Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, USA.
Phys Rev Lett. 2009 Dec 11;103(24):248102. doi: 10.1103/PhysRevLett.103.248102. Epub 2009 Dec 8.
We present a minimal physical model for the flagellar motor that enables bacteria to swim. Our model explains the experimentally measured torque-speed relationship of the proton-driven E. coli motor at various pH and temperature conditions. In particular, the dramatic drop of torque at high rotation speeds (the "knee") is shown to arise from saturation of the proton flux. Moreover, we show that shot noise in the proton current dominates the diffusion of motor rotation at low loads. This suggests a new way to probe the discreteness of the energy source, analogous to measurements of charge quantization in superconducting tunnel junctions.
我们提出了一个鞭毛马达的简化物理模型，该模型使细菌能够游动。我们的模型解释了在不同 pH 值和温度条件下，实验测量的质子驱动大肠杆菌马达的扭矩-速度关系。特别是，在高转速下扭矩的急剧下降（“膝点”）被证明是由于质子通量的饱和所致。此外，我们还表明，在低负载下，质子电流的散粒噪声主导着马达旋转的扩散。这为探测能量源的离散性提供了一种新方法，类似于超导隧道结中电荷量子化的测量。
