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Australasian Biotechnology (backfiles)
AusBiotech
ISSN: 1036-7128
Vol. 8, Num. 6, 1998
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Australasian Biotechnology, Vol.8, No. 6, December 1998
Saccharification of Paper Materials by Mixtures of Cellulase from Penicillium Funiculosum and Aspergillus Niger
Jacobus P.H. van Wyk and Alfred M. Mogale, Department of
Chemistry and Biochemistry, Medical University of Southern Africa, South Africa
Code Number:AU98043
Paper materials were treated with cellulase from Penicillium funiculosum and Aspergillus
niger to hydrolyze there cellulose component and mixtures of these enzymes were applied
to increase the extent of degradation. Cellulases were prepared at equal concentrations
and a ratio mixture of 1 : 1 resulted in the strongest increase of saccharification
relative to the individual action of both enzymes on all substrates. Office paper resulted
in the highest increase of saccharification at this enzyme combination relative to the
action of P. funiculosum cellulase on it. P. funiculosum cellulase showed
the strongest hydrolysis on all substrates except with office paper that exhibited a
higher suscep-tibility for cellulase from A. niger.
Introduction
The recycling of waste is topical not only to conserve the environment but it could
also be applied to develop alternative and renewable energy resources. Used paper
materials constitute a major component of organic based waste dumped annually. The polymer
cellulose is a major structural component of paper materials with its monomeric glucose
units linked by means of b-1,4-glycosidic bonds. Cellulose is susceptible for acid- (Ullal
et al, 1984) and cellulase catalyzed (Van Wyk and Botha, 1997) hydrolysis producing
reducing sugars such as glucose, but its association with hemi-cellulose and lignin
results in a relative high resistance toward these ways of saccharification. The
hydrolysis of cellulose is a complex process and attempts to improve it, receive currently
attention (Baker et al, 1998). Cellulases are mostly manifested in fungi (Persson et
al, 1991) and bacteria (Wood et al, 1986) and mixtures of cellulases from
P.
funiculosum and
A. niger were used to increase degradation of cellulose present
in foolscap paper, filter paper, news paper, office paper and micro-crystalline cellulose.
Materials and Methods
Cellulose Materials
Foolscap paper, filter paper (Whatman no 1), newspaper, office paper were prepared as
pieces of 0.5 cm x 0.5 cm and 20 mg used during an incubation as well as powdered
microcrystalline cellulose (MCC) from Merck.
Enzymes and Incubations
Commercial cellulases from P. funiculosum and A. niger were obtained from
Sigma and prepared separately at a concentration 0.7 mg/ml in 0.05 M Na-citrate buffer pH
4.0. All cellulose materials were incubated with both enzymes individually and at ratios
of P. funiculosum : A. niger, 1:3, 1:1, 3:1. Cellulose materials were mixed
with 1 ml of the enzyme solutions and incubated for 2h at 550C followed by
determination of the total reducing sugars produced. All incubations were performed in
duplicate.
Determination of total reducing sugars and protein
concentration
Reducing sugars were determined with the DNS method (Miller et al, 1960) using
glucose as standard. For protein determinations BSA (fraction V, Sigma) was used as a
standard (Lowry et al, 1951).
Results and Discussion
Figure 1 reflects the saccharification of all paper materials and MCC by cellulases
from P. funiculosum and A. niger as well as mixtures thereof. Foolscap paper
showed the strongest susceptible for hydrolysis by cellulase from P. funiculosum followed
by filter paper, MCC and newspaper. Office paper exhibited the highest resistance towards
degradation by this enzyme whilst it showed a relative high susceptibility toward
degradation by cellulase from A. niger. Foolscap paper also exhibited the highest
susceptibility towards hydrolysis by cellulase from A. niger. Cellulase from P.
funiculosum exhibited however a higher activity on all cellulose materials except with
office paper as substrate.
Cellulase is an enzyme consisting of different components (Lee and Fan, 1980)
responsible for different steps during hydrolysis of cellulose that also contains
structural sections with varying suscep-tibilities for enzymatic catalyzed hydrolysis (Fan
et al, 1980). Cellulases from different sources exhibit different compositions and
a lack of specific components could be supplemented from other sources making the mixing
of cellulases an important procedure for effective hydrolysis of cellulose materials.
Figure 1Formation of total sugars during saccharification of paper materials and microcrystalline cellolose by individual action and mixtures of celluloses from P.funiculosum and A. niger.
To increase the degree of saccharification both cellulases were mixed and incubated
with all cellulosic materials (Figure 1). An equal mixture (1:1) resulted in the strongest
increase in saccharification with all substrates. Similar tendencies with cellulases from P.
funiculosum and Trichoderma reesei on these cellulose materials were observed
(Van Wyk, 1998). The increase in total reducing sugar production at optimum cellulase
ratio relative to individual cellulase action is reflected in Table 1. The highest
increase in saccharification was observed with office paper, relative to the action of
cellulase from P. funiculosum (1640 % increase) on it and with newspaper relative
to the action A. niger cellulase (871% increase).
Due to the lost in structural qualities used paper materials can be recycled only a
number of times before dumping thereof becomes obvious. It is thus important to research
the paper component of organic based waste as a potential resource of bioenergy.
Table 1. Increase (%) of total reducing sugar production from paper materials
and micro-crystalline cellulose at the optimum ratio mixture of cellulase from P.
funiculosum and A. niger relative to the individual cellulase action.
Substrate |
Increase (%) in total reducing sugar
production relative to individual cellulase action |
|
Penicillium funiculosum |
Aspergillus niger |
Foolscap paper |
9 |
70 |
Filter paper |
12 |
66 |
Office paper |
1640 |
30 |
News paper |
126 |
871 |
CMC |
43 |
320 |
References
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Hydrolysis of cellulose using ternary mixtures of purified cellulases. Appl. Biochem.
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Copyright 1998 Australian Biotechnology Association Ltd.
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