Resource and Stress Interactions in Regulating Microbial Communities in a California Grassland Soil

加州大学圣巴巴拉分校从地表到地下水，土壤中都含有丰富的微生物，它们对整个地球发挥着许多至关重要的作用。过去，对土壤微生物的研究主要是通过对土壤表面进行采样，土壤表面富含植物的营养物质，但微生物却经历了极端的湿度和温度。相对而言，研究较少的是深度土壤微生物，那里的湿度和温度压力减少，但微生物更缺乏营养。水胁迫和营养的抵消压力如何影响整个深度剖面中土壤微生物的组成和功能？在这个项目中，将对加州大学塞奇威克自然保护区的土壤进行采样，并在实验室中对水分和碳营养进行控制。基于dna的敏感技术将用于发现微生物如何随着营养的变化而变化，以及营养如何在土壤干燥时促进生存。稳定同位素（13C）形式的碳基质将通过微生物种群追踪，以发现哪些微生物群最积极地处理营养物质。这项研究很重要，因为尽管社会依赖土壤微生物来循环养分和生物降解污染物，但人们对表层和深层土壤微生物的功能知之甚少。从这项研究中获得的知识将有助于理解诸如污染物的命运和全球变暖的后果等广泛关注的问题。为了教育其他人关于深层土壤微生物的重要性，将在研究现场建造一个解释性展示，成人团体和K-12学生通过现有的教育参观计划与讲解员一起参观。

Resource and Stress Interactions in Regulating Microbial Communities in a California Grassland Soil Patricia A. HoldenUniversity of California-Santa BarbaraFrom surface to groundwater, soil is rich in microbes that perform many functions essential to the entire planet. In the past, soil microbes have mostly been studied by sampling the surface where nutrients from plants abound yet microbes experience extremes of moisture and temperature. Comparatively less studied are soil microbes at depth where moisture and temperature stresses are reduced, but microbes are more starved for nutrients. How do the counteracting pressures of water stress and nutrition affect the makeup and function of soil microbes throughout a depth profile? In this project, soils along a well-studied depth profile at the UC Sedgwick Natural Reserve will be sampled and moisture plus carbon nutrition will be manipulated in the laboratory. Sensitive DNA-based techniques will be used to discover how microbes change with changing nutrition and how nutrition facilitates survival when soils are dry. Stable isotopic (13C) forms of carbon substrates will be traced through microbial populations to discover which microbial groups are most actively processing nutrients. This research is important because, while society depends on soil microbes to recycle nutrients and biodegrade pollutants, how surface and deep soil microbes function is only weakly understood. The knowledge gained from this research will help in understanding such broad concerns as pollutant fates and consequences of global warming. To educate others about the importance of deep soil microbes, an interpretive display will be constructed at the research field site where adult groups and K-12 students tour with docents through an existing educational visitation program.