Issue 05/2023

around 28,000 tonnes. It is expected that the worldwide
market for chitin derivatives (including chitosan) should
reach USD 63 billion by 2024, following a report from
Global Industry Analysts (chitin and chitosan derivatives
market report – 2015).
To overcome feedstock dependency and other
disadvantages of the current chitin supply chain (such as,
low traceability, a lack of reproducible and standardised
processes, and a lack of quality control) an alternative,
reliable, reproducible, and highly scalable production
process is needed. Recent studies have shown that chitosan
can be extracted and processed from fungal biomass.For
example, as a byproduct of biotechnological processes in
which filamentous fungi are already used on a large scale
as natural cell factories for the production of platform
chemicals, organic acids, proteins, enzymes, antibiotics,
pharmaceuticals, dyes, and fuels at particularly low costs.
The aim of current research projects is to produce chitosan
from the fungus Aspergillus niger, which is one of the most
important fungal cell factories used in biotechnology.
The fungus achieves enormous throughput in a short
time, with reproducible high quality and purity for gentle
extraction and multiple refining and conversion options with
fully verifiable and tailor-made specifications that meet the
requirements of the relevant markets. In addition to its high
growth and multiplication rate, its acceptance of a broad
food spectrum, including starch, pectins and lignocellulosic
waste from agriculture and forestry, is an advantage. Up to
30 % of its cell walls consist of chitin, which can be further
increased by gene modification and the addition of stressors
in the culture environment.
Chitosan production from fungal biomass can draw on
both primary feedstock streams (direct industrial fungal
cultivation for polymer production) and secondary feedstock
streams (waste streams from established industrial fungal
cultivation for chemical and active ingredient production).
In particular, the use of secondary raw material streams,
i.e. a coupled production of polymer and other substances,
represents a cost advantage that other biopolymers do not
have, which means that chitosan has higher chances of
being truly competitive compared to conventional petroleumbased
polymers. For this reason, the development of a
chitosan industry in Europe is also conceivable, which
serves numerous current demands for regional, sustainable
production, the limitation of water and land requirements as
well as spatially short and traceable supply chains. As the
infrastructure of industrial fungi cultivation is already an
established industrial standard, and chitosan can be spun on
conventional spinning lines used for cellulose and processed
on available textile machines, only the chitin to chitosan
conversion has to be created.
For use in clothing, the fungus-based polymers are very
suitable. Their performance and quality do not have to fear
comparison with cotton or cellulose fibres. Some properties
By:
Simon Kammler, Scientific Assistant
Department of Chemical Technologies for Textile and Fibre Innovations
Institut für Textiltechnik of RWTH Aachen University
Aachen, Germany
are even superior to those of petroleum-based polymers,
the material offers a very pleasant natural feel and high
wearing comfort. The odour-inhibiting effect is just as much
in favour of the mushroom fibres as the temperature – and
climate-balancing function, as the material is characterised
by high moisture absorption and good moisture retention.
The material is visually appealing with its light, silky sheen.
The antibiotic properties of chitosan fibres make them
particularly suitable for medical applications such as hospital
garments and wound dressings, sportswear and footwear,
and clothing where the chitosan can inhibit bacterial growth,
improve hygiene, and prevent odour. The biobased origin and
biodegradability of chitosan fibres contribute to the ongoing
transition of the textile market to more environmentally
friendly products, and are also suitable for use in disposable
textiles. The fact that chitosan is non-toxic and does not
form toxic degradation products makes it additionally
attractive as a raw material, as there are no disposal or
environmental problems.
The low use of resources speaks in favour of the chitosan
polymers, as the production can take place with a closed
water cycle. In addition, the mushrooms can be used
completely within the framework of a coupled production.
In addition, no entire production facilities have to be built,
neither in the raw material production nor in the yarn
production. Antimicrobial treatment with problematic
chemicals is not necessary, nor is the use of pesticides,
herbicides, and artificial fertilisers. In addition, the chitosan
is biodegradable. Currently, the focus is on the fungal strain
Aspergillus niger, but the use of other fungal species is
conceivable in the future.
The research described in this article is part of the project
“Fungal Fibers”, funded by the German Federal Ministry
for Economic Affairs and Climate Protection within the
BioTexFuture Innovation Space.
www.ita.rwth-aachen.de
www.biotexfuture.info/projects/fungalfibers
Fibres / Textiles
bioplastics MAGAZINE | Renewable Carbon Plastics [05/23] Vol. 18
21