Extracellular polymeric substances and aggregate stability - how microorganisms affect soil erosion by water

细胞外聚合物和聚集体稳定性 - 微生物如何影响水土流失

• 批准号: 316446092
• 负责人: Professor Dr. Karsten Kalbitz
• 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: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/316446092?language=en
• 关键词: Extracellular; polymeric; substances; aggregate; stability

Soil erosion determines the shape and surface of many landscapes and the stability of soil aggregates is considered to be a crucial factor regulating soil erosion. Microbial processes have not been discussed as important controls of soil erosion although they should directly be related to aggregate stability by the production of extracellular polymeric substances (EPS). It is unknown whether the composition of the bacterial community as influenced by vegetation affects EPS produced in situ. Changes in amount and composition of EPS and their effects on the stability of soil aggregates and thus on soil erosion by water are largely unknown. Therefore, the main objective of this proposal is to study the complex interactions between vegetation, the composition and capability of the soil bacterial community to produce EPS, and the effects of these EPS on the stability of formed aggregates and subsequently on soils susceptibility to erosion. In our project we will bridge different temporal and spatial scales and enhance our knowledge about biotic modulation of erosion and sediment routing depending on climate. We will use two gradients, three study areas along a precipitation gradient in Southern Spain (Almería Province) and a gradient in vegetation coverage within each study area. The project will start with an explorative field survey to study relationships between vegetation, bacterial community composition, and amount and properties of EPS and how aggregate stability is affected by these relationships. Then, joint greenhouse and rhizobox experiments will be used to study in detail how EPS formed by soil bacteria influence aggregate stability in presence or absence of plant roots. The rhizobox experiment will deliver deep insights in spatial aspects of bacterial EPS production and how it is related to roots and aggregation. Rainfall simulation experiments in the field will be the ultimate proof whether changes in aggregate stability controlled by EPS will be responsible for in situ changes in soil erosion by water. In our project we will establish novel methods to extract and characterize EPS from soils and to determine their spatial distribution patterns. In all experimental approaches we will use the same soil samples and combine advanced methods spanning a broad range from molecular microbial ecology (e.g., 16S rRNA amplicon sequencing, quantitative PCR, PCR-Southern blot hybridization), microscopy (e.g., CLSM, CARD-FISH, gold-FISH, ESEM), soil science (e.g., aggregate size fractionation, stability of aggregates), spectroscopy (fluorescence, pyrolysis GC/MS, high resolution MS) and geomorphology (rainfall simulations). Here we present an innovative and interdisciplinary approach enabling unprecedented insights how soil erosion by water is controlled by bacterial communities via their production of EPS and their effects on aggregate stability.

土壤侵蚀决定了许多景观的形状和表面，而土壤团聚体的稳定性被认为是控制土壤侵蚀的关键因素。微生物过程没有被讨论为土壤侵蚀的重要控制因素，尽管它们应该通过产生胞外聚合物(EPS)与团聚体的稳定性直接相关。目前尚不清楚植被影响的细菌群落组成是否会影响原位产生的EPS。EPS的数量和组成的变化及其对土壤团聚体稳定性的影响，从而对水侵蚀土壤的影响，在很大程度上是未知的。因此，这项建议的主要目的是研究植被之间的复杂相互作用、土壤细菌群落的组成和产生EPS的能力，以及这些EPS对形成的团聚体的稳定性以及随后对土壤对侵蚀的敏感性的影响。在我们的项目中，我们将在不同的时间和空间尺度上架起桥梁，并增强我们关于生物调节侵蚀和泥沙随气候变化的知识。我们将使用两个梯度，三个研究区域沿西班牙南部(阿尔梅里亚省)的降水梯度，以及每个研究区域内植被覆盖的梯度。该项目将从探索性的实地调查开始，研究植被、细菌群落组成与EPS的数量和特性之间的关系，以及这些关系如何影响团聚体的稳定性。然后，通过温室和根箱联合实验，详细研究土壤细菌形成的EPS在有或没有植物根的情况下对团聚体稳定性的影响。根盒实验将对细菌EPS产生的空间方面以及它与根和聚集的关系提供深刻的见解。田间降雨模拟实验将最终证明EPS控制的团聚体稳定性的变化是否会导致土壤水分侵蚀的原位变化。在我们的项目中，我们将建立新的方法来从土壤中提取和表征EPS，并确定它们的空间分布模式。在所有实验方法中，我们将使用相同的土壤样本，并结合先进的方法，这些方法涵盖广泛的领域，包括分子微生物生态学(例如16S rRNA扩增序列、定量PCR、PCR-Southern杂交)、显微镜(例如CLSM、CARD-FISH、Gold-FISH、ESEM)、土壤科学(例如团聚体粒度分级、团聚体稳定性)、光谱学(荧光、热解GC/MS、高分辨率MS)和地貌学(模拟降雨)。在这里，我们提出了一种创新和跨学科的方法，使人们能够前所未有地深入了解细菌群落如何通过产生EPS来控制土壤侵蚀，以及它们对聚集体稳定性的影响。