Production of microbial extracellular polymeric substances in soil-like systems – The role of nutrient imbalances, water availability and presence of mineral surfaces

类土壤系统中微生物胞外聚合物的生产 â 营养不平衡、水的可用性和矿物表面存在的作用

• 批准号: 418940907
• 负责人: Dr. Cordula Vogel
• 金额: --
• 依托单位: Institut für Bodenkunde und Standortslehre
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/418940907?language=en
• 关键词: Production; microbial; extracellular; polymeric; substances

Extracellular polymeric substances (EPS) are composed of a diverse compound mixture including polysaccharides (EPS-PS) and proteins. EPS provide several functions for microbial life and certain soil functions such as aggregation and water retention have been proposed to be shaped by EPS. Although it is known that various soil microorganism are capable to produce EPS, it is still unclear if and how they do that in vitro. The interplay between microorganisms and soil environmental conditions is likely to control microbial EPS production. However, it is not clear how e.g. the lack of resources or an oversupply of nutrients, fluctuation in water availability and the presence of mineral surfaces affect EPS production. Thus, the main goal of this project is to identify and quantify the most important driving factors for EPS production (amount, composition, and spatial expansion) in soil-like systems. By this we aim to assess the quantitative importance of EPS in these systems. We will mainly study the supply of nutrients (C, N, and P), the availability of water within different pore sizes, and the presence of mineral surfaces as driving factors. EPS production will be studied by a series of experimental approaches with increasing complexity from liquid media, over so called "soil Chips" to artificial soil systems by a combination of extraction and visualization techniques. In addition, we will study the effectiveness of EPS extractions influenced by different clay contents and evaluate the usefulness of µCT imaging in combination with contrast agents to study spatial expansion of EPS in 3D. Firstly, production and composition of EPS-PS will be screened under various environmental conditions in liquid media by a microplate platform for high-throughput. Next to total carbohydrate contents, the complete monomer composition will be analyzed via ultra-high performance liquid chromatography coupled with ultra violet and electrospray ionization ion trap detection (UHPLC-UV-ESI-MS). Then, we will increase complexity by analyzing the nutrient supply and water availability within diverse pore size distributions with the “soil chip” approach. This novel technique allows us to visualize EPS production after lectin staining with confocal laser scanning microscopy and thus evaluate the spatial expansion of EPS driven by environmental factors. In the last step, we will further increase complexity and add the third dimension (3D) by using artificial soil column experiments (quartz sand and montmorillonite). In these 3D soil-like systems we study the drivers of EPS production as the availability of mineral surfaces, pore size distribution and nutrient imbalances in a combined way. With the unique combination of extraction and visualization techniques, we will determine the drivers of EPS production and asses the quantitative importance of EPS in soil-like systems. Moreover, our project will deliver the basis for protocols to study EPS in situ in soil science.

细胞外聚合物（EPS）是由多种化合物混合物组成，包括多糖（EPS- ps）和蛋白质。EPS为微生物的生命提供了多种功能，并且某些土壤功能如聚集和保水被认为是由EPS塑造的。虽然已知各种土壤微生物都能产生EPS，但它们在体外是否以及如何产生EPS尚不清楚。微生物与土壤环境条件之间的相互作用可能控制微生物EPS的产生。然而，尚不清楚资源的缺乏或营养物质的过度供应、水供应的波动和矿物表面的存在如何影响EPS的产生。因此，该项目的主要目标是确定和量化类土系统中EPS生产的最重要驱动因素（数量、组成和空间扩展）。通过这种方法，我们旨在评估EPS在这些系统中的定量重要性。我们将主要研究营养物质（C， N， P）的供应，不同孔径内水分的可用性，以及矿物表面的存在作为驱动因素。EPS的生产将通过一系列越来越复杂的实验方法进行研究，从液体介质，所谓的“土壤芯片”到人工土壤系统，通过提取和可视化技术的结合。此外，我们将研究不同粘土含量对EPS提取效果的影响，并评估微CT成像与造影剂联合研究EPS三维空间扩展的有效性。首先，通过高通量微孔板平台在液体培养基中筛选不同环境条件下EPS-PS的生产和组成。除了总碳水化合物含量外，还将通过超高效液相色谱-紫外和电喷雾离子阱检测（UHPLC-UV-ESI-MS）分析完整的单体组成。然后，我们将通过“土壤碎片”方法分析不同孔径分布下的养分供应和水分有效性，从而增加复杂性。这种新技术使我们能够在共聚焦激光扫描显微镜凝集素染色后可视化EPS的产生，从而评估EPS在环境因素驱动下的空间扩张。在最后一步，我们将进一步增加复杂性，并通过使用人工土柱实验（石英砂和蒙脱土）增加第三维度（3D）。在这些三维类土系统中，我们研究了EPS生产的驱动因素，如矿物表面的可用性、孔隙大小分布和营养不平衡。通过独特的提取和可视化技术的结合，我们将确定EPS生产的驱动因素，并评估EPS在类土壤系统中的定量重要性。此外，我们的项目将为土壤科学中原位研究EPS的协议提供基础。