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Bacteria: The Ultimate Environmentalist

Because of their reputation for causing illness, bacteria are not often viewed in a positive light. Most of us actively try to destroy any and all traces using antibacterial sprays, wipes, and soaps.

But these single-cell organisms are found nearly everywhere on Earth, living in colonies of millions of cells. For instance, in one gram of soil, there are an estimated 40 million bacteria cells. In one millimeter of freshwater, there are about one million cells. And inside our bodies, there are trillions of bacteria cells.

Scientists have found uses for them in a number of different areas, from medical diagnostics, to arsenic detection, to wastewater treatment. But their uncanny ability to break down tough material makes them ideal for pollution abatement.

This talent comes from the chemicals they produce called enzymes. Bacteria need to eat nutrients to produce energy. But when they encounter a material that is too complex to digest on their own, their enzymes speed up chemical reactions and break down the material into simple compounds that the bacteria can then consume.

Different strains of bacteria produce different enzymes and some of these can break down the most complex and hazardous materials.

In 2016, Japanese scientists found a strain of bacteria in a waste dump that had naturally evolved to eat one of the world’s most used plastics — polyethylene terephthalate, also known as PET or polyester. This type of plastic is used to make water bottles.

About 30 million tons of it is produced each year, and around 30 to 50 percent is recycled.

Discarded items made of PET can sit in landfills and oceans for hundreds of years before decomposing. This is due to the natural resilience of the material which is made up of molecules that are bonded together very strongly.

The recently discovered species of bacteria are the first organisms able to break apart the molecular bonds and decompose it.

Though, this doesn’t happen overnight. In six weeks, they can completely degrade low-quality plastic, but it takes longer for them to degrade the tougher PET.

Luckily, scientists accidentally sped up the enzyme that eats PET — PETase — when trying to determine how it evolved. Their modified enzyme is 20 percent better than the original and begins breaking down PET in just a few days. They believe they can make it work even faster with more tweaks.,

This past March, scientists discovered another bacteria strain that degrades a type of plastic that is hard to recycle. This time, in another site covered in plastic waste, the bacteria were eating polyurethane.

Polyurethane has a complicated molecular structure, which is why it is extremely durable and hard to break down. It’s used in a variety of industries, from construction, to clothing, to automotive.

As it gradually degrades in landfills, it releases toxic chemicals that usually kill bacteria. But this species of bacteria is known for its ability to withstand harsh environments and it was found to be able to rely solely on polyurethane for its food and energy source.

In the future, bacteria may be used to help us tackle the overwhelming amount of plastic waste piling up on our land and in our oceans. But we are still a long way from that happening. Some scientists estimate that we may have another decade before bacteria can consume large amounts of plastic.

Oil, on the other hand, is a different story.

After the 2010 BP oil spill in the Gulf of Mexico, bacteria ate a large majority of the natural gas and oil trapped beneath the water — around 200,000 tons — in just a few months.

Crude oil contains as much as 1,000 different types of chemical compounds. Some are more difficult than others to degrade, like hydrocarbons.

By looking at the bacteria’s genes, researchers not only identified enzymes that could eat hydrocarbons, but that the different strains of bacteria worked together to eat the various chemicals more efficiently.

With the constant mixing of the ocean currents to enhance their activity, millions of barrels of oil were turned into an estimated 100 sextillion bacteria cells.

But bacteria aren’t able to clean up everything left behind after an oil spill. They are unable to eat compounds that are too large or even smaller molecules if there aren’t enough nutrients present.

Scientists are looking for ways to work in conjunction with the bacteria naturally present in oceans for future oil spills. One way they identified is by ensuring the dispersants they use to break up the oil don’t hinder or kill the bacteria.

More recently, scientists have been investigating how bacteria may help with another hazardous substance — nuclear waste.

Because of its radioactivity, disposing of nuclear waste is extremely challenging.

It is often stored underground, encased in concrete. This leads to a high pH or alkaline environment that causes certain chemical reactions.

One such reaction is the degradation of cellulose into isosaccharinic acid or ISA. Once created, ISA can bond with the radionuclides present, which are unstable and radioactive. If they bond, the radionuclides become more soluble and able to leak out of the storage container and into the environment.

But scientists have discovered certain bacteria they call “extremophiles” that can live in this high pH environment. They can use ISA as a food source and degrade it, which keeps the radionuclides in their solid form so they can’t escape.

During the many thousands of years that nuclear waste remains buried underground, this bacteria could provide another layer of protection for the environment and our health.

 

This article was originally published by Ashleen Knutsen, Medium.com

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