Stirring by microrganisms: the case of Shewanella

微生物的运动在其环境中引入流动，从而影响营养物和其他溶质的分散。流动可以通过跟踪被动平流粒子来可视化和测量，在大肠杆菌和海洋浮游生物莱茵衣藻的情况下，这揭示了扩散过程不遵循正常扩散定律：概率密度函数不是高斯的，扩散定律可以从正常扩散定律变为超扩散定律。在这里，我们建议进一步探索这种行为的结合希瓦氏菌的实验研究和理论建模的分散。不同的希瓦氏菌菌株在游动速度、反转统计以及鞭毛长度和数量上存在差异。这些属性进入将用于模拟传播过程的计算模型，以及基于连续时间随机游走的理论描述。我们计划研究不同密度和不同菌株的混合物的社区，以及在受限的扁平细胞和楔形物中的运动，以深入表征希瓦内拉菌在各种环境中的运动和趋化反应。

The motion of microorganisms introduces flows in their environment that affect the dispersal of nutrients and other solutes. The flows can be visualized and measured by the tracking of passively advected particles, which in the case of Escherichia coli and the marine alga Chlamydomonas reinhardtii has revealed that the spreading process does not follow the laws of normal diffusion: the probability density functions are not Gaussian, and the spreading law can change from a normal diffusive law to a super-diffusive law. We here propose to explore this behaviour further in a combination of experimental studies on Shewanella and theoretical modeling of the dispersion. Different strains of Shewanella show variations in the swimming speed, the statistics of their reversals as well as the length and number of their flagella. These properties enter computational models that will be used to simulate the spreading process, and theoretical descriptions that will be based on continuous time random walks. We plan to study communities of varying densities and mixtures of different strains, as well as the motion in constrained flat cells and wedges, for an in-depth characterization of Shewanellas motility and chemotactic response in various environments.