CAREER: Do extraordinarily long enzyme lifetimes drive microbial community assembly in deep subsurface sediments?

生活在海洋沉积物深处的微生物有助于推动地球的元素循环，影响地球宜居性的关键方面，如大气中的氧气量。地下深处的微生物有着非凡的生活方式。它们以几十年、几百年甚至几千年的时间尺度来转换它们的生物量，而大多数其他环境中的微生物每隔几个小时或几天就会这样做。该项目的驱动假设是，深层地下微生物酶的异常高的稳定性是这些微生物生存的关键。该项目的科学成果将有助于理解海底一个巨大而神秘的生态系统的功能，并可能导致有关酶结构和功能的新发现，这些发现可能在食品或制药行业具有价值应用。该项目支持本科生和研究生的研究和教学培训。此外，参加名为东田纳西自由学校的暑期学校项目的K12学生帮助生成数据和设计实验，让他们及早投入到科学过程中。该教育计划允许一批年轻科学家获得真正的科学研究经验。通过在阿拉斯加湾收集地下沉积物的现场计划、对这些沉积物的实验操作、简化模型系统中的实验室实验以及生物信息学分析，验证了异常稳定的酶有助于地下微生物在较长时间内持续存在的中心假设。对表层和地下沉积物进行超基因组测序，然后构建超基因组组装基因组并计算分析酶的稳定性，以预测地下沉积物中酶的稳定性以及酶稳定性影响群落组装的程度。然后，对地下沉积物的实验操作被用来验证这些预测。研究小组还在表达、纯化和实验确定一组选定的地下酶的结构，以允许对生物信息学预测和简化的实验室实验进行独立测试。总之，这些实验将揭示酶稳定性在推动地下沉积物中微生物群落聚集方面的作用。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Microbes that live deep in ocean sediments help drive Earth's elemental cycles, influencing key aspects of habitability on the planet, such as the amount of oxygen in the atmosphere. Microbes in the deep subsurface have a remarkable lifestyle. They turn over their biomass on timescales of decades, centuries, or even millennia, while microbes in most other environments do so every few hours or days. The driving hypothesis for this project is the unusually high stability of the deep subsurface microbes' enzymes is key to these microbes' survival. The scientific results of this project will help understand the function of a vast and mysterious ecosystem at the bottom of the ocean and may lead to new discoveries about enzyme structure and function that could have valuable applications in the food or pharmaceutical industries. The project supports the training of undergraduate and graduate students in research and teaching. In addition, K12 students participating in a summer school program called East Tennessee Freedom Schools help generate data and design experiments, giving them early input into the scientific process. The educational program allows a set of young scientists to gain experience with authentic scientific research. The central hypothesis that unusually stable enzymes help subsurface microbes to persist over long timescales is tested via a field program to collect subsurface sediments in the Gulf of Alaska, experimental manipulations of those sediments, laboratory experiments in simplified model systems, and bioinformatic analyses. Metagenomic sequencing of surface and subsurface sediments, followed by construction of metagenome-assembled genomes and computational analysis of enzyme stability, are employed to yield predictions on the stability of enzymes in subsurface sediments and the degree to which enzyme stability affects community assembly. Experimental manipulations of subsurface sediments are then used to test those predictions. The research team is also expressing, purifying, and experimentally determining the structure of a selected set of subsurface enzymes to allow independent testing of the bioinformatic predictions and simplified laboratory experiments. Together, these experiments will reveal the role of enzyme stability in driving microbial community assembly in subsurface sediments.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.