Project Description

Project Abstract

Textile waste is an urgent but often hidden part of the plastic pollution crisis. At the heart of the problem is PET, a plastic fiber woven into millions of clothes worldwide and almost impossible to recycle once blended with cotton. Our project explores how engineered enzymes can provide a new solution by breaking down PET so that blended textiles can be reused instead of discarded. Through this approach, we aim to show how synthetic biology can help close the loop in fashion and move toward a sustainable future. Hence, our team worked across Wetlab, Drylab, Human Practice. Together, we achieved the following:

• Successfully completed the molecular cloning and protein extraction/purification of TfCut2 wild type and its 6 variants
• Successfully proved that Variants 3, 4 and 5 exceed the performance of TfCut2 wild type throughout PET film degradation assays at 48 hour in 500 mM HEPES buffer
• Successfully demonstrated that our pretreatment method is capable of decreasing the crystallinity of PET through SEM analysis
• Successfully degraded the cellulose component of blended textiles through DNS assay using CbhA (commercial cellulase)
• Successfully created an AI software interface capable of categorizing various types of textiles

Textile Waste Challenges

The world discards 120 million metric tons of clothes a year, yet only a fraction of disposed textiles are effectively remade into fibers suited for use in new, apparel-grade fabric. Recovering even a quarter of these wasted resources would offset the combined annual materials expenditures of the world’s 30 largest fashion corporations (Nikolina, 2020).

Figure 1: Graphical representation of the amount of textile waste undergoing different types of post-waste treatment (Nebraska Recycling Council, n.d.)

Not only does textile production inflict a considerable strain on resources, textiles, synthetic fabrics like polyester, take decades, even centuries to decompose in landfills. Given that most synthetic fibers like polyester lack biodegradability, the toxic dyes embedded within landfill-disposed clothing are discharged into waterways while textile microfibers, microscopic fibers too miniscule for wastewater treatment filtering, are simultaneously released into bodies of waters, disrupting ecosystems and marine life in its wake (Das et al.,2025). Moreover, the European Union estimates that a single laundry load of polyester clothes discharges up to 700,000 microplastic fibers, posing a significant threat to human health (Circular Taiwan Network, n.d).

As for Taiwan, the Circular Economy Network reports that a decade-high of 78,000 metric tons of used clothing were collected in 2020, and 35% of these garments are incinerated due to a severe lack of available disposal methods (European Parliament, 2020). Evidently, a circular economy model capable of reusing more of that waste would immensely aid the industry by upcycling swaths of waste into novel textiles.

Current Solutions and Disadvantages

Textile waste containing PET can be recycled using mechanical, chemical or enzymatic methods. Companies such as Recover from Spain and Looptworks from USA use mechanical methods, turning textile wastes into yarns and limited run products, where waste garments are shredded and reproduced into fibers. Although the process is relatively fast and widely practiced in industries, this process frequently shortens the polymer chain and degrades the mechanical qualities of the PET (Standring et al., 2025), making it less suitable for complex woven fabrics. Chemical recycling can depolymerize PET into its monomers efficiently and produce high quality PET. However, the process requires harsh solvents, high temperatures, and considerable energy inputs, which limit scalability and raise environmental concerns (Joseph et al., 2024).

In contrast, enzymatic degradation offers a promising biological alternative, especially for cotton-PET blended fabrics, which is the most common textile blend in the market. Although enzymatic recycling methods are more expensive and generally slower, it is substrate-specific. Recent developments in enzyme degradation has shown that PET can be efficiently depolymerized with excellent selectivity using specific enzyme combinations under mild reaction conditions (Soong., 2022). Enzymatic approaches offer fiber selectivity, enabling PET to be hydrolyzed while leaving cotton or elastane fibers intact, which makes them uniquely effective for blended fabrics (Choudhury et al., 2024). Moreover, this method allows recovery of high-purity monomers, terephthalic acid (TPA) and ethylene glycol (EG), which can then be repolymerized into virgin-quality PET (Joseph et al., 2024).

Figure 2: Comparison of different methods of textile recycling

Enzymatic recycling maintains material value and promotes real circularity, in contrast to mechanical systems that struggle with property degradation over multiple cycles (Yang et al., 2023), and is more environmentally friendly compared to chemical recycling. This approach is especially valuable for cotton-PET blended textiles, which pose a major challenge for conventional recycling systems. Through selective depolymerization, enzymatic PET recycling provides an effective and sustainable pathway for recovering high-value recycling of complex textile waste.

Our Solution: Overview

Our project offers a scalable, innovative enzymatic alternative to traditional textile treatment processes. In the short-term, we envision our solution to be packaged as an enzyme kit capable of being distributed across clothing treatment facilities. Once we have finalized the entire streamlined process of degrading blended textiles, we plan to offer our enzymatic solution in the form of a service for corporations/landfill facilities looking to upcycle wasted clothing.

