Bacterial Interactions Underlying Coral Disease Resistance

智力价值：越来越多的疾病，包括一些明显由细菌引起的疾病，正在摧毁全球许多地方的造礁珊瑚。珊瑚是开放的系统，长期暴露于海水中多种多样的外源细菌，并附着在下沉的颗粒上。此外，随着沿海发展的不断扩大，富营养化的加剧，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造成组织损伤和珊瑚死亡的机会性病原体。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。尽管近年来取得了巨大进展，揭示了与珊瑚有关的细菌的显著遗传多样性，但由于缺乏对微生物群落内部以及与珊瑚健康和疾病背后的外源细菌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。细菌的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植和增殖是抗病性的基础。研究者最近的研究表明，暴露于有机物质富集的珊瑚可以被潜在的病原体定植，但群落可以从这种扰动中反弹。通过体外研究，研究者发现细菌-细菌拮抗作用在珊瑚分离株中很常见，这表明它可能是抵抗群落转移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。在这个项目中，研究者将在现场环境中测试这些相互作用。微生物在全球范围内对珊瑚生态系统的功能至关重要，因此，必须在微观尺度上对微生物的相互作用有一个机械的了解。以下假设将被测试，这些假设旨在阐明微生物相互作用阻止珊瑚黏液层（CML）中细菌定植和增殖的生态机制：1) CML中细菌群落的动态平衡是通过排除潜在的定植者来维持的2)珊瑚黏液层内的微空间有机质热点，特别是周围的虫黄藻，创造了强烈生长和拮抗的位点3)空间分散的有机质输入压倒了微尺度热点，使病原体能够定植CML该项目同时提高了我们对珊瑚相关微生物生态学的基本认识，并为海洋资源管理决策提供了必要的科学依据。地方和国际层面的公共教育是所有参与研究人员日常活动的关键组成部分，这些活动将因纳入本研究产生的前沿生态发现而蓬勃发展。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该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.