The contribution of yeast to gastrointestinal microbial ecology and regulation of host physiology

在过去的二十年里，有大量的研究探索肠道微生物群在调节动物生理学中的作用。通过这段时间，已经确定胃肠道中的微生物有助于宿主代谢，免疫发育和动物行为。微生物群包括所有细菌、古细菌、真菌和病毒，然而，绝大多数微生物群研究都集中在细菌组分上。真菌种群主要由酵母菌组成，已被确定为机会致病菌（如白色念珠菌）的来源，但几乎没有研究探索酵母菌在胃肠道中的生态作用。酵母已被相当广泛地用作家畜生产中的益生菌，并且在饮食中添加酵母细胞壁成分已成为改善健康结果的有效手段。我们假设有宿主适应性酵母与宿主有共生关系，与细菌群落相互作用，并有助于微生物群的代谢功能。该研究计划的最终目标是开发基于证据的方法来操纵动物的酵母菌群，以支持高效的畜牧业生产。一个目标将是建立一个改进的库存酵母殖民的胃肠道的多种动物物种。第二个关键目标将是表征酵母如何影响肠道生态，微生物组的代谢活动和宿主反应。这将通过将确定的酵母菌群引入到无菌动物中来实现，所述无菌动物被细菌种群定殖，但不含酵母菌。这将为研究酵母菌的定殖动力学、它们与细菌种群共同产生的代谢产物以及它们对宿主生理学的影响提供机会。将酵母定殖到无菌动物中也将提供对酵母激活和抑制的宿主途径以及肠道环境中酵母代谢活性的深入了解。第三个目标是证明酵母是否适应宿主。这将通过使用竞争性和非竞争性定殖实验引入从不同动物物种分离的酵母来确定。这项研究将解决有关酵母在动物胃肠道微生物生态学中的整体作用的重要问题，并提供有关酵母如何用作治疗剂以支持有效动物生产的见解。

Over the past two decades there has been an exceptional amount of research exploring the role of the intestinal microbiota in regulating animal physiology. Through this time it has been identified that microbes in the gastrointestinal tract contribute to host metabolism, immune development, and animal behaviour. The microbiota includes all bacteria, archaea, fungi, and viruses, however, the vast majority of microbiome research has focused on the bacterial component. The fungal population, which is largely composed of yeast, has been identified as a source of opportunistic pathogens, such as Candida albicans, however there is almost no research exploring the ecological role of yeast in the gastrointestinal tract. Yeast have been used fairly extensively as probiotics in livestock production, and the addition of yeast cell wall components to the diet has been an effective means to improve health outcomes. We hypothesize that there are host-adapted yeast that have a symbiotic relationship with the host, interact with the bacterial community, and contribute to metabolic functionality of the microbiota. The ultimate goal of the research program will be to develop evidence-based approaches to manipulate the yeast population of animals to support efficient livestock production. One objective will be to create an improved inventory of yeast that colonize the gastrointestinal tract of multiple animal species. A second key objective will be to characterize how yeast impact intestinal ecology, metabolic activity of the microbiome, and host response. This will be achieved by introduction of defined yeast populations to germ free animals that are colonized with bacterial populations, but are free of yeast. This will provide the opportunity to study the colonization dynamics of yeast, the metabolites they co-generate with bacterial populations, and the impact they have on host physiology. Colonization of yeast into germ-free animals will also provide insight into the host pathways yeast activate and repress, as well as yeast metabolic activity in the intestinal environment. A third objective will be to demonstrate whether yeast are host adapted. This will be determined by introducing yeast isolated from different animal species using competitive and non-competitive colonization experiments. This research will address important questions regarding the overall role of yeast in animal gastrointestinal microbial ecology and provide insights into how yeast can be utilized as therapeutics to support efficient animal production.