SynBio Approach

Our solution utilizes the degrading capacity of cutinase enzyme from Thermobifida fusca (TfCut2) to break down PET into its monomers. TfCut2 belongs to ⍺/ꞵ hydrolase family and is capable of hydrolyzing ester bonds. In nature, TfCut2 acts on cutin, a waxy polyester polymer found in the aerial surfaces of plants, allowing bacteria or fungi to penetrate plant’s surface (Soong et al., 2022). Previous findings have shown that TfCut2 is able to depolymerise PET films and produce monomeric products including TPA and EG, as well as intermediates mono (2-hydroxyethyl) terephthalate (MHET) (Barth et al., 2015), highlighting its potential in driving enzymatic PET degradation for plastic recycling. Subsequent protein engineering studies established that targeted mutations in cutinases can enhance their stability, substrate binding and catalytic activity (Wei et al., 2016; Liu et al., 2022; Mrigwani et al., 2023).

Building on this foundation, we designed a series of six different TfCut2 variants to further enhance PET degradation efficiency, aiming to improve binding affinity, thermostability, and catalytic efficiency. Toward this goal, we utilized Pymol for protein structure analysis, Chimera for binding affinity results, and a deep learning model Mutcompute for novel mutants designed by computer algorithms. After deriving our six TfCut2 mutants, we conducted molecular cloning purified TfCut2 wild type and variant proteins. To confirm their functionality and activity, we performed pNPB assays at varying conditions as quality control of purified enzymes. Additionally, we evaluated PET hydrolysis through high-throughout screening (HTS) of PET film degradation to optimize TfCut2 digestion conditions for both PET films and textiles.

Figure 3: Visualization of TfCut2 Variants 1, 2, 3, 4, 5 and 6

Our project uniquely tackles the aspect of cotton-PET blends present in a vast majority of clothing and remains difficult to recycle effectively. However, one of the major barriers to PET degradation is its crystalline (arranged in a relatively structured order), as the crystalline regions are notably resistant to enzymatic hydrolysis. To decrease the crystallinity of the textile fibers, we applied an alkaline-thermal pretreatment to disrupt the fibers, making them more enzymatically attackable (Boondaeng et al., 2023). To further enhance PET degradation in cotton-PET blends, we engineered a cellulase triad consisting of CbhA, BhBglA and BsEglS to hydrolyze the cellulose component of blended textiles, leaving PET more exposed for degradation. This approach combines pretreatment with tailored enzymatic degradation strategy, allowing our system to tackle cotton-PET blends effectively and providing a sustainable solution for recycling blended textile while maintaining the integrity of recovered PET (Figure 3).

Additionally, our team engineered a system capable of confirming the success of degradation. Since TfCut2 depolymerizes PET into its monomers, TPA and EG, we designed a TPA reporter system targeted at detecting the presence of TPA in a sample of PET after being treated with TfCut2 as proof of our enzyme’s function (Figure 5).

Figure 4: TPA Reporter System

Integrated Community Engagement and Education

Overview

Our iGEM project recognized that technological advancement on the issue of textile pollution is not enough, requiring education and public awareness to instill real changes. To address this gap in knowledge that was identified through surveys, we developed educational initiatives as well as community based outreach in Dadaocheng, Taiwan's most historically significant place for textile exchange.

Education

Our team developed a multi-level education platform to raise awareness about textile waste. At the elementary level, we introduced sustainability concepts through games, and creative upcycling to help younger students understand the difference between natural and synthetic fibers while empowering them to take action through activities like making tote bags out of t-shirts. For junior high students, we designed workshops that combined group collaboration, critical thinking, and hands-on activity. This included 5R brainstorming that encouraged them to see the real world impact of fast fashion and the potential of synthetic biology solutions. At the high school level, in collaboration with university students, we connected molecular biology concepts to synthetic biology applications through DNA extraction labs, role-play activities, and mentorship discussions, allowing students to envision future academic pathways and careers in synthetic biology fields. Together, these outreach efforts showed how interactive learning, creativity, and mentorship can make complex scientific ideas accessible, while empowering students of all ages to see themselves as part of the solution to plastic and textile pollution.

Dadaocheng

On June 12, 2025, our team organized our largest outreach initiative: a community sustainability event in Dadaocheng, Taipei, in collaboration with Story Wear and Twine. We chose this location for its historic connection to Taiwan’s textile textile trade. The venue symbolized the link between tradition and innovation as we brought scientists, designers, entrepreneurs and the public to address textile waste . Through interactive science booths, creative upcycling workshops, and sustainable fashion showcases, participants learned about the science of enzymatic textile degradation, the health risks of microplastics, and practical ways to reduce textile waste in daily life. The event’s centerpiece was an expert panel featuring leaders from science and public health, who discussed the future of circular fashion and the impact of plastic on human wellbeing. By combining education, creativity, and interdisciplinary dialogue, the Dadaocheng Collaboration transformed synthetic biology into an accessible public conversation and empowered the community to envision a more sustainable future.

Figure 5: Dadaocheng Event