Agrosphere Institute, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
Water Res. 2010 Feb;44(4):1288-96. doi: 10.1016/j.watres.2010.01.017. Epub 2010 Jan 28.
A study was conducted to understand the role of cell concentration and metabolic state in the transport and deposition behaviour of Pseudomonas fluorescens with and without substrate addition. Column experiments using the short-pulse technique (pulse was equivalent to 0.028 pore volume) were performed in quartz sand operating under saturated conditions. For comparison, experiments with microspheres and inactive (killed) bacteria were also conducted. The effluent concentrations, the retained particle concentrations and the cell shape were determined by fluorescent microscopy. For the transport of metabolically-active P. fluorescens without substrate addition a bimodal breakthrough curve was observed, which could be explained by the different breakthrough behaviour of the rod-shaped and coccoidal cells of P. fluorescens. The 70:30 rod/coccoid ratio in the influent drastically changed during the transport and it was about 20:80 in the effluent and in the quartz sand packing. It was assumed that the active rod-shaped cells were subjected to shrinkage into coccoidal cells. The change from active rod-shaped cells to coccoidal cells could be explained by oxygen deficiency which occurs in column experiments under saturated conditions. Also the substrate addition led to two consecutive breakthrough peaks and to more bacteria being retained in the column. In general, the presence of substrate made the assumed stress effects more pronounced. In comparison to microspheres and inactive (killed) bacteria, the transport of metabolically-active bacteria with and without substrate addition is affected by differences in physiological state between rod-shaped and the formed stress-resistant coccoidal cells of P. fluorescens.
进行了一项研究，以了解细胞浓度和代谢状态在荧光假单胞菌的运输和沉积行为中的作用，同时考虑有无底物添加的情况。在饱和条件下使用短脉冲技术（脉冲相当于 0.028 孔隙体积）在石英砂中进行柱实验。为了进行比较，还进行了使用微球和非活性（灭活）细菌的实验。通过荧光显微镜确定了流出液浓度、截留的颗粒浓度和细胞形态。对于无底物添加的代谢活跃的荧光假单胞菌的传输，观察到了双峰突破曲线，这可以通过荧光假单胞菌的杆状和球菌状细胞的不同突破行为来解释。在入口处的 70:30 杆/球菌比在传输过程中急剧变化，在出口处和石英砂包装中约为 20:80。据假设，活跃的杆状细胞收缩成球菌状细胞。在饱和条件下的柱实验中发生的缺氧导致从活跃的杆状细胞到球菌状细胞的转变。底物的添加也导致了两个连续的突破峰值，并且更多的细菌被保留在柱中。通常，存在底物会使假设的应激效应更加明显。与微球和非活性（灭活）细菌相比，有和没有底物添加的代谢活跃细菌的传输受到荧光假单胞菌的杆状和形成的应激抗性球菌状细胞之间生理状态差异的影响。
