Global Ecosystem

The ecosystem, both on land and in the water, depends heavily upon the activity of bacteria. The cycling of nutrients such as carbon, nitrogen, and sulfur is completed by their ceaseless labor. Organic carbon, in the form of dead and rotting organisms, would quickly deplete the carbon dioxide in the atmosphere if not for the activity of decomposers. This may not sound too bad to you, but realize that without carbon dioxide, there would be no photosynthesis in plants, and no food. When organisms die, the carbon contained in their tissues becomes unavailable for most other living things. Decomposition is the breakdown of these organisms, and the release of nutrients back into the environment, and is one of the most important roles of the bacteria.

The cycling of nitrogen is another important activity of bacteria. Plants rely on nitrogen from the soil for their health and growth, and cannot acquire it from the gaseous nitrogen in the atmosphere. The primary way in which nitrogen becomes available to them is through nitrogen fixating bacteria. These bacteria convert gaseous nitrogen into nitrates or nitrites as part of their metabolism, and the resulting products are released into the environment. Some plants, such as liverworts, cycads, and legumes have taken special advantage of this process by modifying their structure to house the bacteria in their own tissues. Other denitrifying bacteria metabolize in the reverse direction, turning nitrates into nitrogen gas or nitrous oxide. When colonies of these bacteria occur on croplands, they may deplete the soil nutrients, and make it difficult for crops to grow.

Bacteria are also used in sewage treatment facilities. Solid matter, after having been separated from liquid wastes by screens and shredders, are added to a group of anaerobic prokaryotes. These bacteria decompose the material, converting it to material that can be used as landfill or fertilizer in landfarming. Additional bacteria to remove the balance of organic matter are then used to treat the remaining wastewater separately, and the resulting outflow (effluent) is then finally released into a river or ocean. If bacteria did not remove the organic matter, the water containing the phosphates and nitrates would pollute the river where the treated water is returned. Too much phosphates and nitrates would allow for rapid reproduction of blue-green bacteria and algae in the water; where they would bloom, pollute the water, and destroy other life.

Bacteria are also used in solving environmental problems because of their selective capability to consume and degrade almost any compound. For instance, certain cultured bacteria are now being sprayed on oil spills and petroleum drilling lagoons, where they rapidly multiply and break down the oil molecules into less toxic compounds. In a similar way, bacteria can also clean up old mines. The water from old mines is filled with highly acidic heavy metals that are highly toxic and expensive to clean up. However, there is an increasing use of bacteria, especially a genus called Thiobacillus, which thrives in acidic water. These microbes can extract copper from the water, and other valuable metals, utilizing oxidize-sulfur to accumulate and extract the metals. These are just two examples of the ways that bacteria can be practically used to solve environmental problems, and over-time many more applications will be developed through selective breeding and mixed production of various bacteria cultures.