Extreme Biotechnology
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.