Indian Journal of Fibre & Textile Research
Vol. 26, March-June 200 1 , pp. 206-2 1 3
B iotechnology applications in textile industry
Deepti Gupta"
Department of Textile Technology, Indian Institute of Technology, Hauz Khas, New Delhi 1 10 0 1 6, India
The applications of biotechnology to textiles are discussed with reference to improvements in natural fibres, novel new
biodegradable fibres and polymers, biofabrics, intermediates and dyes from micro-organisms, and treatment of textile waste
water. Majority of the techniques are not yet commercialized. However, wherever a clear economic justification and market
for a particular product or process exists, progress has been rapid. It is thus expected that in future, many of the
biotechnological processes would help in solving the environmental problems posed by textile industry.
Keywords: Biodegradable fibre, Biofabric, Biotechnology, Dye, Natural fibres
1 Introduction
Biotechnology encompasses a range of scientific
and engineering techniques for applying biological
systems to the manufacture or transformation of
materials in order to develop novel processes and
products. It is not an industry in itself but is expected
to have a large impact on many different industrial
sectors in the future. Techniques have been developed
which directly modify and harness the power of the
DNA molecule, the engine house of any biological
system. Consciousness and expectations for better
quality fabric and awareness about environmental
issues are two important drivers for textile industry to
adopt biotechnology in its various areas.
With the increased realization of the immense
potential of biotechnology applications in textile
industry, major initiatives have been launched world­
wide to encourage research and development activity
in this field. The UK Department of Trade and
Industry launched a 1 3 million pound Bio-Wise
Program in January 1 999. The first Symposium on
Biotechnology in Textile Industry was held at Minho,
Portugal, in May 2000. It was widely attended by
scientists as well as the representatives of enzyme
manufacturers.
This paper discusses the applications of
biotechnology to textiles with reference to the
following emerging areas :
•
•
•
Improvements in natural fibres
Novel fibres and polymers
Biofabrics
UPhone : 659 1 4 17; Fax: 658 1 103;
E-mail : dbg33 @ hotmail.comJdeepti @ textile.iitd.ernet.in
•
•
Dyes and intermediates from micro-organisms
Treatment of wastes of textile manufacturers and
processors
2 Improvements in Natural Fibres
Biotechnology can play a crucial role in production
of natural fibres with highly improved and modified
properties besides providing opportunItIes for
development of absolutely new polymeric materials.
The natural fibres under study are cotton, wool and
silk.
2.1 Cotton
Cotton continues to dominate the market of natural
fibres. It has the greatest technical and economic
potential for transformation by technological means.
Genetic engineering research I on the cotton plant is
currently directed by a two- pronged approach :
•
•
Solving the major problems associated with the
cultivation of cotton crop, namely the improved
resistance to insects, diseases and herbicides,
leading to improved quality and higher yield.
The long- term approach of developing cotton
fibre with modified properties, such as improved
strength, length, appearance , maturity and colour.
2.1.1 Transgenic Cotton
Each year, thousands of research hours and
hundreds of thousands of dollars are spent to prevent
cotton from caterpillars that love to eat cotton. Cotton
growers fight to produce a salable product using
chemical sprays, natural controls, cultural practices,
pheromones
(insect
mating
hormones)
and
monitoring. Use of excessive pesticides is posing a
serious threat to the green image of cotton2 •
GUPTA: BIOTECHNOLOGY APPLICATIONS IN TEXTILE INDUSTRY
After years of research, a completely new kind of
tool is available for cotton growers to ward off the
pink bollworm, one of the maj or cotton pests. About
ten years ago, Monsanto scientists obtained a toxin
gene from the soil bacterium called Bt (which is the
nickname for Bacillus thuringiensis) and inserted it
into cotton plants to create a caterpillar-resistant
variety. The gene is DNA that carries the instructions
for producing a toxic protein. The toxin kills
caterpillars by paralyzing their guts when they eat it.
