The bacteria turning waste plastic into painkillers

Earlier this year, an unusual new use for plastic waste made headlines.

A common bacterium has been genetically engineered to eat a molecule derived from plastic and then digest it. produce daily pain medicationparacetamol.

The microbe used by Stephen Wallace, professor of chemical biotechnology at the University of Edinburgh, was Escherichia coli, better known as E. coli.

The rod-shaped bacterium is found in the intestines of humans and animals, and you may be more familiar with it as a nasty bug. it can make us sick.

Professor Wallace chose it automatically because certain non-pathogenic strains of E. coli are widely used in biotechnology and engineering biology labs to test whether something can work.

E. coli is the workhorse of the field, says Professor Wallace, who has also genetically engineered it in the laboratory to turn plastic waste into vanilla flavoring and greasy sewage waste into perfume.

“If you want to prove something is possible through biology, E. coli is the natural first stage,” he says.

The use of the microbe is not limited to just the laboratory. Industrially, vats of genetically engineered E. coli act as living factories, producing a variety of products, from pharmaceuticals such as insulin, vital for treating diabetes, to various chemicals used to produce fuels and solvents.

But how did E. coli become such a mainstay of biotechnology, why is it so useful, and what does the future hold for it?

E. coli's dominance stems from its role as a model organism for understanding general biological principles, says Thomas Silhavy, a professor of molecular biology at Princeton University who has been conducting research with the bacterium for about 50 years and has documented his story.

Other known model organisms include mice, fruit flies, and baker's yeast. Yeast, like E. coli, has also become an invaluable tool in biotechnology, both in laboratory and industrial applications, but it has a more complex cellular structure and a variety of uses.

E. coli was first isolated in 1885 by German pediatrician Theodor Escherich while studying the gut microbes of infants. Fast growing and easy to use, scientists have begun to use it to study the basics of bacterial biology.

Then, in the 1940s, “a fluke” led to great success, says Professor Silhawi.

A non-pathogenic strain of E. coli (K-12) was used to demonstrate that bacteria not only divide, but can also undergo “bacterial sex” where they share and recombine genes to acquire new properties.

It was a landmark discovery, and E. coli became “everyone's favorite organism,” he says.

Because of this, E. coli has played a central role in many other discoveries and milestones in genetics and molecular biology.

It was used to decipher the genetic code, and in the 1970s it became the first genetically engineered organism when foreign DNA was introduced into it, laying the foundation for modern biotechnology.

This also solved the problem with insulin production. Bovine and porcine insulin has been used to treat diabetes, but has caused allergic reactions in some patients.

But in 1978 first synthetic human insulin was produced using E. coli, which was a huge breakthrough.

In 1997, it became one of the first organisms to have its entire genome sequenced, making it easier to understand and manipulate.

Adam Feist, a professor at the University of California, San Diego, who develops microbes for industrial applications, says he appreciates E. coli for its many beneficial properties.

In addition to the extensive knowledge accumulated about its genetics and the tools that make it easier to design, the bacterium grows quickly and predictably on a wide variety of substrates. It's not as fussy as some, it can be frozen and revived without problems, and it's unusually good at storing foreign DNA.

“The more I work with more microorganisms, the more I appreciate how resilient E. coli is,” he says.

Cynthia Collins is a senior director at Ginkgo Bioworks, a company that helps firms develop biotech products and assists them in the industrial use of E. coli.

While the range of organisms available for large-scale production is somewhat broader than it was a few decades ago – when E. coli was often the only choice – it can often still be a “good choice” depending on the product, Dr. Collins says. (Even with the most intensive bioengineering, E. coli cannot produce everything.)

“It's very economical; you can pump out a lot,” she says, noting that if a bacterium produces something toxic to the cells, tolerance can often be created.

However, there are some who wonder whether the dominance of E. coli is preventing us from finding the best biotech solutions to our problems.

Paul Jensen, a microbiologist and engineer at the University of Michigan, studies the bacteria that live in our mouths. He recently analyzed how little studied most other bacteria were compared to E. coli.

His point is that while we're moving forward with increasingly more engineering of E. coli to do wonderful things, there may be other microbes that do those things naturally—and better—but that are being overlooked, and we're missing out because they're not being looked for or studied.

For example, bioprospecting in landfills could find microbes that start eating not just plastic but all kinds of other waste, he says. And there may be bacteria that do things like make cement or rubber that we didn't even know existed. He notes that only the bacteria that live in our mouths are more acid-resistant than E. coli.

“We're so deep into E. coli that we don't study it enough,” he says.

There are several alternatives that people are working on to increase the number of options, including Vibrio natriegens (V. nat), which has begun to gain attention as a potential competitor to E. coli.

V. nat was first isolated from a salt marsh in the US state of Georgia back in the 1960s, but remained largely ignored in culture collections and freezers until the mid-2010s, when it was recognized for its ultra-fast growth rate (twice that of E. coli), which could be a significant industrial advantage.

It also takes up foreign DNA much more efficiently, says Booz Barstow, a biological and environmental engineer at Cornell University who is among those developing the organism and says its capabilities compared to E. coli are like “going from a horse to a car.”

Dr. Barstow's focus on V. nat is to see how microbes will be used to solve big sustainability problems – from producing jet fuel from carbon dioxide and clean electricity to mining rare earth metals. “Simply put, E. coli is not going to get us to either of these visions. V. natriegens can do this,” he says.

This year, his lab launched a company called Forage Evolution, which is working on tools to help researchers create them in the lab.

Professor Feist acknowledges that V. nat does have attractive properties, but the genetic tools needed for widespread use are not yet available and it has yet to prove itself at scale. “E. coli is difficult to replace,” he says.