Microbial carbon cycling in marine environments: linking micro-scale processes to global carbon dynamics

海洋是复杂多样的微生物的家园，这些微生物以各种方式塑造了这些生态系统的动态。通过其新陈代谢和生长，海洋微生物在全球碳循环中发挥核心作用，并影响被隔离在深海水域和沉积物中的碳的大小和数量。我的研究重点是异养微生物分解有机碳并释放二氧化碳(CO2)作为其新陈代谢的副产品，这被称为有机物的再矿化。异养微生物是海洋中二氧化碳的主要生产者，它们代谢活动的任何实质性变化都有可能显著改变碳在海洋中的处理和储存方式。这项拟议的研究将使用各种分子和同位素工具，以获得对异养微生物的控制以及支撑海洋碳循环的代谢途径和生态相互作用的新见解。研究的核心问题是：1)微生物的代谢潜力如何影响有机质再矿化？(2)微生物之间的生态相互作用是增加还是降低有机质再矿化的速率？以及(3)细胞密度是启动有机质再矿化的酶的产生的重要控制因素吗？这些问题将通过三个可检验的假设来检验，研究由两名硕士学生、两名博士生和四名本科生进行。总体而言，这项研究的结果将促进我们对调节海洋碳通量的微生物机制的理解。最终，这将使我们能够开发出一个亟需的分子水平的框架，以提高我们预测未来气候变暖下海洋碳循环将如何变化的能力。此外，微生物在修复海洋中泄漏的石油方面发挥着直接作用。破译调节微生物活动的基本机制将极大地提高我们制定漏油应急计划和补救战略的能力。这项研究计划将维持和建立加拿大在这一关键研究领域的形象，特别是在全球气候变化威胁我们海洋健康的情况下。我在建立旨在了解微生物和有机碳之间相互作用的新研究工具方面发挥了主导作用。我在同位素地球化学、分子生物学和微生物学领域的跨学科背景，使我唯一有资格领导拟议的研究计划。

The ocean is home to complex and diverse microorganisms that shape the dynamics of these ecosystems in a myriad of ways. Through their metabolism and growth, marine microorganisms play a central role in the global carbon cycle and influence the size and magnitude of carbon that becomes sequestered in deep ocean waters and sediments. My research focuses on heterotrophic microorganisms which break down organic carbon and release carbon dioxide (CO2) as a byproduct of their metabolism, this is referred to as the remineralization of organic matter. Heterotrophic microorganisms are the primary producers of CO2 in the ocean and any substantial change in their metabolic activity has the potential to significantly alter how carbon is processed and stored in the ocean. The proposed research will use a variety of molecular and isotopic tools to gain new insights into the controls on heterotrophic microorganisms as well as the metabolic pathways and ecological interactions that underpin carbon cycling in the ocean. The core research questions are: 1) how does the metabolic potential of microorganisms influence organic matter remineralization? (2) do ecological interactions between microorganisms increase or decrease rates of organic matter remineralization? and (3) is cell density an important control on the production of enzymes that initiate the remineralization of organic matter? These questions will be examined through three testable hypotheses in studies conducted by two MSc students, two PhD students and four undergraduate students. Overall the results of this research will advance our understanding of the microbial mechanisms that regulate carbon fluxes in the ocean. Ultimately, this will allow us to develop a much needed molecular-level framework to improve our ability to predict how marine carbon cycling will change under a future warmer climate. Additionally, microorganisms play a direct role in remediating spilled oil in the ocean. Deciphering the fundamental mechanisms that regulate microbial activity will greatly improve our ability to develop oil spill response plans and remediation strategies. This research program will maintain and build Canada's profile in this critical field of research, especially as global climate change threatens the health of our oceans. I have played a leading role in establishing new research tools that aim to understand the interactions between microorganisms and organic carbon. My interdisciplinary background in the fields of isotope geochemistry, molecular biology and microbiology, make me uniquely qualified to lead the proposed research program.