Bacteria capable of eating plastic were an inevitability. The tiny cells are evolutionary dynamos.
Under optimal growing conditions, many bacteria can clone themselves in 20 to 30 minutes, producing 50 to 75 generations and hundreds of millions of new individuals in 24 hours. This incredible rate of reproduction creates ample opportunity for the genetic mutations that drive “standard” evolutionary change. Additionally, bacteria “swap” genes with each other through a form of direct transfer resembling sexual reproduction in higher organisms and by absorbing genetic material other bacteria release into the environment.
Thus, in a period of a few years, there are literally quadrillions of opportunities for bacteria to evolve that can produce enzymes and develop biochemical pathways that allow them to digest any new source of food they might encounter – plastics, for example.
Plastics are made up of long strings of carbon-based chemical compounds that are similar in their essential structure and composition to sugars, life’s basic food stuff. In fact, some plastics are made by stringing sugar molecules together, and those tend to be relatively biodegradable – meaning they can be broken down (digested) by soil or water bacteria.
But most plastics today are made from petroleum and have been synthesized in laboratories during the past century. Their novel chemical makeup is unfamiliar to the planet’s bacterial population, and rather than breaking down in nature, they have piled up. And piled up.
It is said that in 20 years, there will be more plastic bottles than fish in the sea, and more plastic than any other material in our landfills. The ubiquity of plastic waste is nothing short of an environmental disaster – unless you’re an opportunistic species of bacteria. Then it’s a feast waiting to be devoured.
It’s no surprise, then, that in recent years, plastic-eating bacteria have been discovered in diverse environments and locations. In 2011, marine biologists discovered microbes colonizing and eating bits of plastic floating in the Sargasso Sea, the home of one of several oceanic “garbage patches” filled with floating plastic waste.
In 2014, researchers in China found that a species of waxworms, a type of Asian mealworm, a beetle larva, could chew, digest and live entirely on polyethylene plastic bags. Taking their research further, the same team discovered in 2015 that related worms could thrive eating Styrofoam. Digestion is accomplished by bacteria living in the waxworm’s gut.
Then in 2016, Japanese researchers announced they had discovered bacteria eating scraps of the plastic known as PET in the wastewater pond of a plastic bottle recycling plant. One of the most ubiquitous forms of plastic, PET is used to make bottles of all types, blister packs, pens, syringes, ink cartridges, electronic components and, in its “polyester” form, the majority of the world’s synthetic fibers.
On the surface, these discoveries are good news. It appears that we might finally have a solution to the world’s plastic waste problems. All we have to do is cultivate and perhaps “refine” these bacteria with a little genetic engineering and we can sick ’em on our bourgeoning landfills and polluted oceans.
However, like all environmental “solutions,” bacterial waste remediation can be a two-edged sword. For example, the new PET-eating bacteria have slow metabolisms, so they don’t eat much plastic. Speeding their metabolic and reproductive rate through genetic engineering has been proposed. But do we want to create a superorganism that potentially might develop an appetite for our clothing, medical equipment and computers?
Philip S. Wenz, who grew up in Durango and Boulder, lives in Corvallis, Oregon, where he teaches and writes about environmental issues. Email him at email@example.com or visit his website, www.ecotecture.com.