The role of iron (Fe) in controlling in situ distributions and activities of marine synechococcus

单细胞蓝细菌聚球藻是海洋环境中最丰富的初级生产者之一。它也是非常广泛的;聚球藻已被发现在开放的海洋，沿海，甚至极地环境。与其近亲原绿球藻不同，聚球藻具有利用NO3的能力，并已被证明在野外对NO3输入作出反应，这表明这种生物可能在全球碳循环，特别是新生产中发挥关键作用。到目前为止，已经确定了16个潜在的分支，人们认为这种高多样性允许聚球藻辐射到许多不同的环境条件。然而，尽管聚球藻的普遍存在和丰富，有很少的研究特征的生理和生态位适应的每个分支。铁（Fe）作为生态位适应的一个决定性因素显示出巨大的潜力，因为它的浓度在聚球藻的地理范围内变化，以及每年在特定的位置，并已被证明限制在开放的海洋和沿海环境的初级生产。此外，培养工作表明，聚球藻菌株具有不同的能力，生长在低浓度的铁。比较海洋聚球藻的现有基因组显示出很大的多样性，在存在或不存在已知的基因相关的铁胁迫，这表明铁可能发挥了关键作用，在聚球藻的多样化和生态位适应。 该项目将研究铁对聚球藻11个不同分支的生长和碳固定的影响（尽可能使用每个分支至少2个菌株），以及铁限制在确定聚球藻分支在时间和空间尺度上的分布中的作用。该项目将产生一个全面和系统的数据集的影响，铁特定的生态位分化聚球藻，提供新的洞察力的因素，控制分支分布，并提供聚球藻多样性的地球化学后果的理解。除了在实验室和现场确定Fe限制对海洋聚球藻的作用和影响外，该项目还将开发基于定量PCR的Fe应力诊断，可供社区使用。这些数据还将有助于改进区分浮游植物群体的模型的参数化，从而提高预测生物地球化学循环动态的能力。这项研究的结果将在国家会议上广泛传播。此外，该项目将完全资助并为博士后研究员Jill A Sohm博士以及两名参加夏季研究的本科生提供宝贵的研究经验和职业发展。

The unicellular cyanobacterium Synechococcus is one of the most abundant primary producers in the marine environment. It is also extremely widespread; Synechococcus has been found in open ocean, coastal and even polar environments. Unlike its close relative, Prochlorococcus, Synechococcus has the ability to use NO3 and has been shown to respond in the field to NO3 inputs, suggesting that this organism may play a key role in global carbon cycling and especially new production. To date, 16 potential clades have been identified, and it is thought that this high diversity allows for the radiation of Synechococcus into many different environmental conditions. However, despite the ubiquity and abundance of Synechococcus, there are few studies characterizing the physiology and niche adaptations of each clade. Iron (Fe) shows great potential as a defining factor for niche adaptations, as its concentration varies over the geographic range of Synechococcus, as well as annually at specific locations, and has been shown to limit primary production in both open ocean and coastal settings. In addition, culture work indicates that Synechococcus strains have different abilities to grow on low concentrations of Fe. A comparison of the available genomes of marine Synechococcus shows great diversity in the presence or absence of known genes related to Fe stress, suggesting that Fe could have played a key role in the diversification and niche adaptation of Synechococcus. This project will study the effects of Fe on growth and carbon fixation in 11 different clades of Synechococcus (using at least 2 strains from each clade whenever possible) and the role of Fe limitation in determining the distribution of Synechococcus clades on temporal and spatial scales. This project will produce a comprehensive and systematic data set on the impact of Fe-specific niche differentiation in Synechococcus, offer new insight into the factors that control clade distribution, and provide understanding of the biogeochemical consequences of Synechococcus diversity. Broader Impacts In addition to defining the role and impact of Fe limitation on marine Synechococcus, both in the lab and in the field, this project will develop quantitative PCR-based Fe stress diagnostics that will be available to the community. These data will also allow for improved parameterization of models in which phytoplankton groups are differentiated, therefore improving the ability to predict the dynamics of biogeochemical cycles. The results of this research will be widely disseminated at national conferences. Furthermore, this project will completely fund and provide valuable research experience and career development for post-doctoral fellow Dr. Jill A Sohm, as well as two undergraduates participating in summer research.