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Title: Manganese-dependent cleavage of nonphenolic lignin structures by Ceriporiopsis subvermispora in the absence of lignin peroxidase

Abstract

Many ligninolytic fungi appear to lack lignin peroxidase (LiP), the enzyme generally thought to cleave nonphenolic structures in lignin. However, the fungus, Ceriporiopsis subvermispora, is able to degrade these nonphenolic structures. Experiments showed wood block cultures and defined liquid medium cultures of C. subvermispora rapidly deploymerized and mineralized a {sup 14}C-labeled, polyethylene glycol-linked, high-molecular-weight {beta}-O-4 lignin model compound (model I) that represents the major nonphenolic structure of lignin. The fungus cleaved model I between C{sub {alpha}} and C{sub {beta}} to release benzylic fragments, which were shown in isotope trapping experiments to be major products of model I metabolism. The C{sub {alpha}}-C{sub {beta}} cleavage of {beta}-O-4 lignin structures to release benzylic fragments is characteristic of LiP catalysis, but no detectable LiP activity. Three results pointed, instead, to the participation of a different enzyme, manganese peroxidase (MnP), in the degradation of nonphenolic lignin structures by C. subvermispora. (1) The degradation of model I and of exhaustively methylated (nonphenolic), {sup 14}C-labeled, synthetic lignin by the fungus in liquid cultures was almost completely inhibited when the Mn concentration of the medium was decreased from 35 {mu}M to approximately 5 {mu}M. (2) The fungus degraded model I and methylated lignin significantly faster in the presencemore » of Tween 80, a source of unsaturated fatty acids, than it did in the presence of Tween 20, which contains only saturated fatty acids. Previous work has shown that nonphenolic lignin structures are degraded during the MnP-mediated peroxidation of unsaturated lipids. (3) In experiments with MnP, Mn(II), and unsaturated lipid in vitro, this system mimicked intact C. subvermispora cultures in that it cleaved nonphenolic {beta}-O-4 lignin model compounds between C{sub {alpha}} and C{sub {beta}} to release a benzylic fragment. 41 refs., 7 figs., 2 tabs.« less

Authors:
; ;  [1]
  1. USDA Forest Products Lab., Madison, WI (United States) [and others
Publication Date:
OSTI Identifier:
508349
DOE Contract Number:  
FG02-94ER20140
Resource Type:
Journal Article
Journal Name:
Applied and Environmental Microbiology
Additional Journal Information:
Journal Volume: 62; Journal Issue: 10; Other Information: PBD: Oct 1996
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; 54 ENVIRONMENTAL SCIENCES; LIGNIN; BIODEGRADATION; FUNGI; BIOLOGICAL PATHWAYS

Citation Formats

Jensen, K.A. Jr., Bao, W., and Kawai, S. Manganese-dependent cleavage of nonphenolic lignin structures by Ceriporiopsis subvermispora in the absence of lignin peroxidase. United States: N. p., 1996. Web.
Jensen, K.A. Jr., Bao, W., & Kawai, S. Manganese-dependent cleavage of nonphenolic lignin structures by Ceriporiopsis subvermispora in the absence of lignin peroxidase. United States.
Jensen, K.A. Jr., Bao, W., and Kawai, S. Tue . "Manganese-dependent cleavage of nonphenolic lignin structures by Ceriporiopsis subvermispora in the absence of lignin peroxidase". United States.
@article{osti_508349,
title = {Manganese-dependent cleavage of nonphenolic lignin structures by Ceriporiopsis subvermispora in the absence of lignin peroxidase},
author = {Jensen, K.A. Jr. and Bao, W. and Kawai, S.},
abstractNote = {Many ligninolytic fungi appear to lack lignin peroxidase (LiP), the enzyme generally thought to cleave nonphenolic structures in lignin. However, the fungus, Ceriporiopsis subvermispora, is able to degrade these nonphenolic structures. Experiments showed wood block cultures and defined liquid medium cultures of C. subvermispora rapidly deploymerized and mineralized a {sup 14}C-labeled, polyethylene glycol-linked, high-molecular-weight {beta}-O-4 lignin model compound (model I) that represents the major nonphenolic structure of lignin. The fungus cleaved model I between C{sub {alpha}} and C{sub {beta}} to release benzylic fragments, which were shown in isotope trapping experiments to be major products of model I metabolism. The C{sub {alpha}}-C{sub {beta}} cleavage of {beta}-O-4 lignin structures to release benzylic fragments is characteristic of LiP catalysis, but no detectable LiP activity. Three results pointed, instead, to the participation of a different enzyme, manganese peroxidase (MnP), in the degradation of nonphenolic lignin structures by C. subvermispora. (1) The degradation of model I and of exhaustively methylated (nonphenolic), {sup 14}C-labeled, synthetic lignin by the fungus in liquid cultures was almost completely inhibited when the Mn concentration of the medium was decreased from 35 {mu}M to approximately 5 {mu}M. (2) The fungus degraded model I and methylated lignin significantly faster in the presence of Tween 80, a source of unsaturated fatty acids, than it did in the presence of Tween 20, which contains only saturated fatty acids. Previous work has shown that nonphenolic lignin structures are degraded during the MnP-mediated peroxidation of unsaturated lipids. (3) In experiments with MnP, Mn(II), and unsaturated lipid in vitro, this system mimicked intact C. subvermispora cultures in that it cleaved nonphenolic {beta}-O-4 lignin model compounds between C{sub {alpha}} and C{sub {beta}} to release a benzylic fragment. 41 refs., 7 figs., 2 tabs.},
doi = {},
journal = {Applied and Environmental Microbiology},
number = 10,
volume = 62,
place = {United States},
year = {1996},
month = {10}
}