University of Potsdam, Institute of Physics and Astronomy, 14476, Potsdam, Germany.
Université Côte d'Azur, Laboratoire J. A. Dieudonné, UMR 7351 CNRS, F-06108, Nice Cedex 02, France.
Sci Rep. 2017 Dec 1;7(1):16771. doi: 10.1038/s41598-017-16428-9.
Bacteria swim in sequences of straight runs that are interrupted by turning events. They drive their swimming locomotion with the help of rotating helical flagella. Depending on the number of flagella and their arrangement across the cell body, different run-and-turn patterns can be observed. Here, we present fluorescence microscopy recordings showing that cells of the soil bacterium Pseudomonas putida that are decorated with a polar tuft of helical flagella, can alternate between two distinct swimming patterns. On the one hand, they can undergo a classical push-pull-push cycle that is well known from monopolarly flagellated bacteria but has not been reported for species with a polar bundle of multiple flagella. Alternatively, upon leaving the pulling mode, they can enter a third slow swimming phase, where they propel themselves with their helical bundle wrapped around the cell body. A theoretical estimate based on a random-walk model shows that the spreading of a population of swimmers is strongly enhanced when cycling through a sequence of pushing, pulling, and wrapped flagellar configurations as compared to the simple push-pull-push pattern.
细菌以直线运动的序列游动，这些直线运动被转弯事件打断。它们通过旋转的螺旋形鞭毛来驱动游动。根据鞭毛的数量及其在细胞体上的排列方式，可以观察到不同的跑动-转弯模式。在这里，我们展示荧光显微镜记录，显示用螺旋形鞭毛的极性毛簇装饰的土壤细菌假单胞菌（Pseudomonas putida）可以在两种不同的游动模式之间交替。一方面，它们可以经历一个经典的推-拉-推周期，这在单极鞭毛细菌中是众所周知的，但尚未报道过具有极性多鞭毛束的物种。或者，在离开拉动模式后，它们可以进入第三个缓慢游动阶段，在这个阶段，它们用螺旋束缠绕在细胞体上推动自己。基于随机游走模型的理论估计表明，与简单的推-拉-推模式相比，当通过一系列推动、拉动和缠绕的鞭毛构型循环时，游动种群的扩散会大大增强。
