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1. INTRODUCTON:
Biotechnology is the application of living organisms and their components toindustrial products and processes. In 1981, the European federation of Biotechnologydefined biotechnology as integrated use of Biochemistry, Microbiology, andchemical engineering in order to achieve the technological application of thecapacities of microbes and cultured tissue cells. Defining the scope ofbiotechnology is not easy because it overlaps with so many industries such asthe chemical industry or food industry being the majors, but biotechnology hasfound many applications in textile industry also, especially textile processing and effluent management. Consciousness and expectations for better quality fabric andawareness about environmental issues are two important drivers for textileindustry to adopt biotechnology in its various areas.
2. BIOTECHNOLOGY INTEXTILE PROCESSING
The major areas ofapplication of biotechnology in textile industry are given below:
Improvement of plant varieties used in the production of textile fibres and infibre properties
3. Improvements in Natural fibres:
Biotechnology can playa crucial role in production of natural fibres with highly improved and modified properties besides providing opportunities for development of absolutely newpolymeric material. The natural fibres under study are cotton, wool and silk.
3.1 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 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,
appearances, maturity and color.
3.1.1 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 saleable product using pheromones (insects mating hormones) and monitoring. Use of
excessive pesticides is posing serious threats to the green image of cotton. After
years of research, a completely new kind of tool is available for cotton
growers to ward off the pink bollworm, one of the major 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 is 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
variety carrying the patented gene.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 promotergene capable of delivering a large but highly localized dose of toxin within 30-40s of
an insect biting.
3.1.2
Coloured cotton
Developments 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 the
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
production of blue dye, until a cheaper synthetic method is discovered. By
2005, Monsanto hopes to have this blue-coloured cotton commercially available.
3.1.3
Hybrid cotton
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
introduced into cotton core in a similar manner.
These customized fibres will be tailored to the need 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 containing enzymes that
can biodegrade environmental contaminants. These fibres would be placed in filters
through which contaminated water is passed.
4. 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.
4.1 Protein Polymers:
Biological 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 proteins is being explored.
Efforts in biosynthesis have been directed towards the preparation of precisely defined polymers of three kinds
(1) Natural proteins such as silks, elastins, collagens and marine bioadhesives,
(2) Modified versions of these biopolymers, such as simplified repetitive sequence of the native protein, and (3) synthetic proteins designed de novo that have no close natural analogues. Although such syntheses pose significant technical problems, these difficulties have 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.
4.1.1
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 fibres.
Dragline silk is at least five times as strong as steel, twice as elastic as
nylon, waterproof and stretchable. Moreover, it exhibits the unusual behavior
that the strain required to cause failure actually increases with increasing
deformation.
4.2 Other New Fibres
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:
4.2.1
Chitins and Chitosans:
Chitins and chitosans
both can form strong fibres. Chitin is found in the shells of crustaceans, such
as crab, lobster, shrimps 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.
Wound dressing based on calcium alginate fibres are marketed by Courtaulds under
the trade name Sorbsan. Present supplies of this polysaccharide rely on its
extraction 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 specialty end uses
such as wound dressings. Additional biopolymers, not previously available on a
large scale, are now coming into the market, thanks to biotechnology.
4.2.2 Bacterial cellulose:
Cellulose produced for industrial purposes is usually obtained from plants 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 polysaccharide in the form of ribbon like polymerization, high tensile
strength and tear resistance and high hydrophilicity that distinguishes it from
other forms of cellulose. This bacterial 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 skin substitute and in wound healing bandages.
4.2.3
Corn fibre:
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.
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, papermaking, auto seat
covers and household use. 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 such as woven cloth, thread
and non-woven cloth.
4.2.4
Polyester fibres:
It has been known since
1926 that certain polyesters are synthesized and intra-cellulose deposited in
granules by many micro-organism. 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. It is being commercially produced from Alcaligenes eutrophus by Zeneca Bioproducts and sold under the trade name Biopol. 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 specialty packaging uses. Because of its
immunological compatibility with human tissue, PHB also has utility in
antibiotics, drugs delivery, medical suture and bone replacement applications.
5. 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 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 biofabrics. 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 repellents.
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 pressure2.
