Approximately 400 million tons of plastic are produced worldwide each year1. Despite recycling and waste management efforts, a large percentage is inertly stored in landfill or becomes unregulated waste escaping into our ecosystems, where it could remain for centuries.
While the concept of plastics dates back to the early 20th century, their widespread use surged in the 1950s – 1970s. Post-World War II, plastics became central to consumer goods due to their versatility, affordability, and durability. However, this rapid adoption has also led to serious concerns about the environmental impact, as the durability of plastics translates into long-lasting waste in landfills and oceans. Efforts to address these challenges continue to evolve.
Man-made (plastic) polymers differ from ones found in nature because the microbial enzymes that are able to break down natural things have not yet evolved for plastics. Plastics defy the biodegrading process and simply disintegrate into smaller bits to the point of infesting everything at a microscopic level. Also, the heat, akin to environments where the plastics pile up, is deadly to our microbial friends.
Enzyme
Proteins that speed up biochemical reactions. Enzymes create new products. The target substance goes through a chemical reaction and changes into a new molecule called the product.
Amazingly, there is new evidence that some friendly microbes are not lost to the much-needed biodegrading process of plastics. In 2021, researchers in Japan discovered a bacterial enzyme that is able to digest one common type of plastic (PETs). Coincidentally, there was a nearby discovery of a thermostable enzyme (surviving in higher temperatures). With those two attributes, bioengineers got busy combining the most promising enzymatic genes to create super enzymes, “plastivors” so to speak, that are both efficient and also resilient in typical compost temperatures.
The following TED-Ed video explains the challenges and exciting potential of these organisms.
It is worth noting that advancements in plastic biodegradability include the development of new materials that break down more quickly and safely. Nevertheless, let’s keep our eyes on the evolution and development of these little “plastivors” that may well be the heroes to our legacy plastic problem.
References:
1 UN Environment Programme: https://www.unep.org/interactives/beat-plastic-pollution/
Paper as published in Science Direct: Ideonella sakaiensis, PETase, and MHETase: From identification of microbial PET degradation to enzyme characterization
Authors: Shosuke Yoshida, Kazumi Hiraga, Ikuo Taniguchi, Kohei Oda
https://www.sciencedirect.com/science/article/abs/pii/S0076687920303736
Paper as published in Science Direct: Cutinase fused with C-terminal residues of α-synuclein improves polyethylene terephthalate degradation by enhancing the substrate binding
Authors: Lankai Su, Kun Chen, Shu Bai, Linling Yu, Yan Sun a b c
https://www.sciencedirect.com/science/article/abs/pii/S1369703X22003783