Role Of Non-Phototrophs In The Growth And Fitness Of Biological Soil Crust

生物土壤结皮（或“生物结皮”）是在干旱和山区土壤表面自然生长的微生物群落，其基础是被称为蓝藻的微小植物状生物的光合作用。在未经改变的环境中，生物结壳可以覆盖大部分景观，为生态系统提供了几个重要的好处。例如，它们可以从空气中吸收养分，提高土壤肥力。而且，重要的是，它们形成了真正的表面外壳，保护土壤免受风和水的侵蚀，防止流沙的形成。它们的影响在当地和全球都是可以衡量的。不幸的是，生物外壳受到一些人类活动的负面影响，包括放牧、农业、城市扩张和全球变暖等。这往往会导致土壤质量的退化和粉尘形成的增加。在过去的十年中，生物硬壳的恢复已经成为包括美国在内的许多国家生态恢复工作的目标。然而，由于对这些群落的基本生物学和生态学的了解不足，在这方面的结果并不理想。虽然我们已经了解了很多关于形成这些外壳的光合微生物的生物学知识，但在产生新外壳方面缺乏成功表明了一些未知的因素，这些因素对它们的生长和整体健康至关重要。本研究的重点是与光合微生物建立特定生物学关系的非光合微生物。该项目将为研究生和社区大学学生提供培训，并将提供推进生物结皮恢复所必需的关键信息。该项目将通过实验解决这一知识差距，首先使用纯种培养和分子方法相结合的方法，严格识别和描述参与这种相互作用的主要非光合微生物参与者。随后，该项目将研究相互作用的机制性质，通过重建文化中的互惠相互作用，并通过实验破坏实地样品中互惠相互作用的需要。最后，该项目将评估这些相互作用作为自然生物外壳生长和适应性决定因素的重要性。由于它们特别重要的作用，该项目将重点研究微生物与先驱蓝藻的相互作用和早期生物外壳。该计划要求三个独立的任务，每个任务都由基于初步证据的特定假设驱动。它们是：1)相互作用是形成先驱生物外壳的蓝藻的主要成分；2)这些相互作用是基于特定目的和合作伙伴的互惠关系；3)掠食性细菌构成了生物外壳中普遍的、生态上重要的损失因素。该项目包括努力让利益相关者参与土地管理，促进技术转让，并为各级科学劳动力的发展作出重大贡献。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Biological soil crusts (or “biocrusts”) are communities of microorganisms that develop naturally on the surface of soil from arid and range lands based on the photosynthesis of tiny, plant-like organisms known as cyanobacteria. In unaltered settings biocrust can cover much of the landscape, providing several important benefits to the ecosystem. They can take up nutrients from the air, for example, increasing soil fertility. And, importantly, they build veritable surface crusts that protect the soil from erosion by wind and water and prevent the formation of fugitive dust. Their effects are measurable both locally and globally. Unfortunately, biocrusts are negatively impacted by several human activities, including cattle grazing, agriculture, urban sprawl, and global warming, among others. This often leads to the degradation of soil quality and increases in fugitive dust formation. During the last decade, the rehabilitation of biocrust has become a goal in ecological restoration efforts in many countries, including the US. However, less than optimal outcomes on this front made it patent that knowledge about the basic biology and ecology of these communities is insufficient. While we have learned much about the biology of the all-important photosynthetic microbes that build these crusts, the lack of success in producing new crusts pointed to some yet unknown factor or factors that are crucial for their growth and overall fitness. This research focuses on the non-photosynthetic microbes that establish specific biological relationships with the photosynthetic microbes. This project will provide training to graduate and community college students and will provide critical information necessary to advance biocrust restoration.The project will address this knowledge gap experimentally by first rigorously identifying and characterizing the main non-photosynthetic microbial actors involved in such interactions using a combination of pedigreed cultivation and molecular approaches. Subsequently, the project will study the mechanistic nature of the interactions at play, by reconstructing the mutualistic interactions in culture and by experimentally disrupting the need for a mutualistic interaction in field samples. Finally, the project will assess the importance of these interactions as determinants of growth and fitness in natural biocrusts. Because of their particularly crucial role, the project will focus on microbial interactions with pioneer cyanobacteria and on early stage biocrusts. The plan calls for three discrete tasks, each driven by specific hypotheses based on preliminary evidence. These are: 1) that interactions are a staple of pioneer biocrust forming cyanobacteria, 2) that these are based on mutualisms that are specific with respect to purpose and partner, and 3) that predatory bacteria constitute a universal, ecologically significant loss factor in biocrusts. The project includes efforts to involve stakeholders in land management, to facilitate technological transfer, and contributes significantly to science workforce development at various levels.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.