Acid cellulase, when used in
biopolishing, offers a number of benefits such as improvement in pill
resistance, cooler feel, brighter luminosity of colours and softness, and at
the same time the treatment results in certain adverse effects like loss in
weight and strength, infer K J Vishnu Vardhini and N Selvakumar.
In the textile industry especially in
the apparel sector, cotton, the king of fibres, is widely used because of
properties. Cotton and cotton-blended fabrics are subjected to various wet
processing treatments to enhance its value. The conventional methods of wet
processing of cotton lead to a number of pollution hazards. A number of
environmental regulations are to be fulfilled to safeguard the natural
resources and this has led to growth in the use of enzymes in the textile
industry for greener processing of textiles.
Enzymes are high molecular weight
biological catalysts that mediate all biochemical reactions and are derived
from fungal and bacterial sources for industrial use. These enzymes are
classified into six major classes, based on the reactions they catalyse, and
most of the enzymes used in the textile industry belong to the class ‘hydrolases’(1).
These enzymes catalyse hydrolysis reactions where water insoluble material
is converted into soluble products, which can be washed away. Enzymes called
with a specific name always represent a group of enzymes, which has the same
The first use of enzymes in textile
industry is in desizing cotton fabric with amylase, wherein the starch is
hydrolysed, and this is still used extensively(2). Bioscouring
carried out with a mixture of proteases, pectinases, lipases and cellulases
has also proved to enhance the properties of cotton material(3).
In the bleaching process, glucose oxidase enzyme is used to achieve
controlled production of hydrogen peroxide from oxidation of glucose
released during enzyme desizing(1). In denim washing, neutral
cellulases are used instead of stones or along with stones to give faded
effect(4). Laccases also find application in denim processing to
decolour indigo with the help of a mediator thus giving a bleached effect(5,6).
In flax retting, pectinases and
hemicellulases are used for hydrolysing pectin and lignin(6).
Shrink-proofing and deprickling of wool are carried out
enzymes, which modifies the scales on the fibre(7). A mixture of
cellulases and pectinases is used in the carbonisation of wool(7,8).
Degumming of silk is carried out using serine protease, which degrades
sericin, which is a protein leaving the fibroin, also a protein intact in
the fibre(1,6). Polyester hydrophilisation is done with lipases,
which hydrolyses fatty acid esters and other carboxylic acid esters in the
fibre(6,8). Cellulase enzymes are also found to be useful in
laundry detergents as an alternative to household fabric softeners(9).
Biopolishing is an important finishing treatment carried out on cellulosic
fabrics using acid cellulases to achieve improvement in gloss, luminosity of
colours and resistance to pilling, cooler feel and clear surface(10-12).
This article deals with acid cellulases used for biopolishing of cotton
fabrics, and the effect of their application on cotton fibre and products
made from it, namely, yarns and fabrics.
Cellulases are derived from both fungal
and bacterial sources. They find extensive application on cellulosic
materials, and about 10% of the finishing of these materials is estimated to
be performed by these enzymes to achieve various effects(13).
They also find application in food, pharma and paper industries(14).
Cellulases used in biofinishing of cellulosic fabrics are derived from more
than ten different fungal species, which vary in their component
composition, application pH and special effects produced(13).
Cellulases derived from the fungus, Trichoderma reesei, is widely used in
textile finishing, since it gives higher yield in industrial production. In
addition to cellulases originating from the above fungus, those originating
from Humicola insolens can also degrade cotton cellulose efficiently, and
they find extensive application in biostoning of denim fabric(15-18).
Components of cellulase and mechanism
of its action on cellulose
Cellulase derived from Trichoderma
reesei contains a group of enzymes namely, endoglucanases (EG),
cellobiohydrolases (CBH) or
exoglucanases and b-glucosidases and they act
synergistically to hydrolyse cellulose. It has been found that this fungus
secretes atleast five types of EGs and two types of CBHs. It is estimated
that the secreted enzyme constitutes 60% of CBHI and 10% EGI and EGII. The
structures of EG and CBH shown in Figure 1 reveal the presence of cleft in
the EG and a tunnel in the CBH. It is reported that due to the presence of
tunnel, CBH has a more pronounced effect on the rate of hydrolysis than the
EG(13,19,20). Cellulases can be used for biopolishing as derived
from their sources or after enriching the EG content in the mixture. The
mixture of endoglucanases, exoglucanases and b-glucosidases are called whole
cellulases or total cellulases. Using advances in biotechnology new strains
are being developed for producing novel cellulase compositions(21).
