，并降低加拿大葡萄酒厂不完全(迟缓或卡住)发酵的成本。

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.