Xylanases of marine fungi of potential use for biobleaching of paper pulp
IR@NIO: CSIR-National Institute Of Oceanography, Goa
View Archive Info| Field | Value | |
| Creator |
Raghukumar, C.
Muraleedharan, U. Gaud, V.R. Mishra, R. |
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| Date |
2006-06-28T12:11:35Z
2006-06-28T12:11:35Z 2004 |
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| Identifier |
J. Ind. Microbiol. Biotechnol., vol.31, 433-441p.
http://drs.nio.org/drs/handle/2264/174 |
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| Description |
Microbial xylanases that are thermostable, active at alkaline pH and cellulasefree are generally preferred for biobleaching of paper pulp.. We screened obligate and facultative marine fungi for xylanase activity with these desirable Several fungal isolates obtained from marine habitat showed alkaline xylanase activity. The crude enzyme from NIOCC isolate # 3 (Aspergillus niger) with high xylanase activity, cellulase-free and unique properties containing 580 U L-1 of xylanase, could bring about bleaching of sugarcane bagasse pulp by a 60 min treatment at 55oC, resulting in a decrease of 10 kappa numbers and a 30% reduction in consumption of chlorine during bleaching process. The culture filtrate showed peaks of xylanase activity at acidic pH (3.5) and alkaline pH (8.5). When assayed at pH 3.5 optimum activity was detected at 50o C with a second peak of activity at 90oC. When assayed at pH 8.5 optimum activity was seen at 80oC. The crude enzyme was thermostable at 55oC for at least 4 h and retained about 60% of the activity. Gel filtration of the 50-80% ammonium sulfate precipitated - fraction of the crude culture filtrate separated into two peaks of xylanase having specific activities of 393 and 2457 U mg –1 protein. The two peaks showing xylanase activities had molecular masses of 13 and 18 kDa. Zymogram analysis of xylanase of crude culture filtrate as well as the 50-80% ammonium sulphate - precipitated fraction showed two distinct xylanase activity bands on native PAGE The crude culture filtrate also showed moderate activities of -xylosidase and - L-arabinofuranosidase which could act synergistically with xylanase in attacking xylan. This is the first report showing potential application of crude culture filtrate of a marine fungal isolate possessing thermostable, cellulase-free alkaline xylanase activity in biobleaching of paper pulp.
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229025 bytes
application/pdf |
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| Language |
en
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| Publisher |
Society for Industrial Microbiology
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| Rights |
An edited version of this paper was published by Society for Industrial Microbiology 2004
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| Subject |
Marine fungi
Aspergillus niger |
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| Title |
Xylanases of marine fungi of potential use for biobleaching of paper pulp
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| Type |
Article
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