Denim jeans, a timeless fashion staple, often undergo treatments like bleaching, fraying, and stain removal to enhance their appearance and functionality. However, traditional methods for these processes—such as chemical bleaching and mechanical fraying—pose significant environmental and health risks, including harmful chemical exposure, water pollution, and excessive resource consumption.
To address these challenges, our iGEM team, “New Jeans” has developed an innovative enzyme-based solution. We use engineered Escherichia coliBL21 to produce four key enzymes: laccase for denim bleaching, cellulase for fraying, lipase for oil stain removal, and catalase to enhance laccase efficiency. This eco-friendly approach reduces reliance on harmful chemicals, minimizes water usage, and offers a customizable solution for consumers seeking personalized denim care.
Our enzyme-based “Jeans Care Kit” allows users to easily bleach, fray, and clean their jeans at home, while also promoting sustainability in the fashion industry by extending the lifespan of denim and reducing waste. Through large-scale enzyme production in factories, our solution can be produced cost-effectively, benefiting both consumers and the environment.
Four key enzymes: laccase for denim bleaching, cellulase for fraying, lipase for oil stain removal, and catalase to enhance laccase efficiency
Denim jeans have been a fashion staple for over a century, evolving from practical workwear to a symbol of style and individuality [1]. Their ability to transcend age, gender, and social class has made them a timeless wardrobe essential. As fashion trends shift, jeans continue to evolve, offering endless possibilities for personalization. Designers constantly experiment with various cuts, washes, and treatments to keep this classic item fresh and relevant [2].
Among the most iconic treatments are bleached and frayed effects.Bleaching lightens the denim to create a faded, lived-in look that enhances the casual, laid-back feel of the garment [4]. Fraying , on the other hand, gives jeans a rugged, worn appearance, often seen as a representation of vintage style and authenticity [5]. This process mimics the natural wear that occurs over time, adding character and uniqueness to each pair.
Beyond aesthetics, functionality has become an increasingly important aspect of modern jeans. Consumers today seek not only style but also practical benefits. One key feature is the ability to remove stubborn stains, such as oil and grease, ensuring that jeans remain clean and durable over time [6]. This treatment enhances the longevity of the jeans, meeting the growing demand for practicality and sustainability in fashion.
There are three main methods for bleaching jeans: chemical treatment, laser treatment, and enzyme treatment. Chemical treatment is the most widely used method, relying on bleaching agents such as potassium permanganate and sodium hypochlorite to effectively lighten denim by breaking down the indigo dye. Laser treatment is a highly efficient and environmentally friendly alternative that allows precise control over the bleaching process without the use of harmful chemicals. However, it comes with high production costs, making it less accessible. Finally, enzyme treatment is a more sustainable option, utilizing biological enzymes like laccase to degrade the dye. Although this method is less damaging to the environment, it is still in the development stage and has not yet been widely adopted in industrial settings [7].
Table 1: Existing Methods for Bleaching Jeans and Their Disadvantages
While chemical bleaching is the most common method, it poses several significant challenges. Sodium hypochlorite and potassium permanganate are the main bleaching agents used today. The effectiveness of sodium hypochlorite depends on factors such as concentration, temperature, and treatment time [8]. However, prolonged exposure to these chemicals can cause skin irritation, damage, and even allergic reactions due to their corrosive properties. Workers handling these substances are at risk of injury, particularly from skin or mucous membrane contact. Additionally, chemical bleaching has severe environmental impacts. The wastewater produced contains residues of sodium hypochlorite or potassium permanganate, which can lead to pollution and pose significant ecotoxicological risks, harming aquatic organisms and ecosystems over time [9].
The main methods for fraying jeans include mechanical abrasion, laser technology, and manual techniques. Mechanical abrasion typically uses pumice stones or sandpaper to wear down the denim. While this method is effective, it can release dust and debris, which harms the environment and damages machinery. Laser technology offers a faster and more precise alternative, allowing for detailed control over fraying patterns, but the high cost of equipment makes it less accessible for widespread use. Manual techniques, such as using blades or scissors, allow for fully customized fraying effects. However, this approach requires skilled labor, is time-consuming, and lacks efficiency for large-scale production [10].
