A New Biological and Financial Ecosystem for Plastic

Shaharyar Lakhani published on June 24, 2019:

Plastics have been in popular use for only around 50 years, yet they have managed to saturate the planet. The toxic pollutants in plastics, combined with the long time they take to degrade, have adversely affected land, water, and air pollution. Nearly 300 million tons of plastic are produced every year, with the majority going to waste and ending up in landfills or the ocean. If the current trend continues, by 2050, the total weight of plastic in the ocean will be more than that of fish!

But what if there was a way to turn this plastic into something positive? To have its pervasive presence in the ecosystem actually be a functioning part of that ecosystem? A group of researchers in the Center for Systems and Synthetic Biology at the University of Texas at Austin are working on exactly that: developing microbes that could potentially degrade plastics and convert them to other, useful products. At the heart of these efforts are enzymes released by microbes that would begin the plastics degradation process, converting inedible solids into foodstuffs for these and other bacteria. Hannah Cole, a graduate researcher in the Ellington and Alper labs is improving the stabilities of plastic-degrading enzymes, and is working closely with chemical engineers (Nate Lynd and his group) to study the effects of these enzymes on different plastics (yes, most plastics are as different from one another as are the people who use them!).

Precisely because of the diversity of plastic waste, both in terms of the type of plastic and in how it appears in the environment, parallel efforts for identifying new plastic-degrading bacteria and fungi are being carried out by Dr. Moriah Sandy and a team of undergraduates in the Freshman Research Initiative program. In particular, the team is exploring ways to use these bacteria and fungi to break down nurdles – small pellets of plastic runoff from manufacturers – gathered from the shores of Port Aransas. To cross the “nurdle hurdle” and literally eat away at the plastics problem, the Bioprospecting Stream is carrying out metagenomic analyses of the microbes present in contaminated environments and then carrying out competitions to see which bacteria is the most hungry for a given type of plastic.

Into the future, these researchers envision the development of custom bacteria that are capable of eating one or more plastics, and that can act in packs (or consortia) to eat virtually any plastic product in a landfill. Safety ‘switches’ built into the bacteria will prevent their leaving the landfill. The bacteria themselves can potentially serve as harmless feedstocks for other organisms, or can become part of a new economy in which plastics are converted to other, more biologically friendly materials – a ‘green’ version of the giant refineries of the petroleum industry.

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