Sustainability has become an increasingly important topic for players along the textile value chain. Against the background of resource scarcity, we have to wonder how to handle resources and who – besides nature – generates raw materials for fibre production?
The vision of producing sustainable raw materials equipped with new functionalities is already within reach. With the advent of genetic engineering, technology has reached a stage where sustainable biomaterials can be synthesised by the use of genetically modified microorganisms rather than by use of plant resources or oil.
So, in the post-fossil world of tomorrow, textiles will probably be made biotechnologically using bacteria or fungi. Current research projects conducted by the Hohenstein Institute are focussed on wet-spun biopolymer fibres made of alginate and chitosan from biotechnological production. By variation of fermentation conditions, nutrition media and biopolymer isolation protocols, the characteristics of the raw materials can be adjusted with direct impact on properties of fibres made from those bio-polymers.
In addition, modern biotechnology allows the modifying of microorganisms genetically (genetic engineering) and thus influencing polymer output and characteristics from the very beginning.
Alginate
During the course of a current BMBF-research project (AlBioTex), which was conducted by Hohenstein together with different industry partners, the first alginate fibres made of biotechnologically produced alginate have been developed and characterised.
We were able to show that depending on the bacterial strain and culture conditions, the monomer constitution of the alginate polymer could be modified in order to achieve stable wet-spun fibres with tremendous water absorption capacities. Compared to common alginate made of algae, the biotech-alginate was of constant quality (e.g. controlled monomer sequence, no heavy metals, no endotoxins), non-allergenic and non-toxic.
Due to the controlled production conditions and the adjustable characteristics, biotech-alginate could be used for various applications in the future, e.g. in the medical field (wound dressings).
Chitosan
Another high-potential biopolymer is chitosan, which is usually made of deacetylated chitin by treating shrimps and other crustacean shells with sodium hydroxide.
Chitosan is used for various applications and chitosan fibres are already on the textile market. They are promoted to have an intrinsic antimicrobial activity and good adsorption properties. However, the use of the natural source (chitin crustacean shells) presents some major drawbacks, such as fluctuating material properties and quality, a laborious isolation/deacetylation procedure and the risk of heavy metal and protein residues, which are potentially allergenic for susceptible people.
We, here, present first results of Hohenstein research on chitosan from microbiological sources, e.g. zygomycetes. These organisms can be grown in a sustainable way on waste products from food production and directly produce a high chitosan – not chitin – content in their cell walls. Moreover, the resulting biopolymer is free of heavy metals or endotoxins, is biocompatible and non-allergenic.
Biotechnology and textiles imply the use of microorganisms to synthesise fibres and yarns as well as the use of enzymes to influence processing or properties of fibres, yarns and fabrics with the aim to improve the economy of the overall textile industry.
By using biotechnology it will be possible in the future to produce natural fibres having characteristics of synthetic fibres without planting and harvesting. This technology is a powerful biological tool, which already enables us today to produce a variety of materials with the help of microorganisms, which can then be processed to sustainable man-made fibres.
With this technique, we move in a new direction for the sustainable textile industry of tomorrow: From the microbe via the fibre up to textile end use.