BATANG KELAPA SAWIT SEBAGAI SUBSTRAT BAGI PENGHASILAN ENZIM-ENZIM LIGNOS·ELULOSIK OLEH Aspergillus terreus MELALUI TEKNIK KULTUR SUBSTRAT PEPEJAL
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Date
1998
Authors
TALIB, ANITA
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Abstract
Oil palm stem( ops) was initially separated into three different components,
i.e. parenchyma(P), vascular bundles(V) and also left intact, i.e. whole oil
palm stem(W). Three different whole ops samples were studied i.e. dried
sample(W1), dried and ground up sample(W2) and 'green' samples (W3).
Solid substrate fermentation was then carried out on the oil palin stem
components using Aspergillus terreus. The substrates were supplemented
with Toyama's medium in different opslmedium ratios, ranging from 1: 1 to
1:8 and the results showed that the Aspergillus terreus cultured on
different components of the oil palm stem produced specific cellulase and
g-glucosidase enzyme profiles.
Higher cellulase activities i.e. endocellulase( CMCase) and total
cellulase(FPase) were obtained from the parenchyma portion compared to
the vascular bundles i.e. 18.4SU and 4.01U compared to 12.2U and O.8U/g
substrate respectively.
Highest activities of g-glucosidase was produced from the whole oil palm
stem(W1) whereby the activities are two times(2X) higher compared to gglucosidase
from the vascular bundles(V) and the parenchyma (P).The
CMCase and FPase from the whole oil palm stem(W1) are 14.29U and 2.21 U/g
of substrate, which is relatively quite good.
The enzyme activities were also dependent on the ops/ medium ratios. the
highest R-glucosidase activities were in the 1: 1 ratio which is quite 'dry'.
CMCase and FPase activites were highest in the 1: 4 and 1: 6 ratios
respectively.
This combination of solid substrate fermentation of oil palm stem using
Aspergillus terreus was found to produce other enzymes such as xylanase,
amylase and pectinase.
Several parameters of cultivation were studied i.e. the particle size, time of
incubation, initial pH, temperature, concentration of medium and spore
inoculum size.
The whole oil palm stem(W1) with larger particle sizes (0.5 -1 cm) produced
higher activities of R-glucosidase . Optimum production of R-glucosidase
was found with the following parameters Le. incubation time of 6 days,
with an initial pH of 5, an incubation temperature of 35 OC ,using half
strength medium(1/2X) and 2.1XI07 spores.Following optimisation, Rglucosidase
activities were increased from 4.3U to 5.8U, indicating an
increase of 34.8%.
Characterisation of the crude enzymes has shown the R-glucosidase to be
thermostable with 90% of its activities retained at 600 C. The optimum
temperature is 35OC.The optimum pH is 5.2 and the enzyme is stable between
pH 5 and 6.
The ~-glucosidase produced was finally tested in hydrolysis reactions using
micro crystalline cellulose (Avicel) and parenchyma as substrates. Both
substrates show greater degree of hydrolysis after 2.SU ~-glucosidase was
added to the initial 1% (v Iv) cellulase ,compared to supplementing with
ceUobiase (Novozyme) adjusted to the same activities. The degree of
hydrolysis achieved in both micro crystalline cellulose (Avicel) and
parenchyma were 85% and 19.5% respectively.
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Keywords
SUBSTRAT , LIGNOSELULOSIK