Can Enzymes Revolutionize Plastic Recycling? Exploring Biodegradation

[00:00:00]A portion of this video is  brought to you by Surfshark.

[00:00:02]The vast majority of the world’s  plastic isn’t recycled … and when it is, we spend more money to achieve less quality.  It’s currently cheaper to keep producing newer plastics — at the much higher cost  of human and environmental health.

[00:00:13]But nature has evolved in response. Several  species of insects, bacteria, and fungi can break down plastics all on their own. By studying  the enzymes that make this happen, bioengineers are realizing ways to degrade plastics that don't  involve burning them or dousing them in chemical solvents. Going from taking weeks to break down  plastics in early research to just hours recently.

[00:00:34]And the momentum is building. One company has  successfully developed an enzyme that doesn’t need industrial conditions to work, allowing  consumers to add bioplastics to compost piles at home. We’re already living in a future where it’s  possible to bury a yogurt cup with confidence, knowing it’ll disintegrate the same  way the food scraps will. That’s a big difference from rinsing it out, tossing  it into a bin, and hoping for the best.

[00:00:56]How did researchers get us here? And does this  mean we can have our plastics and eat them, too?

[00:01:00]I’m Matt Ferrell … welcome to Undecided.

[00:01:06]Well, we already know we’re eating our  plastics — and by “we” I mean the entire planet. There’s no doubt about it: the  accumulation of plastic in our water, air, and soil is an exponentially growing problem  with consequences that we aren’t even fully aware of yet. In a previous video I broke down why the  current plastic recycling process isn’t really a recycling process at all. It’s not practical  or profitable, and the numbers don’t lie: A 2017 study estimates that only 9% of all  the plastics humanity has ever created have been recycled. Meanwhile, 80% is either leaching  toxins in a landfill or out disrupting ecosystems.

[00:01:43]And with plastic appearing virtually  everywhere, right down to our own organs, there’s mounting evidence that we really are  what we eat. However, humans and animals aren’t the only organisms that consume plastic…one way  or another. And this can be exploited for good.

[00:01:57]With some species of insects, algae, fungi,  and bacteria as inspiration, scientists have genetically engineered approaches to biorecycling  and biodegradation that could someday be more viable than current recycling practices…like  bioplastic that disappears into dirt.

[00:02:13]Hold that thought, though. How did we ever  come to that? It turns out nature might have been giving us hints all along. So, to  explain how bioengineering has come this far, let’s work from the ground up. Scientists  have actually been identifying species of microbes capable of digesting plastic  as early as the ‘90s. Observations of several species of algae have revealed  their capacity to live on the surfaces of multiple types of plastics and  partially degrade them. We also know of at least 28 species of fungi that can feed  on plastics as sources of carbon or energy.

[00:02:43]It’s grub for grubs, too. The larval forms of  beetles and moths, like mealworms, waxworms, and superworms, don’t seem to mind munching  on polyethylene, or PE. That’s a promising adaptation considering that of the 400 million  tons of plastics churned out each year, PE makes up the most of it. That’s stuff like shopping bags  … the ones you always see “drifting in the wind” or “blowing down a highway alone.” Worms aren’t picky eaters, either. In a 2018  study, researchers from Stanford University and the University of Oklahoma found that baby  beetles could eat both PE and mixtures of PE and polystyrene, or PS. PS is the foam-y kind: Think  egg cartons, meat packaging, and insulation.

[00:03:26]During a 2022 experiment, a team of researchers  from the University of Queensland in Australia noticed that superworms can not only bore right  through PS, but continue to function on an all-PS diet. That wasn’t great for their health — for  us, it would be kind of like living off nothing but potato chips as a kid. Still, they did make  it to adulthood alongside their bran-fed peers.

[00:03:47]Bugs’ stomachs are so big on plastics  because they’re full of secrets. Sure, worms chew their food, but it’s  the chemical, not mechanical, action that really counts. The true stars  of the show are the bacteria inside the insects’ gut biomes, which enable them  to fully digest plastics. And it’s one bacterium in particular that’s kicked off  a global rush to scout for similar species to use as genetic muses. You could say it’s  the world’s most microscopic casting call.

[00:04:14]And what better place to hunt for plastic-eating  bacteria than at a plastics recycling center?

[00:04:18]That’s where researchers from the  Kyoto Institute of Technology and Keio University unearthed the bacterial  breakout talent that started it all: in the sludge surrounding a bottle  recycling site in Sakai, Japan.

[00:04:30]The significance of this needs a little  more context. According to a 2019 report by Plastics Europe, 40% of the global  demand for plastics is for packaging.

[00:04:39]Products like single-serving drinks, peanut  butter, and detergent are typically packaged in containers made of polyethylene  terephthalate, or PET. Among the many branches of the plastic tree, PET is the  most abundant within the polyester group.

