Proteomic profiling: A novel approach to understanding the biological causes of soil hydrophobicity

该项目将为理解（疏水）蛋白的存在或缺失与土壤疏水性之间的关系提供基础。这些结果将有助于确定影响土壤水文和结构的蛋白质组动力学，并最终影响土壤吸收水分、支持生物量生长、储存碳以及捕获和降解污染物的能力。土壤疏水性是由植物和土壤微生物释放有机化合物引起的，它降低或消除了土壤吸收水分的能力。根据其严重程度，受影响的（环境和农业）土壤地区可能在几分钟到几个月的时间内不吸收水分。在最终湿润之后，土壤疏水性通常会在土壤水分水平低于临界阈值的干燥期后恢复。其影响包括减少生物质生产、灌溉用水效率低下、优先浸出农用化学品和增加径流。后者会增加洪水和土壤侵蚀，进而破坏土地。此外，土壤的疏水性可能会影响微生物的流动性，从而影响土壤捕获和降解污染物的能力。疏水性也与土壤中的碳固存有关，因为它保护土壤有机质不被分解。尽管这些影响深远的环境和（农业）经济后果，土壤疏水性的基本生物学原因及其短暂行为尚未得到很好的理解。通过在一个跨学科项目中应用新颖的实验方法，连接土壤微生物学、环境蛋白质组学和土壤水文学领域，现在有可能解决这些研究空白。该项目将主要检查具有各种特性和疏水性的英国草地和沙丘土壤，以确定和关联(i)特定疏水性蛋白质的存在或积累与土壤疏水性的发生和波动；（三）土壤来源蛋白质随土壤疏水性的发生和波动的时间分布。它利用了新的分析技术，其中包括(a)在极端条件下从未应用于环境样品（包括土壤）的疏水蛋白质提取程序；(b)从土壤中提取蛋白质的新方法。该项目将使人们了解土壤蛋白质在确定其周围土壤的疏水性方面的影响，以及随着蛋白质谱反映不同环境条件的变化而改变疏水性的方式。这些知识对于准确预测土壤疏水性的发生和影响，特别是在可湿性和不可湿性状态之间的转变，以及为土壤系统功能制定最佳和可持续的自然资源管理策略至关重要。在未来几十年的气候预测背景下，该项目特别相关和及时，这表明英国和许多其他地区的干旱期更长，降水事件也更强烈。这种气候条件的变化可能导致土壤中疏水性的更广泛发展，从而减少入渗和储水量，并可能增加在强湿期发生洪水事件的次数。

This project will provide the foundation for understanding the relationship between the presence and/or absence of (hydrophobic) protein and soil hydrophobicity. The results will contribute to identifying the proteomic dynamics, which influence soil hydrology and structure, and ultimately the ability of soils to absorb water, support biomass growth, store carbon, and to capture and degrade pollutants. Soil hydrophobicity arises from the release of organic compounds by plants and soil microbes and it reduces or eliminates the ability of soils to absorb water. Depending on its severity, affected (environmental and agricultural) soil areas may not absorb water for periods ranging from minutes to months. After eventually wetting, soil hydrophobicity typically returns following dry periods, when soil moisture levels fall below a critical threshold. Its effects include reduced biomass production, inefficient use of irrigation water, preferential leaching of agri-chemicals and enhanced runoff. The latter contributes to increased flooding and soil erosion, which in turn can damage land. Also, soil water repellency is likely to affect microbial mobility and therefore the ability of soils to capture and degrade pollutants. Hydrophobicity is also relevant for carbon sequestration in soil, as it protects soil organic matter against decomposition. Despite these far reaching environmental and (agro-)economic consequences, the fundamental biological causes of soil hydrophobicity and its transient behaviour are not well understood. Addressing these research gaps is now possible through the application of novel experimental approaches in a crossdisciplinary project, bridging the fields of soil microbiology, environmental proteomics, and soil hydrology. The project will examine mainly UK grassland and dune soils with various characteristics and hydrophobicity, in order to determine and correlate (i) presence or accumulation of specific water-repellent proteins with the occurrence and fluctuations in soil hydrophobicity; (iii) temporal soil-derived protein profiles with the occurrence and fluctuations in soil hydrophobicity. It exploits novel analytical techniques, which include (a) hydrophobic protein extraction procedures under extreme conditions which have never been applied to environmental samples, including soils; and (b) novel general methods for extraction of proteins from soils. The project will lead to an understanding of the influence that soil protein have in determining the hydrophobicity of the soil around them and the manner in which hydrophobicity may change as protein profiles change reflecting varying environmental conditions. This knowledge is critical for accurate prediction of occurrence and effects of soil hydrophobicity, especially the transitions between wettable and non-wettable states, and development of optimum and sustainable natural resource management strategies for soil system functioning. The project is particularly relevant and timely in the context of climate predictions for the coming decades, which suggest more prolonged drought periods as well as more intense precipitation events for the UK and many other regions. Such changes in climatic conditions may induce more widespread development of hydrophobicity in soils, which in turn reduces infiltration and water storage and may increase the number of flooding events during intensely wet periods.