The Chemical Ecology of Marine Sediment Bacteria

智力价值：本项目探索细菌次生代谢物作为化学防御剂的生态功能。它的目标是海洋沉积物，这是一个主要的、尚未被充分探索的海洋生物群落。目的是测试与细菌次生代谢物对共生微生物和原菌食草动物的影响有关的三个假设。重点是Salinispora细菌属，它在海洋沉积物中的多样性和分布方面得到了很好的定义，并在基因组水平和次生代谢物生产方面得到了很好的表征。最近为这些细菌开发的遗传系统将用于建立生物活动与特定次级代谢物之间的联系。通过采用包括成像质谱法在内的各种创新方法，首次有可能深入了解Salinispora次生代谢物在构建海洋沉积物微生物群落中的潜在作用。这些结果将对我们理解海洋环境中调节细菌多样性和分布的因素具有广泛的意义。此外，他们还将提出补充假说，即次生代谢物代表了描述Salinispora物种的生态型定义特征。拟检验的假设为：H1：次生代谢物抑制微生物竞争，H2：次生代谢物影响细菌群落组成，h3：次生代谢物具有无脊椎动物摄食威慑作用。将使用直接激发法测试大量不同的共生微生物对Salinispora次生代谢物的敏感性。这些类型的检测是高度信息性的，因为除了毒性之外，它们还可以检测行为和形态反应。最近开发的成像质谱技术将用于可视化与任何观察到的生物活性相关的次生代谢物。结果将与现有的基因组序列相关联，并用于辅助化合物鉴定。相关的途径将被敲除，为特定化合物的生物活性提供实验支持。鉴于大多数海洋细菌不容易培养，这些实验将通过采用不依赖培养的技术来额外解决次生代谢物对沉积物细菌群落的影响。原位生长室和下一代测序技术将用于测试提取物和纯化合物对沉积物细菌自然组合的影响。研究结果将为未来的栽培工作提供信息，并为天然化学防御所针对的生物体提供更全面的评估。最后，将使用两种模型原生生物开发一种强大的饲养试验，并用于测试细菌次级代谢物作为无脊椎动物摄食威慑物的作用。原位实验将提供深入了解受这些防御影响的无脊椎动物的自然组合。这些研究的总体结果有可能深刻影响我们对微生物次生代谢物的生态功能的理解，以及这些化合物对群落组成的影响程度。更广泛的影响：这项研究提供了一个机会，从根本上推进我们对微生物次生代谢物在主要海洋生物群系中的生态作用的理解。这些活动是高度跨学科的，以前所未有的方式汇集了微生物学，生态学和海洋天然产物化学的各个方面。它加强了与墨西哥同事的国际合作，并包括学生和博士后培训以及向代表性不足的群体的推广。后者包括参加预期的UCSD/HBCU（历史上的黑人学院和大学）计划和UCSD暑期科学研究培训学院（STARS）计划。单独的NIH资金将用于探索发现的任何新的次级代谢物的药用潜力。这些化合物也将提供给美国国立卫生研究院分子图书馆项目，在那里它们将被广泛地提供给科学界。该项目利用现有的nsf资助的船舶时间，有可能产生新的分析模型，将广泛适用于化学生态学研究界。

Intellectual Merit: This project explores the ecological functions of bacterial secondary metabolites as agents of chemical defense. It targets marine sediments, a major and poorly explored marine biome. The aims are to test three hypotheses related to the effects of bacterial secondary metabolites on co-occurring microorganisms and protistan grazers. The focus is on the bacterial genus Salinispora, which is well defined in terms of its diversity and distributions in marine sediments, and well characterized at the genomic level and in terms of secondary metabolite production. A genetic system recently developed for these bacteria will be employed to establish links between biological activities and specific secondary metabolites. By employing a variety of innovative methodologies including imaging mass spectrometry, it will be possible for the first time to gain insight into the potential roles of Salinispora secondary metabolites in structuring marine sediment microbial communities. The results will have broad implications for our understanding of the factors that regulate the diversity and distributions of bacteria in the marine environment. They will additionally address the supplemental hypothesis that secondary metabolites represent ecotype-defining traits that delineate Salinispora species.The hypotheses to be tested are:H1: Secondary metabolites inhibit microbial competitors,H2: Secondary metabolites affect bacterial community composition, andH3: Secondary metabolites function as invertebrate feeding deterrents. A large collection of diverse, co-occurring microbes will be tested for sensitivity to Salinispora secondary metabolites using a direct challenge assay. These types of assays are highly informative in that they can detect behavioral and morphological responses in addition to toxicity. A recently developed imaging mass spectrometry technique will be used to visualize secondary metabolites associated with any observed biological activities. The results will be linked to existing genome sequences and used to aide in compound identification. The associated pathways will be knocked out to provide experimental support for the biological activities of specific compounds.Given that most marine bacteria are not readily cultured, these experiments will additionally address the effects of secondary metabolites on the sediment bacterial community by employing culture independent techniques. In situ growth chambers and next generation sequencing technologies will be used to test extracts and pure compounds against a natural assemblages of sediment bacteria. The results will inform future cultivation efforts and provide a more comprehensive assessment of the organisms targeted by native chemical defenses. Finally, a robust feeding assay using two model protists will be developed and used to test the roles of bacterial secondary metabolites as invertebrate feeding deterrents. In situ experiments will provide insight into the natural assemblage of invertebrates affected by these defenses. The overall results of these studies have the potential to profoundly impact our understanding of the ecological functions of microbial secondary metabolites and the extent to which these compounds affect community composition.Broader Impacts: This research presents the opportunity to fundamentally advance our understanding of the ecological roles of microbial secondary metabolites in a major marine biome. The activities are highly interdisciplinary and bring together aspects of microbiology, ecology, and marine natural products chemistry in unprecedented ways. It strengthens international collaborations with colleagues in Mexico and includes student and postdoctoral training and outreach to under-represented groups. The later includes participation in the anticipated UCSD/HBCU (Historically Black College and University) program and the UCSD Summer Training Academy for Research in the Sciences (STARS) program. Separate NIH funding will be leveraged to explore the medicinal potential of any new secondary metabolites discovered. These compounds will also be provided to the NIH Molecular Libraries program where they will be made broadly available to the scientific community. The project leverages existing NSF-funded ship time and has the potential to yield new assay models that will be broadly applicable to the chemical ecology research community.