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Laccase isozymes of
Pleurotus sajor-caju culture on husk and bran of black
sticky rice and their potential on indigo carmine
decolourisation
Rakrudee Sarnthima1,2 and Saranyu Khammuang1,2*
1Protein
and Enzyme Technology Research Unit, Thailand.
2Department
of Chemistry, Faculty of Science, Mahasarakham University,
Maha Sarakham 44150 Thailand.
*Corresponding author.
E-mail:
skhammuang@yahoo.com.
Tel: +66 43
754246.
Fax:
+66 43 754246.
Accepted
7 August, 2008 |
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Extracellular laccases of Pleurotus sajor-caju grown
on solid state medium consisted of husk and bran of black
sticky rice, were partially purified by DEAE–cellulose
chromatography. These laccases could be separated into three
groups: unboundLac and bound fractions (pool1Lac and
pool2Lac). The optimum pH of these laccases was studied
using ABTS as substrate. It was found that the pH optimum
for unboundLac fell in the range of 3–5 and 3–4 for pool1Lac
and pool2Lac. The indigo carmine decolourisation capacity
was compared between unboundLac and pool2Lac. It was found
that the optimal pH for indigo carmine decolourisation were
5 and 3 for unboundLac and pool2Lac, respectively. In the
range of various dye concentrations tested, it was found
that indigo carmine at 10 µM with the enzyme activity of
0.01 U, gave the best dye decolourisation with 40.47% within
120 min for unboundLac and with 18.61% within 150 min for
pool2Lac. High amount of enzyme used of these laccases might
improve decolourisation ability.
Key
words:
Black
sticky rice, husk, bran, Pleurotus sajor-caju,
laccase, isozyme, purification. |
