Nature

Bioremediation: Nature’s Hazmat Crews

October 15, 2015 | Sarah Tse

Workers contribute to the clean-up effort following the Rena Oil Spill
Photo credit: New Zealand Defense Force

While humans seem hardwired to create pollution, some species of plants, fungi, and bacteria are naturally inclined to clean up the hazardous waste we leave lying around everywhere.

In the last few centuries, we’ve managed to pump the earth full of a lot of dangerous chemicals. Unfortunately, some of these incidents of contamination are a lost cause and their harmful impact on the environment cannot be mitigated. But nature has a remarkable ability to heal itself, and scientists have discovered certain organisms that can alleviate the effects of our rampant abuse of the environment.

SEE ALSO: 3D Printed Fish Eat Toxins in Polluted Water

This technique is called bioremediation, as it harnesses the built-in ability of a biological system to remove or neutralize pollutants. Bioremediation treatments are usually inexpensive and simple to implement, compared to our own bumbling attempts at excavating and removing the hazardous materials — which can sometimes exacerbate the situation and cause even more injury to the environment.* Just by performing their routine metabolic processes, many organisms can eliminate pollutants by degrading, transforming, or absorbing them from their surroundings.

Plants Imbibe on Explosives

It may come as a surprise to people who see plants as little more than passive ornaments, but they can be very effective at cleaning up contamination. Plants like mustard, hemp, and pigweed can take up huge amounts of heavy metals from the soil. Just a few harvest cycles can significantly rejuvenate soil so that it can sustain other, more valuable crops.

One recent innovation in plant-based, or phytoremediation, addresses a problem that has largely slipped the minds of the general public: TNT or trinitrotoluene. Past conflicts have left behind trace amounts of TNT that never exploded. These tiny amounts are extremely difficult and expensive to remove, but they can have a significant health impact on all organisms in the area.

To combat the issue, a team of plant geneticists from the U.K. discovered a mutation in an Arabidopsis plant that enables it to imbibe TNT into its cell walls. By knocking out the gene using traditional breeding methods, they were able to boost the plant’s ability to sequester the TNT out of harm’s way. The gene can be found in all sorts of plants besides Arabidopsis, so this technique can even turn wild grasses and weeds into TNT-slaying machines.

Mushrooms Break Down Oil Spills

Mycoremediation, which uses fungi species, is just as useful. Mushrooms are natural composters, and they can even work their magic on diesel and other organic pollutants. Oil spills are one of the disastrous repercussions from our dependence on fossil fuels — think of those heartbreaking images of baby birds suffocating in a coat of black oil.

When a cargo ship spilled 58,000 gallons of fuel along the San Francisco shoreline in 2007, environmentalists experimented with oyster mushrooms to clean up the mess. They first soaked up the oil using densely woven mats of hair that was generously donated from salons. Then they planted oyster mushrooms onto the mats, and after a few months the oily waste had transformed into harmless compost.

Bacteria Can Do... Pretty Much Anything

And let’s not forget about the unsung heroes of the biosphere: microbes. No other life-forms on this planet could exist without the vast diversity and productivity of bacteria, and scientists are still uncovering new tricks hidden up their diminutive sleeves. In addition to everything else they do for us, bacteria are magnificent garbage-men.

Like fungi, certain types of naturally-occurring bacteria can help with cleaning up oil spills, even without any human intervention or genetic engineering to boost their abilities. The Deepwater Horizon Oil spill of 2010 provided an opportunity to study these ocean microbes in action. They found that the community of microbes acted almost like an army, sending in waves of different species to tackle the changing levels of pollution. The initial response consisted of bacteria able to digest lighter oil molecules, and then tougher troops of bacteria that can devour larger and heavier oil compounds swooped in.

The most hardcore bacteria can even neutralize threats from highly hazardous materials — especially if the bacteria are souped up with additional nutrients and minerals. If fortified with carbon, microbes can dramatically reduce contamination by the pesticide called atrazine. Adding aluminum, copper, and potassium helps them filter out waste to make water suitable for human consumption. Not even radioactive waste is safe from these diligent microorganisms. Bacteria that like salt, called halophiles, produce proteins that are exceptionally good at mopping up the radioactive cesium and strontium ions released from the Fukushima nuclear disaster.

There’s still so much bioremedial potential yet to be found among all the different species of plants, fungi, and especially bacteria. Hopefully we can get our act together and stop contaminating the environment, but in the meantime nature has been charitable enough to give us a hand in cleaning up our messes.

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