Organosulfur cycling in abundant anoxic marine sediments: a case study of saltmarsh sediments

丰富的缺氧海洋沉积物中的有机硫循环：盐沼沉积物的案例研究

• 批准号: NE/S001352/1
• 负责人: Jonathan Todd
• 金额: $ 53.69万
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FS001352%2F1
• 关键词: Organosulfur; cycling; abundant; anoxic; marine

There is abundant oxygen in Earth's atmosphere, oceans and many soils, and this has enabled the evolution of multicellular life. The surface ocean is oxygen-rich because photosynthetic organisms (primary producers) are abundant. Some of these photosynthetic organisms make important molecules that can be released to the atmosphere. Once there, they can react and form clouds, generating rain and acidity in water vapour, and thus are important in climatology and sulfur cycling. The most well-known of these is dimethyl sulfide (DMS), which is derived from the action of marine microorganisms catabolising dimethylsulfoniopropionate (DMSP). An estimated several billion tonnes of DMSP is made each year by marine algae, corals, plants, and, as shown by us, marine bacteria. DMSP has other key roles in marine ecosystems, serving as an osmoprotectant, a nutrient for marine microbes, and, like DMS, it is a chemoattractant for many organisms that link it with food. DMSP and DMS are so abundant in marine environments that the characteristic smell associated with the seaside comes from DMS itself.It is widely believed that only surface waters make significant amounts of DMSP and DMS via photosynthetic organisms. Our discovery that heterotrophic bacteria produce DMSP challenges this belief, since they do not require light. Furthermore, we have shown that large quantities of DMSP (orders of magnitude greater than in surface oceans), DMS and other organosulfur molecules exist in mud that is devoid of oxygen, and is instead filled with reduced iron (termed ferruginous) and reduced sulfur (termed euxinic). This was interesting and important, because we don't know how these molecules are produced or consumed in these very different environments, what organisms are involved and what role these molecules play in the microbial communities living there. Given that marine sediments cover over 70 % of Earth's surface, this topic is of global significance. Moreover, for 85% of Earth's history the ocean was likely free of oxygen, and only contained dissolved iron or sulfur. Were these molecules important in these past oceans? What role did they play?As environmental conditions (including climate) likely affect DMSP/DMS production, and vice versa, it is key to understand and predict these effects. Current estimates of DMSP/DMS production are likely inaccurate due to i) a lack of integrated studies combining molecular, biogeochemical, process and modelling data; and ii) ignorance as to the input from bacterial DMSP-production, particularly from marine sediments.Questions we will explore are: Why is there lots of DMS but none of its related metabolite, methanethiol (MeSH), in iron-rich sediments, while in sulfide-rich sediments it is the opposite? How are organisms making these molecules, and why? What role do these molecules play in bacterial communities in the mud? How significant is the production of these molecules on a global scale?Our project is divided into several work packages. We will carry out a detailed, year-long study at Warham saltmarsh, which has ferruginous and euxinic sediment pools in close proximity. We will take samples and analyse the geochemistry and microbiology of sediments where we have identified these key patterns. We will determine what organisms are there, and what they are doing, using a series of molecular microbiology techniques, including 'omics work (on microbial community DNA & RNA) and stable isotope probing, which allows us to identify organisms actively cycling DMSP. We will then isolate and grow these microorganisms in the lab to understand how the production and consumption of these climatologically important molecules varies in response to the environmental changes we impose. Finally, we will model these changes and extrapolate to determine how important these environments are to the production and consumption of these molecules, which will be a definitive window to both the past and future.

