论文标题
多孔培养基中的形态和细菌菌落的大小控制缺氧微环境形成
Morphology and size of bacterial colonies control anoxic microenvironment formation in porous media
论文作者
论文摘要
厌氧过程（例如甲烷生成和发酵）在很大程度上有助于元素循环和自然污染物的衰减/动员，即使在氧化良好的多孔环境中，例如浅含水层。这种悖论通常是通过细菌呼吸偶联和异质氧（O2）通过孔隙水通过孔隙水的转运而产生的小规模缺氧微环境的解释。这样的微环境使师生的厌氧菌细菌可以在有害环境中增殖。由于在不透明的沉积物和土壤基质中直接观察到的生物量和O2分布的挑战，微环境动力学仍然很少了解。为了克服这些局限性，我们将微流体设备与透明的O2平面光学传感器集成在一起，以测量溶解的O2浓度和生物量分布的时间行为与延时视频微镜检查。我们的结果表明，在流动的多孔系统中，细菌菌落形态具有很高的变化，可以控制缺氧微环境的形成。我们通过比较溶解的O2扩散和细菌O2摄取速率的菌落尺度的Damkohler数来合理化观察结果。我们的Damkholer数字可以预测系统中缺氧微环境所占据的孔隙空间，并且鉴于细菌组织，它可以应用于3D多孔系统。
Anaerobic processes (e.g., methanogenesis and fermentation) largely contribute to element cycling and natural contaminant attenuation/mobilization, even in well-oxygenated porous environments, such as shallow aquifers. This paradox is commonly explained by the occurrence of small-scale anoxic microenvironments generated by the coupling of bacterial respiration and the heterogeneous oxygen (O2) transport by porewater. Such microenvironments allow facultatively and obligately anaerobic bacteria to proliferate in oxic environments. Microenvironment dynamics are still poorly understood due to the challenge of directly observing biomass and O2 distributions at the microscale within an opaque sediment and soil matrix. To overcome these limitations, we integrated a microfluidic device with transparent O2 planar optical sensors to measure the temporal behavior of dissolved O2 concentrations and biomass distributions with time-lapse video-microscopy. Our results reveal that bacterial colony morphology, which is highly variable in flowing porous systems, controls the formation of anoxic microenvironments. We rationalize our observations through a colony-scale Damkohler number comparing dissolved O2 diffusion and bacterial O2 uptake rate. Our Damkholer number enables predicting the pore space occupied by anoxic microenvironments in our system, and, given the bacterial organization, it can be applied to 3D porous systems.
