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On the motion of magnetotactic bacteria: theoretical predictions and experimental observations.
European Biophysics Journal ( IF 2.2 ) Pub Date : 2019-09-13 , DOI: 10.1007/s00249-019-01394-z
Daniel Acosta-Avalos 1 , Elton Rodrigues 1
Affiliation  

The movement of magnetotactic bacteria is done in a viscous media in the low Reynolds number regime. In the present research, the simple model for magnetotactic bacteria motion, proposed by Nogueira and Lins de Barros (Eur Biophys J 24:13-21, 1995), was used to numerically simulate their trajectory. The model was done considering a spherical bacterium with a single flagellum and a magnetic moment positioned in the sphere center and parallel to the flagella. The numerical solution shows that the trajectory is a cylindrical helix and that the body Euler angles have linear dependencies on time. Using that information, analytical expressions were obtained for the first time for the center-of-mass coordinates, showing that the trajectories are helixes oriented to the magnetic field direction. They also show that the magnetic moment does not align to the magnetic field, but it precesses around it, being fully oriented only for very high magnetic fields. The analytical solution obtained permits to relate for the first time the flagellar force to the axial velocity and helical radius. Trajectories of uncultivated magnetotactic bacteria were registered in video and the coordinates were obtained for several bacteria in different magnetic fields. The trajectories showed to be a complex mixture of two oscillating functions: one with frequency lower than 5 Hz and the other one with frequency higher than 10 Hz. The simple model of Nogueira and Lins de Barros shows to be incomplete, because is unable to explain the trajectories composed of two oscillating functions observed in uncultivated magnetotactic bacteria.

中文翻译:

关于趋磁细菌的运动:理论预测和实验观察。

趋磁细菌的运动在低雷诺数条件下的粘性介质中完成。在本研究中,由Nogueira和Lins de Barros提出的简单的趋磁细菌运动模型(Eur Biophys J 24:13-21,1995)被用于数值模拟它们的轨迹。考虑带有单个鞭毛的球形细菌,并在球体中心并平行于鞭毛的磁矩来完成模型。数值解表明,该轨迹是圆柱螺旋形,并且体欧拉角与时间呈线性关系。利用这些信息,首次获得了质心坐标的解析表达式,表明轨迹是朝向磁场方向的螺旋线。他们还表明,磁矩并不与磁场对齐,而是绕着磁场进动,仅在非常高的磁场下才完全定向。所获得的分析解决方案首次允许将鞭毛力与轴向速度和螺旋半径相关联。在视频中记录了未培养的趋磁细菌的轨迹,并获得了在不同磁场中几种细菌的坐标。轨迹显示为两种振荡函数的复杂混合:一种振荡频率低于5 Hz,另一种振荡频率高于10 Hz。Nogueira和Lins de Barros的简单模型显示是不完整的,因为它无法解释在未培养的趋磁细菌中观察到的由两种振荡功能组成的轨迹。但它绕着它进动,仅在非常强的磁场下完全定向。所获得的分析解决方案首次允许将鞭毛力与轴向速度和螺旋半径相关联。视频中记录了未培养的趋磁细菌的轨迹,并获得了在不同磁场中几种细菌的坐标。轨迹显示为两种振荡函数的复杂混合:一种振荡频率低于5 Hz,另一种振荡频率高于10 Hz。Nogueira和Lins de Barros的简单模型显示是不完整的,因为它无法解释在未培养的趋磁细菌中观察到的由两种振荡功能组成的轨迹。但它绕着它进动,仅在非常强的磁场下完全定向。所获得的分析解决方案首次允许将鞭毛力与轴向速度和螺旋半径相关联。视频中记录了未培养的趋磁细菌的轨迹,并获得了在不同磁场中几种细菌的坐标。轨迹显示为两种振荡函数的复杂混合:一种振荡频率低于5 Hz,另一种振荡频率高于10 Hz。Nogueira和Lins de Barros的简单模型显示是不完整的,因为它无法解释在未培养的趋磁细菌中观察到的由两种振荡功能组成的轨迹。所获得的分析解决方案首次允许将鞭毛力与轴向速度和螺旋半径相关联。视频中记录了未培养的趋磁细菌的轨迹,并获得了在不同磁场中几种细菌的坐标。轨迹显示出是两个振荡函数的复杂混合:一个振荡频率低于5 Hz,另一个振荡频率高于10 Hz。Nogueira和Lins de Barros的简单模型显示是不完整的,因为它无法解释在未培养的趋磁细菌中观察到的由两种振荡功能组成的轨迹。所获得的分析解决方案首次允许将鞭毛力与轴向速度和螺旋半径相关联。视频中记录了未培养的趋磁细菌的轨迹,并获得了在不同磁场中几种细菌的坐标。轨迹显示出是两个振荡函数的复杂混合:一个振荡频率低于5 Hz,另一个振荡频率高于10 Hz。Nogueira和Lins de Barros的简单模型显示是不完整的,因为它无法解释在未培养的趋磁细菌中观察到的由两种振荡功能组成的轨迹。视频中记录了未培养的趋磁细菌的轨迹,并获得了在不同磁场中几种细菌的坐标。轨迹显示出是两个振荡函数的复杂混合:一个振荡频率低于5 Hz,另一个振荡频率高于10 Hz。Nogueira和Lins de Barros的简单模型显示是不完整的,因为它无法解释在未培养的趋磁细菌中观察到的由两种振荡功能组成的轨迹。视频中记录了未培养的趋磁细菌的轨迹,并获得了在不同磁场中几种细菌的坐标。轨迹显示出是两个振荡函数的复杂混合:一个振荡频率低于5 Hz,另一个振荡频率高于10 Hz。Nogueira和Lins de Barros的简单模型显示是不完整的,因为它无法解释在未培养的趋磁细菌中观察到的由两种振荡功能组成的轨迹。
更新日期:2019-11-01
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