6. ENZYMES IN TEXTILE FINISHING:
Textile finishing
sector requires different chemicals, which are harmful to the environment.
Sometimes they may affect the textile material if not used properly. So instead of using such chemicals we can use the enzymes. The finishing of denim
garments has been revolutionized by application of enzymes. Enzymes are very
specific in action when they are used under the required conditions. The processes in which enzymes can be used are desizing, scouring, bleaching, biowashing, degumming
etc.
Amylase, pectinase, and glucose oxidase are enzymes used for desizing, scouring, and bleaching respectively in enzymatic preparation processes. Desized samples show completely size removal using amylase enzyme. Samples scoured with pectinase are immediately and uniformly wet. Amount of pectin and other substances left on scoured samples from both conventional and enzymatic processes were measured along with sample strength and whiteness index. Samples bleached with glucose oxidase obtain whiteness index 15-20 degree improvement with low strength loss. Conventional preparation of cotton requires high amounts of alkaline chemicals and consequently, huge quantities of rinse water are generated. An alternative to this process is to use a combination of suitable enzyme systems. Amyloglucosidases, Pectinases, and glucose oxidases have been selected that are compatible concerning their active pH and temperature range. A process has been developed that allows the combination of two or all three preparation steps with minimal amounts of treatment baths and rinse water. Whiteness, absorbency, dyeability and tensile properties of the treated fabrics have been evaluated.
The use of biocatalyst in the textile industry is already state of the art in
the cotton sector. Research and development in this sector is primarily concentrating on:
● Optimizing and making routine the use of technical enzymes in processes that are already established in the textile industry today.
● Preparing enzyme-compatible dyestuff formulations, textile auxiliary agents and chemical mixtures.
● Producing new or improved textile product properties by enzymatic treatment.
● Providing biotechnological dyes and textile auxiliary agents, which are suitable for industrial use, and can possibly be synthesized in-situ (i.e. on-line for the application process).
6.1 Extremophile Micro-Organisms:
Numerous
micro-organisms have learnt to live in very different and difficult
environmental conditions, e.g. in high temperatures, in acid and alkaline
conditions and in the presence of salt concentrations. These extremophile
micro-organisms live in the most inhospitable and unspoilt environments on
earth. Where other micro-organisms do not exist, they are to be found in the
deepest oceans under pressures of more than 100 bar, in hot volcanic sources at
over 100 C in cold regions at temperatures around freezing point, in salt lakes
(up to 30% salt concentration) and also in surroundings with extreme pH values
(pH <2,> 9). The cell components (enzymes, membranes) of extremophile are
optimally adapted to extreme environmental conditions, and have characteristics
(stability, specificity and activity), which make them interesting for
biotechnological application.
At the Hamburg-Harburg (D) University of Technology, a comprehensive screening programmed for isolating exremophile micro-organisms (like starch, proteins, and hemicellulose for example) has been implemented which is able to produce enzymes for breaking down biopolymers, alkanes, polyaromatic carbohydrates (PAK) plus fats and oils. Within the framework of these studies, a range of biotechnologically relevant enzymes like amylases, xylanases, proteases, lipases and DNA polymerases for example have been enriched and characterized.
6.2.
Conversion of Natural Polymers By Extremozymes:
Starch is one of the
most important biopolymers on this earth. The macromolecule built up from
glucose units, plays an outstanding role in the food industry under the
collective concept modified starch this is found in many foods. Amylases and
branching enzymes for example are used for modifying starch. With the aid of
thermostable starch-modifying enzymes, starch finishing can be carried out more
purposefully and efficiently, since for example the space-time yield at high
temperatures is significantly better due to improved starch solubility.
Thermo-alkali-stable enzymes (active at pH >8 and 600C) are used in washing
and harness rinsing agents in order to remove tenacious starch accumulations
with simultaneous reduction in detergent quantity.
6.3.