Table 2: Existing Methods for Frayed Jeans and Their Drawbacks
Pumice stone fraying is one of the most widely used methods in mechanical abrasion. Pumice is a porous volcanic rock, lightweight and filled with small holes, which allows it to float in water [11]. In this process, jeans are placed in a machine along with water and pumice stones of various sizes. As the machine rotates, the pumice stones rub against the fabric, creating a worn and frayed look. However, this method presents several significant problems. The use of pumice stones generates a large amount of limestone waste, and the dust and debris produced during the process can pollute the environment and damage machinery. Each wash cycle also requires a substantial amount of water, contributing to excessive water consumption. Moreover, after use, pumice stones tend to accumulate denim fibers, indigo dye, and chemical residues. If not properly disposed of, they can cause further environmental damage.
Stubborn oil stains on jeans have become a common problem. Many people discard jeans because regular detergents fail to remove these stains, leading to unnecessary waste. Current stain removal methods each have their shortcomings: regular detergents are often ineffective against tough stains, strong stain removers may damage the fabric and harm the environment, natural methods like baking soda and vinegar are eco-friendly but less effective, and high-temperature steam cleaning is efficient but costly and may damage the fabric. These challenges make cleaning oil stains from jeans difficult [12].
Table 3: Existing Methods for Removing Oil Stains from Jeans and Their Drawbacks
Our team (New Jeans) has developed an innovative enzyme-based solution. By using E. coli BL21 to produce laccase, catalase, cellulase, and lipase, we have replaced several traditional denim processing methods. This breakthrough effectively tackles the challenges of environmental pollution, stubborn stain removal, and high costs associated with conventional techniques. Our solution offers a customized, eco-friendly, and highly efficient approach to jeans bleaching, fraying, and stain removal.
In our project, we chose the E. coli BL21 strain for the efficient expression of the enzymes we need, including laccase, cellulase, lipase, and catalase. E. coli BL21 was selected due to its well-characterized genetic background, high efficiency in expressing target proteins, rapid growth rate, and simple cultivation requirements, making it an ideal chassis organism for expression [13].
Laccase can degrade indigo
Laccase is a multifunctional oxidase, first discovered in 1883 from the sap of lacquer trees. It catalyzes the oxidation of various phenolic and amine compounds, making it particularly suitable for denim bleaching [14]. We selected the Bpul (laccase gene) from Bacillus pumilus to achieve efficient indigo degradation. Through oxidation, laccase breaks down localized indigo dye attached to the denim fabric, achieving precise bleaching effects. Compared to chemical bleaches, laccase is not only more environmentally friendly but also reduces the risk of indigo backstaining, while maintaining the texture and uniform color of the fabric [15].
Indigo is an organic synthetic dye commonly used in the textile industry. Laccase breaks down indigo, enabling adjustments in color depth and brightness during the dyeing process, making each pair of jeans unique. By degrading the indigo attached to the fabric, laccase helps create different shades and color changes in the jeans [16].
Present laccase on the surface of cells for the degradation of indigo dye
The principle of this technology involves using genetic engineering to attach an INP (ice nucleation protein) tag to the target protein. The INP tag directs the target protein to the cell surface during expression in the host cell. This method allows functional proteins, which are typically located inside the cell or in the external environment, to be displayed on the cell surface, thereby giving the cell new properties and functions [17]. In our project, we introduced a truncated INP sequence upstream of the Bpul laccase gene and cloned it into the pET23b plasmid. The recombinant plasmid was then transformed into E. coli BL21. After antibiotic plate selection and sequencing verification, we successfully obtained the engineered strain BL21/INP-Bpul.
