The biotechnology of dealing with microplastics—tiny plastic particles less than 5mm in size—is an emerging and rapidly developing field. It focuses on biological solutions to detect, degrade, and prevent the accumulation of microplastics in the environment.
For well over 30 years now we have been generating PET plastic and disposing of most of it in landfill sites. Much of that PET is used in single-use food and cosmetics packaging. There has been recycling of PET but clearly not enough to remove an increasingly difficult packaging material from the environment. We have seen PET plastic breaking into these small particles – microplastics (microparticles). These microplastic particles pose a significant physical and toxicological risk to all animals and to the wider environment. So much so they can find there into our bloodstream when we inadvertently ingest these materials.
1. Microbial Biodegradation
Concept: Use of microorganisms (bacteria and fungi) that can digest plastic polymers into simpler, harmless compounds.
Key Microbes:
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Ideonella sakaiensis: Can degrade PET (polyethylene terephthalate) by producing two enzymes—PETase and MHETase.
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Pseudomonas spp.: Known for breaking down polyurethane and other plastics.
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Aspergillus and Penicillium fungi: Capable of degrading plastics like polyethylene and PVC under specific conditions.
Applications:
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Bioreactors or biofilters in wastewater treatment plants.
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Inoculation of contaminated soils or marine areas.
2. Enzymatic Degradation
Concept: Use of purified enzymes from microbes to break down plastic polymers directly.
Examples:
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PETase and MHETase: Degrade PET into its monomers (terephthalic acid and ethylene glycol). These are substrate specific enzymes.
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Laccases and peroxidases: Oxidative enzymes that can act on plastic surface bonds.
Advancements:
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Protein engineering (e.g., directed evolution) is being used to enhance enzyme activity, stability, and specificity. PETases are manufactured by mutants of the bacteria which are generated largely by computational strategies. These PETases have better thermostability and improved degrading activity.
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Immobilization techniques are being explored to reuse enzymes efficiently in industrial processes. One aspect has been to focus on nanoparticles/nanoflowers. A recent study (Su & Goddard, 2025) has modified PETase with an SBP and linker proteins before immobilization to silica. This protein system was expressed in a recombinant E.coli system before linking to silica. This immobilized enzyme system was effective at destroying PET.
3. Synthetic Biology and Metabolic Engineering
Concept: Genetically engineer microbes or enzymes for optimized plastic degradation and valorization (converting waste into valuable products).
Example Approaches:
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Engineering bacteria to metabolize plastic-derived compounds into bioplastics (like PHAs).
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Designing microbial consortia with complementary enzymatic toolkits.
4. Algae and Photosynthetic Organisms
Emerging research is exploring algae (like cyanobacteria or green algae) engineered to:
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Secrete enzymes that degrade plastics.
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Absorb or encapsulate microplastics in water treatment processes.
5. Bioflocculation and Biosorption
Bioflocculation: Use of microbial byproducts (e.g., extracellular polymeric substances) to aggregate microplastics for easier removal from water.
Biosorption: Microbes or biofilms can adsorb microplastics onto their surfaces, concentrating them for mechanical removal.
6. Bioplastics and Circular Design
Although more preventative than remedial, biotechnology is also used to:
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Develop biodegradable plastics (like PLA, PHA) that do not form harmful microplastics.
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Engineer plastic-producing microbes for sustainable materials.
Challenges and Limitations
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Efficiency: Natural biodegradation is slow; improving it without releasing toxins is key.
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Environmental Safety: Genetically modified organisms (GMOs) must be safely contained.
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Scalability: Lab results don’t always translate to large-scale or real-world conditions.
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Detection: Biotech tools for identifying and quantifying microplastics in complex environments are still developing.
Future Directions
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CRISPR-based synthetic biology for tailored plastic-degrading microbes.
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Enzyme cocktails to tackle mixed plastic waste.
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In situ bioremediation approaches using engineered ecosystems.
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Integration with AI and nanotech for microplastic detection and degradation.
References
Su, S., Goddard, J.M. (2025) Silica Immobilized PETase for Microplastic Bioremediation. IFT 2025 Posters (Biotechnology Division) IFT First Chicago. USA.
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