Hydrodynamics of helical-shaped bacterial motility.
Hydrodynamics of helical-shaped bacterial motility.
复制标题
螺旋形细菌运动的流体动力学。
DOI：
10.1103/physreve.80.021921
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
R. Netz
中科院分区：
文献类型：
--
作者：
H. Wada;R. Netz
为了揭示潜在的流体动力学机制的细菌螺旋体的定向推进，我们制定了一个粗粒度的弹性聚合物模型与域交替螺旋沿着轮廓。使用流体动力学模拟和分析参数，我们表明，螺旋畴壁的传播导致定向推进的细胞体相反的畴壁行进方向。我们的模型再现了螺原体运动的几个关键特征。我们特别表明，螺原体meliferum，psi=35度，观察到的螺旋桨距角，是最佳的最大游泳速度和能量转换效率。我们的分析理论的基础上细长体流体动力学近似同意非常好，我们的数值数据表明如何手性开关传播沿着螺旋细胞体被转换为细胞体本身的平移推力。我们详细考虑了热效应对螺旋形状的取向波动和构象波动形式的推进效率。体长度依赖的细胞运动的数值研究和我们的近似解析理论相比。对于固定的俯仰角psi=35度，游动速度在细胞体长度与域长度的比率为约2-3时最大化，这是真实的细胞的典型值。我们还提出了简单的分析参数的游泳速度的提高，增加溶液粘度，考虑到在聚合物网络中的螺旋细胞体的瞬态限制的影响。与聚合物网状物中的鞭毛细菌的游泳速度的广义理论的比较表明，有限大小的细菌头部的存在下，在有限的溶液粘度产生最大的游泳速度，而在没有头部的情况下，游泳速度随着粘度的增加而单调增加。
To reveal the underlying hydrodynamic mechanism for the directed propulsion of the bacterium Spiroplasma, we formulate a coarse-grained elastic polymer model with domains of alternating helicities along the contour. Using hydrodynamic simulations and analytic arguments, we show that the propagation of helical domain walls leads to the directed propulsion of the cell body opposite to the domain-wall traveling direction. Several key features of Spiroplasma motility are reproduced by our model. We in particular show that the helical pitch angle observed for Spiroplasma meliferum, psi=35 degrees , is optimized for maximal swimming speed and energy-conversion efficiency. Our analytic theory based on the slender-body hydrodynamic approximation agrees very well with our numerical data demonstrating how the chirality switch propagating along the helical cell body is converted to a translational thrust for the cell body itself. We in detail consider thermal effects on the propulsion efficiency in the form of orientational fluctuations and conformational fluctuations of the helix shape. The body length dependence of the cell motility is studied numerically and compared to our approximate analytic theory. For fixed pitch angle psi=35 degrees , the swimming speed is maximized at a ratio of cell-body length to domain length of about 2-3, which are typical values for real cells. We also propose simple analytic arguments for an enhancement of the swimming velocity with increasing solution viscosity by taking into account the effects of transient confinement of a helical cell body in a polymeric meshwork. Comparison with a generalized theory for the swimming speed of flagellated bacteria in polymeric meshworks shows that the presence of a finite-sized bacterial head gives rise to a maximal swimming speed at a finite solution viscosity, whereas in the absence of a head the swimming speed monotonically increases with increasing viscosity.
软体的运动性。
影响因子：
3.4
作者：
Wolgemuth,CharlesW;Igoshin,Oleg;Oster,George
通讯作者：
Oster,George
影响因子：
5.6
作者：
Trachtenberg, Shlomo;Dorward, Lori M.;Leapman, Richard D.
通讯作者：
Leapman, Richard D.