Fe Acquisition by Trichodesmium: Role of the Associated Microbial Community

束毛藻是一种群体性的海洋固氮蓝藻，在贫营养的热带和亚热带海洋中对新的氮库有重要贡献。由于重氮营养生长对铁的高需求和海洋沃茨中铁的低有效性，铁的有效性已被认为是束毛藻生长和固氮的重要限制因素。目前对束毛藻获得铁的机制知之甚少。 在这个项目中，生活在与束毛藻菌落密切相关的细菌正在研究它们在促进菌落铁获取中的作用，通过生产铁螯合剂（例如，铁螯合剂）。铁载体）。 这些PI表征与束毛藻菌落相关的微生物群落，并通过使用培养菌株、群落成员的近亲或分子方法研究该群落产生铁络合物的能力。 放射性示踪剂研究束毛藻吸收溶解和胶体铁，包括铁络合物与海洋铁载体从束毛藻相关的细菌正在进行在实验室和现场。 目前正在对种植和自然种群进行分子和吸收研究。非纯性和纯性束毛藻菌株的培养允许比较有和没有细菌存在下的铁载体摄取和胶体铁溶解。收集自然种群的工作正在与百慕大大西洋时间序列站和夏威夷海洋时间序列研究以及机会航行进行中的方案一起进行。

Trichodesmium are colonial marine N2-fixing cyanobacteria that contribute significantly to new nitrogen pools in the oligotrophic tropical and subtropical oceans. Due to the high iron requirement for diazotrophic growth and the low availability of iron in oceanic waters, iron availability has been proposed to be an important limiting factor for Trichodesmium growth and N2 fixation. Currently little is known about the mechanisms employed by Trichodesmium to acquire iron. In this project, bacteria living in close association with Trichodesmium colonies are being studied in their role in facilitating colony iron acquisition, through the production of Fe chelating agents (eg. siderophores). These PIs are characterizing the microbial community associated with Trichodesmium colonies, and investigating the ability of the community to produce iron-complexing compounds by using cultivated strains, close relatives of community members, or molecular approaches. Radiotracer studies of Trichodesmium uptake of dissolved and colloidal iron, including iron complexes with marine siderophores from Trichodesmium-associated bacteria are being carried out both in the laboratory and in the field. Molecular and uptake studies are being carried out with both cultivated and natural populations. Cultivation of non-axenic and axenic Trichodesmium strains are allowing comparison of siderophore uptake and colloidal iron dissolution with and without the presence of bacteria. Collection of natural populations are being carried out in conjunction with ongoing programs at the Bermuda Atlantic Time Series station (BATS) and the Hawaii Ocean Time-series study (HOT) as well as on cruises of opportunity.