Cyclising Enzymes:
So-called cylodextrins
can be produced from starch with the aid of cyclising enzymes cyclodextringlycosyl-transferase,
CGTase) from the recently isolated thermoalkaliphile bacterium Anaerobranca
gottschalkii. Hydrophobic active substances or volatile aromas can be
encapsulated in these cyclodextrins. Cyclodextrins were isolated by Villiers as
early as 1891. In those days, cyclodextrins were regarded as curiosities of no
technical value.The properties of cyclodextrins have been altered by chemical
change (derivatives). The target of much research work is to fix a reactive
cyclodextrin derivative on cellulosic or protein fibres by forming a new
chemical bond on the fibre. The molecules have a hollow space, which is
suitable for absorbing diverse substances like perfume for example. Many
application possibilities and effects arise out of this complexing like for
example:
● Increased water solubility
● Change of rheological characteristics
● Stabilization against UV radiation, thermal disintegration, oxidation and hydrolysis
● Reduction of unpleasant smells
● Absorption of microbe-eliminating products
6.4.
Cellulose from Extremophile Micro-Organisms:
Cellulose is also a
biopolymer built up of glucose units. It forms the framework of higher plants
and is an important resource in the textile industry. The use of cellulases in
detergents leads to colour revival (colour detergent) and the improved removal of vegetable soiling. Cellulases are also successfully used in biostoning. In
contrast to conventional cellulases, which are obtained from mesophilic fungi
as a rule, cellulose-hydrolyzing enzymes from extremophile micro-organisms have
the advantage of being capable of use even at high temperatures and pH values.
6.5 Xylanolytic enzymes:
Xylanolytic enzymes
form another group. Xylan is heterogeneous molecule (basic component: xylose
sugar), which makes up the largest proportion of the polymeric vegetable cell
wall component hemicellulose. Xylanophile micro-organisms have enormous
biotechnological potential. Thermobile xylanases are already being produced on an industrial scale today, and are used as fodder and food additives. In past years,
interest in xylanases was concentrated particularly on enzymatic paper bleaching.
Current studies have shown that the enzymatic treatment of paper is an
ecologically and economically sound alternative to the hitherto employed
chlorine-based bleaching process. Enzymes which can for example destroy the
coloured attendant substances of cotton are of interest to the textiles
industry. The quantity of caustic soda and salt required in peroxide bleaching
could be reduced by this type of enzymatic bleaching.
Reuse of the bleaching liquor after hydrogen peroxide bleaching is already
possible today by using the enzyme catalase after bleaching. This enzyme
destroys excess hydrogen peroxide, making use of the bleaching liquor for other
finishing stages possible. Windel Textil GmbH & Co. (D) already uses the
so-called Bleach-Cleanup process, in which bleaching agent residues are
removed from textiles, resulting in a reduction of energy, time and
water-intensive washing operations at high temperatures.
Research projects at the German Wool Research Institute (DWI) in Aachen (D) are devoted to the use of enzymes in wool processing, including the removal of vegetable residues from the wool, increasing the degree of whiteness, improving handle, improving dyeability by increasing intensity of colour and for felt-free finishing. Already interesting in practice is the felt-free finishing of wool. An enzyme not previously employed in the textile industry modifies the scale-like surface of wool fibres preventing felting. The enzyme Lanazym has hitherto been used only in discontinuous batch processing.3
7.
DECOLOURISATION OF DYES BY USING BIOTECHNOLOGY:
The synthetic dyes are
designed in such a way that they become resistant to microbial degradation
under the aerobic conditions. Also the water solubility and the high molecular
weight inhibit the permeation through biological cell membranes. Anaerobic processes convert the organic contaminants principally into methane and carbon dioxide, usually
occupy less space, treat wastes containing up to 30 000 mg/l of COD, have lower
running costs and produce less sludge4. Azo dyes are susceptible to anaerobic
biodegradation but reduction of azo compounds can result in odour problems. Biological systems, such as biofilters and bioscrubbers, are now available for the
removal of odour and other volatile compounds. The dyes can be removed by
biosorption on apple pomace and wheat straw5. The experimental results showed
that 1 gm of apple pomace and 1 gm of wheat straw, with a particle size of
600m, were suitable adsorbents for the removal of dyes from effluents. Apple pomace
had a greater capacity to adsorb the reactive dyes taken for the study compared
to wheat straw.