Plants with the Bt toxin gene produce their own toxin
and thus can kill caterpillars throughout the season
without being sprayed with insecticide. Because the
toxin is lethal to caterpillars but harmless to other
organisms, it i s safe for the public and the
environment. Monsanto registered their Bt gene
technology for transgenic cotton under the trademark
Bollgard® and authorized selected seed companies to
develop cotton varieties carrying the patented gene3 .
More stable, long lasting and more active Bts are
now being developed for the suppression of loopers
and other worms in cotton. Insect resistance is also
being developed using a 'wound- inducible promoter'
gene capable of delivering a large but highly localized
dose of toxin within 30-40s of an insect biting.
Introduction of the controversial terminator gene i n
cotton renders the second generation o f cotton
impotent and the farmer has to depend on fresh supply
of seed.
Development of fibres containing desirable shades
in deep and fast colours would change the face of the
entire processing industry. Coloured cottons are also
being produced not only by conventional genetic
selection but also by direct DNA engineering.
Although several naturally coloured cotton varieties
have been obtained by traditional breeding methods,
no blue variety exists. As blue is in great demand in
Lhe textile industry, particularly for jeans production,
synthetic fabric dyes are used. However, the
ingredients of these synthetic dyes are often
hazardous and their wastes are polluting.
Additionally, they take time and energy to work into
the cloth. Natural blue cotton does not have these
disadvantages and, therefore, has great market
potential. The genetic engineers plan to insert into
cotton plants the genes that are responsible for the
production of blue colour i n the i ndigo plant, formerly
the source of blue dye, until a cheaper synthetic
method is discovered. By 2005, Monsanto hopes to
have this blue-coloured cotton commercially
available.
207
Another major breakthrough has been the ability to
produce cotton containing natural polyester, such as
polyhydroxybutyrate (PHB), inside their hollow core,
thereby creating a natural polyester/cotton fibre.
About 1 % polyester content has been achieved and it
has led to 8-9% increase in the heat retention of
fabrics woven from these fibres. Other biopolymers,
including proteins, may also be i ntroduced into cotton
4
core i n a similar manner •
A US biotechnology company, Agracetus, has
already been awarded a patent covering the entire
cotton 'genome' and is setting up a company
FibreOne to create, produce and market these
speciality products. With its genetically engineered
cotton, Agracetus wants to develop and market
speciality fibres that will combine the preferred
appearance and texture of cotton with enhanced fibre
properties. These customized fibres will be tailored to
the needs of the textile industry. New properties may
include greater fibre strength, enhanced dyeability,
improved dimensional stability, reduced tendency for
shrinking and wrinkling and altered absorbency.
Greater strength will allow higher spinning speeds
and improved strength after wrinkle- free treatments.
Improved reactivity will allow more efficient use of
dyes, thus reducing the amount of colour in effluents.
To reduce the waste generated during scouring and
bleaching processes, it would be interesting to have
fibres with less of pectins , waxy materials and
undesirable colour. Another example is the fibres
contammg
enzymes
that
can
biodegrade
environmental contaminants. These fibres would be
pklced in filters. through which contaminated water is
passed5•
2.2 Wool6
Developments are also taking place for other
natural fibres. Maximum work is being carried out on
animal hair fibres, the most prominent among them
being wool.
Studies are underway in New Zealand and
Australi a to make use of biotechnological methods for
enhancing the quality and yield of wool fibres. One of
these techniques is the ,use of DNA markers to
identify useful genes . This will allow breeders to
more accurately select rams for improved production
and wool quality . The other technique is the use of
genetic engineering to modify the genetic makeup of
animals to provide them with specific properties that
would be hard to introduce by conventional breeding
procedures. Modem reproductive technologies
208
INDIAN J. FIBRE TEXT. RES., MARCH-JUNE 200 1
including artificial insemination, semen freezing,
embryo transfer and embryo micromanipulation have
been applied to produce animals with new genes.
