EAGER: Cyanobacteria-Bacteria Associations in the Ocean and Their Biogeochemical Consequences

Azam EAGER 1036613知识专长：浮游海洋细菌和浮游生物（“细菌”）在海洋浮游植物固定的碳的生物地球化学命运的变化中起着重要作用。因此，细菌与初级生产者的耦合对气候和生态系统模型有影响。由于细菌与有机物，包括浮游植物细胞，在纳米至微米尺度上相互作用，了解细菌与初级生产者的生物地球化学耦合需要了解微米尺度上相互作用的性质和强度。PI最近使用原子力显微镜（AFM）发现，相当一部分异养（非光合作用）细菌，包括以前被认为是自由生活的聚球藻的天然组合，似乎与其他细菌结合。在一个初步的实验中，浮游细菌也与原绿球藻的培养物相关联（我们还不知道原绿球藻的天然组合是否含有结合细菌）。鉴于聚球藻属和原绿球藻属作为海洋中主要初级生产者的生物地球化学重要性，它们与异养细菌的共生可能产生深远的影响。EAGER的研究有可能改变对微生物碳循环和海洋生态系统功能的看法。它可能揭示了一个新的微观空间背景，例如，碳和营养循环的“热点”，特别是在贫营养沃茨，聚球藻和原绿球藻是主要的初级生产者。这种潜在的变革性，但高风险的研究，是一个非常适合EAGER模型的资金。尖端的方法，包括冷冻电子断层扫描，nanoSIMS和单细胞遗传学将通过多学科合作来测试共生体的超微结构和生态系统功能的假设。将通过直接显微操作海水样品以挑选单个结合细胞，然后通过MDA（多重置换扩增）分析来确定结合伴侣的系统发育身份。细胞间元素交换的NanoSIMS分析将表征共生体的性质和地球化学意义。实地研究将检查共生体的分布与相关环境因素的关系。PI详细描述的目标的成功应该产生对共生体的机械理解和生物地球化学意义。我们将在广泛发行的期刊上迅速传播我们的研究成果，并通过在适当的会议上进行演讲。更广泛的影响：本研究项目旨在深入了解微生物在海洋生态系统功能、生物碳循环和海洋在全球气候变化中的作用的基本机制。因此，研究结果还应与渔业和气候变化等紧迫的社会问题相关。PI的实验室积极参与从地方到国际各级的公共教育，拟议研究的结果将以适当的无障碍形式向公众广泛传播。一名博士后和一名研究生将在本研究期间接受培训。

Azam EAGER 1036613Intellectual Merit: Pelagic marine bacteria and Archaea ("bacteria") play major roles in the variability in the biogeochemical fate of carbon fixed by phytoplankton in the ocean. The coupling of bacteria with the primary producers therefore has implications for climate and ecosystem models. Since bacteria interact with organic matter, including phytoplankton cells, at the nanometer to micrometer scale, understanding the biogeochemical coupling of bacteria with primary producers requires knowledge of the nature and strength of interactions at the micrometer scale. Using Atomic Force Microscopy (AFM) the PI recently discovered that a substantial fraction of heterotrophic (non-photosynthetic) bacteria, including the natural assemblages of Synechococcus, previously considered free-living, appeared conjoint with other bacteria. In a preliminary experiment, pelagic bacteria also became associated with cultures of Prochlorococcus (we do not yet know whether natural assemblages of Prochlorococcus harbor conjoint bacteria). In view of the biogeochemical importance of Synechococcus and Prochlorococcus as major primary producers in the ocean, their symbioses with heterotrophic bacteria could have far-reaching consequences.This EAGER study has the potential to change ideas on microbial carbon cycling and marine ecosystems functioning. It may reveal a novel microspatial context, e.g., carbon and nutrient cycling 'hot spots', particularly in oligotrophic waters where Synechococcus and Prochlorococcus are major primary producers. This potentially transformative, but high risk research, is an excellent fit to the EAGER model for funding. Cutting edge methodologies, including cryo-electron tomography, nanoSIMS and single cell phylogenetics will be used through multidisciplinary collaborations to test hypotheses on the ultrastructure and ecosystem function of the symbioses. The phylogenetic identity of the conjoint partners will be determined by direct micromanipulation of seawater samples to pick individual conjoint cells followed by analysis by MDA (Multiple Displacement Amplification). NanoSIMS analysis of intercellular elemental exchanges will characterize the nature and biogeochemical significance of the symbioses. Field studies will examine the distribution of the symbioses in relation to relevant environmental factors. Success in the goals detailed by the PI should yield mechanistic understanding and biogeochemical significance of the symbioses. We will rapidly communicate our findings in a wide circulation journal as well as through talks at appropriate conferences.Broader Impacts: This research project is aimed at gaining insights on fundamental mechanisms underlying the roles of microbes in the functioning of marine ecosystems, biological carbon cycling and the ocean's role in global climate variability. Therefore, the result should also be relevant to pressing societal issues fisheries and climate change. The PI's lab is actively involved in public education from local to international levels, and the findings of the proposed research will be disseminated broadly to the public in appropriately accessible formats. One postdoctoral fellow and one graduate student will receive training during this research.