29-01-2013, 10:14 AM
BIOMACHINING
WHY BACTERIA AS A TOOL
They can remove materials at the nm level,
They exert negligible forces on the workpiece and produce no thermal damage,
Ecofriendly,
Can be cultured continuously, and thus are self-renewing
tools.
CLASSIFICATION OF ORGANISMS
Every organism can be classified based on where it obtains its carbon, used for growing and repairing damage.
1) lithotrops: Obtain carbon from inorganic compounds, including
carbon dioxide.
Chemolithotrophs: They are those organisms that extract
energy by processing matter.
Photolithographs: Energy production method involves using
energy from light e.g: Plants.
2) Organotrophs: on the other hand, obtain all the carbon they use
from organic compounds.
Chemoorganotrophs are organisms that extract energy by
processing Organic matter. Eg:Humans
Acidthiobacillus ferrooxidans
(Acidthiobacillus ferrooxidans)
The Acidthiobacillus ferrooxidans organism is a small, rod-like bacterium.
Measuring about 1 μm long and 0.5 μm in diameter.
It contains a unique set of attributes that makes it suitable as a living micro-machining tool.
Obtain energy by the oxidation of inorganic substrates rather than the usual substances such as glucose.
Basic Reactions of The Biomachining Process
The overall reaction employed by a ferrooxidans can be summarized as a combination of the continued oxidation of ferrous iron (Fe2+) to ferric iron (Fe3+) as well as the reduction of H+ ions (from the acidic environment) with oxygen to produce water.
The reaction is shown below:
2 Fe2+ + ⅟2O2 + 2H+ 2 Fe3+ + H2O
The ferric iron is able to oxidize both pure, neutral copper and iron into
charged, soluble forms, thus being able to corrode a solid surface of either metal
Iron Oxidation
The iron bacteria are chemolithotrophs that use ferrous iron (Fe2+) as their sole energy source.
Some phototrophic purple bacteria can oxidize Fe2+ to Fe3+ anaerobically.
It is the production of the ferric iron that makes this organism useful in micromachining of metals.
The ferric iron is able to oxidize both pure, neutral copper and iron into charged, soluble forms, thus being able to corrode a solid surface of either metal.