Microscopic Fluid Mechanic Research for Propulsion of Bacteria with Flagella

细菌鞭毛推进的微观流体力学研究

基本信息

批准号：
12650168
负责人：
TAKANO Yasunari
金额：
$ 2.3万
依托单位：
UNIVERSITY OF SHIGA PREFECTURE (2001)Tottori University (2000)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

The swimming motion of Vibrio alginolyticus, a bacterium with a single flagellum was observed using a dark-field biological microscope with CCD camera and was record by a video recorder. The linear relation between the rotation rate of the cell body and the propulsive speed was obtained for each individual bacterium. Computations were carried out for propulsion of the bacteria with a single flagellum applying the boundary element method based on the Stokes flow. the comparison is well between the observations and the simulations.In the present investigation, the forward and backward swimming speeds were also measured for a lot of Vibrio alginolyticus. The speed of backward swimming is 1.5 times larger than that of forward swimming on average. The difference of the speed between the forward and the backward swimming might be caused by several factors such as asymmetry of the motor torque with respect to the rotational direction and deformation of the flagellum filament due to hydrodynamic forces.An analysis was conducted for the small deformation of flexible flagellum of swimming bacteria. The resistive force theory was applied to estimate the force exerted on flagellum. The torsional as well as the bending moments determine the curvature and the torsion of the deformed flagellum according to the Kirchhoff model for elastic rod. The speeds were simulated for the forward and the backward swimming taking account of deformation of flagellum. It is shown that the difference between the forward and the backward speeds is not generated by the deformation of the flagellum.

使用带有CCD摄像头的深场生物学显微镜观察到颤音藻溶解度的游泳运动，这是一个带有单个鞭毛的细菌，并由视频记录器记录。对于每个细菌，获得了细胞体旋转速率与推进速度之间的线性关系。使用单个鞭毛进行基于stokes流的边界元素方法的单个鞭毛进行计算以推进细菌。在观测和模拟之间进行了很好的比较。在当前的研究中，还测量了许多颤音静脉曲张的前向和向后游泳速度。向后游泳的速度平均比向前游泳高1.5倍。向前和向后游泳之间的速度差异可能是由于多种因素引起的，例如，由于流体动力的旋转方向和鞭毛丝的变形，电动机扭矩的不对称性。电阻理论用于估计施加在鞭毛上的力。根据弹性杆的Kirchhoff模型，扭转和弯矩决定了变形的鞭毛的曲率和扭转。为前锋和向后游泳的速度模拟了鞭毛的变形。结果表明，前向速度和向后速度之间的差异不是通过鞭毛的变形产生的。