地球的大气层、海洋和许多土壤中有丰富的氧气，这使得多细胞生命得以进化。海洋表面富含氧气，因为光合生物（初级生产者）非常丰富。这些光合生物中的一些产生重要的分子，可以释放到大气中。一旦到达那里，它们可以反应并形成云，产生雨和水蒸气中的酸性，因此在气候学和硫循环中很重要。其中最著名的是二甲基硫醚（DMS），它来自海洋微生物分解代谢二甲基磺基丙酸酯（DMSP）的作用。据估计，每年有数十亿吨的DMSP由海藻、珊瑚、植物以及我们所展示的海洋细菌产生。DMSP在海洋生态系统中还有其他重要作用，如作为海洋微生物的营养物质和生物保护剂，以及与二甲硫醚一样，它是许多生物的化学引诱物，将其与食物联系起来。DMSP和DMS在海洋环境中非常丰富，以至于与海滨相关的特征气味来自DMS本身。人们普遍认为，只有表层沃茨通过光合生物产生大量的DMSP和DMS。我们发现异养细菌产生DMSP挑战了这一信念，因为它们不需要光。此外，我们已经表明，大量的DMSP（数量级大于海洋表面），DMS和其他有机硫分子存在于缺乏氧气的泥浆中，而是充满了还原铁（称为含铁）和还原硫（称为富氧）。这很有趣也很重要，因为我们不知道这些分子是如何在这些非常不同的环境中产生或消耗的，涉及哪些生物以及这些分子在生活在那里的微生物群落中扮演什么角色。鉴于海洋沉积物覆盖了地球表面的70%以上，这一主题具有全球意义。此外，在地球85%的历史中，海洋可能不含氧气，只含有溶解的铁或硫。这些分子在过去的海洋中重要吗？他们扮演了什么样的角色？由于环境条件（包括气候）可能影响DMSP/DMS的生产，反之亦然，因此了解和预测这些影响至关重要。目前对DMSP/DMS产量的估计可能不准确，因为i）缺乏结合分子、生物地球化学、工艺和建模数据的综合研究;以及ii）对细菌DMSP生产的输入一无所知，特别是来自海洋沉积物的输入。我们将探讨的问题是：为什么富铁沉积物中有大量的二甲基硫，而没有其相关代谢产物甲硫醇（MeSH），而富硫化物沉积物中则相反？生物是如何制造这些分子的，为什么？这些分子在泥浆中的细菌群落中扮演什么角色？这些分子的生产在全球范围内有多重要？我们的项目分为几个工作包。我们将在沃勒姆盐沼进行一项为期一年的详细研究，那里附近有铁质和富氧沉积物池。我们将取样并分析我们已经确定这些关键模式的沉积物的地球化学和微生物学。我们将使用一系列分子微生物学技术，包括“组学工作（微生物群落DNA和RNA）和稳定同位素探测，确定那里有什么生物，以及它们在做什么，这使我们能够识别活跃循环DMSP的生物。然后，我们将在实验室中分离和培养这些微生物，以了解这些气候重要分子的生产和消费如何随着我们施加的环境变化而变化。最后，我们将对这些变化进行建模，并推断这些环境对这些分子的生产和消费有多重要，这将是了解过去和未来的一个明确窗口。

项目成果

Bacterial SBP56 identified as a Cu-dependent methanethiol oxidase widely distributed in the biosphere.

• DOI: 10.1038/ismej.2017.148
• 发表时间: 2018-01
• 期刊: The ISME journal
• 作者: Eyice Ö;Myronova N;Pol A;Carrión O;Todd JD;Smith TJ;Gurman SJ;Cuthbertson A;Mazard S;Mennink-Kersten MA;Bugg TD;Andersson KK;Johnston AW;Op den Camp HJ;Schäfer H
• 通讯作者: Schäfer H

SAR92 clade bacteria are potentially important DMSP degraders and sources of climate-active gases in marine environments.

• DOI: 10.1128/mbio.01467-23
• 发表时间: 2023-12-19
• 期刊: MBIO
• 影响因子: 6.4
• 作者: He, Xiao-Yan;Liu, Ning-Hua;Liu, Ji-Qing;Peng, Ming;Teng, Zhao-Jie;Gu, Tie-Ji;Chen, Xiu-Lan;Chen, Yin;Wang, Peng;Li, Chun-Yang;Todd, Jonathan D.;Zhang, Yu-Zhong;Zhang, Xi-Ying
• 通讯作者: Zhang, Xi-Ying

Function and wide distribution of DMSOP cleaving enzymes in marine organisms

DMSOP裂解酶在海洋生物中的功能和广泛分布

• DOI: 10.21203/rs.3.rs-2412526/v1
• 发表时间: 2023
• 作者: Carrion O