Magnetotactic

Classification

Higher order taxa:

Bacteria; Proteobacteria; unclassified Proteobacteria

Species:

Magnetococcus sp. MC-1, environmental samples. (source NCBI Taxonomy)

Description and Significance

Magnetococcus, also known as magnetotactic bacteria, are the smallest organisms that use a navigational method by using the earth's geomagnetic field to develop an internal compass. Magnetotactic bacteria were discovered in 1975 by Richard P. Blakemore when he noticed that some of the bacteria that he observed under the microscope always moved to the same side of the slide. These bacteria are able to move in a particular direction because they make tiny, iron-containing magnetic particles. Each of these particles is a magnet with a north pole and a south pole. The bacteria arrange these tiny magnets in a line to make one long magnet. They use this magnet as a compass to align themselves to the earth's geomagnetic field.

Magnetotactic bacteria use their magnetic compass to tell them which way is down in an aquatic environment. These bacteria don't like oxygen and move from areas with high oxygen towards area with low or no oxygen. The level of oxygen decreases as one moves deeper into the water so magnetotactic bacteria live in the deeper parts of their aquatic environments, using their compass to help them.

The geomagnetic field guides the direction of motion of magnetotactic bacteria. In the Northern Hemisphere, the geomagnetic north actually oints down to an angle; the magnetotactic bacteria that are aligned to this field are also pointing down. By moving north along this field, they move deeper into the water, and into areas with less oxygen. In the Southern Hemisphere, the geomagnetic north actually points up and at an angle so magnetotactic bacteria in this half of the world are "south-seeking", which points them downward. The magnetotactic bacteria found at the equator are a mixture of north-seeking and south-seeking bacteria because the geomagnetic north doesn't point either up or down.

The practical applications of magnetotactic bacteria are of significant interest to scientists. The tiny magnets that these nacteria make are far superior to those produced by people. Scientists and engineers are trying to develop ways to use this magnetic material in places where tiny magnets are much better than big magnets.

References

Clement, Sandi; "Magnetic Microbes"; Digital Learning Center for Microbial Ecology