The mechanism of cellulase action on
cellulose (Figure 2)(14) is as follows: (i) The endoglucanases
degrades cellulose by selectively cleaving through the amorphous sites and
breaking long polymer chains into shorter chains (ii) Cellobiohydrolases
degrades cellulose sequentially from the ends of glucose chains, thus
producing cellobiose as the major product and it plays a mediator role in
degrading cellulose and (iii) b-glucosidases complete the hydrolysis
reaction by converting cellobiose into glucose (4,15,22,23).
Activity of cellulase
Activity of an enzyme, expressed as U/g
or U/ml, is a measure of conversion of substrate molecules into products by
a g or ml of an enzyme in a
unit time. Cellulases form glucose as product.
The substrates commonly used for characterisation of cellulases are carboxy
methyl cellulose (CMC), phosphoric acid swollen Avicel and filter paper
(FP). Among these CMC is amorphous cellulose, whereas FP has both amorphous
and crystalline cellulose. Screening of whole cellulase preparations is done
predominantly using FP activity(24) involving Whatman No:1 filter
paper. This type of characterisation of cellulase using activity is not much
useful in textile applications since the activity determined does not have
any correlation with weight loss and strength loss obtained in fabrics(25).
Effect of total cellulase and their components on cotton
attacks the 1, 4 - b-glucosidic bonds of cellulose and forms glucose, cotton
products treated with this enzyme experience weight loss. Moreover, the
treatment results in change in many other properties also and the extent of
these changes depends on various factors. Literature pertaining to studies
carried out with total cellulases and total cellulases with some components
enriched in it are given below.
Effect on supramolecular structure
Kleman – Leyer et al(22) studied the molecular size distributions of
cotton cellulose treated with EGI, CBHII and their combination for periods
varying from 12 to 192 hours. The treatment carried out for 12 hours with
EGI and its combination with CBHII has found to increase polydispersity by
two fold whereas the treatment for longer duration resulted in decreased
polydispersity values. The above actions reveal that the EGI continuously
degrades cellulose. Molecular size distributions of cotton treated with
CBHII was found to be unaffected. The fibre crystallinity index after
cellulase treatment on cotton substrates was found to be unchanged
regardless of the extent of agitation and also the nature of the enzyme used
ie, monocomponent EG and total cellulase(21,26).
Marie – Alice et al(20)
studied the effect of time of treatment of whole cellulase on supramolecular
structure of cotton. The SEM photographs of the samples revealed that the
treatments have caused damage to the primary wall. The results namely
increase in number average molecular weight and a reduction in
polydispersity obtained in the study confirmed the removal of primary wall
and this damage increased with treatment time. It was also found that there
was no change in pore size distribution and disordered and highly ordered
Effect on fibre and yarn properties
Melissa Ann Stewart(27)
reported that treatment with biopolishing enzyme results in strength loss in
cotton fibres. An attempt on yarns spun using
fibres treated with
monocomponent cellulases CBHI, CBHII, EGI, EGII and commercial enzyme
revealed that the tenacity of the yarns spun using the above fibres were
lower than that of yarns spun with untreated fibres. The EGI, EGII and
commercial enzyme treated yarns show higher yarn hairiness and it is
suggested that such a behaviour is due to the endo-activity of these
enzymes. All the enzymes used in the study were found to have insignificant
effect on yarn evenness(28).
