David C. Smith, Assistant Professor
Graduate School of Oceanography
Microorganisms have been found in almost every inhospitable environment
on earth. These environments include the superheated waters of hydrothermal
vents, the frozen dry valleys of Antarctica, and acid mine drainage fields.
For the most part, microbes living in these environments do nothing fundamentally
different than those living in more mundane environments; they are simply equipped
to carry out the routine functions of life under extreme conditions. Many microbiologists
are "bioprospecting" in these environments for new ways to do everything
from cleaning clothes to treating disease.
Enzymes are the target molecule for most bioprospectors. They are manufactured by organisms to catalyze the myriad reactions necessary to sustain life. Commercial applications of enzymes include food and textile processing, additives in detergents, and animal feed. Extremozymes, enzymes that function under extreme conditions, present possibilities for new commercial applications. For example, many manufacturing processes are more efficient at higher temperatures. Therefore, enzymes isolated from hyperthermophiles (heat-loving microbes) are of particular interest to manufacturers. Enzymes from alkaliphilic microbes (those that grow at high pH) are useful additives to laundry detergents because they are able to degrade the common components of stains (proteins, carbohydrates, and lipids) in the high pH environment of soapy water. The list goes on.
Because culturing commercial quantities of extremophiles is usually difficult and requires special facilities, the genes encoding the information used to produce the enzymes are often cloned into a bacterium that grows at more normal conditions. This allows commercial production of the enzyme at a reasonable cost. By directly cloning DNA extracted from extreme environments and then screening the clones for enzyme activity, the initial, and often most difficult, step of culturing extremophiles can be avoided. This strategy is employed by some biotechnology companies to increase their chances of finding new products. Continued efforts to exploit the extremozymes will undoubtedly expand the range of useful applications for enzymes in biotechnology.
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