Merino sheep that grow (about l 3%) faster and larger
than normal have been produced. This has been
achieved by genetic modification of the sheep using a
unique gene that alters the amount of growth hormone
circulating in the bloodstream. Genetic technologies
are being employed to reduce costs and improve
production efficiency by increasing the parasite
resistance among animals.
In 1 998, a revolutionary biowool harvesting
process (Bioclip) became available. The technique
relies on an artificial epidermal growth factor which
when injected into sheep interrupts hair growth. A
month later, breaks appear in the wool fibre and the
fleece can be pulled off whole, without the use of a
mechanical hand piece, in half the normal shearing
time. Wool harvested using it will be free of second
cuts and skin pieces contaminating the fleece.
Trends in apparel continue to be for lighter, softer
and more comfortable products. To meet these
requirements, fine diameter fibres are needed.
OPTIMTM is the transformed wool fibre developed by
CSIRO Wool Technology and The Woolmark
Company. This newly developed fibre is thinner,
longer and stronger. The diameter of wool is reduced
typically by 3-4)lm and the knitwear produced is 2030% lighter than the normal.
79
2.3 DNA Profiling of Animal Hair Fibres 0
Identification of both raw and processed speciality
animal fibres is important to help combat adulteration
or false declaration and to ensure adherence to the
international trading agreements. Cashmere, in
particular, is frequently adulterated with much
cheaper fibres such as wool or yak hair. Thus, there is
a clear need for a quick and objective method of fibre
analysis.
British Textile Technology Group has developed a
novel technique based on DNA hybridization analysis
to objectively confirm the type of animal fibres
present in an unknown sample or blend. This
technique can be used to demonstrate the presence of
adulterants in commercial samples of exotic cashm�re
fibres and other speciality fibres. Further research is
being conducted to make possible the quantitative
analysis of blends using DNA profiling methods.
Similar probes are now being identified to
disti nguish between cotton , ramie, kapok, coir, flax,
jute and hemp fibres. The technique can also be used
to establish the degree of pre-processing of the fibre
(from its pattern of DNA degradation) and thereby
distinguish virgin from recycled fibres.
Research is being conducted in China and
elsewhere to overcome the dependence of silkworms
on mulberry leaves, improve the strength and fineness
of silk, increase the viral resistance , and even
produce coloured fibres.
3 Novel Fibres
The use of biotechnology has the potential of
control and specificity in polymer synthesis which is
difficult, if not impossible, to achieve in chemical
systems. New materials produced using advanced
biologically - based approaches represent the textiles
of the future. Two of the tools of molecular biology,
namely recombinant DNA and genetic engineering
techniques, now make it possible to construct highly
specific polymers. For example, both polyamides
(i.e.protein polymers) and polyesters have been
produced in this manner.
3.1 Protein Polymers
B iological systems are able to synthesize protein
chains in which molecular weight, stereochemistry,
amino acid composition and sequence are genetically
determined at the DNA level. A current area of
investigation is to understand those features of protein
polymers that confer high tensile strength, high
modulus and other advantageous properties. Once
those features are understood, the tools of
biotechnology will make possible entirely new
paradigms for the synthesis and production of
engineered protein polymers. If they can be made
economically viable, these new approaches will help
to reduce the dependence on petroleum and
furthermore will enable the production of materials
that are biodegradable. Use of transgenic plants for
large-scale production of these and other synthetic
. .
11
protems I S bemg expI ored lo•
.
Efforts in biosynthesis have been directed towards
the preparation of precisely defined polymers of three
kinds: (i) natural proteins such as silks, eiastins,
collagens and marine bioadhesives, (ii) modified
versions of these biopc.lymers, such as simplified
repetitive sequences of the native protein, and (iii )
synthetic protei ns designed de novo that have n o close
natural analogues. Althol.gh such syntheses pose
significant technical problems, these difficulties have
GUPTA: BIOTECHNOLOGY APPLICATIONS IN TEXTILE INDUSTRY
all been successfully overcome in recent years. Using
this technology, a whole new class of synthetic
proteins with advanced properties, known as
bioengineered materials, is being created.
