Microbes: Building Blocks for Biotechnology - haspi

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Issue 37 June, 1998 Published by AG-WEST BIOTECH INC.
Agbiotech Information Bulletin for Schools courtesy of Ag-West Biotech Inc.
Microbes: Building Blocks for Biotechnology
ItÕs safe to say that without microbes, biotechnology would
be an extremely limited science. Microbes are microscopic
organisms such as fungi (which include yeasts), bacteria and
viruses. They not only provide the foundation for much of the
basic research involved in biotechnology, they help to create
many of the processes which are integral to this science.
The early scientific study of microbes concentrated on their
effects, such as causing disease. Eventually, scientists discov-
ered microbes could be used for the study of processes which
are common to all living organisms. MicrobesÕ rapid growth
and multiplication means they can be produced quickly and in
large numbers in the laboratory. This gives scientists an
opportunity to look at several generations in a fairly short time.
They can then study processes like genetics (the examination
of inherited characteristics) more quickly than in other organ-
isms.
The genetic traits of various microbes are used in genetic
exchange, recombination and engineering. These processes
involve taking genetic material from one organism and trans-
ferring it to another. For example, scientists use these methods
in creating Òedible vaccines.Ó The goal is to produce foods, like
potatoes or bananas, which immunize people against certain
diseases. In some areas of this research, scientists isolate a
bacterial gene which can be used to create a vaccine. Then,
using another bacterium, they transfer this gene to a specific
plant, like the potato. Eventually, scientists can develop a
potato which naturally contains the desired vaccine.
Sometimes microbes are used as vehicles to express (show
the characteristics of) genes. They are also used as vectors, to
transfer genetic material. Viruses are often used to carry
genetic material into a cell. Sometimes the vectors are bacterial
plasmids. These are small, circular DNA molecules. These
sections of genetic material, derived from the same or different
species, are capable of duplicating themselves in the host cell.
World of microbes
Although the various classifications of microbes have
similar functions or uses in biotechnology, they are distinctly
different.
Fungi are a group of organisms which include microbes
like land and aquatic moulds, and yeasts. Although some fungi,
like mushrooms, appear similar to plants, they do not use
photosynthesis (the process of converting light energy to
chemical energy). They feed on organic matter.
Yeast is a general term for single-celled fungi that repro-
duce by budding. Some yeasts can ferment carbohydrates
(starches and sugars) and thus are important in brewing and
baking. Yeast is the key component in the creation ethanol, an
environmentally friendly fuel produced through the use of
fermentation. This is the process of growing certain yeasts in
order to produce various chemical compounds, like ethanol.
Bacteria are members of a large group of microorganisms
with a very simple cell structure. Some bacteria manufacture
their own food, others live in association with other organisms
and some live on organic matter. One of the most important
uses of bacteria is as tools to study inheritance and expression
of genetic trails.
Bacteria are everywhere. Researchers have even discovered
bacteria in solid rock many kilometres below the earthÕs
surface, in hot springs and in salty water. These bacteria
survive even though there is very little organic material
available to them. They live by manufacturing many of their
own organic compounds, using carbon and hydrogen (basic
elements in all organic compounds) taken from the carbon
dioxide and hydrogen gas dissolved in the rock.
Viruses are extremely tiny organisms which contain genetic
information, but which cannot reproduce on their own. To
reproduce, they must invade the cells of another organism and
use the cellsÕ reproductive machinery. Viruses are parasites of
animals, plants and some bacteria-they must use the cells of
these other organisms in order to live.
Following are just two examples of the ways microbes are
used to aid agriculture and the environment:
Microbial Pest Control
Substances which kill or control pests are called pesticides.
Insecticides kill or control insects, while herbicides destroy or
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For example, a bacterium called Bacillus thuringiensis, B.t.
for short, has been used for the past 60 years to create environ-
mentally friendly insecticides.
Recently, a team of scientists from the University of
Wisconsin-Madison, in collaboration with researchers at
DowElanco, have identified another bacterium which also kills
insects. It is called Photorhabdus luminescens. It contains a
toxin which has been shown to kill a wide variety of pests.
The bacterial toxin can be concentrated for use as an
insecticide spray. The greatest application, however, lies in
transferring the toxin-producing genes from strains (varieties)
of the bacterium to the genetic material of plants which are
grown as crops. In Saskatoon, Mycogen Corp. is a leader in the
technology of engineering plants to contain natural insect
resistance.
Microbes in the Environment
Cleaning up environmental pollutants like oil, gas and
heavy metals is a considerable challenge. However, biotechnol-
ogy is coming to the aid of the environment through the
development of bioremediation and biosorption, the use of
living organisms to return the environment to its natural state.
Some microbes have an appetite for gas, oil or other toxic
chemicals. When the chemicals are degraded or absorbed and
accumulated by the microbes, the chemicalsÕ structure can
undergo changes. With the use of the right microbes, toxic, and
sometimes explosive, materials can be converted into some-
thing harmless, like water and carbon dioxide.
To make some microbes more efficient at breaking down
chemicals, genetic engineering is used to add new information
to the microbesÕ genetic make-up. New genetic information can
also be added so that the microbe attacks a new or different
chemical.
Once scientists have determined which microbes they need
to use to tackle an environmental problem, they need to grow
the microbes in large numbers. One of the ways of doing this is
through the use of a bioreactor. This is a package of equipment
that brings together the microbes and the contaminated material
they must digest. Bioreactors are also used in other circum-
stances. A sewage treatment plant is an example of a bioreactor
which processes sewage wastes.
In some cases, scientists can improve the local soil condi-
tions so that naturally occurring bacteria can more easily
attack environmental pollutants. In Eastern Europe, for ex-
ample, scientists have developed methods of bioremediation
which reduce heavy metal pollution. Bacteria are used to take
metals such as copper, zinc, cadmium and arsenic out of the
soil. The microbes immobilize these metals by creating
sulphides (compounds of the element sulphur). Once this
happens, the metals do not leach from the contaminated site
into the groundwater. To help the bacteria grow and attack the
heavy metals, scientists improve the soil conditions for the
bacteria and add nutrients such as phosphate (salts based on
the element phosphorus).
More Uses
The role of microbes in biotechnology is much broader than
has been discussed here, and new uses are continually being
discovered. Without microbes, biotechnology would not be as
advanced as it is, nor would it include such a broad range of
applications. Microbes are a fundamental element of biotech-
nology.
Special thanks to Dr. George Khachatourians, of the Department
of Applied Microbiology and Food Science, University of
Saskatchewan, for his help in preparing this issue of Infosource.
control weeds. Bioinsecticides and bioherbicides use fungi,
bacteria and viruses to control insects and weeds.
Biofungicides utilize microbes that kill fungi.
Certain microbes have toxic gene products, which act only
on specific plants and insects. Therefore, they have an advan-
tage over some chemicals because they can be used in limited
amounts and have much more specific effects.
Bioinsecticides are used to control insect pests.