OCE-PRF Track 1 (Broadening Participation): Impact of Phytoplankton-Bacteria Interactions on Metal Bioavailability

在这个为期两年的博士后研究奖学金中，该研究员将分析细菌-微型浮游植物相互作用如何影响沙漠尘埃中微量金属的利用。这些实验的结果将阐明生产金属螯合剂所赋予的生物优势，因为它揭示了细菌在浮游植物金属获取中所起的作用，并将促进对海洋初级生产和碳循环的理解。该研究员将通过以海洋科学和海洋微量金属营养为重点的教学单元和研究实习，扩大代表性不足的群体对当地高中和多样化服务学院海洋科学的参与。该研究由赞助科学家、伍兹霍尔海洋研究所的Mak Saito博士主持。该研究探讨了细菌和浮游植物之间的相互作用如何调节沙漠灰尘中金属的生物利用度，从而影响金属吸收和浮游植物的生长。这项工作解决了以下假设：细菌在picophytoplankton文化的存在将（a）使铁和钴的溶解，（B）刺激picophytoplankton金属的吸收和生长，（c）导致铁吸收转运蛋白的表达，更接近于他们在自然海洋环境中的表达。具体地，微真核生物Ostreococcus和蓝细菌Crocosphaera将在无菌条件（对照）下、在有细菌分离株（实验室培养实验）和在天然细菌群体存在下（船上培养实验）、在添加和不添加沙漠灰尘的情况下、在痕量金属清洁条件下在半连续培养物中生长。Ostreococcus和Crocosphaera是微真核生物光合作用和固氮过程的代表模式生物。将测量处理对生长速率、金属吸收和配体条件稳定性常数的影响。铁载体转运蛋白和其他参与铁吸收的蛋白质将通过蛋白质组学方法检测。此外，差异和定量的蛋白质组学方法将允许在地下海洋样品中的铁吸收参与蛋白质的检测，以比较的转运蛋白和转运蛋白的表达水平的实验培养。

In this two year postdoctoral research fellowship, the fellow will analyze how bacteria-picophytoplankton interactions impact the utilization of trace metals from desert dust. Results of these experiments will elucidate biological advantages conferred by the production of metal chelators, as it reveals the role that bacteria play in phytoplankton metal acquisition, and will advance understanding in oceanic primary production and carbon cycling. The fellow will broaden participation of under-represented groups in ocean sciences at local high schools and diversity-serving colleges through teaching modules and research internships focusing on the ocean sciences and marine trace metal nutrition. The fellow is being hosted by sponsoring scientist Dr. Mak Saito at Woods Hole Oceanographic Institution.The research examines how the interactions between bacteria and phytoplankton modulate the bioavailability of metals from desert dust, and thus impact metal uptake and the growth of phytoplankton. The work addresses the following hypothesis: The presence of bacteria in picophytoplankton cultures will (a) enable iron and cobalt solubilization, (b) spur picophytoplankton metal uptake and growth, and (c) lead to expression of iron uptake transporters which more closely resembles their expression in the natural marine environment. Specifically, the picoeukaryote Ostreococcus and the cyanobacterium Crocosphaera will be grown in semi-continuous cultures under axenic conditions (control), with bacterial isolates (laboratory culture experiments) and in the presence of natural bacterial populations (shipboard culture experiments), with and without addition of desert dust, under trace metal clean conditions. Ostreococcus and Crocosphaera are representative model organisms for processes of picoeukaryotic photosynthesis and nitrogen fixation. Treatment effects on growth rate, metal uptake, and ligand conditional stability constants will be measured. Siderophore transporters and other proteins involved in iron uptake will be detected by proteomic methods. Further, a differential and quantitative proteomic approach will allow for the detection of proteins involved in iron uptake in subsurface ocean samples, in order to compare to the transporters and transporter expression levels of experimental cultures.