Bacteria-Mediated Coral Disease Resistance

珊瑚日益受到疾病引起的死亡的威胁，而海洋表面温度的升高可能会通过促进病原体生长或毒力、降低宿主对感染的抵抗力或两者兼而有之而增加感染风险。该项目将研究与珊瑚相关的细菌通过细菌-细菌相互作用来调节抗病能力的假设，并且这种抗病机制会随着温度的升高而改变。该项目测试了与细菌介导的耐药性假说相关的三个假说：(1)珊瑚相关细菌之间的拮抗相互作用限制了病原体在粘液层内的定植和增殖。细菌之间的拮抗相互作用影响海洋中上层和附生生物群落中细菌的多样性和空间分布，部分原因是阻止一些细菌进入已建立的群落。珊瑚表面粘液层中的类似过程将通过实验室分析和使用可培养细菌的原位实验，结合荧光原位杂交、特定种型特异性PCR和变性梯度凝胶电泳来评估非可培养细菌。(2)温度升高改变了细菌的生长速度和细菌-细菌的拮抗作用，促进了病原菌的定植和增殖。生长速度是影响细菌群落动态的基本力量，并可以影响群落内系统类型的相对丰度。温度可以影响细菌的生长速度和抗生素的产生，从而改变细菌与细菌相互作用的结果。依赖于培养和独立的技术将被用来探索暴露在各种温度处理下的珊瑚上的细菌-细菌相互作用，以及珊瑚礁上永久标记的珊瑚的临时样本。(3)与珊瑚有关的微生物群落的其他成员(如真核食草动物、病毒)影响与珊瑚有关的细菌的丰度和动态，有可能改变抗病能力。珊瑚粘液栖息地不仅有原核生物，也有真核食草动物和病毒。这些捕食者强烈影响水柱中的细菌群落，它们在珊瑚粘液层中的作用被认为是类似的。该项目的学术价值在于将珊瑚礁生态学和微生物生态学结合起来，以解决有关珊瑚健康和疾病的基本问题。依赖于培养和独立的技术将被用来研究可培养细菌的生态相互作用，并评估整个群落的动态。考虑到珊瑚礁地位的下降和对未来下降的预测，这项工作是及时和必要的。该项目的更广泛影响包括通过为斯克里普斯(加利福尼亚州拉荷亚)桦树水族馆的教育工作人员举办专业发展系列研讨会，将研究与教育结合起来。将通过以下方式鼓励代表不足群体参加：1)与世界银行/全球环境基金珊瑚礁针对性疾病研究小组合作，在菲律宾和东非举办国际珊瑚疾病讲习班，2)辅导关岛大学本科生，3)为少数族裔高中生编写海洋科学课程，并为国家海洋科学碗辅导少数族裔高中生团队。

Corals are increasingly threatened by disease induced mortality, and the risk of infection may be increased by elevated sea surface temperature either by promoting pathogen growth or virulence, reducing host resistance to infection, or a combination of both. This project will investigate the hypothesis that coral-associated bacteria mediate disease resistance through bacteria-bacteria interactions and this resistance mechanism is altered by elevated temperatures. The project tests three hypotheses related to the bacteria mediated resistance hypothesis: (1) Antagonistic interactions among coral-associated bacteria limit pathogen colonization and proliferation within the mucus layer. Antagonistic interactions among bacteria affect the diversity and spatial distribution of bacteria in marine pelagic and epibiotic communities, in part by preventing some bacteria from entering the established community. Analogous processes in the coral surface mucus layer will be examined with laboratory assays and in situ experiments using cultivable bacteria, combined with fluorescent in situ hybridization, phylotype-specific PCR, and denaturing gradient gel electrophoresis to assess non-cultivable bacteria. (2) Elevated temperature alters bacterial growth rates and bacteria-bacteria antagonism, facilitating pathogen colonization and proliferation. Growth rates are a fundamental force influencing bacteria community dynamics and can influence the relative abundance of phylotypes within a community. Temperature can affect growth rate as well as bacterial antibiotic production, thus altering the outcome of bacteria-bacteria interactions. Culture-dependent and -independent techniques will be used to explore bacteria-bacteria interactions on corals exposed to various temperature treatments and temporal samples of permanently tagged corals on the reef. (3) Other members of the coral-associated microbial community (e.g., eukaryotic grazers, viruses) impact the abundance and dynamics of coral-associated bacteria, potentially altering disease resistance. The coral mucus habitat contains not only prokaryotes but eukaryotic grazers and viruses. These predators strongly influence bacteria communities in the water column and their role is proposed to be analogous in the coral mucus layer. The intellectual merit of this project lies in the integration of coral reef ecology and microbial ecology to address fundamental questions regarding coral health and disease. Both culture-dependent and-independent techniques will be utilized to examine the ecological interactions of cultivable bacteria and assess dynamics of the whole community. The work is timely and imperative given the declining status of coral reefs and predictions of future decline. The broader impacts of this project include integration of research and education by developing seminars for the Professional Development Series for Education Staff at the Birch Aquarium at Scripps (La Jolla, CA). Participation of under-represented groups will be encouraged through 1) international coral disease workshops in the Philippines and East Africa facilitated in conjunction with the World Bank / Global Environment Fund Coral Reef Targeted Disease Research Group, 2) Mentoring of undergraduate students from the University of Guam, and 3) Developing a curriculum to engage minority high school students with ocean sciences and mentoring a team of minority high school students for the National Ocean Sciences Bowl.