Kleyer Hannah, Tecon Robin, Or Dani
Soil and Terrestrial Environmental Physics, Department of Environmental Systems Science, Swiss Federal Institute of Technology in Zurich (ETH Zürich), Zürich, Switzerland
Soil and Terrestrial Environmental Physics, Department of Environmental Systems Science, Swiss Federal Institute of Technology in Zurich (ETH Zürich), Zürich, Switzerland.
Appl Environ Microbiol. 2019 Dec 13;86(1). doi: 10.1128/AEM.02057-19.
The complexity of natural soils presents a challenge to the systematic identification and disentanglement of governing processes that shape natural bacterial communities. Studies have highlighted the critical role of the soil aqueous phase in shaping interactions among soil bacterial communities. To quantify and improve the attributability of soil aqueous-phase effects, we introduced a synthetic and traceable bacterial community to simple porous microcosms and subjected the community to constant or dynamic hydration conditions. The results were expressed in terms of absolute abundance and show species-specific responses to hydration and nutrient conditions. Hydration dynamics exerted a significant influence on the fraction of less-abundant species, especially after extended incubation periods. Phylogenetic relationships did not explain the group of most abundant species. The ability to quantify species-level dynamics in a bacterial community offers an important step toward deciphering the links between community composition and functions in dynamic terrestrial environments. The composition and activity of soil bacteria are central to various ecosystem services and soil biogeochemical cycles. A key factor for soil bacterial activity is soil hydration, which is in a constant state of change due to rainfall, drainage, plant water uptake, and evaporation. These dynamic changes in soil hydration state affect the structure and function of soil bacterial communities in complex ways often unobservable in natural soil. We designed an experimental system that retains the salient features of hydrated soil yet enables systematic evaluation of changes in a representative bacterial community in response to cycles of wetting and drying. The study shows that hydration cycles affect community abundance, yet most changes in composition occur with the less-abundant species (while the successful ones remain dominant). This research offers a new path for an improved understanding of bacterial community assembly in natural environments, including bacterial growth, maintenance, and death, with a special focus on the role of hydrological factors.
天然土壤的复杂性对系统识别和厘清塑造天然细菌群落的主导过程构成了挑战。研究强调了土壤水相在塑造土壤细菌群落间相互作用方面的关键作用。为了量化并提高土壤水相效应的可归因性，我们将一个合成的、可追踪的细菌群落引入简单的多孔微观模型，并使该群落处于恒定或动态水合条件下。结果以绝对丰度表示，并显示了物种对水合和营养条件的特异性反应。水合动态对丰度较低物种的比例产生了显著影响，尤其是在延长培养期后。系统发育关系并不能解释最丰富物种的群落。量化细菌群落中物种水平动态的能力为解读动态陆地环境中群落组成与功能之间的联系迈出了重要一步。土壤细菌的组成和活性对于各种生态系统服务和土壤生物地球化学循环至关重要。土壤细菌活性的一个关键因素是土壤水合作用，由于降雨、排水、植物水分吸收和蒸发，土壤水合作用处于不断变化的状态。土壤水合状态的这些动态变化以复杂的方式影响土壤细菌群落的结构和功能，而这些方式在天然土壤中往往难以观察到。我们设计了一个实验系统，该系统保留了水合土壤的显著特征，但能够系统评估一个具有代表性的细菌群落对干湿循环的反应变化。研究表明，水合循环会影响群落丰度，但组成的大多数变化发生在丰度较低的物种中（而优势物种仍占主导）。这项研究为更好地理解自然环境中细菌群落的组装提供了一条新途径，包括细菌的生长、维持和死亡，特别关注水文因素的作用。
