Sustainable fashion: self-dyeing vegan leather

According to the UN, the fashion industry contributes to around 10% of global emissions which is nearly twice as much as the shipping industry (3%) and aviation (2.5%) combined.

Wasteful fashion

Clothing is something we covet in some form or another, whether it’s the latest trends or individual style. However, ‘Fast’ or ‘throwaway’ fashion is a big environmental concern – with trends constantly changing and consumers generally buying more than they need. In fact, research carried out by Oxfam estimates that the average Briton has 57 unworn items.

It is these global environmental concerns that are steering both industry and academia interests towards alternative materials such as bacterial cellulose.

Cellulose is a naturally existing element found in a plant’s cell wall and in several bacteria. Bacterial cellulose, aka microbial cellulose, is a biodegradable, natural cellulose that is synthesised by bacteria.

The industry enigma that academia is helping to solve is: how do we protect the environment whilst growing the economy without one compromising the other? This conundrum was posed in 1987 in the Brundtland Report, published by the United Nations World Commission on Environment and Development.

It is here that researchers from Imperial College London have been looking at the environmental fashion fallout and working on a way to combat it.

Nature is an amazing

The researchers have been developing environmentally friendly solutions to the impact caused by the fashion industry, and their focus has led to the creation of a sustainable alternative to traditional leather, utilising the unique properties of genetically engineered bacterial cellulose.

This new material is biodegradable and it is also capable of self-pigmentation, significantly reducing the environmental degradation associated with the leather dyeing process.

The innovation involves modifying Komagataeibacter rhaeticus, a bacterium, to produce melanin, thus enabling the bacterial cellulose (BC) to naturally assume a rich black colour. This process is facilitated by the enzyme tyrosinase, which catalyses the conversion of tyrosine into melanin, embedding the pigment directly into the cellulose fibres.

The implications of this research present an opportunity to shift towards more sustainable practices in fashion design and manufacturing. The synthetic dyeing process, particularly for black dyes used in leather production, is among the most environmentally damaging aspects of the fashion industry. By using the capabilities of engineered bacteria to produce both a material and its pigment, the researchers at Imperial College London have set a precedent for integrating biology into textile manufacturing.

The method behind the magic

Their innovative method, detailed in the journal Nature Biotechnology, involves a two-step pigmentation process:

Cultivation of the genetically modified bacteria under standard conditions to form a pellicle.

Treatment of this pellicle in a melanin-inducing buffered solution, which embeds the colour directly into the material without the need for conventional dyeing methods.

This approach provides a cleaner alternative to textile production and showcases versatility in its potential applications. The resultant material has been used to create prototypes such as shoes and wallets.

The researchers partnered with material designer Jen Keane to explore the practical applications of this material in fashion. One notable achievement was the development of a shoe upper, formed by cultivating a sheet of bacterial cellulose within a bespoke, shoe-shaped mould. This process was followed by a colour activation phase, where the shoe was subjected to conditions that stimulated the production of the black pigment by the bacteria, dyeing the material intrinsically.

Further exploring the potential of genetically engineered bacterial cellulose, the team demonstrated the ability to alter the material's colour in response to external stimuli such as blue light. This capability allows for the embedding of patterns or logos directly into the material as it grows, adding a new dimension of customisation to the textile production process.

The researchers are expanding the colour palette of the bacterial cellulose by experimenting with various pigments that can also be synthesised by the microbes. This exploration is supported by a £2 million grant from the Biotechnology and Biological Sciences Research Council (BBSRC), which will aid in addressing other environmental issues associated with fashion production, such as the toxic use of chromium in leather manufacturing.

This research highlights the transformative potential of engineered living materials (ELMs) not only in fashion but also in other industries. Applications range from producing bio-cement bricks and generating electrical energy to creating medical products and environmental remediation solutions. As industries increasingly seek sustainable alternatives, the work being done at Imperial College London represents an important step towards enabling a greener, more sustainable, yet uncompromised future.