Mining and Martians

• Prokaryotic cells - no nucleus, no membrane bound organelles
• Magnetotactic bacteria (Magentospirillum magnetotacticum) - produce intracellular magnets
• Cells fed with high iron concentration - magnets

  cells fed with low iron concentration - no magnets
• Ferrous transport - iron is transported in the blood in the form of ferritin
• Ferric transport - uses Fe3+ siderophores to transport iron
• Widely accepted hypothesis on why they produce magnets - Magnetonavigation and Magnetoreception
• Magnetonavigation - A navigation system that uses a magnetic field to determine the position of the vehicle.
• Magnetoreception - the ability of some animals to detect changes in Earth's magnetic field
• Magnetonavigation and Magnetoreception - for migration along iron and oxygen gradients using the Earth's magnetic field lines
• Magnetoaerotactic bacteria - bacteria that can sense magnetic fields and is sensitive to the presence of oxygen
• Microaerobe

  • If magnet is placed in low oxygen area, microaerobe will go to the low oxygen site
  • If magnet is placed in high oxygen area, microaerobe will go to the middle of the capillary tube
• Strict Anaerobe

  • If magnet is placed in low oxygen area, bacteria will go to the low oxygen area
  • If magnet is placed in high oxygen area, cells will still be in the low oxygen area but will turn around
• • Cells fed with HIGH IRON concentration will produce magnets
  • Cells fed with LOW or ZERO IRON concentration will not produce magnets
• Biotechnological applications of Magnetotactic Bacteria

  1. Extracellular products
  2. Isolated magnetosome particles
  3. Whole living cells and their magnetotactic behavior
• Siderophores - example of extracellular products that can be utilized for drug delivery (Trojan Horse Strategy)

  • Beta-lactam antibiotic will connect with the bacterium's native siderophore - once it enters the cells through the receptor, the beta-lactam denatures the cell membrane = CELL DEATH
• Magnetotactic Bacteria for Trojan Horse Strategy

  • bacterial magnetic particles have well controlled size and morphology
  • covered with organic membrane
  • non-toxic
• Whole living cells and their magnetotactic behavior

  • adsorption of cadmium
  • bioaccumulation of metals like manganes, copper, and cobalt
  • bioaccumulation of tellurium useful material for optical discs, solar cell materials, and thermoelectric elements, manganese, copper
• Two conditions for Magnetosome Formation:

  1. Low or zero concentration of oxygen
  2. An extraordinary high amount of iron
• Effects of Cadmium Contamination

  • Ecosystem
  • Toxicity
  • Interferes with the food chain
  • Human Health
  • Painful bone disorders
  • Respiratory and ion regulatory function
• 0.005 ppm - toxic level of cadmium safe for humans
• Magnetosome - Magnetite + Membrane
• OATZ - Oxygen Anoxic Transition Zone