[00:04:52]On top of this, the majority of PET is  crystalline. This makes it notoriously “recalcitrant” — AKA just plain stubborn … like  a typical 3 year old — so it’s much harder to degrade. The chemical recycling that does work  is more expensive than creating new plastic from scratch, and mechanical recycling reduces PET’s  value. As a result, PET is the most recycled of its plastic peers in the U.S., but only 31%  of it. The European Union recycles about half.

[00:05:19]When it comes to plastic bottles specifically,  only about 14% are recycled around the world.

[00:05:24]If only we had a flagellate hero to save the  day. But what’s that on the ground? Is it a worm?

[00:05:29]Is it a fungus? No — it’s Ideo-nella  sakaie-nsis. With the power of two enzymes…and friendship…a community of  bacteria can break down a thin film of PET.

[00:05:38]The 2016 discovery of this very hungry  bacterium was a cause for excitement, hope, and inspiration. But every superhero  has a weakness, and in this case, it would be that I. sakainesis does  its thing only when they’re held at a consistent temperature of 30 C (or 86 F).  The process also takes six weeks, and that’s too slow for an industrial scale. Plus, the germ  has its own Kryptonite. Its weapons of choice, the enzymes PETase and MHETase, are no match  against crystalline PET, the most common kind.

[00:06:08]We can do better than that though, right? When  your weapons aren’t good enough, you upgrade them.

[00:06:12]Before we get to that upgrade, I’d like to  thank Surfshark for sponsoring this portion of today's video. I always recommend using  a VPN when using public Wifi, but VPNs can be very useful even when you’re home. A lot of  online services use some pretty sophisticated commercial tracking and machine learning to apply  very targeted advertising... a VPN can protect you from some of that. SurfShark’s CleanWeb does  a great job blocking ads, trackers, and malicious websites making it safer to use the internet even  at home. And you can even make it look like your IP address is coming from a completely different  country. This can come in handy if you want to stream a video that’s only available from a  specific location. One of the best parts of SurfShark is that it’s easy to set up on all your  devices, whether that’s iPhone or Android, Mac or PC. SurfShark is the only VPN to offer one account  to use with an unlimited number of devices. Use my code to get 83% off plus 3 extra months for free.  SurfShark offers a 30-day money-back guarantee, so there’s no risk to try it out for yourself.  Link is in the description below. Thanks to Surfshark and to all of you for supporting  the channel. So, back to the weapon upgrade.

[00:07:11]Smart enzymes get spliced at the lab. And  spliced they were. Multiple times. In fact, it was a double-mutant of PETase that took  center stage in 2018 when an international collaboration of researchers accidentally  engineered it to perform better than the original. The sequel to PETase  works 20% faster. More crucially, it can gobble up PET with a crystallinity of  roughly 15%. That’s about the same crystallinity you see in the bottles you get out of vending  machines. For comparison, the natural PETase studied by the Japanese research team involved  PET films with a crystallinity of about 1.9%.

[00:07:46]As an added bonus, this new and improved PETase  can also degrade an up-and-coming bioplastic derived from sugar, polyethylene furanoate (or  PEF). But members of the research team, led by the University of Portsmouth in England and the US  Department of Energy's National Renewable Energy Laboratory (NREL), didn’t want to stop there. They  knew they could go further, concluding that while their results were encouraging, “the performance  would need to be enhanced substantially.” How do you double-time a double-mutant? Where do  you find clues on how to push past an enzyme’s limits? Have you tried the pile of leaves in the  backyard? Because those are the humble origins of the next breakthrough. Plants have cuticles,  too, and just like our own, they’re protective surfaces. The building blocks of this leafy skin  are the all-natural twin polymers cutin and cutan.

[00:08:30]The story goes that scientists identified  leaf and branch compost cutinase, or LCC, within DNA sampled from a compost heap. As you  might expect from its name, cutinase can break up cutin, and in 2012, scientists found that  it could also snap PET like twigs. The problem is that like a lot of enzymes (and people),  LCC doesn’t work well in high heat, and the target temperature for industrial recycling of  PET is about 75 C, or 167 F. So, LCC hung out behind the curtain as an understudy for a while.  I guess you could say it was a little too “green.” But now the pressure to evolve is on, and  researchers are leaving no stone unturned.

[00:09:07]In 2020, French researchers from the  University of Toulouse examined the reaction rates of bacterial enzyme mutations,  using LCC as one of its springboards. After studying over 200 variants, the team finally  optimized the fastest iteration of PETase yet, clocking in a minimum 90% degradation over a  mere 10 hours. And it’s not just efficient — it works comfortably at 72 C. This version of  PETase also yields a lot of terephthalate, or TPA, which can then be reprocessed into PET  that’s good as new. Emphasis on “good as new”: this means that the enzyme can produce recycled  plastic with the same properties as factory-fresh.

