Magnetobacterium

What is Magnetobacterium?

Magnetobacterium is a bacteria that can synthesize intracellular crystals of magnetic iron oxide or iron sulfide minerals.

What is Magnetotaxis?

Magnetotaxis is the ability for the crystals to cause the bacteria to migrate and orient along geomagnetic fields.  They are indigenous in sediments or stratified water columns.

Physical characteristics:

• Stain Gram negative

• Prokaryotes

• Proteobacteria ; disbursed in the alpha and delta subclass

• large size (34-30 um)

• 16S, rRNA

• motile by means of flagella

• shapes include: vibrios, spirilla, cocci, ovoids, and rods

• G + C is 64-71 mol %

Biochemical & Growth Characteristics 

• aerobic

• Carbohydrates are not utilized

• catalase and oxidase may be present or not be

• preferred substrates are intermediates of the carboxylic acid cycle and acetate

What are Magnetosomes?

All magnetic bacteria have contain magnetosomes, which are intracellular structures comprising magnetic iron mineral crystals enveloped in phospholipid membranes.  Magnetosomes are able to control bilogically over the nucleation and growth of mineral particles , ie: magnetite (Fe3O4) and greigite (Fe3S4)

What is magnetite synthesis?

This can be divided into three steps:

• extracellular iron has to be transported across the cell wall to the inside of the cell

• once inside the cell, iron must accumulate in specialized compartments, the magnetosome vesicles

• there, the iron presumably precipitates and transforms or grows into single- magnetic- domain magnetite crystals with a specific morphhology

How can Magnetobacterium help/ affect us?

Understanding the factors controlling the te biomineralization of iron in magnetosomes synthesis within the bacteria could also be helpful for the elucidation of similar processes in animals, man, and artificial synthesis of biominerals.

Experiment

One simple method is to put a drop of water or sediment on a microscope slide and place a bar magnet on the microscope stage in such a way that all the magnetotactic bacteria are guided in one direction until they reach and accumulate at the edge of a drop of water/ sediment where they can be visualized.

References/Links

http://www.geophysik.uni-muenchen.de/groups/biomag/research/bavaricum.htm

Magnetism Research Group - University of Munich

http://www.sciencenewsden.com/2006/bacteriumhavestrangemagneticpersonality.shtml

Presented by Debora Suarez 12/5/02