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区系在调节动物生理方面的作用。通过这段时间，已经发现胃肠道中的微生物对宿主新陈代谢、免疫发育和动物行为做出了贡献。微生物区系包括所有的细菌、古菌、真菌和病毒，然而，绝大多数微生物组研究都集中在细菌成分上。真菌种群主要由酵母菌组成，已被确定为条件致病菌的来源，如白色念珠菌，但几乎没有研究探索酵母在胃肠道中的生态作用。酵母作为益生菌在畜牧业生产中得到了广泛的应用，在饲料中添加酵母细胞壁成分是改善健康状况的有效手段。我们假设存在宿主适应的酵母，它们与宿主具有共生关系，与细菌群落相互作用，并对微生物区系的代谢功能做出贡献。该研究计划的最终目标将是开发基于证据的方法来操纵动物的酵母种群，以支持高效的畜牧业生产。其中一个目标是建立一个改进的酵母菌库存，这些酵母菌在多种动物的胃肠道中定居。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。这将通过将定义的酵母种群引入到有细菌种群但没有酵母的无菌动物中来实现。这将为研究酵母的定植动态、它们与细菌种群共同产生的代谢物以及它们对宿主生理的影响提供机会。酵母在无菌动物中的定植也将有助于深入了解酵母在肠道环境中激活和抑制的宿主途径，以及酵母的代谢活动。第三个目标将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植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中的整体作用的重要问题，并为如何利用酵母作为治疗药物来支持高效的动物生产提供见解。

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.