1994 Fiscal Year Final Research Report Summary
Microbial degradation of ether bonds between carbohydrates and residual lignin from kraft pulp
| Project/Area Number |
05660189
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
林産学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
WATANABE Takashi Kyoto University, Wood Research Institute, Kyoto Univ., Assoc.Prof., 木質科学研究所, 助教授 (80201200)
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| Co-Investigator(Kenkyū-buntansha) |
KUWAHARA Masaaki Kyoto University, Wood Res.Inst., Kyoto Univ., Prof., 木質科学研究所, 教授 (40035978)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Kraft Pulp / Biobleaching / LCC / White-rot fungi / Lignin |
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| Research Abstract |
A water-soluble xylanase-resitant chromophoric xylan fraction (LF-D) was separated from a hard wood unbleached kraft pulp (UKP) by a cellulase/xylanase bioreactor and silica gel column chromatography. Chemical and spectroscopic analyzes revealed that LF-D contained a large amount of unremovable inorganic atoms including Si, Na and S,together with non-branched beta-1,4-linked xylan chain. In a nitrobenzen oxidation of LF-D,existence of a large amount of qunoid structure was suggested. In adittion, it was found that lignin in LF-D had been demethylated during the course of kraft pulping. On the other hand, a higher molecular weight residual fraction (HF-P) was found to contain much diphenylmethane (DPM) structure. LF-D was more effectively decolorized by bacterial microflora from soil rather than selected white rot fung. However, C.versocolor was found to decolorize both the chromophric xylan fraction and intact UKP itself among the white-rot fungi tested. In both cases, activities of lignin peroxidase, Mn-peroxidase, laccase and xylanase were not detected during the hole time of cultivation.
Although a purified LiP (H8) from P.chrysosporium wa oxidized a p-ethylated beta-O-4LCC model, carbohydrate moiety was not detected in the reaction mixture. Therefore, screening of microorganisms which quantitatively cleave p-etherified benzyl ether bonds was carried out using a fluorescence-sensitive benzyl ether model compound. As a result, several bacterial single colonies which emit fluorescence were isolated. Further study on the characterization of these microorgansims would lead to an environmentally safe biobleaching system of pulps.
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Research Products
(4 results)