100% cotton and cotton/polyester yarns made
from different spinning systems were evaluated by Radhakrishnaiah et
al(29,30) after treating them with a commercial cellulase enzyme. The cotton
yarns were spun from ring, rotor and OE friction systems while the
cotton/polyester yarns were spun from ring, rotor and air-jet systems. It
was reported that cotton and cotton/polyester yarns spun from various
spinning systems and cotton/polyester bicomponent yarns suffered a
significant loss in strength and breaking elongation on treatment with
cellulase. The only exception found in this case was the friction spun
cotton yarn. Changes due to cellulase enzyme hydrolysis of cellulosic
fabrics have been studied by Buschle-Diller et al(31). They found that
strength loss in yarn increased with increased weight loss in cotton
Effect on fabric properties
Cellulase treatment of fabric results
in a number of changes in their properties. On treating with whole
cellulases, loss in breaking strength was observed and it was found to have
non-linear relationship with weight loss(30). The knitted fabrics were found
to show reduction in bursting strength and improvement in pilling resistance(31). Ramkumar and Gus
Abdalah(32) reported that the cellulase
enzyme treatment significantly improved the fabric smoothness, which is
measured in terms of frictional parameters. The cellulase treated cotton
woven fabrics show reduction in bending rigidity and hysteresis of shear
force(33). Joao et al(34), reported that the dimensional stability of cotton
woven and knitted fabrics improved on cellulase treatment. The low stress
mechanical properties of cellulase treated fabrics were found to improve.
The fabrics became smoother, softer and fuller and offered less resistance
to bending and stretching. Comparison between the properties of cellulase
treated cotton fabrics and alkali treated polyester fabrics showed that the
former undergoes a reduction in residual curvature and residual shear strain
to a lesser extent than the latter(33).
Effect on dyeing
Buschle – Diller reported that the colour yield of cotton increases on
cellulase pretreatment. Ibrahim et al(37) found increase in
colour yield for
direct and reactive dyes with increasing weight loss on cellulase treatment
on cotton. In contrast to this, Koo et al(38) reported reduction in colour
yield with increase in weight loss. Investigation by Buschle – Diller et
al(39) showed no significant change in colour yield for medium weight loss.
They further reported that there is an improvement in colour yield for
reactive dyes and it further increased with increase in weight loss. Vat
dyes also showed an improvement in colour yield but it decreased with
increase in weight loss. Anand Kanchagar(40) found that there were no
changes in colour yield for reactive dyes for smaller weight losses. The
results of the above studies reveal that there is a need for further work in
order to understand the behaviour of various classes of dyes on the colour
yield obtained on cellulase treated cotton materials.
cellulase action on cotton Pretreatment
Mercerised fabrics subjected to
cellulase enzyme treatment were found to increase rate of hydrolysis due to
increased available adsorption sites. Further cellulase treatment results in
higher strength loss in mercerised fabrics compared to unmercerised fabrics(41). Moika Nicolai and Axel
Nechwatal(42) reported that
pretreatments with ammonia and NaOH enhanced the effect of enzymatic
treatment on cotton yarns.
Kier boiled cotton yarn samples subjected to
various pretreatments were considered for evaluating the rate of hydrolysis
on treatment with cellulase enzyme. Pretreatments namely mercerisation with
24% NaOH, decrystallisation using liquid ethylamine at icebath temperature
and decrystallisation using liquid ethylamine under ambient conditions were
used. The rate of hydrolysis obtained for all the pretreated samples were
higher than that of the sample not subjected to pretreatment. Among the
pretreated samples decrystallisation treatment carried out using liquid
ethylamine under ambient conditions was found to give highest rate of
hydrolysis. The same trend was observed with respect to degree of
polymerisation and % crystallinity of the pretreated samples(43).
of pretreatments such as steaming, oxidation with Fenton’s reagent and
washing with mild and strong alkalis on the accessibility of cotton fibres
for cellulase was determined. It was found that all the pretreatments
improved accessibility of cotton towards cellulase. The order of
accessibility of cellulases was in the following order of steaming <
oxidation < mild alkaline wash < strong alkaline wash(28).
