CAREER: Soil Microbial Ecology and Evolution in a Warming World

职业：变暖世界中的土壤微生物生态和进化

• 批准号: 1749206
• 负责人: Kristen DeAngelis
• 金额: $ 95.41万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1749206&HistoricalAwards=false
• 关键词: CAREER; Soil; Microbial; Ecology; Evolution

Microorganisms are important components of every ecosystem. They virtually never live in isolation in nature; only as part of communities with other microbes. Soil microbial communities are major actors in the Earth's elemental cycles, and their response to environmental change can determine whether microbes help soil to retain more of compounds such as carbon, or whether it will be emitted in gaseous forms. As Earth's environment changes, so does the ability for soil to effectively store carbon, reducing the beneficial ecosystem services that soils provide, and releasing stored carbon gas into the atmosphere. In a 25-year long field experiment ongoing in a temperate forest in central Massachusetts, increases in temperature have resulted in a large loss of soil carbon as carbon dioxide gas. The loss is mostly due to microbes, with periods of soil carbon decay punctuated by changes in microbial community composition. This cyclic nature of soil carbon loss over decades suggests the existence of long-term microbial control over carbon in soil. In this experiment, increases in temperature have negatively affected soil fungi but not bacteria, suggesting that bacteria are adapting to these new environmental conditions, and that further adaptations to long-term environmental stress are possible. Over time, the quality of carbon compounds has been degraded, and examination of hundreds of bacterial isolates showed that the bacteria from chronically heated soils have an increased ability to metabolize degraded forms of carbon. Going forward, in this NSF CAREER project, research will examine the ecology and evolution of soil bacteria from the long-term warming experiment, in an effort to better predict the effect of environmental stress on terrestrial ecosystems. By doing much of the research in the classroom setting, this project will also help train the next generation of students in environmental microbiology. This research is designed to evaluate the central hypothesis that soil bacteria have acquired traits associated with adaptation to decades of chronic increases to soil temperature. The first aim is to directly measure the plasticity of in situ microbial community traits associated with declining soil organic matter quality and quantity over decades of chronic temperature stress. A laboratory incubation experiment will use stable isotope probing to measure temperature sensitivity of microbes associated with soils collected from a long-term warming experiment. The field experiment is an analysis of soils collected from before, during and after the heat is turned off for three months in the long-term study. Measures of different components of biomass and microbial products like enzymes and exopolysaccharides will be made and evaluated for changes due to long-term temperature increases. The second aim is to understand evolutionary adaptation of individual bacteria to long-term warming. Isolates will be screened for traits associated with oligotrophy (adaptation to low quantity substrate) and traits associated with degradation of complex carbon (adaptation to low quality substrate, including lignin analogs). The genomes of a subset of species with ecophysiology data will be sequenced for a study of trait evolution associated with oligotrophy or ability to degrade complex substrates. These organisms will also be part of a common garden experiment in an effort to link genomic features associated with long-term temperature stress to changes in fitness in soils. Altogether, these data will be used to estimate a rate of evolutionary adaptation for microbial parameters important to soil carbon modeling. This project will provide graduate student training in research and teaching, as well as undergraduate and high school student training in microbial physiology, ecology and genomics. Understanding bacterial adaptation might help to explain the non-linear pattern of soil C loss over decades of chronic temperature increase, and would define how environmental controls over the carbon cycle may act in a non-linear over longer time scales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

微生物是每个生态系统的重要组成部分。 他们几乎从不生活在自然界中。仅作为与其他微生物的社区的一部分。土壤微生物群落是地球元素周期中的主要参与者，它们对环境变化的反应可以确定微生物是否有助于土壤保留更多的化合物，例如碳，或者它是否会以气态形式发射。随着地球环境的变化，土壤有效存储碳的能力也会减少土壤提供的有益生态系统服务，并将储存的碳气释放到大气中。在马萨诸塞州中部的温带森林中进行的25年长期实验中，温度升高导致土壤碳作为二氧化碳气体的大量损失。损失主要是由于微生物，土壤碳衰减的周期因微生物群落组成的变化而打断。数十年来，土壤碳损失的这种环状性质表明，存在对土壤中碳的长期微生物控制。在该实验中，温度的升高具有负面影响的土壤真菌，但没有细菌，这表明细菌正在适应这些新的环境条件，并且可以进一步适应长期的环境压力。 随着时间的流逝，碳化合物的质量已降解，对数百种细菌分离株的检查表明，来自慢性加热土壤的细菌具有代谢降解形式的碳的能力增加。 展望未来，在这个NSF职业项目中，研究将研究长期变暖实验中土壤细菌的生态和演变，以更好地预测环境压力对陆生生态系统的影响。通过在课堂环境中进行大量研究，该项目还将帮助培训下一代的环境微生物学学生。这项研究旨在评估中心假设，即土壤细菌已经获得了与数十年慢性升高到土壤温度相关的特征。第一个目的是直接测量与数十年来慢性温度压力相关的原位微生物社区特征的可塑性。实验室孵化实验将使用稳定的同位素探测来测量与长期变暖实验收集的土壤相关的微生物的温度敏感性。现场实验是对在长期研究中从前，期间和之后收集的土壤进行分析。将对生物量和微生物产物（如酶和外多糖）的不同成分的度量进行评估，并因长期温度升高而变化。第二个目的是了解单个细菌对长期变暖的进化适应。分离株将筛选与寡头营养（适应低量基材）和与复杂碳降解相关的特征（适应低质量底物，包括木质素类似物）。将对具有生态生理学数据的物种子集的基因组进行测序，以研究与寡头营养或降解复杂底物的能力相关的性状进化。这些生物也将是一个常见的花园实验的一部分，以将与长期温度应激相关的基因组特征与土壤适应性变化联系起来。总的来说，这些数据将用于估计对土壤碳建模很重要的微生物参数的进化适应速率。该项目将提供研究和教学的研究生培训，以及微生物生理，生态学和基因组学的本科和高中学生培训。了解细菌适应可能有助于解释数十年来慢性温度升高的土壤C损失的非线性模式，并将定义环境控制对碳循环的环境控制如何在更长的时间尺度上以非线性作用。这项奖项反映了NSF的法定任务，并通过使用基金会的知识优点和广泛的范围来评估来表现出值得通过评估来进行评估，以此来评估。