Linking microbial ecology and biogeochemistry in the St. Lawrence Estuary through functional genomics.

沿海水生环境，如加拿大东部的圣劳伦斯河口（SLE），是支持多种生物群落的生产性生态系统，包括具有重要商业价值的海洋生物。在许多方面，这些生态系统是由微生物的活动维持的。例如，微生物参与有机物（OM）的产生和转化，影响全球碳(C)和氮(N)循环，并控制通过海洋生态系统的能量和营养物质的流动。目前，由于人类活动，海洋的化学成分正在全球范围内发生变化，这可能导致全球和局部的海洋酸化和缺氧。要了解与碳氮循环相关的控制这些过程的因素，需要对整个水柱和沉积物中不同细菌群落的结构和功能进行表征。在这里，我们寻求财政支持，以建立几年的基础研究，其总体目标是扩大我们在SLE中微生物群落动态与C和N转化之间联系的时间序列工作。我们将结合新颖的采样技术、功能基因组学、微生物学以及有机和无机地球化学方法，更好地约束SLE中细菌多样性/动力学、OM循环和淡水-盐水过渡中氧浓度之间的联系。我们将收集样本进行分类学和基因组学研究。此外，我们在之前的工作的基础上，加入了一个实验功能基因组学组件，在那里我们将操纵C和营养物质的可用性，并跟踪微生物的反应，以进一步表征河口中C和N循环背后的微生物群和代谢途径。我们的取样工作是适度的，但至关重要，因为它将允许收集活的材料，看看细菌多样性，活性和动态的当今动态。这些信息对于我们了解沿盐度和氧气梯度的细菌动力学，以及细菌如何受到海岸系统中OM化学成分，反应性和再循环的影响至关重要。

Coastal aquatic environments, such as the St. Lawrence Estuary (SLE) in Eastern Canada, are productive ecosystems that support diverse biological communities, including commercially important marine life. In many respects, these ecosystems are sustained by the activity of microorganisms. For example, microbes are involved in the production and transformation of organic matter (OM), which influences global carbon (C) and nitrogen (N) cycles and controls the flow of energy and nutrients through marine ecosystems. Presently, the chemistry of the oceans is changing at a global scale due to human activity, which can lead to ocean acidification and hypoxia both globally and locally in the SLE. Understanding the factors controlling theses processes in relation to the C and N cycles requires a characterization of the structure and function of different bacterial communities thriving throughout the water column and the sediments. Here, we seek financial support to build upon several years of foundational research with an overall objective of expanding our time series work on the linkages between microbial community dynamics and C and N transformations in the SLE. We will combine novel sampling techniques, with functional genomics, microbiological, as well as organic and inorganic geochemical methods to better constrain the links between bacterial diversity/dynamics, OM cycling and oxygen concentrations along the fresh-salt water transition in SLE. We will collect samples for taxonomic and genomic studies. Moreover, we are building on our previous work by including an experimental functional genomics component, where we will manipulate the C and nutrient availability and track microbial responses in order to further characterize the microbial groups and metabolic pathways that underlie C and N cycling in the estuary. Our sampling effort is modest but critical as it will allow collecting live material to look at present-day dynamics of bacterial diversity, activity and dynamics. This information is pivotal to our understanding of bacterial dynamics along the salinity and oxygen gradients, and on how bacteria are affected by and affect OM chemical composition, reactivity and recycling in coastal systems.