Imagine having an ancestor who is 3.8 billion years old and who would dive into a pool filled with boiling water. Well, that is everyday life for some microorganisms. Not only are they the oldest form of life on the planet, but they can also live in almost every environment, even the most extreme ones.

A bacterium that likes the cold: Polaromonas vacuolata

The Arctic and Antarctic oceans are the refuge of microorganisms that like the cold, the psychrophiles. Eucaryotic cells, algae, diatoms, and bacteria colonize these frozen seas. P. vacuolata, for example, is a bacterium whose growth is optimal at 4°C and whose reproduction is inhibited at 12°C, a temperature that it finds already too high. These cold-loving bacteria are important for producers of processed foods, fragrances, and laundry detergents since their enzymes work at freezing temperatures.

An extremophilic bacterium: Thermus aquaticus

In the 1960s, a team from the University of Wisconsin in Madison discovered Read More
Imagine having an ancestor who is 3.8 billion years old and who would dive into a pool filled with boiling water. Well, that is everyday life for some microorganisms. Not only are they the oldest form of life on the planet, but they can also live in almost every environment, even the most extreme ones.

A bacterium that likes the cold: Polaromonas vacuolata

The Arctic and Antarctic oceans are the refuge of microorganisms that like the cold, the psychrophiles. Eucaryotic cells, algae, diatoms, and bacteria colonize these frozen seas. P. vacuolata, for example, is a bacterium whose growth is optimal at 4°C and whose reproduction is inhibited at 12°C, a temperature that it finds already too high. These cold-loving bacteria are important for producers of processed foods, fragrances, and laundry detergents since their enzymes work at freezing temperatures.

An extremophilic bacterium: Thermus aquaticus

In the 1960s, a team from the University of Wisconsin in Madison discovered T. aquaticus, the first extremophilic bacterium to be identified. This bacterium likes extreme conditions, since it lives in thermal waters where the temperature is greater than 70°C. This microorganism’s thermostable enzymes have made possible the technology called “polymerase chain reaction” used in research laboratories since the 1980s.

Bioluminescent algae: Pyrocystis lunula

Pyrocystis lunula can be seen in the Atlantic ocean on the coast of São Paulo and in the Pacific ocean close to the shore of California. These algae with two flagella are unicellular, microscopic, and... bioluminescent. Like fireflies, they produce their own light.

© Armand-Frappier Museum, 2008. All rights reserved.

A bacterium that likes the cold: Polaromonas vacuolata

Photo : Roar Irgens, John Gosink et James T. Staley

© Roar Irgens, John Gosink et James T. Staley


An extremophilic bacterium: Thermus aquaticus

Photo : Diane Montpetit, Agriculture Canada

© Diane Montpetit, Agriculture Canada


Bioluminescent algae : Pyrocystis lunula

Photo : David Morse, University of Montreal

© David Morse, University of Montreal


Microorganisms are always present in water, in variable quantities. They often act as natural purifiers, degrading organic waste as well as pollutants found in these natural environments.

Not all water is fit to drink…

Only a small percentage of the many organisms present in water can be harmful to our health. If destined for human consumption, water coming from lakes and rivers must first be filtered and decontaminated to eliminate all pathogenic microbes.

Swamps : important water purification areas

Microorganisms are particularly plentiful in swamps. In addition to being a source of food for numerous animals who are then eaten by larger animals, they “digest” water pollutants, transforming them into particles that can be absorbed by vegetation. The water exiting the swamp is thus cleaner than when it entered it.

Bodies of water, like other terrestrial environments, contain great quantities and a great variety of microorganisms. In water, one can find representatives of each type of microorganism: protozoa, algae, bacteria, fung Read More
Microorganisms are always present in water, in variable quantities. They often act as natural purifiers, degrading organic waste as well as pollutants found in these natural environments.

Not all water is fit to drink…

Only a small percentage of the many organisms present in water can be harmful to our health. If destined for human consumption, water coming from lakes and rivers must first be filtered and decontaminated to eliminate all pathogenic microbes.

Swamps : important water purification areas

Microorganisms are particularly plentiful in swamps. In addition to being a source of food for numerous animals who are then eaten by larger animals, they “digest” water pollutants, transforming them into particles that can be absorbed by vegetation. The water exiting the swamp is thus cleaner than when it entered it.

Bodies of water, like other terrestrial environments, contain great quantities and a great variety of microorganisms. In water, one can find representatives of each type of microorganism: protozoa, algae, bacteria, fungi and even viruses! Luckily for us, these microorganisms are for the most part harmless to humans.

Without microorganisms in water, there would be no fish!

You have probably heard of the “food chain”, in which plants are eaten by herbivorous animals, and then herbivorous animals are eaten by carnivorous animals. In aquatic environments, microorganisms are at the bottom of the food chain. It is because of their presence in water that fish exist.

