Bioremediation & Oil Spills: Methods of Treatment

Instructor: Angela Hartsock

Angela has taught college Microbiology and has a doctoral degree in Microbiology.

Oil spills are devastating to the environment, learn about how tiny living organisms can help to clean up the oil by a process called bioremediation and how we can pitch in by providing nutrients to the microbial clean up crew in a process called biostimulation.

Disasters of Epic Proportions

It's next to impossible to not be affected by the environmental devastation associated with oil spills. You've probably seen plenty of those pictures of birds covered in oil and dead fish washing up on beaches. Pretty big contrast from the wildlife-rich marine habitats you saw on shows like Planet Earth, isn't it?

When we use the term oil, we're talking about petroleum, a complex mixture of organic hydrocarbons (chemical compounds made up of hydrogen and carbon). These naturally occurring hydrocarbons were formed over really big geologic time scales during the breakdown of buried organic matter (like, no joke, dead dinosaurs!). When confronted with the devastation of an oil spill it's easy to reflexively become anti-oil, but right now our reliance on fossil fuels for energy makes these disasters, while infrequent, still a distinct possibility. Drilling for and transporting these big amounts of oil will eventually result in accidental spills. So, the question really becomes, when we make these messes, what's the best way to clean them up?

Workers attempt to clean up an oil spill.
Clean up of an oil spill

An Army of Microbes

When you think about oil spill clean-up, what pictures come to your mind? Probably things like airplanes spraying oil dispersant chemicals, boats stringing barriers to direct or contain the oil slick, and clean up crews in full body suits trying to save wildlife and manage coastal impacts, right? But in reality, we would have to look much more closely to see the real clean up at work.

And by closer, we'd have to look at the microscopic level. Here we'd see a community of microorganisms, microscopic living things, mostly bacteria, that live in the impacted environment. The growth of some of these bacteria might be inhibited by the oil, some might not be affected at all, and some might actually be thriving. The bacteria that thrive during an oil spill are the ones that can usually be credited with cleaning up a large portion of the spill. So, what exactly are these bacteria doing to help clean up the oil?

Eating Oil

Bacteria look pretty simple but at a metabolic level they're basically whiz-kids. They're able to consume totally normal stuff like sugars, fats, and proteins, but they're also able to metabolize really weird things like organic solvents, pesticides, metals, and petroleum compounds (oil!). When bacteria are able to consume or convert environmental pollutants into harmless by-products, we call this bioremediation. The biological organisms are effectively remedying (remediating) the problem. Bacteria that can consume oil have genes that make proteins that can chop up long hydrocarbons. And since oil has a lot of long hydrocarbons, it makes this bacteria perfect for cleaning it up! These bacteria chop off little pieces of the long hydrocarbons and convert them to benign end products like carbon dioxide and water. For the bacteria, this process provides energy for growth and we benefit from the removal of the oil from the environment.

Problem (not exactly) Solved

If bacteria can eat up spilled oil then why are oil spills such a big problem? Well for starters, the breakdown of oil can be very slow, taking weeks to months. In the long run, the process is useful but in the short term, marine life still suffers. In general, studies have shown that oil-degrading microbes are already present in the environment and flourish during oil spills (since they can eat the oil to support their growth). However, sometimes the growth and oil metabolism of these bacteria is limited by a lack of additional nutrients, things like nitrogen, phosphorous, or oxygen. In this case, bioremediation can be enhanced by adding additional nutrients to the environment, which is called biostimulation.

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