3.2
Spider Silk
Spider dragline silk is a versatile engineering
material that performs several demanding functions.
The mechanical properties of dragline silk exceed
those of many synthetic fibers. Dragline silk is at least
five times as strong as steel, twice as elastic as nylon,
waterproof and stretchable . Moreover, it exhibits the
unusual behaviour that the strain required to cause
failure
actually
increases
with
increasing
12.
deformation
Spiders extrude an aqueous solution of silk protein
to spin the molecules into oriented fibres. The female
garden cross spider can use seven different glands,
each containing silk with a unique amino acid
sequence, to produce fibres with different properties.
Work is under way to fully characterize the molecular
weight and sequence distribution; the nature of the in
vivo solution (speculated by some to be liquid
crystalline); and the structure, size and orientation of
the crystalline regions and their interconnection to the
amorphous regions in such materials.
Active research is going on at the University of
Massachusetts to try and synthesize spider silk in the
laboratory. This material comprises two amino acids
(glycine and alanine) and it has been shown that it is
the alignment of these amino acids which is
responsible for spider silk' s incredible strength.
Having established the alignment, the specific gene is
cloned and inserted into bacteria such as E. coli. The
bacteria reproduce and eventually form a cloned
colony that produces the synthetic polymer by way of
13
protein synthesis •
Another approach, being tried out, is to produce
spider silk in the milk of transgenic goats.
Researchers at Nexia Biotechnologies, Montreal, have
successfully produced high quality spider silk by
splicing the spider silk gene into the mammary glands
of milk animals 14 .
Other New Fibre Sources
There are many more biopolymers, of particular
interest in sanitary and wound healing applications,
which
include bacterial
cellulose
and
the
polysaccharides such as chitin, alginate, dextran and
hyaluronic acid. Some of these are discussed below :
3.3
209
Chitins and Chitosans
Chitins and chitosans both can form strong fibres.
Chitin is found in the shells of crustaceans, such as
crab, lobster, shrimp, etc. Resembling cellulose, the
chitin consists of long, linear polymeric molecules of
beta- ( 1 -4) linked glycans. The carbon atom at
position 2, however, is aminated and acetylated.
Fabrics woven from them are antimicrobial and serve
as wound dressing products and as anti-fungal
stockings. Chitosan also has promising applications in
the field of fabric finishing, including dyeing and
shrink proofing of wool. It is also useful in filtering
and recovering heavy and precious metals and
dyestuffs from the waste streams l5 •
3.3.1
Wound dressings based on calcium alginate fibres
are marketed by Courtaulds under the trade name
'Sorbsan'. Present supplies of this polysaccharide rely
on its extraction from brown seaweeds. However, a
polymer of similar structure can also be produced by
fermentation from certain species of bacteria.
Dextran, which is manufactured by the fermentation
of sucrose by Leuconostoc mesenteroides or related
species of bacteria is also being developed as a
fibrous nonwoven for speciality end uses such as
wound dressings. Additional biopolymers, not
previously available on a large scale, are now coming
onto the market, thanks to biotechnology. Another
example is hyaluronic acid, a poly disaccharide of D­
glucuronic acid and N-acetyl glucosamine. This acid
is found in the connective tissue matrices of
vertebrates and is also present in the capsules of some
bacteria. Fermentech, a British biotechnology
company, is now producing hyaluronic acid by
16.
fermentation
3.3.2
Bacterial Cellulose17,18
Cellulose produced for industrial purposes is
usually obtained from plant sources or it can be
produced by bacterial action. Acetobacter xylinium is
one of the most important bacteria for cellulose
production as sufficient amounts can be produced
which makes it industrially viable. Cellulose produced
by Acetobacter, which has the ability to synthesize
cellulose from a wide variety of substrates, is
chemically pure and free of lignin and hemicellulose.