Studies conduced on enzymatic action of cellulase enzyme on dyed cotton
using direct, reactive and vat dyes reveal that the cellulase action is
retarded either by the presence of dye molecules or interactions between dye
and cellulose molecules(36-38, 44-47). Factors, namely, dye class and size,
substantivity and functionality of the dye molecule, which influence the
retardation of cellulase action also have been investigated(37,44,46-48). It
is proposed that the blockage caused by the dye molecules prevents cellulase
approaching 1, 4-b glucoside linkages in cellulose resulting in the
retardation of the action of cellulase.
Agitation is an important
factor in cellulase treatment of cotton fabrics. A number of studies have
been conducted to understand the effect of agitation on fabric properties.
Especially, for the depilling of fabrics agitation plays an important role
as it helps in cellulase adsorption followed by cutting of fibres and
fibrils which were weakened by cellulase action(15). SEM photographs of
cellulase treated fabrics showed that higher level of agitation used for the
treatment affect the fibre surface in a short treatment time itself(26).
was found that when treatment was given in jet and winch machine using same
type of enzyme and similar process conditions, the level of effects produced
on fabrics were different which is due to the difference in agitation
provided by these machines(49). Jim Liu et al(25) based on study conducted
involving enzymes namely monocomponent endoglucanases, endoenriched
cellulases and total cellulases at different levels of agitation suggested
that when selecting cellulases for biopolishing, the machine to be used has
to be given due importance.
Study conducted by Lenting and
reveal that a minimum level of agitation is to be employed for optimum
performance of cellulase towards biopolishing. Also when suggesting for
minimizing tensile strength loss on cellulase treatment to fabrics agitation
is considered as an important factor(44) and on measuring the tactile
properties of fabrics treated with and without mechanical agitation, it was
found that they were highly influenced by agitation and positive effects
were found due to agitation(35).
Treatment time has a greater influence
on cellulase action on cotton. Fibre damage increases dramatically when
longer treatment durations are used(15). Longer treatment times with no
agitation were found to affect the internal structure, whereas short
treatment times with higher agitation affect the fibre surface(25).
Generally, increase in treatment time results in greater weight loss and
strength loss. The relationship between time of treatment with these
properties were found to be non linear(15,25,43). The enzymatic hydrolysis
for longer treatment time leading to higher weight loss results only in a
slight decrease in degree of polymerisation(44). An attempt was made by Ajoy
and Nolan(51) to model the enzymatic hydrolysis involving initial substrate
concentrations, flow rate and treatment time. The following empirical
equation was suggested. Fractional conversion, Pt/So = where, Pt is the
product concentration (mg/ml) at time t, So is the initial substrate
concentration (mg/ml), x, y, z are flow rate dependant constants.
Yarns produced with different structural features subjected
to cellulase treatment were evaluated for their hand related mechanical
behaviour. Cotton yarns spun from ring, rotor and OE friction systems and
cotton/polyester yarns spun from ring, rotor and air-jet systems were
considered. Also polyester cotton bicomponent yarns that exhibit systematic
differences in fibre arrangement within the yarn were considered. It was
found that hand related properties of all the above yarns improved on
Among the cotton and P/C yarns, OE friction spun cotton
yarn and air-jet spun P/C yarn showed maximum improvement in hand related
properties. The treatment altered the properties of blended P/C ring spun
yarn more than those of the P/C bicomponent yarn. The fibre arrangements in
the bicomponent yarn was found to influence the weight loss suffered by the
cellulase treatment(29,30). Nilgun Ozdil et al(32) reported that knitted
fabrics, produced from yarns spun using spinning routes such as OE rotor,
combed ring and carded ring, on treatment with cellulase give difference in
weight loss, strength loss and pilling rate showing that the type of yarn
used for fabric production has influence on cellulase treatment.
structure also influences the weight loss on cellulase treatment. It was
found that weight loss was more in knitted fabrics than the woven fabrics
due to structural differences. When poplin and flannelette fabrics of
different EPI and PPI were treated with different compositions of enzyme at
low and higher agitations, its effect on weight loss, ratio of breaking load
to weight loss and pilling level which reveal that fabric structure
influences the cellulase treatment(15,21).
