ClassX Video Lessons The smallest solution to one of our biggest problems – Tierney Thys & Christian Sardet
Right now, everything around us is being consumed by tiny organisms we can’t even see. These microbes, which include bacteria, archaea, and fungi, live on every surface and have evolved to produce enzymes that break down tough organic materials into nutrients. However, there’s one material that most microbes can’t break down: plastics.
Plastics are made from molecules derived from oil, gas, and coal. These molecules are transformed into long chains called polymers through a process that involves high temperatures, pressure, and chemical changes. The synthetic polymers in plastics are very different from natural ones, and since plastics have only been around since the 1950s, microbes haven’t had enough time to evolve enzymes to digest them.
Moreover, breaking down the chemical bonds in most plastics requires high temperatures, similar to those used in their production, which are too hot for most microbes to survive. As a result, plastics don’t biodegrade; instead, they break into tiny, indigestible pieces. Common plastics like polyethylene, polypropylene, and polyester-terephthalate have been accumulating for decades. Each year, we produce about 400 million tons of plastic, with 80% becoming waste. Only 10% of this waste is recycled, while 60% is incinerated or sent to landfills, and 30% leaks into the environment, polluting ecosystems for centuries. An estimated 10 million tons of plastic waste end up in the ocean each year, mainly as microplastic fragments that contaminate the food chain.
Fortunately, some microbes might help solve this problem. In 2016, Japanese researchers found a bacterium called Ideonella sakaiensis 201-F6 at a plastic-bottle recycling plant. This bacterium had two enzymes that could slowly break down PET polymers at relatively low temperatures. Researchers isolated the genes for these enzymes, allowing bioengineers to enhance them and create super-enzymes that could degrade PET up to six times faster. Even so, these lab-grown enzymes still took weeks to degrade a thin film of PET and worked best below 40˚C.
Another group of scientists in Japan studied bacterial enzymes adapted to high-temperature environments, like compost piles. In one warm pile of decomposing leaves and branches, they found gene sequences for powerful enzymes called Leaf Branch Compost Cutinases. By using fast-growing microorganisms, researchers genetically engineered large quantities of these enzymes and enhanced variants that could degrade PET plastic in environments up to 70˚C—a temperature that weakens PET polymers and makes them digestible.
With the help of these resilient microorganisms, the future of PET recycling looks promising. However, PET is just one type of plastic. We still need ways to biologically degrade other types, like polyethylene and polypropylene, which only start breaking down at temperatures above 130˚C. Currently, no microbes or enzymes are known to withstand such high temperatures.
For now, the main methods for dealing with these plastics involve energy-intensive physical and chemical processes. Only a small fraction of plastic waste can currently be biologically degraded by microbes. Researchers are actively searching for more heat-tolerant plastic-degrading organisms in extreme environments and engineering better plastic-degrading enzymes in the lab. However, we can’t rely solely on these tiny helpers to clean up our mess. We need to rethink our relationship with plastics, make better use of existing materials, and stop producing more of the same. Additionally, we urgently need to design more environmentally friendly polymers that can be easily broken down by our growing array of plastic-degrading organisms.
Conduct a research project where you explore the latest advancements in microbial enzymes capable of degrading plastics. Present your findings in a detailed report, highlighting the potential of these enzymes in reducing plastic waste.
Analyze the lifecycle of a common plastic product, from production to disposal. Create a visual presentation that outlines each stage and suggests improvements for reducing environmental impact, incorporating insights from microbial degradation research.
Participate in a debate on the feasibility of replacing traditional plastics with biodegradable alternatives. Prepare arguments based on current scientific research and consider the role of microbes in the degradation process.
Organize a field study to collect and analyze microplastic samples from a local water body. Use your findings to discuss the implications of microplastic pollution and the potential role of microbial solutions in mitigating this issue.
Attend or organize a workshop focused on the genetic engineering of enzymes for plastic degradation. Learn about the techniques used to enhance enzyme efficiency and discuss the challenges and opportunities in this field.
At this very moment, almost everything around you is being consumed. Invisible to the naked eye, organisms known as microbes inhabit every surface. Various types of bacteria, archaea, and fungi have evolved to produce powerful enzymes that break down tough organic material into digestible nutrients. However, there is one particularly widespread type of material that almost no microbes can biodegrade: plastics.
To create most plastics, molecules derived from oil, gas, and coal are refined and transformed into long, repeating chains called polymers. This process often requires high temperatures, significant pressure, and various chemical modifications. The resulting synthetic polymers differ greatly from those found in nature. Since plastics have only been around since the 1950s, most microbes have not had sufficient time to evolve enzymes capable of digesting them.