Cellulose is produced as an extra cellular
polysacaccharide in the form of ribbon like
microfibrils. It has high crystallinity, high degree of
polymerization, high tensile strength and tear
resistance, and high hydrophilicity that distinguishes
it from other forms of cellulose. This bacterial
INDIAN J. FIBRE TEXT. RES., MARCH-JUNE 2001
210
cellulose is being used by Sony Corporation of Japan
in acoustic diaphragms for audio speakers. They are
also being used in the production of activated carbon
fibre sheets for absorption of toxic gas and as
thickeners for niche cosmetic applications. In medical
field, because of the hydrophilic and mechanical
properties of bacterial cellulose, it is used temporarily
as a skin substitute and in wound healing bandages.
A second biotechnological route being explored for
the production of cellulose is the in vitro cultivation
of plant cells. It has been possible to produce cotton
fibres in vitro by culturing cells of various strains of
Gossipium. Plant tissue culture provides an exciting
opportunity for producing cotton all the year round, of
a consistent quality and free from the contamination
from pests.
3.4 Corn Fibre
l9.20
An entirely new type of synthetic fibre derived
from a plant is Lactron. This environment- friendly
corn fibre was jointly developed by Kanebo Spinning
and Kanebo Gohsen of Japan. Lactron, the polylactic
acid fibre, is produced from the lactic acid obtained
through the fermentation of corn starch. Strength,
stretchability and other properties of Lactron are
comparable to those of petrochemical fibres such as
nylon and polyester (Table 1 ). As the material is
compatible with human body, it is being used for
sanitary and household applications. In addition to
clothing, the company is also promoting its non­
clothing applications, e.g. construction, agricultural,
paper making, auto seat covers and household use21 •
The energy required for production of corn fibre is
low and the fibre is biodegradable. Moreover, no
hazardous gases are created when it is incinerated and
the required calories for combustion are only one­
third or half of those required by polyethylene or
polypropylene. It safely decomposes into carbon
dioxide, hydrogen and oxygen when disposed of in
soil. Lactron is being marketed in various forms s'!,ch
as woven cloth, thread and non-woven cloth. Shinwa
and Unichika companies of Japan have launched
spunbonded nonwovens, films and sheets made from
this new fibre. Developments for thermal-bonded and
spun-lace nonwoven types are also underway22 .
3.5 Polyester Fibres
It has been known since 1 926 that certain
polyesters are synthesized and intra-cellularly
deposited in granules by many micro-organisms.
Some of these materials have been formed into fibres.
Polyhydroxybutyrate (PHB) is an energy storage
material produced by a variety of bacteria in response
to environmental stress and is a homopolymer of D-(­
)-3-hydroxybutyrate which has properties comparable
to polypropylene . It is being commercially produced
from Alcaligenes eutrophus by Zeneca Bioproducts
4
and sold under the trade name Biopo1 2 ,25 . As the cost
of production of Biopol was very high, new methods
for more efficient production of PHB have been
developed by using transformed E.coli strains. This
process gives higher yields of PHB . The cost of
production is greatly lowered as the expensive
glucose- based substrate is substituted by whey which
is a much cheaper substitute26 .
As PHB is biodegradable, there is considerable
interest in using it for packaging purposes to reduce
the environmental impact of human garbage. Thus, it
is already finding commercial application in speciality
packaging uses. Because of it's immunological
compatibility with human tissue, PHB also has utility
in antibiotics, drug delivery, medical suture and bone
replacement applications.
4 Biofabrics
The development of biocidal fabrics was based on
the idea of activating textiles with reactive chemicals
to impart desirable properties. The latest research,
however, is aimed at producing fabrics containing
genetically engineered bacteria and cell strains to
manufacture the chemicals within the textiles ,
thereby making the chemical stores within the fabrics
the self-replenishing materials.
