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Bioremediation is the process of bacteria or other microbes consuming and breaking down harmful contaminants and returning the environment to a healthier state, for example clearing up pollutants in soil following the closure of a mine. This process can either occur naturally, or it can be kickstarted by scientists. Here in Canada, any bacteria added to the soil must be approved by Environment Canada to ensure anything added to the environment is safe. So how does it work?
Imagine you’ve been out for dinner at a restaurant and had the most delicious soup you’ve ever tasted. You go home and try to recreate the recipe, but you don’t know all the ingredients, so as you taste it you think “oh this needs some salt” and add some in. Then you taste it again a little later and think “their soup was a little bit spicy, so I might pop in some chili powder.”
This is a little like how bioremediation is done. Bacteria in soil have important roles, making sure the right nutrients are present to allow plants to grow, so it is important that all the right bacteria are present in the soil being remediated. Environmental DNA (eDNA) from the affected soil is sampled, and the scientists can identify from the soil sample that DNA from a desirable bacterium is not present, perhaps one that makes the soil less acidic. They can then add this bacterium to the soil, resample a little while later and see if conditions have improved. They may then identify that other beneficial bacteria are still missing, perhaps one to reduce the amount of sulfate in the soil. They can continue tweak the microbe ‘recipe’ until they have the best blend of bacteria in the soil. The end goal is to produce a healthy ecosystem that is self-sustaining on land that has previously been impacted by mining.
Bioremediation isn’t just useful to regenerate land around closed mines, it can also be used to help clean drinking water that has been exposed to contaminants, clear up oil spills in the ocean and ‘eat’ plastics in landfill. Being able to help remediate these problems at the site of the issue is also cheaper and more eco-friendly than either treating the problem at another site, or with chemicals. Utilizing helpful microbes can speed up processes that would otherwise be impossible, or take much, much longer.