Magnetic Bacteria

In order to watch magnetic bacteria a bit suspended sediment
is placed underneath a cover slip as hanging drop
Often magnetic bacteria are named magnetotactic. This is, however, probably not correct. The bacteria are passively turned parallel to the magnetic field lines. In a homogeneous field they are neither attracted by the north nor by the south pole. However, they react chemotactically towards oxygen.

Magnetic bacteria can be watched easily in a hanging drop. A little sediment sample is taken from the oxic-anoxic boundary and diluted with water. A drop of the slurry is placed on a cover slip, which is then turned around and placed on an O-ring. Now sediment particles settle on the ground while the watery phase can be watched under the microscope.

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