Fe Acquisition by Trichodesmium: Role of the Associated Microbial Community

Trichodesmium是一种殖民地海洋固氮蓝藻，对热带和亚热带低营养海洋的新氮池有重要贡献。由于重氮营养生长对铁的需要量大，而海水中铁的有效性低，铁有效性被认为是毛菌生长和固氮的重要限制因素。目前对木霉获得铁的机制知之甚少。在这个项目中，与毛菌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（如铁螯合剂）。含铁细胞)。这些pi正在表征与毛霉菌落相关的微生物群落，并通过培养菌株、群落成员的近亲或分子方法研究该群落产生铁络合化合物的能力。目前正在实验室和实地对木霉吸收溶解铁和胶体铁的放射性示踪剂进行研究，包括与与木霉有关的细菌的海洋铁载体的铁络合物。正在对栽培种群和自然种群进行分子和摄取研究。培养非无菌菌株和无菌菌株可以比较铁载体的摄取和胶体铁溶解有和没有细菌的存在。自然种群的收集正在与百慕大大西洋时间序列站（BATS）和夏威夷海洋时间序列研究（HOT）正在进行的项目以及机会巡航一起进行。

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.