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Metals Bioprocessing
| Article
# : |
15201 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
4 / 1989 |
2,638 Words |
| Author
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Gregory J. Olson and Frederick E. Brinckman
Gregory J. Olson, a microbiologist, and Frederick E.
Brinckman, a research chemist, are jointly researching
microorganisms that can process metals at the National
Institute for Standards and Technology in Gaithersburg,
Maryland. |
Although plastics are replacing metals for many uses, our industrialized society still requires an assured supply of many different kinds of metals. Thus the increasing exhaustion of metal-rich ore sources, problems associated with waste cleanup, and the rising costs of energy are spurring the development of new technologies for recovering metals from source rocks or from the tailings of previous mining or refining activities. One promising new technology, metals bioprocessing, uses minute, single-celled organisms to dissolve, immobilize, or otherwise transform metals and metal compounds. Thus, the industries involved in mining, refining of metals, and burning of fossil fuels are increasingly studying and evaluating the metabolic activities and products of microorganisms in order to harness their reliable, unique powers.
The interaction of microorganisms with metals may at first seem unlikely to those familiar with microbiological transformations--both beneficial and harmful--of organic compounds. Among the transformations yielding negative consequences, some of the better-known include food spoilage, tooth decay, and infection and disease. In addition, microorganisms also play an essential, positive role in processing sewage and recycling dead plant and animal remains. They also produce beer and wine, and the antibiotics that man has added to his technological arsenal for fighting disease.
Microbes are so ubiquitous, versatile, and hardy that some species even react routinely with ionic forms of such metals as iron, copper, or gold. Some microorganisms extract energy from metals, while others cause toxic metals to precipitate from solution or to be released as a gas. For metals producers used to working with chemicals and large machinery, microorganisms now offer a promising and inexpensive alternative approach.
For example, one species of bacterium, Thiobacillus ferrooxidans, can extract energy from the ionic form of metals--such as ferrous iron (Fe2+) and cuprous copper (cu+)--in solution. T. ferrooxidans contains proteins that are adapted to the task of accepting an electron from the metal ion, and then coupling that electron's potential energy with the energy-generating bilk-machinery located in the cellular membrane. Ultamately, the electrons from the metals are passed on to oxygen atoms as the microorganism forms water molecules, and in the process captures the available energy of the electron for use in the cell. The cell uses this energy exactly as would any other organism that obtains its energy from organic compounds, that is, for movement, growth, multiplication, and other key cellular functions. T.
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