Borer Benedict, Tecon Robin, Or Dani
Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 16, 8092, Zürich, Switzerland.
Nat Commun. 2018 Feb 22;9(1):769. doi: 10.1038/s41467-018-03187-y.
Microbial activity in soil is spatially heterogeneous often forming spatial hotspots that contribute disproportionally to biogeochemical processes. Evidence suggests that bacterial spatial organization contributes to the persistence of anoxic hotspots even in unsaturated soils. Such processes are difficult to observe in situ at the microscale, hence mechanisms and time scales relevant for bacterial spatial organization remain largely qualitative. Here we develop an experimental platform based on glass-etched micrometric pore networks that mimics resource gradients postulated in soil aggregates to observe spatial organization of fluorescently tagged aerobic and facultative anaerobic bacteria. Two initially intermixed bacterial species, Pseudomonas putida and Pseudomonas veronii, segregate into preferential regions promoted by opposing gradients of carbon and oxygen (such persistent coexistence is not possible in well-mixed cultures). The study provides quantitative visualization and modeling of bacterial spatial organization within aggregate-like hotspots, a key step towards developing a mechanistic representation of bacterial community organization in soil pores.
土壤中的微生物活动在空间上是异质的，常常形成对生物地球化学过程贡献不成比例的空间热点。有证据表明，细菌的空间组织有助于缺氧热点的持续存在，即使在非饱和土壤中也是如此。此类过程在微观尺度上很难原位观察，因此与细菌空间组织相关的机制和时间尺度在很大程度上仍停留在定性阶段。在此，我们基于玻璃蚀刻微米级孔隙网络开发了一个实验平台，该平台模拟土壤团聚体中假定的资源梯度，以观察荧光标记的需氧和兼性厌氧细菌的空间组织。两种最初混合的细菌物种，恶臭假单胞菌和维罗纳假单胞菌，会因碳和氧的相反梯度而分离到优先区域（在充分混合的培养物中不可能有这种持续共存的情况）。该研究提供了聚集体状热点内细菌空间组织的定量可视化和建模，这是朝着建立土壤孔隙中细菌群落组织的机制性表示迈出的关键一步。