Bacteria and fungi are very important in the food chain. They feed on other organisms! They clean the system by decomposing most of the dead organisms that they find in it.

© Armand-Frappier Museum, 2008. All rights reserved.

Unicellular aquatic microorganisms whose cell walls are composed of silica.

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Nitrogen is one of the elements essential to life since it is present in DNA (the blueprint of life) as well as in proteins (cell constituents characteristic of every living being). In gaseous form, nitrogen constitutes 79 % of the atmosphere but most living creatures cannot assimilate it. However, certain bacteria, present in soil, can chemically reduce atmospheric nitrogen (N2). The bacteria transform nitrogen into ammonia which can be assimilated by plants and which can then circulate up the food chain from plants to herbivores and from herbivores to carnivores. A few legumes and certain shrubs, such as the specked alder, have developed symbiotic relationships with these microorganisms (e.g., Rhizobium leguminosarum). They provide them with sugars and carbohydrates and receive, in return, the nitrogen required for their metabolism.
Nitrogen is one of the elements essential to life since it is present in DNA (the blueprint of life) as well as in proteins (cell constituents characteristic of every living being). In gaseous form, nitrogen constitutes 79 % of the atmosphere but most living creatures cannot assimilate it. However, certain bacteria, present in soil, can chemically reduce atmospheric nitrogen (N2). The bacteria transform nitrogen into ammonia which can be assimilated by plants and which can then circulate up the food chain from plants to herbivores and from herbivores to carnivores. A few legumes and certain shrubs, such as the specked alder, have developed symbiotic relationships with these microorganisms (e.g., Rhizobium leguminosarum). They provide them with sugars and carbohydrates and receive, in return, the nitrogen required for their metabolism.

© Armand-Frappier Museum, 2008. All rights reserved.

The microorganims that help plants absorb the nutrient nitrogen from soil are found near the roots.

Armand-Frappier Museum

© Armand-Frappier Museum


Animals are hosts to a great number of microorganisms. In some cases, they are even essential to the animal's health. Without the 1011 microbes per millilitre present in their stomachs, ruminants could not digest the grass they eat.

The stomach of ruminants is made of four compartments: the rumen, the reticulum, the omasum, and the abomasum or rennet bag.

Bacteria

Energy in plant cells is stored in the form of long molecules of sugar called cellulose. In the rumen, the bacterial flora is particularly efficient in digesting cellulose. This process is called cellulolysis. The champion cellulolysis bacteria are Fibrobacter succinogenes, Ruminococcus flavefaciens and Ruminococcus albus. Other bacteria, such as Lachnospira multipara, Prevotella ruminicola, Butyrivibrio fibrisolvens and Streptococcus bovis are responsible for degradation of pectin, another plant compound

Protozoa

It is unclear whether ciliate protozoa participate in the digestion of cellulose in the rumen. If they do, it might actually be due to the work of some of their intracellular b Read More
Animals are hosts to a great number of microorganisms. In some cases, they are even essential to the animal's health. Without the 1011 microbes per millilitre present in their stomachs, ruminants could not digest the grass they eat.

The stomach of ruminants is made of four compartments: the rumen, the reticulum, the omasum, and the abomasum or rennet bag.

Bacteria

Energy in plant cells is stored in the form of long molecules of sugar called cellulose. In the rumen, the bacterial flora is particularly efficient in digesting cellulose. This process is called cellulolysis. The champion cellulolysis bacteria are Fibrobacter succinogenes, Ruminococcus flavefaciens and Ruminococcus albus. Other bacteria, such as Lachnospira multipara, Prevotella ruminicola, Butyrivibrio fibrisolvens and Streptococcus bovis are responsible for degradation of pectin, another plant compound

Protozoa

It is unclear whether ciliate protozoa participate in the digestion of cellulose in the rumen. If they do, it might actually be due to the work of some of their intracellular bacteria. Among cellulolytic protozoa, there are Eudiplodinium maggii, Epidinium ecaudatum and Ostracodinium dilobum.

Fungi

Fungi represent 8 % of the microbial mass in the rumen. Most of the anaerobic rumen fungi are cellulolytic and their cellulases (proteins carrying out cellulolysis) are very active. In addition, the enzymatic activity of microorganisms that digest plant particles is increased when Neocallimastix frontalis and Piromyces communis are present.

© Armand-Frappier Museum, 2008. All rights reserved.

The protozoan Endodinium simplex

Photo : Gaillard-Martinie Brigitte, INRA

© Gaillard-Martinie Brigitte, INRA


The microscopic fungus Neocallimastix

Photo : Daniel A. Wubah, University of Florida

© Daniel A. Wubah, University of Florida


Learning Objectives

The learner will:
  • familiarize himself with the vocabulary used in microbiology;
  • explain the relationship between developments in imaging technology and the current understanding of the cell;
  • identify which microorganisms are infectious, how the immune system fights against them, and the reinforcements of modern medicine;
  • describe the benefits of microorganisms .

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