A collaborative project is on between the textile
Table I--Comparative properties of Lactron and polyester fibre23
Property
Tenacity,g/den
Alignment, %
Young's modulus,kg/mm�
Crystallinity, %
Melting point, °C
Lactron
Monofilament
Multifilamt>nt
4.5-5.5
30-40
4.5-5
2 5 -3 5
Polyester
4.5-5
30-40
400-600
400-600
1 1 00- 1 300
70
70
50-60
1 75
1 75
26)
GUPTA: BIOTECHNOLOGY APPLICATIONS IN TEXTILE INDUSTRY
science research team at University of Massachusetts,
Dartmouth and the bio-engineers at Harvard Medical
to carry out research leading to the production of a
class of fabrics with special properties called
biofabrics27 . Biofabrics will contain micro-fabricated
bio-environments and biologically activated fibres.
These fabrics will have genetically engineered
bacteria and cells incorporated into them, that will
enable them to generate and replenish chemical
coatings and chemically active components.
Niche applications for bio-active fabrics exist in
the medical and defense industries, e.g. drug
producing bandages or protective clothing with highly
sensitive cellular sensors, but biofabrics may form the
basis of a whole new line of commercial products as
well, e.g. fabrics that literally eat odours with
genetically engineered bacteria, self -cleaning fabrics,
and fabrics that continually regenerate water and dust
repellants.
For such an approach to be successful, technologies
will have to be developed to micro-fabricate devices
able to sustain cellular or bacterial life for extended
periods, exhibit tolerance to extremes of temperature,
humidity and exposure to washing agents, as well as
tolerance to physical stress on the fabrics such as
tension, crumpling and pressure.
5 Dyes and Intermediates from Micro-organisms
Textile auxiliaries, such as dyes, can be produced
from the plants or by the fermentation in future. It is
known that some microbial species can produce, up to
30% of their dry weight, pigment or a mixture of
pigments.
Several of these
(benzoquinone,
naphthoquinone, anthraquinone , perinaphthenone and
benzofluoranthenequinone derivative), in some
instances, have been shown to resemble the vat dyes.
5.1
Naphthoquinone Dye
One of the major breakthroughs in the
biotechnological production of dyes is the commercial
production of shikonin using plant cell culture
methods. The red pigment traditionally extracted from
Lithospermum species gave an yield of about 1 -2%.
The new method yields about 1 5% of the dry weight
of root cells as pure pigment. The method IS
successfully being used in Japan since 1 983.
21 1
dyestuff intermediates. Anthraquinones have been
isolated from a number of fungi including Drechslera,
Trichoderma, Aspergillus and Curvularia strains.
Most of these fungi produce a mixture of
anthraquinones. A strain of Curvularia lunata
produces cynodontin of up to 70% purity. This has
been successfully converted into two anthraquinone
biodyes- CI Disperse Blue 7 and CI Acid Green 28.
The properties of these dyes are similar to those of
their synthetic counterparts28 .
The advantages of such a process are that the
medium of fungal culture requires no expensive
chemicals and the fermentation is carried out at room
temperature and neutral pH so that the expensive fuel
consuming high temperatures and non-environment
friendly strong acids and alkalis for the chemical
synthesis are not required. Further, work is directed
towards identifying and manipulating the genes
required for anthraquinone synthesis so that the
anthraquinone produced by the fungi could be
specifically designed. Yields could be increased by
genetically promoting the production of the
anthraquinone synthase enzyme system which is
responsible for producing the required chemical.
5.3
Indigo
The
commercial
chemical
processes
for
manufacturing indigo result in the generation of
significant quantities of toxic waste products. Thus, a
method whereby indigo may be produced without the
generation of toxic byproducts has always been
desired. The production of microbial indigo was first
reported in 1 928. However, it was not until the early
1 980s when scientists seeking a greener alternative
method of indigo production looked at the · micro­
organisms more seriously. Now, through the
commercial application of recombinant DNA
technology, it has been possible to develop a novel
and environmentally sound biosynthetic indigo
production method. In this system, a precursor for
indigo production (indole) is produced intra-cellularly
at high levels from glucose by microbes. Indole
produced in this manner can then be converted to
indigo through the action of another enzymatic system
followed by exposure to air29 . High purity indigo has
been obtained from the strains of the microbe
Pseudomonas putida3o•
5.2 Anthraquinones
Several attempts are being made to exploit the
fungal synthesis of anthraquinones for producing
cheap and environment-friendly anthraquinone
6 Treatment of Textile Waste Water
Biotechnological techniques are also being
employed for the elimination of toxic wastes from
INDIAN 1 . FIBRE TEXT. RES., MARCH-JUNE 2001
212
textile effluents. Some major environmental problems
faced by the textile industry include the removal of
colour from dye bath effluent and handling of toxic
wastes such as PCPs, insecticides and heavy metals.
