Bacteria get a bad rap. We think about them only when they make us sick. We are always going around with disinfectant sprays, and taking antibiotics in the hopes of exterminating the organisms that make life on Earth possible.
We are not saying we shouldn’t kill bacteria some of the time. Some of them do make us sick and proper attention to food handling practices and prompt and proper use of antibiotics in cases of infection can do wonders for our health. However, the vast majority of bacteria are overwhelmingly beneficial. In fact, move over pooch, human’s best friends are actually bacteria.
Throughout most of our history, our approach to waste disposal has been primitive. We would pour things on the ground or dig a hole and bury them. As the nature of things poured into those holes has changed in the last century, the scope for environmental damage has broadened. A vast array of our pollutants percolate down into groundwater, but things would be much, much worse if bacteria hadn’t been bailing us out.
Bacteria are able to degrade many toxic man-made substances. The reason they are able to do this is sometimes these substances resemble a chemical that bacteria would naturally encounter, for example some large coal tar-like molecules resemble the large complex molecules in wood. Another reason is many pollutants are actually found in nature, just not in the areas and quantities that have been deposited by humans. Oil, after all, comes from the Earth and bacteria can degrade it.
The ability of bacteria to break down a wide variety of materials can be exploited. The use of bacteria to clean up pollution is called bioremediation.
Bioremediation has been used successfully on marine oil spills and on many forms of pollution in land, groundwater and surface water. Often, in a polluted area, bacteria just need a little encouragement. This often means giving them the right food and fertilizers, or modifying their environment in a way that favours growth and activity of certain bacteria. Some compounds such as oil, gasoline, and gasoline additives such as benzene can be degraded by bacteria best when bacteria have enough oxygen. Underground, there is often not enough oxygen available and if oxygen is provided, by bubbling it directly or by adding an oxygen-containing chemical, biodegradation occurs.
Similarly, there are chemicals, such as fluids used in dry cleaning, that degrade best when no oxygen is present. Conditions can be manipulated to eliminate oxygen in the ground where these substances are present to promote biodegradation of these chemicals.
Bioremediation is a technology that is growing as more research is done and more about the capabilities of bacteria is learned. Not all the chemicals we produce are easily degraded by bacteria, but provided with the right conditions, and time, bacteria can make a big dent in the chemicals we release into the environment.
So use that antibacterial spray in your bathroom, but as you do, give silent thanks for the billions of bacterial stewards of the Earth.
Andrew Laursen is an assistant professor in the department of chemistry and biology at Ryerson University and is a member of the environmental applied science and management program in graduate studies. His research is in the area of ecosystem ecology. Sophia Dore is an environmental scientist with Conestoga-Rovers & Associates, an environmental consulting company. Contact Andrew Laursen at firstname.lastname@example.org