酿酒酵母菌(Saccharomyces cerevisiae)在全世界范围内被广泛应用于酒类酿造和食品发酵等行业，被称为“第一种家养微生物”。该菌同时也是分子生物学等研究领域中最常用的真核模式生物。然而，我们对其在自然界中的生态分布、遗传多样性、群体结构以及其驯化群体起源和演化等，依然所知甚少。近年来的研究表明，中国或东亚地区的S. cerevisiae野生群体的遗传多样性最高；而非洲驯养群体的遗传多样性大于其他地区，因此提出了东亚起源和非洲起源说，但均缺乏足够的证据。本项目拟通过对中国和非洲这两个酿酒酵母菌可能的起源地进行其遗传多样性和群体演化的研究，阐释其自然演化和人工驯化历史，并进一步探讨其发酵和抗逆性能因人工驯化而提高的分子机制，从而为培育适应新的生产技术需求(如生物质燃料乙醇生产等)的优良酵母菌株提供优质资源和理论依据。

The budding yeast Saccharomyces cerevisiae is used worldwide as a microbial agent for baking, fermentation of wine, beer and other alcoholic beverages, with a domestication history of nearly 10 thousand years. It is also a most-used model system in eukaryotic genetics, genomics and molecular biology and is becoming a powerful tool to illuminate ecological and evolutionary principles. It is now clear that S. cerevisiae exist in both wild and domestic populations which are genetically distinct; however, the genetic diversity and evolutionary relationships among the populations of the species remain elusive. A Far East Asian origin hypothesis has been proposed based on recent studies on wild S. cerevisiae populations. However, a study on domestic populations of the species also raised the possibility that S. cerevisiae was domesticated in Africa. Further worldwide investigation on genetic diversity of S. cerevisiae in the wild and man-made environments, especially in Far East Asia and Africa, will be necessary for a better understanding of the origin and evolution of S. cerevisiae. Therefore, we propose here to investigate 1) the ecological and geographic distribution of S. cerevisiae in natural and man made environments in China and Africa; 2) the genetic diversity, population structure and evolution of wild and domestic S. cerevisiae populations from the two regions; and 3) the adaptive evolution of S. cerevisiae due to domestication. The results will offer new insights into the ecology, biogeography and evolution of this species, and will be of great potential for the breeding of improved yeast strains for different purposes, including bio-ethanol production from lignocellulosic biomass.

本项目对中国和非洲这两个酿酒酵母菌可能的起源地进行了野生和驯养酿酒酵母的菌种分离，在此基础上，对其进行了糖类利用和抗逆能力测定以及多基因和全基因组分析，具体结果如下：1)从中国和非洲四国新分离野生和驯养酿酒酵母菌各120和2500余株；多基因序列分析发现中国和非洲驯养酵母菌均具有很高的遗传多样性；2)系统发育基因组学分析发现，酿酒酵母菌的驯养群体形成了一个独立于野生群体的单系类群，说明其可能起源与单个驯养事件；3) 整个驯养群体可分为固态和液态发酵两个大的亚群，不同来源的菌株，如白酒、黄酒、青稞酒、马奶酒、葡萄酒、发面和市售活性干酵母等，分别形成了独立的谱系；而来自不同国家、不同基物的非洲菌株也形成了彼此独立的谱系，但未从非洲发现真正的野生菌株；4) 相对野生菌株，驯养菌株多具有较高的糖类利用和抗逆能力，尤其是对麦芽糖的利用能力显著提高，而马奶酒发酵菌株显著提高了半乳糖的利用速率；5)基因拷贝数差异(CNV)分析发现在驯养群体中麦芽糖代谢基因和许多抗逆基因发生了显著的基因倍增，而在马奶酒菌株中，则发生很多包括半乳糖转运蛋白GAL2在内的谱系特异性基因扩增。本研究结果为酿酒酵母菌的东亚起源说提供了更有力的证据，并揭示了酿酒酵母菌适应性进化机制，为培育新的优良酵母菌株提供了优质资源和理论依据。