Synergistic effects of cellulase
action on cotton
Lea Heikinheimo and Johanna Buchert(19) studied the
synergistic effect of T reesei cellulases namely CBHI, CBHII, EGI and EGII
alone and in different combinations on knitted fabrics. Results obtained on
the properties evaluated reveal that there are clear differences between the
action of individual enzymes and their defined mixtures. No correlation was
found to exist between high weight loss and good pilling results as well as
weight loss and strength loss. It is suggested that the reduced pilling
tendency can be obtained with lower strength loss by tailoring different
cellulases in the enzyme mixture.
Jim Liu et al(25) carried out studies with
monocomponent endoglucanase, endoenriched cellulase and total cellulase and
found that there is a correlation between weight loss and pilling note for
each of the above enzymes but among enzymes there is no concurrence in
Cavaco Paulo and Almedia(15) have conducted studies on
different fabrics and found that the ratio of breaking load to weight loss
differ for different compositions of enzymes used. The activity of total
cellulase was found to be affected by the level of agitation used in the
treatment. At high agitation levels, EG activity in the total cellulase was
found to increase as against the reduction in the CBH activity(26). Further
EG treatment at high level of agitation makes fabrics feel harsher whereas
total cellulase treatment makes fabrics feel softer. In order to minimise
tensile strength loss in cellulase application, EG enriched cellulase on
even, monocomponent EG is found to be suitable(52).
It is clear
from the number of studies carried out pertaining to acid cellulases and its
application on cotton materials that the use of this enzyme results in both
beneficial and adverse effects. Research findings bring out the facts
regarding the enzyme as well as the effect of pretreatment, material
parameters and process variables on cellulase action. Findings also give an
understanding on the effect of cellulase action on post treatments.
there are areas that require the attention of researchers in order to gain
better understanding on acid cellulase and its action on cotton fibre and
its products having varying degrees of structural complications as well as
associated process conditions used. It is hoped that this review would
certainly be of use to those who are involved in the research and
application of this enzyme, ‘Acid cellulase’.
A and Giibitz G M: Textile Processing with Enzymes, Woodhead Publishing Ltd,
2.Etter J N and Annis P A: Am Dyest Rep, 87 (1998).
Pawar S B, Shah H D, and Andhorika G R: Man-Made Textiles in India, 45 (4)
4. Roshan Paul and Prakash D Pardeshi: ATJ, 11 (1) (2002) 29.
Vinod Shelke: Colourage, 48 (1) (2001) 25.
6. Rekha R: Man-Made Text in
India, 45 (10) (2002) 398.
7. Elisabeth Heine and Hartwig Hocker: Rev Prog,
Colouration, 25 (1995) 57.
8. Rashesh Doshi and Vinod Shelke: IJFTR, 26
(1-2) (2001) 202.
9. Annacleta Chiweshe and Patricia Cox Crews: Am Dyest
10. Hemmpel W H: ITB, 37 (3) (1991) 5.
11. Nikhil Verma and Anitha
Nishkam: Textile Trends, 45 (4) (2002) 133.
12. Muthu Manikam M and Ganesh
Prasad J: Colourage, 52 (10) (2004) 41.
13. Arja Miettinen Oinonen,
Trichoderma reesei: Strains for Production of Cellulases for the Textile
Industry, PhD thesis, Genetics University of Helsinki, (2004).
15. Arthur Cavaco-Paulo: Carbohydrate Polymers, 37 (1998) 273.
Schulein: Journal of Biotechnology, 57 (1997) 71.
17. Rui Campos, Arthur
Cavaco-Paulo, Jurgen Andreaus and Georg Gubitz: Textile Res J, 70 (2000)
18. Jurgen Andreaus, Rui Campos, Georg Gubitz and Arthur Cavaco-Paulo:
Textile Res J, 70 (7) (2000) 628.
19. Lea Heikinheimo and Johanna Buchert,
Textile Res J 68 (4) (2001) 273.
