Studies on hypersaline-tolerant white-rot fungi III: biobleaching of unbleached kraft pulp by hypersaline-tolerant manganese peroxidase from a marine white rot isolate, <Emphasis Type="Italic">Phlebia </Emphasis>sp. MG-60 |
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Authors: | X Li R Kondo K Sakai |
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Institution: | (1) Department of Forest and Forest Products Sciences, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan Tel. +81-92-642-2811; Fax +81-92-642-2811 e-mail: kondo@brs.kyushu-u.ac.jp, JP |
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Abstract: | A marine white rot isolate, Phlebia sp. MG-60, secreted lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase under different sea salt incubation conditions.
Its MnP production was strongly enhanced by adding 3% sea salts, and the MnP showed high tolerance to sea salts and NaCl.
The crude enzyme secreted at 3% sea salt concentration by Phlebia sp. MG-60, in which the main component was MnP (cMnP), was then used to bleach unbleached hardwood kraft pulp (UKP) in vitro.
The pulp was brightened 11 points by 4 U of cMnP, and the kappa number was decreased 6 points when only 0.5 mM H2O2 was added continuously. When 0.5 mM H2O2 (1.22 mg H2O2 /g pulp) was added at the initial bleaching, the pulp brightness increased 6 points with a dosage of 4 U of cMnP. When crude
MnPs were employed to bleach UKP with organic-free model white-water instead of the Milli Q water usually used, the pulp was
brightened 10 and 13 points by 4 and 20 U of cMnP, respectively, and 5 and 6 points by 4 and 20 U of MnP, respectively, of
Phanerochaete chrysosporium.
Received: September 28, 2001 / Accepted: March 15, 2002
Correspondence to:R. Kondo |
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Keywords: | White-rot fungus Manganese peroxidase Biobleaching Hypersaline tolerance Model white water |
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