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)，是支持各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，微生物参与有机质(OM)的生产和转化，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流动。目前，由于人类活动，海洋的化学成分在全球范围内正在发生变化，这可能导致全球和局部SLE的海洋酸化和缺氧。理解与C和N循环相关的控制这些过程的因素，需要描述在整个水柱和沉积物中茁壮成长的不同细菌群落的结构和功能。在这里，我们寻求资金支持，以建立在几年的基础研究的基础上，总体目标是扩大我们在SLE中微生物群落动态与C和N转化之间的联系的时间序列工作。我们将结合新的采样技术，与功能基因组学、微生物学以及有机和无机地球化学方法相结合，更好地限制SLE淡水-咸水过渡过程中细菌多样性/动态、OM循环和氧气浓度之间的联系。我们将收集样本进行分类和基因组研究。此外，我们在以前工作的基础上，加入了一个实验性的功能基因组学组成部分，在那里我们将操纵C和养分的可用性并跟踪微生物的反应，以便进一步表征支撑河口C和N循环的微生物群和代谢途径。我们的采样工作是有限的，但至关重要的，因为它将允许收集活的材料，以查看当今细菌多样性、活性和动态的动态。这些信息对于我们了解细菌沿盐度和氧气梯度的动态，以及细菌如何受到沿海系统中OM的化学成分、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.