Microorganisms are very tiny one-celled organisms, viruses,
fungi, and bacteria, and are found everywhere in the world. They are found in
all living things, plants and animal. There are more microorganisms on and
inside your body than there are cells that make up your entire body.
Microorganisms can live in the air, on land, and in fresh or salt water
environments. Some of them, pathogens, can be harmful and causes diseases, but
there are some microorganisms that are needed for living things to survive.
Land Microbes
All of the living things, plant and animal, in earth's
environmental communities of forests, deserts, tundra, water, air, and all of
the rest depend on the cryptobiotic crust or micro biotic layer in the soil.
This is the layer of soil that most microbes live in. These microbe communities
are made up of fungi, cyanobacteria and lichens. They look like a grayish cover
on the ground when they are first forming, but do form in clumps of lichen that
look like little hills after about 50 years of growth.
The cyanobacteria Nostoc lives on the land and forms in
filaments of hyphae that hold the microbial mat of lichen together.
The cyanobacteria called Nostoc helps lichen produce food
during photosynthesis.
Microbial Crust
The microbial crust found in the desert is all dried up for
most of the year. All it takes is a little bit of water to make it active
again.
This is the microbial crust from the picture to the left
after it was put in water. The arrows are pointing to a kind of lichen in this
section, another form of lichen is inside the square, and cyanobacgteria are
inside the circle.
Airborne Microbes
Airborne microbes cause a lot of illnesses and diseases in
humans. Microorganisms can enter the air when a human or animal sneezes, or by
the wind picking up the light particles and blowing them where humans are. When
a human sneezes microorganisms leave the lungs at around 200 miles per hour.
Some of the microorganisms that are growing in the mucus in the respiratory
tract enter the air with the moisture particles that are sneezed out of the
lungs. These microorganisms can be breathed into the lungs of another person
and that person could get sick.
How are microorganisms identified?
Microorganisms are put into groups, but a lot of
microorganisms can belong to more than one group. One way that microorganisms
are grouped is by the temperature in their environment. Another way to organize
microorganisms is by placing them in either the prokaryot or eukaryot group.
How do microorganisms reproduce??
Thermophiles reproduce either by sexual or asexual
reproduction. Sexual reproduction requires a male and female organism, but
asexual reproduction happens by cell division, mitosis. Thermophilic fungi
reproduce by producing male and female spores that come in contact with each
other to produce a new organism.
What do microorganisms do?
Microorganisms also are responsible for building fertile
soil for plants to grow in. Microbes stick to the roots of plants and decompose
dead organic matter into food for the plant to absorb. The plants that live and
grow because of the microorganisms that live on them make a home for other
animals to live in. Some microorganisms make people, animals, and plants sick,
but others make people well and kill the bacteria on plants that make them
sick. Drug companies that make medicines use hundreds of different
microorganisms to make medicines that will help cure diseases. Human waste
products are broken down into safer particles by some microorganism. Scientists
are always looking for new ways to use microbes, and only a few uses have been
listed here.
The Littlest Organisms
Let's study the wee ones of the world known as the microbes
or the microorganisms. If you spend your life studying them, you would be a
microbiologist. These are the smallest of the small and the simplest of the
simple. Some of them, like viruses, may not even be alive as we currently
define life.
What is a Microbe?
What makes a microbe? We suppose you need a microscope to
see them. That's about it. There is a huge variety of creatures in this
section. They can work alone or in colonies. They can help you or hurt you.
Most important fact is that they make up the largest number of living organisms
on the planet. It helps to be that small. It's not millions, billions, or
trillions. There are trillions of trillions of trillions of microbes around the
Earth. Maybe more.
Calling all Microscopes
As with all of science, discovery in biology is a huge
thing. While microbes like bacteria, fungi, some algae, and protozoa have always
existed, scientists did not always know they were there. They may have seen a
mushroom here or there, but there were hundreds of thousands of species to be
discovered.
It took one invention to change the way we see the world of
microbes - the microscope. In 1673,Anton von Leeuwenhoek put a couple offenses
together and was able to see a completely new world. He made the first
microscope. It wasn't that impressive, but it started a whole history of
exploration. More important to us, scientists were eventually able to discover
the cause and cure of many diseases.
