The global plastics crisis refers to the overwhelming environmental, social, and economic problems caused by the production, use, and disposal of plastics. While plastic has become essential to many areas of modern life, from packaging and medicine to construction and electronics, the way it is made, used, and discarded has created a global problem. Recognizing this crisis, science and industry have looked to address the issue through improved design of plastics (which are reusable or more easily recycled), and developing biodegradable alternatives or new approaches to biodegradation processes.
Factors contributing to the global plastics crisis
The global plastics crisis is driven by three main factors. Firstly, there is still massive and increasing demand for and production of predominantly single-use plastics. Secondly, less than 10% of all plastic produced is recycled, the rest ends up in landfills, incinerators, or the environment. Finally, health and environmental impacts resulting from our heavy reliance on fossil fuels (with associated emissions) for production and degradation of plastics, and increasing concern on environmental leaching of microplastics into the environment and through to the food chain.
Despite decades of messaging and campaigns to promote recycling, the reality is that recycling alone is not able to solve the global plastics crisis. It is compounded by a number of issues:
Low recycling rates - only a small fraction of plastics are recyclable at all
Downcycling - recycled plastic is often of lower quality with more limited uses
Economic barriers - whereby virgin plastic is often cheaper than recycled plastic
Recycling infrastructure gaps - particularly in limited resource settings such as the Global South
How engineered bacteria can help address the global plastics crisis
There are a number of ways microbes and engineered bacteria could be deployed to help address the global plastics crisis. The main focus has been on biodegradation (plastic degradation) and biotransformation (upcycling plastic waste into valuable products) technologies.
a) Biodegradation
Despite the challenging physicochemical properties of plastics, a number of microbes (e.g., microalgae, fungi, as well as some bacterial species) have been identified and characterized for their ability to degrade certain plastics.
Bacteria have, to date, been the most studied biodegradation facilitator, and in particular much focus has been on Ideonella sakaiensis, which has the ability to digest polyethylene terephthalate (PET) plastic. I. sakaiensis carries two hydrolytic enzymes, PET hydrolase (PETase) and MHET hydrolase (MHETase), which are capable of synergistically converting PET into its monomeric building blocks.
This discovery has, through exploiting rational design or directed evolution, enabled genetic engineering approaches to improve plastic biodegradation:
Modify enzymes to increase catalytic rate or to function at higher temperatures (where plastics soften)
Incorporate the genes for PETase/MHETase into more robust bacterial species that replicate faster and/or are more tolerant of industrial conditions
Combine multiple enzymes into one bacterial host to broaden the range of plastic that can be broken down
Leverage naturally occurring mechanisms of biofilm formation and other cell-surface adhesion properties to maximize association of engineered bacteria with plastic surfaces to increase the rate of degradation
b) Biotransformation
Instead of just breaking plastic into useless fragments, engineered bacteria can be deployed to convert plastic monomers into useful materials, such as biofuels, bioplastics (e.g., PHA), and industrial chemicals.
A good exemplification of this approach is through exploitation of engineered Escherichia coli to employ a novel biosynthetic pathway that directly converts terephthalic acid, which is derived from recycled PET, into vanillin. Vanillin is a valuable flavor compound commonly found in the food and cosmetic industries, and it also serves as an important bulk chemical.
Challenges and limitations
The current technologies give validation and hope for a role of engineered bacteria in helping address the global plastics crisis, but there are a number of challenges that remain to be overcome to really see a transformative impact. The most studied bacteria and enzyme systems only break down PET and are not able to handle most other plastics (e.g., polyethylene, polypropylene, PVC). The scale and speed of bacterial degradation is currently no match for industrial recycling processes and the energy costs associated with biodegradation are high (e.g. running, maintaining, and optimizing bioreactors). There also has to be rigorous control and containment to ensure engineered bacteria are safely managed to avoid any ecological or environmental risks.
The future outlook
The groundwork outline here provides a good base from which to further evolve and optimize biodegradation approaches. Enzyme engineering, benefitting from AI modeling, will be able to rapidly identify enzyme variants with improved efficiency or characteristics. There is the promise and opportunity for synthetic biology to inform custom microbial communities that have the ability to digest mixed waste streams. Ultimately it is likely that combination approaches (mechanical and biological recycling) will be needed to make processes economically viable and able to deliver at the required scale.
In short, it is unlikely that engineered bacteria can eliminate the global plastics crisis alone, but they can play a major role in transforming waste management - especially when integrated with other recycling technologies and crucially supported by policy and design changes.
References and suggested reading
Liu X-h, Jin J-l, Sun H-t, et al. (2025) Perspectives on the microorganisms with the potentials of PET-degradation. Front. Microbiol. 16:1541913. doi: 10.3389/fmicb.2025.1541913
Ermis, H. A mini-review on the role of PETase in polyethylene terephthalate degradation. Rev Environ Sci Biotechnol 24, 545–555 (2025). https://doi.org/10.1007/s11157-025-09737-3
Schneier, A., Melaugh, G. & Sadler, J.C. Engineered plastic-associated bacteria for biodegradation and bioremediation. Biotechnol Environ 1, 7 (2024). https://doi.org/10.1186/s44314-024-00007-0
Sadler, J.C. & Wallace, S. Microbial synthesis of vanillin from waste poly(ethylene terephthalate). Green Chemistry, 2021; DOI: 10.1039/D1GC00931A
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