Researchers Identify Plastic-Gobbling Microbes That Like To Eat Our Garbage

Plastic like this can take hundreds of years to degrade. Larina Marina/Shutterstock

You might recall that just last week, divers spotted what looked like a plastic bag and candy wrappers at the bottom of the Mariana Trench, i.e. the very deepest part of the ocean.

At the same time, it was revealed the far-flung Cocos (Keeling) Islands – 2,000 kilometers (1,200 miles) off the Australian coast and only inhabited by a tiny handful of people – have become an accidental garbage patch overrun with plastic waste.

Needless to say, our plastic addiction is reaching crisis point. There are an estimated 100 million tonnes (110 tons) of it in the oceans today and it is thought that by 2050 plastic will outweigh fish.

Fortunately, there may be a solution. A team of international researchers writing in the Journal of Hazardous Materials have found microscopic marine microbes nibbling away at plastic waste, (very slowly) breaking it down.

For the study, the team collected polyethylene and polystyrene waste from two beaches in Chania, Greece. Polyethylene is the most commonly used, found in everything from shampoo bottles to bulletproof vests, while polystyrene is a harder sort that is used in food packaging and electronics.

The trash had already undergone certain natural chemical changes, encouraged by UV radiation and ocean water movement among other things, to turn it more brittle – a process that needs to happen to make it “edible”, at least as far as the tiny plastic-munching microbes are concerned. 

The researchers then dunked the plastic into a tank of saltwater populated with various microbes. Some were species that naturally occur in the sea. Others had been genetically engineered to create stronger biofilms. Five months later, they came back to check the results.

They found that the microbes had changed the chemical composition of the plastic trash, causing it to break down and lose weight. The polythene’s weight was up to 7 percent lower than it had been at the start and the polystyrene did even better, dropping as much as 11 percent of its original weight. The most impressive results came from “acclimated” microbes, i.e. those that had previously been exposed to polyethylene and polystyrene. (As previous research has shown, bacteria is actually evolving to eat our plastic garbage.)

It is certainly not the first time scientists have narrowed in on the power of microbes to speed up the biodegradation process, nor is it likely to fix our plastic crisis in the near future. It's not yet on a scale large enough. But maybe one day it could help offer a solution.

"Engineering the functional potential of natural microbial assemblages that colonize plastic surfaces is a key issue in plastic waste management and in mitigation of plastic debris in the marine environment," the study authors write.

"Closing the gap between the hypothetic and realistic employment of microbial networks for plastic degradation could contribute to the development of mitigation measures and sustainable policies."

In the meantime, it might be a good idea to try to decrease our reliance on plastic – and remember the three "r"s: reduce, reuse, recycle.

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