Angiolillo Giovanny, Abreu Fernanda, Acosta-Avalos Daniel
Centro Brasileiro de Pesquisas Fisicas-CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, RJ, 22290-180, Brazil.
Instituto de Microbiologia Paulo de Góes, Universidade Federal Do Rio de Janeiro-UFRJ, Rio de Janeiro, RJ, 21941-902, Brazil.
Eur Biophys J. 2024 Feb;53(1-2):69-76. doi: 10.1007/s00249-023-01698-1. Epub 2024 Jan 12.
Magnetotactic bacteria are microorganisms that produce intracellular magnetic nanoparticles organized in chains, conferring a magnetic moment to the bacterial body that allows it to swim following the geomagnetic field lines. Magnetotactic bacteria usually display two swimming polarities in environmental samples: the South-seeking (SS) polarity and the North-seeking (NS) polarity, characterized by the bacteria swimming antiparallel or parallel to the magnetic field lines, respectively. It has been observed that in the presence of inhomogeneous magnetic fields, NS magnetotactic bacteria can change their swimming polarity to SS or vice versa. The present study analyzes populations of NS cocci obtained from SS cocci isolated in the presence of a magnet. The aim was to study differences in the swimming characteristics and magnetic moment among both populations of cocci. For that, trajectories were recorded and the velocity and angle among the velocity and the applied magnetic field were calculated. In addition, micrographs from both SS and NS cocci were obtained and their magnetosomes were measured to analyze their length, width, aspect ratio and magnetic moment, to finally obtain the magnetic moment for each coccus. The results showed the following properties of NS relative to SS cocci: higher velocities, narrow bacterial magnetic moment distribution, higher dispersion in the distribution of angles among the velocity and the applied magnetic field and lower magnetic field sensibility. Those differences cannot be explained by the simple change in magnetic polarity of the magnetosome chain and can be related to the existence of an active magnetoreceptive process in magnetotactic bacteria.
趋磁细菌是一种微生物，它能产生排列成链状的细胞内磁性纳米颗粒，赋予菌体一个磁矩，使其能够沿着地磁场线游动。在环境样本中，趋磁细菌通常表现出两种游动极性：向南（SS）极性和向北（NS）极性，其特征分别是细菌逆着或顺着磁场线游动。据观察，在非均匀磁场存在的情况下，NS趋磁细菌可以将其游动极性转变为SS极性，反之亦然。本研究分析了从在磁场存在下分离得到的SS球菌中获得的NS球菌群体。目的是研究这两种球菌群体在游动特性和磁矩方面的差异。为此，记录了轨迹，并计算了速度以及速度与外加磁场之间的夹角。此外，获取了SS和NS球菌的显微照片，并对它们磁小体的长度、宽度、纵横比和磁矩进行了测量，最终得出每个球菌的磁矩。结果显示NS球菌相对于SS球菌具有以下特性：速度更高、细菌磁矩分布更窄、速度与外加磁场之间夹角分布的离散度更高以及磁场敏感性更低。这些差异无法通过磁小体链磁性极性的简单变化来解释，可能与趋磁细菌中存在活跃的磁感受过程有关。
