A team of scientists has accidentally developed an enzyme that breaks down plastic bottles and enable the full recycling of these bottles for the first time, a report in The Guardian said.

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Scientists have created a mutant enzyme that breaks down plastic drinks bottles – by accident. The breakthrough could help solve the global plastic pollution crisis by enabling for the first time the full recycling of bottles.

The new research was spurred by the discovery in 2016 of the first bacterium that had naturally evolved to eat plastic, at a waste dump in Japan. Scientists have now revealed the detailed structure of the crucial enzyme produced by the bug.

The international team then tweaked the enzyme to see how it had evolved, but tests showed they had inadvertently made the molecule even better at breaking down the PET (polyethylene terephthalate) plastic used for soft drink bottles. “What actually turned out was we improved the enzyme, which was a bit of a shock,” said Prof John McGeehan, at the University of Portsmouth, UK, who led the research. “It’s great and a real finding.”

The mutant enzyme takes a few days to start breaking down the plastic – far faster than the centuries it takes in the oceans. But the researchers are optimistic this can be speeded up even further and become a viable large-scale process.

Industrial enzymes are widely used in, for example, washing powders and biofuel production,

India's plastic problem:

The development is good news for India, where usage of plastic products is rampant, despite a ban in 25 states an union territories. The problem is lax implementation, and plastic–which takes hundreds of years to decompose–continues to be used, according to a report in IndiaSpend.

In Jammu and Kashmir, many vendors have not heard of the three-month-old ban. In Karnataka and Punjab, where a ban is in place since 2016, it remains ineffective in most parts, as there is widespread availability of and demand for polythene bags. In Arunachal Pradesh and Uttar Pradesh, there is confusion about permissible grades of polythene. In Uttarakhand, the use is “gradually fading out”, experts said, while in Rajasthan, awareness campaigns seem to be paying off.

Jammu & Kashmir and Maharashtra became the latest states to ban the use of polythene carry bags–in January and March 2018, respectively.

Using a plastic bag can attract fines–from Rs 500 to Rs 25,000– and storage and distribution can lead to imprisonment up to five years.

Every day, Indian cities generate 15,000 tonnes of plastic waste–enough to fill 1,500 trucks, at 10 tonnes per truck–of which 9,000 tonnes are collected and processed/recycled, while the remaining 6,000 tonnes, or 600 truckloads, usually litter drains, streets or are dumped in landfills, according to a January 2015 assessment report of the Central Pollution Control Board (CPCB).

About 66% of plastic waste is mixed waste–polybags and pouches used to pack food, mainly from residential localities, the CPCB report said.

India generates 5.6 million tonnes of plastic waste annually, and the country accounts for 60% of plastic waste dumped into the world’s oceans every year, estimates suggest.

Three of the world’s ten rivers which carry 90% of plastic to the world’s oceans are in India–the Indus, the Ganga and the Brahmaputra, according to an October 2017 article in Environmental Science & Technology, a global journal.

First Published:Apr 18, 2018 12:42 PM IST