Bacterial transformations of dimethylsulfoniopropionate in the Weddell Sea

威德尔海中二甲基磺基丙酸盐的细菌转化

• 批准号: 462567243
• 负责人: Dr. Judith Piontek
• 金额: --
• 依托单位: Leibniz-Institut für Ostseeforschung Warnemünde (IOW)
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/462567243?language=en
• 关键词: Bacterial; transformations; dimethylsulfoniopropionate; Weddell; Sea

Dimethylsulfide (DMS) is a climate-relevant trace gas of marine origin that acts as a precursor of cloud condensation nuclei in the atmosphere. The Southern Ocean is recognized as a region of significant sea-to-air transfer of DMS. Hotspots of DMS production were detected close to the Antarctic continent and in the zone of seasonal sea ice melting. Model simulations revealed that the perturbation of ocean-atmosphere DMS fluxes can alter the cloud coverage and, thereby, potentially affect the atmospheric radiative balance. Consequently, understanding and predicting marine DMS production is critical to future climate change scenarios. DMS is produced in the surface ocean by the bacterial degradation of phytoplankton-derived dimethylsulfoniopropionate (DMSP). Bacterial DMSP degradation occurrs via two competing, enzymatically mediated pathways: the demethylation pathway and the cleavage pathway. Since only the cleavage pathway results in the production of DMS, a better understanding of environmental factors and genetic capabilities that control the balance between the two pathways is of high importance to assess the regulation of biologically driven DMS fluxes from the ocean to the atmosphere. While global-scale implications of marine DMSP cycling had been recognized for more than 30 years, only recently developed methods in molecular biology and ‟omics” approaches identified genes involved in the bacterial DMSP metabolism and provided insight into their phylogenetic distribution. To date, our understanding of DMSP cycling is largely derived from studies conducted at low- and mid-latitudes, while the knowledge on polar oceans is very limited. The analysis of the bacterial community composition in the Weddell Sea by means of 16S rRNA amplicon sequencing revealed high abundances of potentially DMS-producing bacterial groups like the Roseobacter clade und SAR11. In the proposed project, we want to apply state-of-the-art methods in molecular biology combined with bioinformatics tools to(1) analyse the environmental regulation of bacterial DMSP degradation (2) investigate the diversity and taxonomy of DMSP-degrading bacteria,(3) analyse the gene inventory for DMSP transformations and(4) characterize metabolic and ecological strategies of keystone species in the Weddell Sea. Seawater samples collected along the Eastern Weddell Sea ice shelf, the Filchner-Ronne ice shelf and in the Weddell Gyre will be analyzed. Expected results will improve the mechanistic understanding of bacterial DMSP degradation in the Weddell Sea and contribute to reliable projections of marine DMS emissions in the Southern Ocean under future climate scenarios.

二甲基硫化物(DMS)是一种海洋来源的与气候有关的痕量气体，它是大气中云凝结核的前体。南大洋被认为是海洋向空中转移二甲基硫的重要区域。在南极大陆附近和季节性海冰融化带发现了二甲基硫的生产热点。模式模拟表明，海洋-大气DMS通量的扰动可以改变云的覆盖率，从而潜在地影响大气辐射平衡。因此，了解和预测海洋DMS产量对未来气候变化情景至关重要。DMS是由浮游植物衍生的二甲基磺基丙酸酯(DMSP)在表层海洋中通过细菌降解而产生的。细菌DMSP的降解通过两条竞争的酶介导途径发生：去甲基化途径和裂解途径。由于只有裂解途径导致DMS的产生，因此更好地了解控制这两条途径之间平衡的环境因素和遗传能力对于评估生物驱动的DMS从海洋到大气的通量的调节具有重要意义。虽然认识到海洋DMSP循环在全球范围内的影响已有30多年，但直到最近发展起来的分子生物学方法和“组学”方法才确定了参与细菌DMSP新陈代谢的基因，并提供了对其系统发育分布的洞察。到目前为止，我们对DMSP循环的了解主要来自中低纬度地区的研究，而对极地海洋的了解非常有限。通过16S rRNA扩增序列分析韦德尔海的细菌群落组成，发现了大量可能产生DMS的细菌群，如Rosebacter Clade und SAR11。在拟议的项目中，我们希望应用最先进的分子生物学方法和生物信息学工具来(1)分析细菌DMSP降解的环境调节，(2)调查DMSP降解菌的多样性和分类学，(3)分析DMSP转化的基因库，(4)描述韦德尔海关键物种的代谢和生态策略。将对沿东部韦德尔海冰架、费尔奇纳-罗恩冰架和韦德尔环流采集的海水样本进行分析。预期结果将提高对威德尔海细菌DMSP降解的机理的了解，并有助于在未来气候情景下可靠地预测南大洋海洋DMS的排放量。