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

世界各地的牡蛎数量都在下降，但珊瑚礁的修复工作和不断扩大的水产养殖业务正在帮助满足消费者的需求。除了它们的食用价值外，牡蛎还通过它们的滤食机制改善水质，从而净化周围的水，清除可能导致低氧“死区”的有机物，并帮助缓解陆地径流中的氮和磷等营养物质。牡蛎含有微生物群落，其中可能包括有害细菌和有益细菌，参与营养循环和其他生态系统服务。人们对这些微生物群落的结构和功能知之甚少，尤其是在暖温带和热带水域生境中。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这项工作的重点。特别是，研究小组将调查与溶解氮气转化为氮气相关的微生物群。这个过程去除了氮，这些氮可以作为一种肥料，防止沿海水域出现不受欢迎的藻类水华。研究人员的假设是，与牡蛎相关的微生物是河口水域大量氮损失的原因，这些微生物改善了水质，减少了藻类大量繁殖和鱼类死亡。该项目还将加强两所历史悠久的黑人学院/大学的研究和培训活动，并进一步促进对少数民族学生进行STEM学科的教育和培训。对牡蛎微生物群的全面了解将提高对沿海系统营养动态的了解，并有助于改进沿海水质管理和减少营养污染的战略。牡蛎及其相关微生物群具有显著的环境效益，包括去除氮，这是沿海和河口富营养化的主要原因。然而，牡蛎体内微生物内共生菌的存在、丰度、代谢活性和生态意义仍然知之甚少，特别是在暖温带和热带水域。牡蛎微生物群的很大一部分是由分类上未解决的潜在的新微生物组成的。填补这一知识空白是至关重要的，因为牡蛎水产养殖和牡蛎礁的恢复在墨西哥湾和南大西洋海岸正在大幅扩张。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，他们还将重点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。一个重要的假设是，牡蛎微生物群为河口系统的脱氮提供了重要的生态系统服务。他们将测量溶解和颗粒氮的种类、转化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素动态中的作用。来自两个HBCU的生态学家、微生物学家、生物信息学家和生物地质学家组成的小组将利用几种新出现的“组学”技术，从而支持这些机构研究能力的发展和扩大。该项目还包括一个重要的教育部分，包括资助学生和一名博士后研究员。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了解，并可能为沿海水质管理提供更好的战略。该奖项由该基金会的综合生态生理学项目和人力资源发展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NSF的法定使命，并通过使用基金会的智力优势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.