RUI: Collaborative Research: Genetic and ecological drivers of microbial adaptation to high-nickel serpentine soils

RUI：合作研究：微生物适应高镍蛇纹石土壤的遗传和生态驱动因素

• 批准号: 1755454
• 负责人: Stephanie Porter
• 金额: $ 57.31万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1755454&HistoricalAwards=false
• 关键词: RUI; Collaborative; Research; Genetic; ecological

As Earth's geology varies across the landscape, so do the properties of soil microbial communities. Variation among these microbial communities reflect an adaptive process in which genes providing benefits in a particular soil habitat are more common in the microbes dwelling there. Grassland landscapes in California are naturally punctuated by unusual patches of toxic, nickel-rich soil. For thousands of years, these patches have been sites of microbial adaptation to toxic metals. The primary goal of this project is to discover genes that allow the nitrogen fixing soil bacteria, Mesorhizobium, to tolerate toxic metals, to understand how these genes are distributed among bacteria across a patchy landscape, and to test whether these tolerance genes impose disadvantages when toxic metals are not present. Insights from this study will assist in developing strategies for biologically based remediation of human-contaminated soils and provide insight into adaptation of microbes to toxic environments. Since rhizobial bacteria, which include the Mesorhizobium, are responsible for approximately half of the biological nitrogen fixation, this research has agricultural implications. The project will integrate an undergraduate-focused training program that provides students with authentic research experiences. In this program, students will isolate bacterial strains with extremely high tolerance to toxic metals, and investigate whether their genomes include genes known to provide heavy metal tolerance. The funded work therefore contributes to understanding how organisms adapt to extreme environments and employs the efforts of young scientists at a critical stage of their training.This project explores a critical frontier in microbial evolutionary ecology: microbial local adaptation in nature, and the role of fitness trade-offs in determining genotype distributions across heterogeneous environments. In this project, mesorhizobia, nitrogen-fixing bacteria that are easily isolated from symbiotic host plants, will be isolated from serpentine and non-serpentine soils. These Mesorhizobium strains will be subjected to straightforward laboratory physiology and fitness assays under varying nickel levels. Whole genome sequencing, transcriptional profiling, as well as molecular genetic manipulations, will also be used to characterize these strains. This highly tractable system will enable the identification of genes and mechanisms of nickel adaptation, along with direct measurement of fitness trade-offs. The project will additionally link trade-offs to the distribution of specific adaptations across a landscape of serpentine patches that vary in size and level of nickel enrichment, thereby testing general evolutionary-ecological theories about the relationship between specialization and fitness trade-offs. Undergraduates will be involved in characterization of the physiology, taxonomy, genetics, and genomics of Mesorhizobia during a course based research experience. Additionally, outreach will be performed to K-12 schools to expose these students to STEM research.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.

由于地球的地质在景观上各不相同，土壤微生物群落的特性也各不相同。这些微生物群落之间的变化反映了一个适应过程，在这个过程中，在特定土壤生境中提供益处的基因在栖息在那里的微生物中更常见。加州的草原自然地被不寻常的有毒、富镍土壤所打断。数千年来，这些斑块一直是微生物适应有毒金属的场所。该项目的主要目标是发现允许固氮土壤细菌Mesorhizobium耐受有毒金属的基因，以了解这些基因如何在斑块景观中的细菌中分布，并测试这些耐受基因是否在有毒金属不存在时造成不利影响。这项研究的见解将有助于制定人类污染土壤的生物修复策略，并提供对微生物适应有毒环境的见解。由于根瘤菌，其中包括中根瘤菌，负责约一半的生物固氮，这项研究具有农业意义。该项目将整合以本科生为重点的培训计划，为学生提供真实的研究经验。在这个项目中，学生将分离出对有毒金属具有极高耐受性的菌株，并研究它们的基因组是否包含已知提供重金属耐受性的基因。因此，受资助的工作有助于了解生物体如何适应极端环境，并利用年轻科学家在其培训的关键阶段的努力。该项目探讨了微生物进化生态学的一个关键前沿：微生物在自然界中的局部适应，以及适应性权衡在确定异质环境中的基因型分布中的作用。在本项目中，中根瘤菌，很容易从共生宿主植物中分离的固氮细菌，将从蛇纹石和非蛇纹石土壤中分离。这些中慢生根瘤菌菌株将在不同的镍水平下进行简单的实验室生理学和适应性测定。全基因组测序，转录谱，以及分子遗传操作，也将用于表征这些菌株。这种高度易处理的系统将使镍适应的基因和机制的识别，沿着与健身权衡的直接测量。此外，该项目还将权衡与特定适应性在大小和镍富集程度不同的蛇形斑块景观中的分布联系起来，从而测试关于专业化和健身权衡之间关系的一般进化生态理论。本科生将在基于研究经验的课程期间参与Mesorhizobia的生理学，分类学，遗传学和基因组学的表征。此外，还将对K-12学校进行推广，让这些学生接触STEM研究。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。