Too Many to Count, Too Small to Find
Did you know that there are more microorganisms in your body
than there are people on Earth? We spend millions of dollars each year on
anti-bacterial soaps and antibiotics to fend off germs, but, in fact,
microorganisms play an essential role in human health and in the functioning of
all ecosystems.
Microorganisms include viruses, bacteria, fungi, protozoa,
algae, and nematodes, in roughly decreasing order of size. They are the oldest
form of life on Earth and are found virtually everywhere, from boiling hot
springs deep in the Earth to the depths of the oceans to the Arctic. It is
believed that the biological activity of microorganisms are responsible for
producing sufficient amounts of oxygen in the Earth?s atmosphere more than two
billion years ago in order to support life.
Microorganisms play a critical role in the various
biogeochemical cycles, as well as being a particularly important component of
plant and soil ecosystems. They break down dead plant and animal tissues and
make their nutrients, including carbon and nitrogen, available to support plant
growth. There are generally between one and ten million microorganisms in each
gram of soil; similar numbers occur on plants and animals.
Microorganisms play a similarly critical part within both
animal and human bodies. Bacteria, for example, play an important role in
digestion, helping to synthesize vitamin K and absorb certain nutrients; they
also help convert bile and acids in the intestines. Some also help to prevent
other, more harmful bacteria from invading the intestines or other areas of the
body. Microorganisms normally found in animal and human bodies are referred to
as "normal flora."
The discovery of the role of microorganisms, or germs, in
causing disease was the beginning of a revolution in health care. Although
Anton van Leeuwenhoek first observed bacteria in the late 1600s, it was not
until late in the 19th century that the germ theory of disease became generally
accepted. The research of French scientist Luis Pasteur provided persuasive
evidence that certain microorganisms were responsible for human illness. Among
his other findings, he discovered three bacteria, Staphylococcus, Streptococcus
and Pneumococcus, that can become pathogenic.
However, pathogenicity among microorganisms is an exception,
not the rule. Considering the huge population of microorganisms in our
environment and in our own bodies, it is a relatively rare occurrence that the
symbiotic relationships become harmful. After all, microorganisms are neutral
or have little to gain, in an evolutionary sense, from killing their host. As
physician and microbiologist Lewis Thomas reminded us, ?The man who catches a
meningococcus is in considerably less danger for his life, even without
chemotherapy, than meningococci with the bad luck to catch a man.?
It is not completely understood why some immunological
reactions occur. Symptoms of infection are the result of the immune system?s
response to the presence of potential threats. Fever, for example, is part of
the body?s natural defense mechanism; higher temperatures reduce the ability of
viruses and bacteria to replicate. In most cases, the body?s immune system is
very successful in preventing serious harm. Indeed, infections bestow a benefit
on human health in building up the body?s immunity. In fact, over the last
several decades as people have increased their use of antibiotics to treat
routine infections, we have seen a serious unintended consequence - an increase
in the number of microorganisms that are resistant to antibiotics and/or are
difficult to treat.
Although modern science and medicine has made vast
improvements in human, animal, and plant health, it is remarkable how much
remains to be learned and understood. New infectious viruses appear from time
to time, posing a threat to human health. The origin of some of these is
unknown, and no one knows within an order of magnitude how many microorganisms
actually exist.
- illustration of the
bacillus microorganisms Royalty Free Stock Photo
We'll give the big overview on the variety of microorganisms
here. There is no simple explanation of a microbe besides the fact that they
are small. The list goes on. Just remember that there is a lot of variety going
on here.
-Microorganisms Under a Microscope –
They can be heterotrophic or autotrophic. These two terms
mean they either eat other things (hetero) or make food for themselves (auto).
Think about it this way: plants are autotrophic and animals are heterotrophic.
They can be solitary or colonial. A protozoan like an amoeba
might spend its whole life alone, cruising through the water. Others, like
fungi, work together in colonies to help each other survive.
They can reproduce sexually or asexually. Sometimes the DNA
of two microbes mixes and a new one is created (sexual reproduction). Sometimes
a microbe splits into two identical pieces by itself (asexual reproduction).