[00:09:45]The plot thickened a few months later,  when researchers from the University of Portsmouth and NREL collaboration declared  that they had done it again. By combining the capacities of PETase and MHETase the same  way Ideo-nella sakaie-nsis does in nature, they boosted the speed of their 2018  mutation of PETase six times over.

[00:10:03]More recently, researchers from the University  of Texas at Austin threw their hat into the ring with yet another PETase that they call  “functional, active, stable and tolerant,” or FAST. With five mutations under its belt,  FAST-PETase stands out from the crowd with its range. It can work between 30 and 50 C and  can officially degrade 51 different PET-based products in a week. In some cases, it only needs  hours or days. The team has patented the method, and as of April 2022, it’s seeking out  corporate partners for commercialization.

[00:10:35]That brings us back to today, when it  seems that science has a pretty strong grip on biodegrading PET. But whether these  developments are substantial enough to make a dent in plastic waste is still questionable.  Enzymes can require a variety of specialized conditions. Just among the PETases we’ve  covered, each operated under different temperatures. And even if an enzyme can easily  be integrated into industrial conditions, that infrastructure doesn’t exist yet.  When simply making more is so cheap, it’ll probably be harder to break plastic  production habits than the plastics themselves.

[00:11:04]And PET is only one head on the plastic  hydra. We’ve got a dizzying number of other forms to worry about. Something as seemingly  simple as a handful of LEGO, for example, can involve up to at least 12 different plastics,  all of which have been washing up on beaches for decades. The LEGO Group says it wants to work  toward shifting to sustainably sourced plastic by 2030, though. It’s currently prototyping  toy bricks made from recycled PET bottles.

[00:11:28]That's great and all, but world-changing  technologies are difficult to implement at a commercial scale when solving any kind  of problem. The good news is, though there’s no guarantee that enzymatic plastic degradation  will become the norm, a few enzymes have already begun to prove their mettle out in the real  world, with intriguing results. In 2014, the French company Carbios debuted an enzyme with the  ability to degrade 90% of polylactic acid or PLA, a form of bioplastic, within 48 hours. Working  in tandem with its subsidiary Carbiolice, Carbios achieved certification of the  enzyme “Evanesto” as an additive for PLA packaging in 2020. Once incorporated into  PLA products during manufacturing, Evanesto lets you compost anything from mulching film to  coffee pods at room temperature, right at home.

[00:12:13]The company claims that items made of PLA  plastic will biodegrade in 255 days (or less), and because PLA is typically sourced from starches  like corn or sugarcane, you don’t have to worry about any toxins or residue left behind. Its  FAQ page even clarifies that you don’t have to waste water by washing out your yogurt cups  before you throw them onto the compost heap.

[00:12:34]That’s not all. Since September 2021, Carbios  has been in the pilot phase of commercializing its enzymatic PET recycling technology  at a demonstration plant. Last month, the company announced the end of its CE-PET  research project, which it says validated multiple processes at an industrial scale. Carbios  managed to address both plastic and textile PET waste by producing bottles made entirely out  of both. Interestingly, it also substantiated a method of producing white fiber from recycled PET  waste, regardless of the original plastic’s color.

[00:13:05]While not everyone in the plastics and  petrochemical industries is optimistic about enzymatic recycling, Carbios has  received funding from the French State, and the corporations behind several major brands  have also jumped in, including L’Oréal, Nestlé, Pepsi, and Puma. The company plans to establish  its first industrial plant in early 2025.

[00:13:23]No matter who or what is eating plastic, figuring  out how we clean up our mess is complicated. It’s clear that we can look to algae, fungi, plants,  and bacteria for guidance on how to break plastics, but maybe we’re better off viewing them  as examples of how to build plastics. Seaweed, mycelium fungus, and algae all have the  potential to form our go-to materials someday. As ubiquitous as the plastic we’re  familiar with is now, it hasn’t really been around for that long — and maybe it won’t have  to much longer. Definitely some food for thought.

[00:13:51]So do you think enzymes like this are  the key to solving our plastic problem?

[00:13:54]Jump into the comments and let me know. And  be sure to check out my follow up podcast Still TBD where we'll be discussing some  of your feedback. If you liked this video, be sure to check out one of these videos  over here. Thanks to all of my patrons, who get ad free versions of every video, for your  continued support. And welcome to new Supporter+ member Nick Salve. You're helping to reduce my  dependence on YouTube to pay for producing these videos. And thanks to all of you for watching  and commenting. I’ll see you in the next one.