Dissertation Research: Diversity, Distribution, and Cultivation of Novel Soil Bacteria from Snowmelt-Saturated Alpine Tundra

微生物的活动是全球养分循环的基本驱动力。然而，这些微生物中的绝大多数都是未经培养的，因此是完全未知的。研究新型微生物的生物学对于了解它们在快速变化的生物圈中的功能、反应和反馈至关重要。土壤是微生物特别复杂的栖息地。它拥有高度的微生物多样性和生物量，是研究的前沿，因为在自然土壤环境中完全没有对特定新微生物的研究。这项工作的目标是确定从融雪淹没的高山苔原土壤中新发现的细菌的作用。初步结果表明，这些细菌在地理上无处不在，它们位于氧气耗尽的土壤表面之下，但也普遍存在于冬季积雪下的土壤表面。基于DNA序列的方法将用于将这些新型细菌的存在与各种环境特征联系起来。据预测，这种新型细菌将在寒冷、无氧的环境中茁壮成长，并将通过模仿这些条件进行培养。事实上，这项工作的一个主要目标是在实验室中分离出这种新型细菌。这项研究将首次深入了解特定的未开垦的新型土壤细菌的生态学，并揭示无氧土壤带的范围和结构，这是养分循环中一个被忽视的因素。

The activity of microorganisms is the fundamental driver of global nutrient cycling. Yet, the vast majority of these microbes are uncultivated, and thus completely unknown. It is critical to investigate the biology of novel microbes to understand their function, response, and feedback on a rapidly changing biosphere. Soil is a particularly complex habitat for microbes. It harbors high microbial diversity and biomass, and is a frontier for research as studies of specific novel microbes within their natural soil environment are completely absent. The goal of the proposed work is to determine the roles of newly discovered bacteria from snowmelt-flooded alpine tundra soil. Preliminary results suggest that these bacteria are geographically ubiquitous, are located beneath the soil surface where oxygen is depleted, but are also prevalent at the soil surface under winter snowpack. DNA sequence-based approaches will be used to correlate the presence of these novel bacteria with various environmental characteristics. The novel bacteria are predicted to thrive in cold, oxygen-free habitats, and will be targeted for cultivation by mimicking these conditions. Indeed, a major goal of this work is to isolate the novel bacteria in the laboratory. This study will yield the first insights into the ecology of specific uncultivated, novel soil bacteria, and reveal the extent and structure of oxygen-free soil zones, an overlooked factor in nutrient cycling.