Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS, UMR7283, Aix-Marseille Université, Marseille Cedex 20, F-13402, France; Laboratoire International Associé de la Biominéralisation et Nanostructure, CNRS-Marseille, Marseille, F-13402, France.
Environ Microbiol Rep. 2014 Feb;6(1):14-20. doi: 10.1111/1758-2229.12102. Epub 2013 Sep 16.
Magnetotactic bacteria (MTB) have the unique capacity to align and swim along the geomagnetic field lines downward to the oxic-anoxic interface in chemically stratified water columns and sediments. They are most abundant within the first few centimetres of sediments below the water-sediment interface. It is unknown how MTB penetrate into the sediment layer and swim in the pocket water, while their movements are restricted by the alignment along the magnetic field lines. Here we characterized the swimming behaviour of the marine fast-swimming magnetotactic ovoid bacterium MO-1.We found that it rotates around and translates along its short body axis to the magnetic north (northward). MO-1 cells swim forward constantly for a minimum of 1770 μm without apparent stopping. When encountering obstacles, MO-1 cells squeeze through or swim southward to circumvent the obstacles. The distance of southward swimming is short and inversely proportional to the magnetic field strength. Using a magnetic shielding device, we provide direct evidence that magnetotaxis is beneficial to MO-1 growth and becomes essential at low cell density. Environmental implications of the fast-swimming magnetotactic behaviour of magnetococci are discussed.
趋磁细菌 (MTB) 具有独特的能力，可以沿着地磁场线排列并向下游游动到化学分层水柱和沉积物中的有氧-缺氧界面。它们在水-沉积物界面以下的沉积物的最初几厘米内最为丰富。目前尚不清楚 MTB 是如何穿透沉积物层并在口袋水中游动的，而它们的运动受到沿着磁场线排列的限制。在这里，我们描述了海洋快速游动趋磁卵形菌 MO-1 的游动行为。我们发现，它围绕并沿着其短体轴旋转到磁北极（向北）。MO-1 细胞向前游动至少 1770μm 而不停歇。当遇到障碍物时，MO-1 细胞会挤过障碍物或向南游动以绕过障碍物。向南游动的距离很短，与磁场强度成反比。使用磁屏蔽装置，我们提供了直接的证据表明趋磁作用有利于 MO-1 的生长，并且在细胞密度较低时变得至关重要。讨论了趋磁行为对趋磁球菌的环境意义。