7.1 Decolourization of the Dye House
Effluent Using Enzymes:
The use of lignin
degrading white-rot fungi has attracted increasing scientific attention as
these organisms are able to degrade a wide range of recalcitrant organic
compounds such as polycyclic aromatic hydrocarbons, chlorophenol, and various
azo, heterocyclic and polymeric dyes. The major enzymes associated with the
lignin degradation are laccase, lignin peroxidase, and manganese peroxidase.
The laccases are the multicopper enzymes, which catalyze the oxidation of
phenolic and non-phenolic compounds.
However, the substrate of the laccases can be extended by using mediators such
as 2, 2-azoinobis-(3-ethylthiazoline-6-sulfonate), 1-hydroxybenzotriazole. The
following fungi have been used for laccase production and for the decolourization
of synthetic dyes. Trametes Modesta, Trametes Versicolour, Trametes Hirsuta,
and Sclerotium Rolfsii 6 from the results obtained it was clear that Trametes
Modesta laccase showed the highest potential to transform the textile dyes into
colourless products. The rate of the laccase catalyzed decolourization of the
dyes increases with the increase in temperature up to certain degree above
which the dye decolourization decreases or does not take place at all. The
optimum pH for laccase catalyzed decolourization depends on the type of the dye
used. Dyes with different structures were decolourized at different rates. From
these results it can be concluded that the structure of the dye as well as the
enzymes play major role in the decolourization of dyes and it is evident that
the laccase of Trametes Modesta, may be used for decolourization of textile
dyestuffs, effluent treatments, and bioremediation or as a bleaching agent.
Another study carried out by E. Abadulla et al, has shown that the enzymes Pleurotus ostreatus, Schizophyllum Commune, Sclerodium Rolfsii, Trametes Villosa, and Myceliophtora Thermiphilia efficiently decolourized a variety of structurally different dyes. This study also shows that the rate of reaction depends on the structure of the dye and the enzyme7.
Activated sludge systems can also be used to treat the dyehouse effluents. But
the main difficulty with activated sludge systems is the lack of true contact
time between the bacteria of the system and the suspended and dissolved waste present. Immobilized microbe bioreactors (IMBRs) address the need of increased microbial/waste
contact, without concomitant production of excessive biosolids, through the use
of a solid but porous matrix to which a tailored microbial consortium of
organisms has been attached. This allowed greater number of organisms to be
available for waste degradation without the need of a suspended population and
greater increased contact between the organisms and the waste in question8.
8. CONCLUSION:
The advent of
biotechnological applications in textile processing widens the already existing
wide horizons to produce aesthetically colourful magnanimous and ecologically
friendly textiles, ringing in a new era of synergetic application of life
sciences. As of today the huge textile industry is open to welcome the immense
possibility of the various biotechnological applications limited by the
limitations of being eco friendly and not harming either the food web or the
life cycle of any other living creature. Such awareness is gradually
metamorphosing a tool that could be intelligently used to meet the demand of
our fashion trends. Enzymes, bacteria and insects could be biologically
modified into a fashion promoter if engineered with great caution. A major
breakthrough in the textile industry is eagerly awaited through these
biotechnological applications.
REFERENCES:
Biotechnology, Edited
by H. J. Rehm and G. Reed Biotechnology application in textiles industry,
Deepti Gupta, Indian Journal of Fibres & Textile Research Vol.26,
March-June 2001.Biotechnology: process and products, Andrea Bohringer, Jurg
Rupp, International Textile Bulletin, June 2002.
The Biotechnology Approach to Colour Removal from Textile Effluent, by Nicola
Willmott et al. J of Soc. Of
Dyers and Col., 1998, 114, 38-41.
Removal of dyes from a synthetic textile dye effluent by Biosorption, by T.
Robinson, et al, Water Research, 36, 2002, 2824-2830.
Decolourization of textile dyes by laccases, by G. S. Nyanhongo, et al, Water
Research, 36, 2002, 1449-1456.
Enzymatic decolourization of Textile Dyeing Effluents, by E. Abadulla et al,
Textile Res. J. 70 (5), 2000, 409-414
Improving Bio-treatment For Textile Waste Decolourization, by Caroline A.
Metosh et al, American Dyestuff Reporter, July/August19
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