Straw, a major global agricultural by-product, represents both a significant waste burden and an untapped sustainable resource. While current utilization methods remain limited, the fashion industry's growing demand for eco-friendly materials creates a compelling opportunity to transform this biomass into high-value textiles. Our project addresses the core challenge of converting rigid, lignin-rich straw into spinnable fibers through innovative bio-design. We developed an enzymatic pretreatment system employing laccase, versatile peroxidase, and LPMO enzymes—displayed on a synthetic yeast consortium—for efficient lignin degradation without hazardous waste. Furthermore, we enhanced fiber strength by integrating cellulose-binding structural proteins inspired by natural materials. This integrated approach not only demonstrates a viable pathway to sustainable fashion but also creates a circular economy model that benefits agricultural communities while addressing environmental pollution.

Straw, the agricultural residue of cereal crops (e.g., maize, rice, wheat, and sugarcane), is an abundant agricultural byproduct rather than a primary harvest. Globally, approximately 5 billion tons of straw are produced annually, with China contributing nearly 900 million tons—a number that continues to grow with increasing agricultural output (Bhatia et al., 2017).

Currently, straw is utilized in five main categories—fertilizer, animal feed, fuel, base material for agricultural (such as mushroom farming), and raw material for industrial products like paper or tableware- a concept collectively termed as the "five-material utilization" (Sun et al., 2022). However, these applications remain limited due to high costs for collection, transportation and processing. Faced with storage difficulties and low returns, farmers often treat straw as a waste burden, resulting in widespread open burning. This practice not only compounds socioeconomic pressure on farmers, but also contributes to atmospheric CO₂ emissions, particulate pollution, and reduced air quality (Bhatia et al., 2017).

Individually, cellulose, hemicellulose, and lignin—straw's three main components—serve as valuable resources: cellulose can be spun into fibers or films for packaging; hemicellulose is used in food additives and biodegradable materials; lignin is turned into biochar or functional coatings. Yet, when bound within the native plant structure, they form a recalcitrant composite often treated as waste. Efficient, fractionated, and targeted valorization is therefore essential to transform straw into high-value feedstock. We believe converting straw into textile fibers represents a particularly promising valorization pathway, as the apparel industry not only represents a large and growing market but also demonstrates increasing willingness to pay premium prices for sustainable materials (Li et al,. 2022).

The performance of cellulose fibers in textiles depends critically on the content of α-cellulose—the highly crystalline, stable form of cellulose that governs strength, crystallinity, and spinnability. Materials such as lyocell—produced from hardwood pulp with high α-cellulose (>92%) (Jiang et al., 2020)—exhibit superior properties, and bamboo fiber has also been commercially spun with similarly high purity. In contrast, straw typically contains lower α-cellulose and more impurities, yielding weaker fibers even after delignification. However, corncob shows significant potential (Lawson et al., 2023); its lower hemicellulose and lignin content enables more efficient removal by alkali or other treatments, theoretically giving higher purity α-cellulose.

The main challenge in converting straw to textile is the sustainable removal of lignin and enhancement of fiber properties. Straw's natural structure—bound by lignin and hemicellulose—is too rigid for spinning. Conventional alkali processing generates hazardous waste and cannot overcome straw's inherent limitations: low α-cellulose and high impurity content, which lead to weak and poorly spinnable fibers. Therefore, an efficient, green pretreatment must not only remove lignin to toughen the fiber, but also strengthen it for textile use.

The main challenge in converting straw to textile is the sustainable removal of lignin and enhancement of fiber properties. Straw’s natural structure—bound by lignin and hemicellulose—is too rigid for spinning. Conventional alkali processing generates hazardous waste and cannot overcome straw’ inherent limitations: low α-cellulose and high impurity content, which lead to weak and poorly spinnable fibers. Therefore, an efficient, green pretreatment must not only remove lignin to toughen the fiber, but also strengthen it for textile use.

To address the limitations of conventional lignin removal methods—such as the high energy consumption and industrial wastewater generation associated with alkali cooking, and the extended processing times required by enzymatic approaches (Jin et al., 2019)—we developed a targeted enzymatic pretreatment system for efficient lignin breakdown and fiber toughening. This multi-enzyme system employs laccase (Lac), versatile peroxidase (VP), and lytic polysaccharide monooxygenase (LPMO) to synergistically degrade lignin. We expressed these enzymes in Pichia pastoris, chosen for its eukaryotic processing ability and high expression yield of fungal and actinobacterial enzymes. Lac oxidizes phenolic lignin units, generating H₂O₂ that VP utilizes to depolymerize lignin (Perna et al., 2020). This synergistic interaction broadens the range of degradable substrates. To further enhance efficiency, LPMO was incorporated to consume small-molecule lignin derivatives and produce H₂O₂, thereby sustaining VP activity. Simultaneously, VP supplies electrons to LPMO, establishing a positive feedback cycle that accelerates lignin breakdown (Ye et al., 2024). Additionally, LPMO degrades various hemicelluloses, further enhancing cellulose purity (Agger et al., 2014). We hope these actions improve cellulose exposure and fiber toughness.

To further improve synergy, we designed a synthetic microbial consortium: Saccharomyces cerevisiae EBY100 was engineered to display a mini-scaffold that co-localizes the three enzymes on the cell surface via dockerin-cohesin interactions. This engineered complex mimics natural cellulosomes, enhancing intermediate transfer and catalytic efficiency through spatial proximity, thereby reducing diffusion losses and increasing lignin degradation rates (Wang et al., 2023). The system also enables gradual polysaccharide degradation, supplying yeast with low-cost sugars and reducing cultivation costs while toughening the straw fibers through efficient lignin removal.

Given the inherently low α-cellulose content in straw-based fibers, reinforcement becomes essential to achieve textile-grade performance. Inspired by the LINKS-China 2021 iGEM team, which enhanced bacterial cellulose using spider silk fibroin, we screened a range of high-performance proteins—including squid beak protein, octopus sucker ring teeth protein, and springtail elastin. We were particularly drawn to the histidine-rich proteins derived from squid beak, which form their rigid structure through natural chitin-binding domains that mediate cross-linking with chitin (Tan et al., 2015). This inspired us to investigate whether replacing the native binding domain with a cellulose-binding module (CBM3) could improve the toughness of straw-based fibers. In parallel, we introduced bagworm silk fibroin, motivated by the larva’s ability to construct sturdy shelters from plant debris. This silk has been reported to exhibit performance superior to spider silk (Yoshioka et al., 2019), making it a promising candidate for fiber reinforcement.

By integrating these CBM3-fused proteins into the straw-derived cellulose matrix, we aim to produce composite fibers with enhanced strength, toughness, and textile applicability. This bio-inspired strategy offers a novel and sustainable route to transform straw into high-value textile materials.

By integrating these CBM3-fused proteins into the straw-derived cellulose matrix, we aim to produce composite fibers with enhanced strength, toughness, and textile applicability. This bio-inspired strategy offers a novel and sustainable route to transform straw into high-value textile materials.

Strawtopia transforms agricultural waste into the next generation of sustainable textiles, bringing the story of the field directly to your wardrobe. By turning straw into high-performance, biodegradable fabric, we offer a scalable circular solution that benefits farmers, reduces environmental impact, and meets the growing demand for eco-friendly materials in the fashion industry.

This innovation not only supports greener manufacturing but also embodies our commitment to returning value to those at the heart of agriculture—empowering farmers. By providing a model of stakeholder-driven bio-design that the iGEM community can build upon. Together, we are reimagining how fields and fashion connect—creating clothing that honors the earth, rewards the grower, and inspires the future.

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