我国驯养酵母菌资源、遗传多样性与群体演化研究

The budding yeast Saccharomyces cerevisiae is used worldwide as a microbial agentfor baking, fermentation of wine, beer and other alcoholic beverages. In China, it has been used in wine making for nearly 10 thousands of years, being similar to the domestication history of plants and animals. Through the long history of intentionally or unintentionally artificial selection, the yeast has become a domesticated microbe with improved fermentation and stress tolerance abilities, being a highly valuable bio-resource for applied and basic research. However, we have not comprehensively investigated the application range of the yeast, collected and preserved the bio-resource and investigated its genetic diversity and population structure. Moreover, the genetic diversity of the yeast has been being threatened by the urbanization and commercialization trend in China. Therefore, we propose here 1) to systematically and intensively isolate and preserve the domesticated yeast populations used for different food and beverage production in China; 2) to compare their phenotypic characters in terms of fermentation of different sugars and tolerance to different stresses including freezing, high temperature, ethanol, osmosis and hydrolysates of natural lignocellulosic biomass. and 3) to investigate the genetic diversity and population structure and evolution of domestic yeast on the basis of DNA fingerprinting, multiple gene sequencing and population genetics analysis. The results will be of great potential for the breeding of improved yeast strains for different purposes.

酿酒酵母菌(Saccharomyces cerevisiae)被广泛应用于酒类酿造和食品发酵等行业，其在我国已具有近万年的应用历史。经过长期有意或无意的人工选择，该菌已经成为适应不同发酵环境和过程、发酵和抗逆性能显著提高的驯养微生物资源，具有重要的开发利用和研究价值。但是，我们对其尚缺乏全面系统的资源调查、收集保藏、应用价值评估和基础研究，而城镇化和商业化正在使其遗传多样性加速消失。本项目拟对参与我国民间传统发酵食品、饮料以及传统酒类酿造过程的驯养酵母菌资源进行全面系统的抢救性收集和保藏；在此基础上，评估其发酵和抗逆性能；并进一步利用DNA指纹分析和多基因系统发育分析等手段，揭示驯养酵母菌的遗传多样性和群体演化，为培育适应新的生产技术需求的优良酵母菌株，提供优质资源和理论依据。

本项目主要对参与我国民间传统发酵食品、饮料以及传统酒类酿造过程的驯养酵母菌资源进行全面系统的抢救性收集和保藏；在此基础上，评估其发酵和抗逆性能；并进一步利用DNA指纹分析和群体基因组学等研究手段，揭示驯养酵母菌的遗传多样性和群体演化，为培育适应新的生产技术需求的优良酵母菌株，提供优质资源和理论依据。本项目圆满完成了各项指标，主要研究内容和结果包括：1）从全国范围内和部分非洲国家共新分离驯养和野生酿酒酵母菌2300余株，对其进行了精确鉴定和安全长效保藏在中国普通微生物菌种保藏中心(CGMCC)；2）对300余株进行了糖类利用能力和抗逆能力评价，表明驯养菌株显著提升了麦芽糖利用能力，马奶酒菌株显著提升了半乳糖利用速率，大多数驯养菌株显著提高了对高温和高乙醇的耐受能力；3）DNA指纹分析发现不同酒类酿造菌株具有非常高的遗传多样性，并在发酵过程中发生了明显的菌系演替，根据多基因序列分析结果研发了拉格啤酒酵母菌物种和株系快速分子鉴定的新方法；4）对106株野生和160株驯养酿酒酵母菌进行了基因组重测序，并整合了此前国际上发表的287株酿酒酵母菌株的基因组数据，进行了群体基因组、系统发育基因组和比较基因组学分析，全面揭示了酿酒酵母菌野生和驯养群体的遗传多样性、起源地和演化历史，结果表明中国既是该种野生群体，也是其驯养群体的起源中心；所有驯养群体起源于一个由野生菌株杂交而成的杂合体祖先，最初为了适应富含麦芽糖的发酵环境，随后分化为固态和液态发酵两大分支，并通过大规模基因扩增、删减、横向转移和基因渐渗等方式，实现了发酵和抗逆能力的提高及对不同发酵环境的适应性进化。已发表或接受发表研究论文3篇，其中2篇分别发表在高影响因子SCI期刊Nature Communications和Current Biology上，预计将在高影响因子SCI期刊上再发表2-3篇研究论文。