The Role of Fungi in Biogeochemical Transformations of Mn and Other Micro- and Macro-nutrients Along Chemoclines of the Baltic Sea

真菌在波罗的海化学跃层沿线的锰及其他微量和大量营养素的生物地球化学转化中的作用

• 批准号: 2318228
• 负责人: Paraskevi Mara
• 金额: $ 87.64万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2318228&HistoricalAwards=false
• 关键词: Role; Fungi; Biogeochemical; Transformations; Mn

Mounting evidence suggests that fungi constitute an active and diverse fraction of the microbial community inhabiting marine environments. Among these, globally-distributed low-oxygen, and low salinity open-ocean and coastal waters are expected to expand and intensify with climate change. Manganese (Mn) is a nutrient that is distributed throughout low-oxygen marine systems that plays an essential role in major elemental cycles, including those performed by microorganisms. Manganese is thus intricately linked to the health, metabolism, and function of the ocean microbiome. Despite the potential for active fungi in low-oxygen and brackish ecosystems to make significant contributions to Mn and other nutrient cycling, little is known about the roles and impacts of fungi on those processes. Ascomycota and Basidiomycota fungal species are identified as important nutrient and carbon recyclers in various marine settings, however there are few studies of fungi in chemocline settings (water columns with transitions in oxygen concentration). Fungal isolates are known that link chemical transformation of Mn (Mn(II) oxidation) to organic carbon degradation and production of reactive oxygen species (ROS), and fungal production of ROS may play a central role in the cycling and bioavailability of metals like Mn, as well as carbon and nitrogen in low-oxygen/anoxic (zero oxygen) marine environments. The Mn-rich Baltic Sea is an ideal model ecosystem for studying the future coastal ocean due to anthropogenic impacts experiences, and its salinity gradients. This project aims to contribute to understanding of fungal diversity and roles in manganese, nitrogen and sulfur cycling, as well as production of reactive oxygen species in low oxygen and brackish marine ecosystems. Fungal activities in these habitats may influence important global marine biogeochemical cycles, and knowledge of their role(s) and impacts allows more accurate predictions of the biogeochemistry of a future ocean and climate. The culture collection generated by this study is anticipated to recover many new fungal strains, whose ecology, novel properties, and potential medically-relevant bioactive compounds can be explored by interested researchers. Six undergraduate students, one graduate student, and 2 high school students per year are included in this research, and a collaboration is established with a local high school art teacher to teach an art-in-science unit, and to displayed its product at the community library, along with education materials on marine fungi and their ecological roles. The project involves international collaboration, as well as training of early career and under-represented minority scientists. This proposal leverages a sampling opportunity during a scheduled cruise in early 2024 to collect water samples from 3 depths along the chemocline at two stations in the Baltic Sea with distinct profiles of O2 concentration, and N and Mn species. The overall goal of this project is to characterize the diversity of prokaryotic (bacteria and archaea) and fungal taxa present in these samples, and those expressing genes involved in biogeochemical cycles related to transformations of manganese, iodine, oxygen, and nitrogen, with a specific emphasis on the role of fungi. The workplan incorporates analysis of taxonomic marker genes for fungi and micro-eukaryotes, and prokaryotes, as well as catalyzed-reporter deposition fluorescence in situ hybridization (CARD-FISH) to estimate the in situ abundance of major fungal groups. Poly-A and non polyA transcriptomics of water samples provide a general overview of expressed metabolic genes, and specifically identify genes involved in Mn oxidation. High-throughput culturing efforts incorporating laser nephelometry are used to gather the broadest possible representation of culturable marine fungi in these chemocline habitats, and to identify those that carry genes of interest involved in coupling Mn(II) oxidation to organic carbon degradation. Shipboard incubation studies incorporating fungal and prokaryotic inhibitors are used to determine the extent to which fungi contribute to Mn transformation processes. Coupled RT-qPCR and metatranscriptome analyses of incubation studies are used to elucidate expression of fungal genes related to Mn transformations (e.g., Mn peroxidases), nitrogen cycling (e.g., key fungal denitrification genes p450nor, nirK), and ROS production/decay (SOD1, NOXA).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.

越来越多的证据表明，真菌构成了海洋环境中微生物群落中活跃且多样化的部分。其中，全球分布的低氧、低盐度的公海和沿海水域预计将随着气候变化而扩大和加剧。锰 (Mn) 是一种分布在整个低氧海洋系统中的营养物质，在主要元素循环（包括微生物执行的元素循环）中发挥着重要作用。因此，锰与海洋微生物群的健康、新陈代谢和功能有着错综复杂的联系。尽管低氧和微咸生态系统中的活性真菌有可能对锰和其他养分循环做出重大贡献，但人们对真菌在这些过程中的作用和影响知之甚少。子囊菌门和担子菌门真菌物种被认为是各种海洋环境中重要的营养物和碳回收者，但是对趋化素环境（氧浓度变化的水柱）中的真菌的研究很少。已知真菌分离株将 Mn 的化学转化（Mn(II) 氧化）与有机碳降解和活性氧 (ROS) 的产生联系起来，而真菌产生的 ROS 可能在 Mn 等金属的循环和生物利用度中发挥核心作用，以及低氧/缺氧（零氧）海洋环境中的碳和氮。由于人为影响经历及其盐度梯度，富含锰的波罗的海是研究未来沿海海洋的理想生态系统模型。该项目旨在帮助了解真菌多样性以及在锰、氮和硫循环中的作用，以及低氧和微咸海洋生态系统中活性氧的产生。这些栖息地的真菌活动可能会影响重要的全球海洋生物地球化学循环，了解其作用和影响可以更准确地预测未来海洋和气候的生物地球化学。这项研究产生的培养物保藏预计将回收许多新的真菌菌株，感兴趣的研究人员可以探索其生态学、新颖特性和潜在的医学相关生物活性化合物。这项研究每年包括 6 名本科生、1 名研究生和 2 名高中生，并与当地高中艺术老师合作教授科学艺术单元，并在社区图书馆，以及有关海洋真菌及其生态作用的教育材料。该项目涉及国际合作，以及对早期职业和代表性不足的少数族裔科学家的培训。该提案利用 2024 年初预定巡航期间的采样机会，从波罗的海两个站的化跃线沿线 3 个深度收集水样，这些水样具有不同的 O2 浓度以及 N 和 Mn 形态。该项目的总体目标是表征这些样本中存在的原核生物（细菌和古生菌）和真菌类群的多样性，以及那些表达参与与锰、碘、氧和氮转化相关的生物地球化学循环的基因的物种，并具有特定的特征。强调真菌的作用。 该工作计划包括对真菌、微型真核生物和原核生物的分类标记基因的分析，以及催化报告基因沉积荧光原位杂交（CARD-FISH），以估计主要真菌类群的原位丰度。水样的多聚腺苷酸和非多聚腺苷酸转录组学提供了表达代谢基因的总体概述，并具体鉴定了参与锰氧化的基因。结合激光比浊法的高通量培养工作用于收集这些趋化素栖息地中可培养海洋真菌的尽可能广泛的代表性，并鉴定那些携带参与 Mn(II) 氧化与有机碳降解耦合的感兴趣基因的真菌。结合真菌和原核抑制剂的船上培养研究用于确定真菌对锰转化过程的贡献程度。 RT-qPCR 和孵化研究的元转录组分析相结合，用于阐明与 Mn 转化（例如 Mn 过氧化物酶）、氮循环（例如关键真菌反硝化基因 p450nor、nirK）和 ROS 产生/衰变 (SOD1) 相关的真菌基因的表达，NOXA）。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的评估进行评估，被认为值得支持影响审查标准。