Some of these wastes are toxic enough to poison the
systems used to treat them.
The dyes are capable of forming toxic aromatic
amines . The majority of colour removal techniques
work either by concentrating the colour into a sludge
or by the partial / complete breakdown of the colour
molecule. While disperse, direct and basic dyes get
removed from the waste water via adsorption onto
activated sludge, the acid dyes and reactive dyes
exhibit low adsorption values and thus pass through
the activated sludge processes largely unaffected.
Waste water originating from reactive dye
processes create a particular problem as the dyes can
exhibit low levels of fixation with the fibre. The
unfixed dyes are highly water soluble and are not
removed by conventional treatment systems. This is
particularly noticeable as the human eye can detect
reactive dyes at concentrations as low as 0.005 mglL
in clear river water. In response to this, several waste
treatment systems based upon aerobic and anaerobic
bacterial action have been developed. It has been
found that only biotechnological solutions can offer
complete destruction of the dyestuff with a reduction
in biological oxygen demand (BOD) and chemical
oxygen demand (�OD).
Biological systems, such as biofilters and
bioscrubbers, are also now available for the removal
of odour and other volatile compounds. BAF systems
(biological aerated filters or biofilters) comprise a
submerged packed bed with fixed biofilm which is
continually aerated.
6.1 Fungi for Decolouration
Azo dyes constitute the largest group of synthetic
dyes being used by the textile industry. They do not
occur in nature and are resistant to aerobic bacterial
degradation. However, the azo linkage is susceptible
to reduction and the anaerobic bacteria can readily
reduce the azo linkage to yield potentially
carcinogenic aromatic amines. It is believed that in
many cases, decolouration of reactive azo dyes under
anaerobic conditions is due to the action of azo
reductase enzymes.
Azo-reductase
R) -N=N-R2 + 4e
-
+ 4H+
� R)-NH2 + R2NH2
where R) and R2 are the aromatic substituents in dye
molecules.
More recent research shows that the wood
degrading white rot fungus P. chrysosporium is the
only known organism that can completely degrade a
number of azo dyes. The laccase produced by P.
chrysosporium is capable of oxidizing the phenolic
azo dyes. Laccase oxidation might detoxify azo dyes
because this reaction releases azo linkages as
)
molecular nitrogen which prevents amine formation3 .
This new approach involving direct microbial attack
on the azo linkage of organic dyestuffs is already
being tested in some pilot units in a couple of major
UK dye houses.
In another study, a new peroxidase enzyme
produced by white rot fungus P.ostreatus has been
shown to successfully decolorize Remazol Brilliant
Blue R and the triphenyl methane dye Crystal Violet
by an oxidative mechanism32 .33. Other researchers
have shown that the oxidation of azo dyes -Methyl
Orange and Eriochrome B lue Black--by lignin
peroxidases is enhanced by the inclusion of additives
4
such as tryptophan or indole in the system3 .
Alternatively, it is known that many gut organisms
produce extracellular flavanoid compounds which
reduce azo bonds in food grade dyes. The gram
negative bacteria shewanella species isolated from an
industrial effluent stream was shown to degrade a
range of reactive dyestuffs, including the
commercially important dye Remazol Black B. The
decolorization mechanism involving the bacteria
appears to function with the aid of an extracellular
flavin35 •
6.2 Metal and Toxin Removal
Fungi are also being employed to absorb heavy
metals from effluent streams. The ligninase producing
white wood rot fungus have been used in the paper
and pulp industry for removing lignin bound chlorine.