Catalase breaks down hydrogen peroxide and boosting laccase activity
To improve the efficiency of laccase, we added catalase to the solution to enhance its ability to degrade indigo. Catalase catalyzes the conversion of hydrogen peroxide into water and oxygen. Since laccase requires oxygen molecules for indigo degradation, and the amount of dissolved oxygen in water is limited, the addition of catalase helps generate more oxygen by breaking down hydrogen peroxide. This increases the reaction rate of laccase, significantly boosting its bleaching efficiency [18]. As a result, we can achieve a more effective and efficient bleaching process for denim.
Cellulase can break down cellulose in fabrics
Laccase is responsible for the bleaching process, while cellulase handles the fraying. Cellulase is a type of hydrolase that breaks down cellulose in fabrics, converting it into simple carbohydrates. In our denim treatment, we selected the Bgls cellulase gene from Bacillus subtilis. Through hydrolysis, cellulase cuts and degrades cotton fibers, breaking them down into shorter cellulose molecules. As the reaction progresses, cellulase penetrates the fibers and causes irreversible damage. This process softens the surface of the jeans and creates fine irregularities, giving the fabric a naturally worn appearance [19].
In addition to bleaching and fraying, lipase is also added to our products. Lipase is a water-soluble enzyme that catalyzes esters. It plays an important role in the digestion, transportation and shearing of esters [20]. In the jeans industry, we chose Pseudomonas aeruginosa 7323 containing the lipA gene. Lipase has excellent fat removal capabilities even at low temperatures, so it is widely used in the laundry industry. At the same time, it also has a cumulative effect, and the decontamination ability can be better increased with the increase in the number of washes. After this environmentally friendly and efficient process, the jeans will become cleaner and softer.
Our products are mainly aimed at home consumers who are not satisfied with the current state of their jeans and want to give them a new style; consumers who want to repair and clean old jeans; and young people who are keen on DIY personalized clothing. To meet these needs, we have launched a Jeans Care Kit based on bio-enzyme technology. The kit contains three different bio-enzyme products to help consumers easily achieve personalized transformation and professional care of jeans.
During the production process, we first screen and cultivate microbial strains that can efficiently produce target enzymes. Next, using an industrial-scale culture system, large-scale fermentation culture is carried out under strictly controlled conditions, and key parameters such as temperature, pH value and culture medium are optimized to ensure high yield of enzyme solution. After the culture is completed, the bacterial solution will undergo multiple steps of separation and purification processes to finally obtain a high-purity bio-enzyme preparation. After further drying, the preparation is made into a dry powder product that is easy to store and use.
Bleaching effect:
Consumers who want to achieve the bleaching effect of jeans can use the laccase and catalase enzyme combination. Add the two enzyme powders to warm water and mix them thoroughly. Apply the enzyme solution evenly to the jeans by dipping a cloth in the mixture, and rub the fabric on the desired areas. Let the jeans dry naturally. If a more pronounced bleaching effect is needed, repeat the process until the desired result is achieved.
Frayed effect:
For consumers aiming for a natural frayed look, use the cellulase enzyme from the kit. Dissolve the cellulase powder in 30°C water, mix thoroughly, then dip a cloth in the solution and rub it on the areas where you want the worn effect. Allow the jeans to air dry naturally, and the fabric will appear distressed after drying.
Decontamination cleaning:
To clean stubborn stains on jeans, use the lipase enzyme. Dissolve the lipase powder in warm water, mix well, and then dip a cloth in the solution, rubbing it over the stained areas. Once the jeans have dried, the oil or other tough stains should be effectively removed.
1. Eco-Friendly: Enzyme-based methods reduce environmental pollution by minimizing water usage and eliminating harmful chemical by-products, making the process safer for both the environment and workers.
2. Cost-Effective: By reducing water consumption and eliminating the need for chemical treatments, companies can lower operating costs and wastewater treatment expenses, while also facing fewer regulatory restrictions due to the eco-friendly nature of the process.
3. Customization & Flexibility: Enzymes like laccase and cellulase allow for greater flexibility in denim processing. They enable more precise control over bleaching and fraying patterns, offering personalized and fashionable designs tailored to customer preferences.
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