Geyser with Bacteria and Lichen
Yellowstone National Park, Wyoming, July, 1999

See lectures from Environmental Health course for review of the morphological characteristics as well as their importance as normal flora and role in some human diseases. The ecological importance of the bacteria will be discussed here. It should be noted that protozoa and fungi play ecological roles similar to bacteria although they are not found in as large quantities in the soil as are bacteria.

Many of the roles of bacteria in the biosphere have already been discussed. They are essential as decomposers and in the recycling of chemical compounds and elements. Indeed, it is this recycling process that maintains life on Earth and microorganisms play a vital role in this process particularly through their conversion of organic compounds into inorganic compounds. Microorganisms participate in the recycling of nitrogen, oxygen, carbon, phosphorus, sulfur, iron, calcium, as well as the other elements essential for life.

Bacterial photosynthesis is also very important. Cyanobacteria account for approximately one half of the primary production in aquatic environments. Cyanobacteria also play a key role in the transformation of rock to soil. Their ability to grow on the surface of rocks produces substances that support the growth of other microorganisms, all of which produce acids that dissolve the rock and eventually make conditions suitable for lichens and ultimately ( with the production of soil), plants.

Click here to go to the Fall 1999 Page!