Animal skins are currently used as a source of natural leather for the footwear industry – a major source of environmental and sustainability concerns. This is because livestock require enormous amounts of food, pastureland, water and fossil fuel, and animal skin and hides need tanning to be stabilised, what results is significant pollution of the air and waterways, as well as harmful effects on our health. One alternative is synthetic leather produced by the chemical industry, but this also generates environmental impacts related to contamination by plastics, CO2 footprint, and the release of toxic chemicals to the environment. Hence, there is an urgent need to develop new alternatives to both animal and synthetic leather. The EU-funded BacLEATHER project addressed this challenge, developing an eco-friendly leather-like material that requires less time, water and energy to manufacture, and employs no harmful chemicals. “This ‘cultured leather’ can provide a safe, sustainable and economical alternative to leather for the footwear industry,” says Concepción García, project leader and co-founder and CEO of Spanish SME Patent Shoes.
A new approach
Synthetic leather is typically made by bonding a plastic coating to a fabric backing. However, depending on the type of plastic used, the material’s environmental impact differs. Currently, there are several materials used to produce synthetic leather: polyvinyl chloride (PVC) and polyurethane (PU) remain the most commonly used. They do not represent a sustainable and eco-friendly alternative to animal leather because of the toxic substances released during the processing and disposal of synthetic leather (PVC and PU). The SME Patent Shoes responded by successfully designing and developing a biotechnological process based on microorganisms at the laboratory scale to produce nano-bacterial cellulose (NBC) sheets. Following a simple process of dyeing and impermeabilisation, the sheets yield a biomaterial with very similar characteristics to animal leather, BacLEATHER, which can be used as a leather substitute by the footwear industry. The material is based on a mixture of bacteria and yeast cells that work as a symbiotic culture to produce biofilms and form a cellulose matrix of NBC. “BacLEATHER is obtained by the fermentation of these cultures to yield a strong biopolymer of controllable thickness, which can be dyed, dried, glued and sewn. Its properties, after processing, are like animal leather used in the footwear industry,” explains García.
Boost to circular economy
Due to the hydrophilic characteristics of the bacterial cellulose, it is necessary to carry out a specific step for waterproofing the material. “We used a 100 % biodegradable material that is also compostable and can be bound to the biopolymer. It also gives BacLEATHER an appearance similar to patent leather,” notes García. “Our cultured bio-leather does not use toxic chemicals during its production and is made with renewable resources, thereby enabling the sector to move towards a circular economy, with no environmental impact.” The ultimate goal according to García is for Patent Shoes to be the first worldwide company to produce industrially and on-demand a biodegradable product (bio-leather) for footwear manufacturing. “Since BacLEATHER is made of biological and recyclable materials, non-toxic, and with reduced costs in water and energy consumption it will not only benefit the footwear industry but also help to mitigate the impacts of climate change,” she points out.
BacLEATHER, leather, footwear, polyvinyl chloride (PVC), polyurethane (PU), nano-bacterial cellulose (NBC), biopolymer