20. Marie-Alice Roussella, Noelie R
Bertoniere, Phyllis S Howely and Witton R Goynes: Textile Res J, 72 (11)
21. Cavaco-Paulo A, Almedia L and Bishop D: Text Chem Color, 28
(6) (1996) 28.
22. Karen M Kleman-Leyer, Matti Shiika, Turla T Teeri and
Kent Kirkl T: Applied and Environment Microbiology, 62 (8) (1996) 2883.
Alemdia L and Cavaco-Paulo: Melliand Textilber 74 (1993) 404-407.
Stephen R Decker: Applied Biochemistry and Biotechnology, 107 (1-3) (2003)
25. Jim Liu, Eric Otto, Niels Lange, Philip Husain, Brian Condon and
Henrik Lunel: Text Chem Color, 32 (5) (2000).
26. Artur Cavaco. Paulo, Luis
Almedia and David Bishop: Textile Res J, 66 (5) (1996) 287.
27. Melissa Ann
Stewart: Biopolishing Cellulosic Nonwovens, PhD Thesis, North Carolina State
28. Jaakko Pere, Arja Paulakka, Pertti Nousiainen and
Johanna Buchert: Journal of Biotechnology, 89 (2001) 247.
Radhakrishnaiah P, He Jingwu, Cook L Fred and Gisela Buschle Diller: Textile
Res J 75 (3) (2005) 265.
30. Radhakrishnaiah P, He Jingwu, Cook L Fred and
Gisela Buschle Diller, Textile Res J 75 (4) (2005) 293.
31. Buschle- Diller,
G, Zeronian S H, Pan N and Yoon A: Textile Res J 64 (1994) 270-279.
Nilgun Ozdil, Esen Ozdooan and Tulin Oktem: Fibres and Textiles in Eastern
Europe, 11(4) (2003) 58.
33. Mori R, Haga T and Takagishi T: Textile Res J,
69 (10) (1999) 742.
34. Joao M Cortaz, John Ellis and David P Bishop:
Textile Res J, 72 (11) (2002) 673.
35. Radhakrishnaiah, Xiaomin Meng, Gan
Huang, Buschle-Diller G and Walsh W K: Textile Res J, 69 (10) (1999) 708.
36. Trarore M K and Buschle Diller G: Textile Chem Color and American
Dyestaff Reporter, 1 (1999) 51.
37. Ibrahim N A, EL-Zairy M R, Allam E,
Morsy M S and Hassan T M: Colourage Annual, (1999) 47.
38. Koo H, Ueda M,
Wakida T, Yoshimura Y and Igarashi T: Textile Res J, 64 (1994) 70-74.
40. Anand P Kanchagar: Colourage
Annual, (2001) 29.
41. Koo H, Ueda M, Wakida T, Yoshimura Y and Idrashi T:
Textile Res J 64 (1994) 615.
42. Monika Nicolai and Axel Nechwatal: I T B, 6
43. Reese E T, Segal L and Tripp V W: Textile Res J 27 (1957)
44. Trarore M K: AATCC Book of Papers, IC & E, Nahville, TN, (1996)
45. Mori R, Haga T and Takagishi T: J Appl Polym Sci, 45 (1992)
46. Choe E K, Park S Y, Cha H C and Jeon B D: Textile Res J, 67
47. Buschle-Diller G and Traore M K: Textile Res J, 68
48. Mori R, Haga T and Takagishi T: J Appl Polym Sci, 48 (1993)
49. Cortez J M, Ellis J and Bishop D P: Journal of Biotechnology,
89 (2001) 239.
50. Lenting H B W and Warmoeskerken M M C G: Journal of
Biotechnology, 89 (2001) 217.
51. Ajoy K Sarkar and Nolan Etters J: The
Journal of Cotton Science, 8 (2004) 254.
52. Lenting H B M and Warmoeskerken
M M C G: Journal of Biotechnology, 89 (2001) 227.
K J Vishnu Vardhini Department of Textile Technology, A C
College of Technology, Anna University, Chennai 600 025. N Selvakumar.
Department of Textile Technology, A C College of Technology, Anna
University, Chennai 600 025 Asst Professor.