Topics in microbial ecology

Microbial ecology is a large field that includes many topics. Click on one of the pictures below to learn more about that particular aspect of microbial ecology.


Evolution and Creation Biodiversity Exobiology Ecology
Bioremediation Recycling Food Microbiology Biotechnology


Evolution and Creation

How did we get here? This is one of the first questions that many people ponder. The study of the origin and early evolution of microorganisms may provide information on the critical early stages of life. Microbes were the first living creatures on Earth, first appearing over 3.7 billion years ago, long before multicellular plants and animals, which evolved 600 million years ago. Because microbes are simple relative to humans, they provide a model for understanding how evolution works and insight into the origin of all life on Earth.

microbial ecology


Many years of evolution have created a stunning diversity of microbes. Understanding the richness of this awesome and mind-expanding microbial world puts our lives into perspective and gives us new respect for other beings.

The huge numbers of microbial species are only beginning to be known. Of the more than one million species of bacteria suspected to exist, only about 4200 species of bacteria are described. The infant science of microbial systematics has only recently acquired the sophisticated tools required to assess this tremendous biodiversity. It is estimated that we know less than 1% of the microbial species on Earth.

To learn more about microbial biodiversity, check out the biodiversity page.

microbial ecology


Does life exist elsewhere in the universe? If there is life elsewhere in the universe, it is probably microbial. Fascination with extraterrestrial life has fueled enthusiasm for shows such as the "X-Files" and one of the most talked about news stories of 1996: evidence for past microbial life on Mars. While the evidence for microbes on Mars is intriguing, the debate continues about life on Mars, and the search goes on to detect life beyond our own planet.

While we may never know whether life exists elsewhere in the universe, microbes will probably play a key role in helping us explore and colonize space.

microbial ecology


Ecology is the study of organisms in their environment. Ecology is one of the most complex scientific disciplines because of the myriad of organisms' interactions. Using microbes to study ecology may provide clues to how complex ecosystems operate because bacteria are small so large populations can be studied and quick to reproduce compared to larger organisms. A better understanding of ecology may help us better manage Earth and its dwindling renewable resources and to protect global ecological systems.

Global Ecology - Microbes play important global roles:

  • Global Geochemical Cycles
  • Carbon
  • Nitrogen
  • Iron,
  • Sulfur
  • El Niño - what role do microbes play in El Niño?
  • Global Warming - The average temperature of the Earth has been steadily increasing over the past one hundred years. What role do microbes play in this global warming trend?
  • Gaia - the Earth's biosystem is known to some as Gaia. Because microbes are responsible for most of the cycling of elements, they are the foundation of this system.

Human Ecology - The study of simple microbial communities may shed light on one of the most complex (and for most of us most fascinating) communities - the microbial community within a human being. We are hosts to billions of microbes which colonize our intestinal tracts, our skin, hair, teeth. Sometimes microbial colonization causes us problems when disease results. Some scientists have joked that humans are microbes' invention to move around.

Population Interactions - Microbes interact with plants and animals and each other in myriad ways with large plants and animals having hundreds of associations with different microbial species.

  • plant-microbe interactions
  • symbiosis - e. g. rhizobium which converts nitrogen to a form that can be used by plants
  • disease
  • animal-microbe interactions
  • symbiosis - e.g. probiotics = beneficial gut microflora
  • disease
  • Microbe-microbe Interactions - e.g. lichens
microbial ecology


Environmental degradation is one of the worst threats facing humanity. Many enviornmetal problems may be cured by microbes.

Bioremediation of toxic wastes: bioremediation, or the use of microbes to clean-up toxic wastes. Microbes are used to clean up the following:

  • Oil spills
  • Pesticides
  • Industrial wastes
microbial ecology


Microorganisms recyle most organic wastes in nature into reusable resources. Humans have harnessed the power of microbes to recycle in the systems below:

  • waste treatment: Microbes are used in sewage treatment for nutrient recycling, methane recovery and disease control.
  • animal waste treatment: Microbes clean up waste produced by farm animals.
  • yard composting: Composting is now the fashionable practice (championed by Bette Midler among others) of converting kitchen and yard wastes into a rich soil amendment.  Although worms have gotten good press for their contribution to composting, the real workhorses of composting are microbes.
  • municipal composting: Thousands of tons of leaves and grass clippings are composted in large municipal composting facilities.
microbial ecology

Food Microbiology

All of us depend upon food crops for sustenance, and in turn these crops depend on healthy soils with its balanced microbial life. Much of the protein that we eat is the result of bacterial fixation of nitrogen from the air from microbes such as Rhizobium. Many of our foods are prepared with the aid of microbes, such as yeast in bread, and lactobacilli in yogurt.

Many of our food supplements, from vitamins, amino acids to flavor enhancers and preservatives, come from microbes.

Some of our foods are microbes, such as salted yeast paste found in Vegemite, and single cell protein.

Although not a food, microbes are used as probiotics, a digestion supplement that colonizes the intestines, preventing the colonization of bad, disease-causing microbes.

microbial ecology


Microbes are used as workhorses in the production of many compounds, from fuel, to pharmaceuticals, to chemicals. They are also used in mining, insect and disease control, genetic engineering and some are even used to make computer biochips.

Fuel Production - ethanol production for automobile fuel.Mining - leaching of metals from ore-bearing rocks by microbes.

  • 5% of world's copper ore is produced by bio-leaching
  • Uranium is mined with help of bacteria

Biocontrol - Using microbes to combat pests is called biocontrol. One of the most popular forms of biocontrol is the use of Bacillus thuriengensis, a bacterium that produces a toxin that kills over 40 problem pests such as the gypsy moth.Computer Biochips - Microorganisms may some day be used to produce protein-based microprocessors with more switches than conventional microchips.Genetic Engineering - Some microorganisms are used to carry genes into other organisms.