Excellence in Research: Microbiome of the Eastern Oyster (Crassostrea virginica) and its denitrification potential in benthic systems

牡蛎数量在世界范围内下降，但珊瑚礁恢复工作和扩大水产养殖业务有助于满足消费者的需求。除了它们的食物价值外，牡蛎还通过它们的滤食机制改善水质，从而清洁周围的水，去除可能导致低氧“死区”的有机物，并帮助减少陆地径流中的氮和磷等营养物质。牡蛎含有微生物群落，可能包括有害和有益的细菌，参与营养循环和其他生态系统服务。这些微生物群落的结构和功能尚不清楚，特别是在暖温带和热带水域。因此，在各种生长条件下，更好地评估野生和养殖牡蛎中存在的微生物及其环境功能是本工作的重点。特别是，研究小组将研究与溶解氮转化为氮气相关的微生物群。这个过程除去了氮，氮可以作为沿海水域中不受欢迎的藻类繁殖的肥料。研究人员的假设是，与牡蛎相关的微生物是河口水域中大量氮流失的原因，改善了水质，减轻了藻华和鱼类死亡。该项目还将加强两所历史上的黑人学院/大学的研究和培训活动，并进一步教育和培训STEM学科的少数民族学生。对牡蛎微生物群的全面了解将有助于提高对沿海系统营养动态的认识，并有助于改进管理沿海水质和减少营养物污染的策略。牡蛎及其相关的微生物群提供了显著的环境效益，包括去除氮，这是沿海和河口富营养化的主要原因。然而，对牡蛎内共生微生物的存在、丰度、代谢活性和生态意义，特别是在暖温带和热带水域，仍然知之甚少。许多牡蛎微生物群由分类上未解决的和潜在的新微生物组成。填补这一知识缺口至关重要，因为在墨西哥湾和南大西洋沿岸，牡蛎养殖和牡蛎礁的恢复正在大幅扩大。为此，研究小组将调查在不同营养、温度和盐度条件下生长的野生和养殖牡蛎的微生物群。除了微生物群落组成和新微生物的潜在鉴定外，他们还将关注与生物地球化学循环有关的微生物，特别是反硝化作用。一个主要的假设是牡蛎微生物群在河口系统中提供了重要的氮去除生态系统服务。他们将测量溶解态和颗粒态氮、转化速率和反硝化基因丰度（nosZI和nosZII），以更好地了解牡蛎微生物群在氮动力学中的作用。来自两所hbcu的生态学家、微生物学家、生物信息学家和生物地球化学家组成的团队将利用几种新兴的“组学”技术，从而支持这些机构的研究能力的发展和扩大。该项目还包括一个重要的教育组成部分，包括为学生和博士后提供资金。更好地了解牡蛎微生物群的结构和功能将促进对河口生态的认识，并可能为管理沿海水质提供改进的策略。该奖项由综合有机体系统部门的综合生态生理学项目和人力资源开发部门的历史黑人学院和大学本科项目共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Oyster populations have declined worldwide, but reef restoration efforts and expanding aquaculture operations are helping to meet consumer demands. In addition to their food value, oysters improve water quality via their filter feeding mechanism, thus cleaning the surrounding water, removing organic matter than can cause low-oxygen 'dead zones', and assisting in mitigation of nutrients like nitrogen and phosphorus from terrestrial runoff. Oysters contain microbial communities that may include harmful as well as beneficial bacteria, involved in nutrient cycling and other ecosystem services. The structure and function of these microbial communities are poorly understood, especially in warm temperate and tropical water habitats. Therefore, obtaining a better assessment of what microbes are present, and their environmental functions, in wild and cultured oysters under a variety of growth conditions are the focus of this work. In particular, the research team will investigate the microbiomes associated with the conversion of dissolved nitrogen into nitrogen gas. This process removes nitrogen that can act as a fertilizer for undesirable algal blooms in coastal waters. The investigators' hypothesis is that oyster-associated microorganisms are responsible for significant nitrogen losses within the estuarine waters, improving water quality and mitigating algal blooms and fish kills. This project will also enhance research and training activities at two historically black colleges/universities, and further the education and training of minority students in STEM disciplines. A comprehensive understanding of the oyster microbiome will improve understanding of nutrient dynamics in coastal systems and help improve strategies for managing coastal water quality and reducing nutrient pollution.Oysters and their associated microbiomes provide significant environmental benefits, including removal of nitrogen, a major cause of coastal and estuarine eutrophication. However, the presence, abundance, metabolic activity and ecological significance of microbial endosymbionts within oysters, especially in warm temperate and tropical waters, remain poorly understood. Much of the oyster microbiome consists of taxonomically unresolved and potentially novel microorganisms. Filling this knowledge gap is critical because oyster aquaculture and restoration of oyster reefs is greatly expanding in the Gulf of Mexico and south Atlantic coasts. Towards this end, the research team will investigate the microbiomes of wild and cultured oysters grown under different nutrient, temperature and salinity regimes. In addition to the microbiome community composition and potential identification of novel microbes, they will focus on microbes associated with biogeochemical cycling, particularly denitrification. One major hypothesis is that oyster microbiomes provide a significant ecosystem service of nitrogen removal in estuarine systems. They will measure dissolved and particulate nitrogen species, rates of transformations and denitrification gene abundances (nosZI and nosZII), to better understand the oyster microbiome's role in N dynamics. Several emergent "omics" techniques will be utilized by a team of ecologists, microbiologists, bioinformaticians and biogeochemists from two HBCUs, thus supporting the development and expansion of research capacity at these institutions. The project also includes a significant education component, including funding for students and a postdoctoral fellow. Better understanding of the structure and function of oyster microbiomes will advance knowledge of estuarine ecology and may provide improved strategies for managing coastal water quality. This award was co-funded by the Integrative Ecological Physiology Program in the the Division of Integrative Organismal Systems and the Historically Black Colleges and Universities Undergraduate Program in the Division of Human Resource Development.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.