Fe Acquisition by Trichodesmium: Role of the Associated Microbial Community

Trichodesum是一种群体海洋固氮蓝藻，对热带和亚热带海洋中新的氮库有重要贡献。由于重氮营养生长对铁的需求很高，而海水中铁的利用率很低，铁的有效性被认为是木霉生长和固氮的重要限制因素。目前，人们对毛霉获取铁的机制知之甚少。在这个项目中，与毛霉菌落密切相关的细菌正在研究它们在促进菌落铁获取方面的作用，通过生产铁络合剂(例如。铁载体)。这些PI正在表征与毛霉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来调查群落产生络合铁化合物的能力。正在实验室和实地开展对木霉对溶解和胶体铁的吸收的放射性示踪剂研究，包括与木霉相关细菌的海洋铁载体形成的铁的络合物。目前正在对栽培种群和自然种群进行分子和吸收研究。培养非无菌和无菌木霉菌株可以比较有无细菌存在时铁载体的摄取和胶体铁的溶解。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)以及机遇号邮轮正在进行的方案一起进行自然种群的收集。

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.