Compounding the issue, breaking most plastics’ chemical bonds requires high temperatures similar to those used in their production, which are lethal to most microbes. Consequently, most plastics do not biologically degrade; instead, they break down into countless tiny, indigestible pieces. The most common plastics, such as polyethylene, polypropylene, and polyester-terephthalate, have been accumulating for decades. Each year, humanity produces approximately 400 million tons of plastic, with 80% discarded as waste. Of that plastic waste, only 10% is recycled, while 60% is incinerated or sent to landfills, and 30% leaks into the environment, polluting natural ecosystems for centuries. An estimated 10 million tons of plastic waste end up in the ocean each year, primarily in the form of microplastic fragments that contaminate the food chain.
Fortunately, there are microbes that may help address this growing issue. In 2016, a team of Japanese researchers sampling sludge at a plastic-bottle recycling plant discovered a previously unidentified bacterium, Ideonella sakaiensis 201-F6. This bacterium contained two enzymes capable of slowly breaking down PET polymers at relatively low temperatures. Researchers isolated the genes responsible for these plastic-digesting enzymes, enabling bioengineers to combine and enhance them, creating super-enzymes that could degrade PET up to six times faster. Even with this enhancement, these lab-grown enzymes still required weeks to degrade a thin film of PET and operated best at temperatures below 40˚C.
Another group of scientists in Japan had been studying bacterial enzymes adapted to high-temperature environments, such as compost piles. Within one particularly warm pile of decomposing leaves and branches, they discovered gene sequences for powerful degrading enzymes known as Leaf Branch Compost Cutinases. By using fast-growing microorganisms, researchers were able to genetically engineer high quantities of these enzymes and enhance special variants that could degrade PET plastic in environments reaching 70˚C—a temperature that can weaken PET polymers and make them digestible.
With the assistance of these and other resilient microorganisms, the future of PET recycling appears promising. However, PET is just one type of plastic. We still need methods to biologically degrade all other types, including abundant polyethylene and polypropylene, which only begin breaking down at temperatures well above 130˚C. Currently, researchers are unaware of any microbes or enzymes capable of withstanding such high temperatures.
For now, the primary methods for dealing with these plastics involve energy-intensive physical and chemical processes. Today, only a small fraction of plastic waste can be biologically degraded by microbes. Researchers are actively searching for more heat-tolerant plastic-degrading organisms in the planet’s most extreme environments and engineering better plastic-degrading enzymes in the lab. However, we cannot rely solely on these tiny helpers to clean up our significant mess. We need to completely rethink our relationship with plastics, make better use of existing materials, and halt the production of more of the same. Additionally, we urgently need to design more environmentally friendly types of polymers that can be easily broken down by our growing array of plastic-degrading organisms.
Microbes – Microscopic organisms, such as bacteria, viruses, and fungi, that play essential roles in various biological processes and ecosystems. – Microbes are crucial for nutrient cycling in ecosystems, breaking down organic matter into simpler compounds.
Plastics – Synthetic materials made from polymers that are widely used but pose environmental challenges due to their persistence and difficulty in degrading. – The accumulation of plastics in marine environments has significant impacts on wildlife and ecosystem health.
Enzymes – Proteins that act as biological catalysts, speeding up chemical reactions in living organisms. – Enzymes are essential for metabolic processes, such as digestion and energy production, in all organisms.
Polymers – Large molecules composed of repeating structural units, which can be natural, like cellulose, or synthetic, like nylon. – Polymers like DNA and proteins are fundamental to the structure and function of living cells.
Biodegrade – The process by which organic substances are broken down by living organisms, typically microbes, into simpler compounds. – Certain types of bioplastics are designed to biodegrade more quickly than traditional plastics, reducing environmental impact.
Environment – The complex of physical, chemical, and biotic factors that surround and affect an organism or ecological community. – Human activities have a profound impact on the environment, influencing climate, biodiversity, and natural resources.
Recycling – The process of converting waste materials into new materials and objects, which helps reduce consumption of fresh raw materials and energy usage. – Recycling plastics can significantly reduce the amount of waste that ends up in landfills and oceans.
Degradation – The breakdown of materials or compounds into simpler forms, often through chemical or biological processes. – The degradation of organic matter by microbes is a key process in nutrient cycling within ecosystems.
Ecosystems – Communities of living organisms interacting with their physical environment, functioning as a unit. – Coral reefs are diverse ecosystems that provide habitat for a wide variety of marine species.
Organisms – Individual living entities that can react to stimuli, reproduce, grow, and maintain homeostasis. – All organisms, from the smallest bacteria to the largest mammals, play a role in their ecosystems.