They are also effective against biphenyls, aromatic
hydrocarbons and chlorinated compounds such as
PCP and DDT.
7 Conclusion
B iotechnology has already led to the development
of new products, opened new markets, speeded up
production of pure products and helped reduce the
pollution load . Textile industry is a key sector where
immense possibilities exist for biotechnological
applications but the current awareness of
biotechnology is less. Therefore, the applications are
as yet limited. Experience has shown (as in case of
GUPTA: BIOTECHNOLOGY APPLICATIONS IN TEXTILE INDUSTRY
enzyme applications) that wherever a clear economic
justification and market for a particular product or
process exists, progress has been rapid. So, it can be
predicted that in the long term, more and more of the
cumbersome and polluting chemical procedures
employed by the textile industry will be substituted or
supported by the biotechnological processes.
References
I Byrne C, Textile Institute's Dyeing and Finishing Group
Conference, Nottingham, November 1995
2 http://ag.arizona.eduJpubs/general/resrptI 996/t_cotton.html.
3 http://www.nal. usda.govlbic/Biotech_Patents/1 994patents/053
34520.htmI.
4 Byrne C, J Soc Dyers Colour. 1 14 ( 1 998) 8 1 .
5 Bijman J , Biotech Dev Monitor, ( 2 1 ) ( 1994) 8-9.
6 http://www.csiro.au/.
7 www.biotext.com.
8 www.biotechsupportindia.com.
9 Hamlyn P F. Proceedings. World Textile Congress on Natural
and Natural-Polymer fibres (University of Huddersfield,
UK),1997.
10 http://www.nap.edu/readingroom!bookslbmrnl# Polymers.
I I http://www.ntcresearch.org/currentlyear8/1M98-C05.htm.
12 Kaplan D, in Silk Polymers: Materials Science and
Biotechnology, American Chemical Society Symposium Series
544, edited by D Kaplan, W W Adams, B Farmer, & C Viney
(American Chemical Society, Washington, D.C.), 1994, 1 76- 1 84.
13 www.accessexcellence.orgIWN/SU/spider.html.
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
213
http://natural biopolymer.com.
Hamlyn P F, Text Mag. 3 ( 1 995) 6- 1 0.
www.woza.co.zalforum2/juI99/spidersilk23.htm.
http://www.esb.ucp.ptl-bungahlcelluloslmaria2.htm.
http://www.rensselaer.edu/deptlchem-englBiotechEnvironlCELLULOSElcell l .htm.
http://www.kanebo.co.jp/.
http://www.progressivefarmer.comlissuel0999/cornldefaultasp.
http://www.jnmr.comldezlonline/contentnlp3.htm!.
Jpn Nonwovens Rep, ( 1 1 )( 1998) 28.
http://www.technica.netlNFlNFlllactron.htm.
http://natural biopolymer.com.
http://www.ntcresearch.org/currentlyear91M99-G I I .htm.
http://www.naI. usda.govlbiclBiotech]atentsl I 994patentsl053
34520.htmI.
http://www.ntcresearch.org/currentlyear9IMOO-D03.htm
Hobson D B & Wales D S, J Soc Dyers Colour, 1 14 (2)
( 1998) 42.
Douglas M,US Pat 05374543 ( 1 994).
Connor K E O', Dobson A D W & Hartmans S, Appl Environ
Microbiol. ( 1 997) 4287-429 1 .
Chivukula M & Renganathan V , Appl Environ Microbial,
December ( 1 995) 4374-4377.
Shin K S, Oh I K & Kim C J, Appl Environ Microbiol, May
( 1 997) 1 744- 1 748.
Vyas B R M, Molitoris H P, Appl Environ Microbial.
November ( 1 995) 3 9 19-3927.
Collins P J, Field J A, Teneunissen P & Dobson A D W, Appl
Environ Microbiol, July ( 1 997) 2543-2548.
Willmott N, Guthrie J & Nelson G, J Soc Dyers Colour, 1 1 4
( 1998) 38-4 1 .