Bacterial Interactions Underlying Coral Disease Resistance

智力优势：在地球仪的许多地方，越来越多的疾病，包括一些明显由细菌引起的疾病，正在大量毁灭造礁珊瑚。珊瑚是开放系统，持续暴露于上覆海水中各种各样的外源细菌，并附着在下沉颗粒上。此外，随着沿海开发继续扩大，富营养化加剧，人们越来越担心，正常珊瑚相关群落中的内源性细菌可能会增殖，成为机会性病原体，造成组织损伤和珊瑚死亡。珊瑚如何抵抗细菌入侵是一个复杂的问题，其中一个关键方面是内源性细菌抵抗潜在病原体定植和增殖的能力。尽管近年来在揭示与珊瑚有关的细菌的显著遗传多样性方面取得了很大进展，但由于缺乏对微生物群落内以及与构成珊瑚健康和疾病基础的外源细菌之间的原位生态相互作用的了解，珊瑚疾病的缓解和管理仍然受到阻碍。细菌附着和增殖是感染过程中的关键步骤，因此抑制或防止病原体的定殖和增殖是抗病性的基础。 研究人员最近的研究表明，暴露于有机物富集的珊瑚可能会被潜在的病原体定殖，但这些群落可以从这种扰动中反弹。在进行体外研究时，研究人员发现细菌-细菌拮抗作用在珊瑚分离物中很常见，这表明它可能是抵抗群落变化和病原体定植的一种机制。因此，它可以推动珊瑚相关微生物群落的恢复力。 在本项目中，研究人员将在原位环境中测试这些相互作用。 微生物是至关重要的珊瑚生态系统的功能在全球范围内，因此，它是必不可少的，在微观尺度上的微生物相互作用的机械理解。 将对以下假设进行检验，这些假设旨在阐明微生物相互作用防止细菌在珊瑚粘液层（CML）中定植和增殖的生态机制：1）CML中的细菌群落动态平衡通过排除潜在的定殖者来维持2）珊瑚粘液层内的微空间有机物热点，特别是围绕动物源性珊瑚，3）空间分散的有机物输入压倒了微尺度热点，使病原体能够在CML中定植更广泛的影响：该项目同时提高了我们对珊瑚相关微生物生态学的基本理解，并为海洋资源管理决策提供了必要的科学依据。地方和国际两级的公众教育是所有参与研究人员日常活动的一个关键组成部分，这些活动将因纳入本研究产生的尖端生态研究结果而蓬勃发展。此外，三名博士后研究人员（两名全职，一名每年两个月）和一名研究生将接受通过此次更新支持的综合研究和教育活动的培训。

Intellectual Merit: An ever-growing variety of diseases, including some demonstrably caused by bacteria, are decimating reef-building corals in many places around the globe. Corals are open systems persistently exposed to a great diversity of exogenous bacteria in the overlying seawater and attached to sinking particles. Furthermore, as coastal development continues to expand, increasing eutrophication, there is increasing concern that endogenous bacteria among the normal coral associated community could proliferate to become opportunistic pathogens causing tissue damage and coral death. How corals resist bacterial invasions is a complex issue, one critical aspect being the ability of endogenous bacteria to resist colonization and proliferation of potential pathogens. Despite great strides in recent years uncovering the remarkable genetic diversity of coral-associated bacteria, mitigation and management of coral diseases remains hampered by a lack of understanding of in situ ecological interactions within the microbial community and with exogenous bacteria that underlie coral health and disease. Bacterial attachment and proliferation are critical steps in the infection process, thus inhibiting or preventing colonization and proliferation of pathogens is fundamental to disease resistance. Recent research by the investigator demonstrates that corals exposed to organic matter enrichment can become colonized by potential pathogens, but the communities can rebound from such perturbations. Conducting in vitro studies, the investigator found that bacteria-bacteria antagonism is common among coral isolates which suggests it may be a mechanism to resist community shifts and pathogen colonization. It could thus drive resilience within coral-associated microbial communities. In this project the investigator will test these interactions in an in situ context. Microbes are critical for the functioning of coral ecosystems at the global scale and, therefore, it is essential that a mechanistic understanding of microbial interactions at the microscale be attained. The following hypotheses will be tested which are designed to elucidate the ecological mechanisms by which bacterial colonization and proliferation in the coral mucus layer (CML) are prevented by microbial interactions: 1) Bacterial community homeostasis in the CML is maintained through the exclusion of potential colonizers 2) Microspatial organic matter hotspots within the coral mucus layer, particularly surrounding zooxanthallae, create loci of intense growth and antagonism 3) Spatially dispersed organic matter inputs overwhelm microscale hotspots and enable pathogens to colonize the CML Broader Impacts: This project simultaneously improves our fundamental understanding of coral associated microbial ecology and provides a necessary scientific basis for marine resource management decisions. Public education, at both the local and international levels, is a key component of the routine activities of all participating researchers, and these activities will prosper from inclusion of cutting-edge ecological findings generated by this research. Additionally, three postdoctoral researchers (two full time and one at two months per year) and one graduate student will receive training from the integrated research and education activities supported through this renewal.