Abstract
Lignin model dimers are valuable tools for the elucidation of microbial ligninolytic mechanisms, but their low molecular weight (MW) makes them susceptible to nonligninolytic intracellular metabolism. To address this problem, we prepared lignin models in which unlabeled and alpha-14C-labeled beta-O-4-linked dimers were covalently attached to 8,000-MW polyethylene glycol (PEG) or to 45,000-MW polystyrene (PS). The water-soluble PEG-linked model was mineralized extensively in liquid medium and in solid wood cultures by the white rot fungus Phanerochaete chrysosporium, whereas the water-insoluble PS-linked model was not. Gel permeation chromatography showed that P. chrysosporium degraded the PEG-linked model by cleaving its lignin dimer substructure rather than its PEG moiety. C alpha-C beta cleavage was the major fate of the PEG-linked model after incubation with P. chrysosporium in vivo and also after oxidation with P. chrysosporium lignin peroxidase in vitro. The brown rot fungus Gloeophyllum trabeum, which unlike P. chrysosporium lacks a vigorous extracellular ligninolytic system, was unable to degrade the PEG-linked model efficiently. These results show that PEG-linked lignin models are a marked improvement over the low-MW models that have been used in the past.
Full Text
The Full Text of this article is available as a PDF (279.3 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Hammel K. E., Jensen K. A., Jr, Mozuch M. D., Landucci L. L., Tien M., Pease E. A. Ligninolysis by a purified lignin peroxidase. J Biol Chem. 1993 Jun 15;268(17):12274–12281. [PubMed] [Google Scholar]
- Kern H. W., Kirk T. K. Influence of Molecular Size and Ligninase Pretreatment on Degradation of Lignins by Xanthomonas sp. Strain 99. Appl Environ Microbiol. 1987 Sep;53(9):2242–2246. doi: 10.1128/aem.53.9.2242-2246.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kirk T. K., Connors W. J., Bleam R. D., Hackett W. F., Zeikus J. G. Preparation and microbial decomposition of synthetic [14C]ligins. Proc Natl Acad Sci U S A. 1975 Jul;72(7):2515–2519. doi: 10.1073/pnas.72.7.2515. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kirk T. K., Farrell R. L. Enzymatic "combustion": the microbial degradation of lignin. Annu Rev Microbiol. 1987;41:465–505. doi: 10.1146/annurev.mi.41.100187.002341. [DOI] [PubMed] [Google Scholar]
- Kirk T. K., Tien M., Kersten P. J., Mozuch M. D., Kalyanaraman B. Ligninase of Phanerochaete chrysosporium. Mechanism of its degradation of the non-phenolic arylglycerol beta-aryl ether substructure of lignin. Biochem J. 1986 May 15;236(1):279–287. doi: 10.1042/bj2360279. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Moen M. A., Hammel K. E. Lipid Peroxidation by the Manganese Peroxidase of Phanerochaete chrysosporium Is the Basis for Phenanthrene Oxidation by the Intact Fungus. Appl Environ Microbiol. 1994 Jun;60(6):1956–1961. doi: 10.1128/aem.60.6.1956-1961.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scherrer R., Gerhardt P. Molecular sieving by the Bacillus megaterium cell wall and protoplast. J Bacteriol. 1971 Sep;107(3):718–735. doi: 10.1128/jb.107.3.718-735.1971. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scherrer R., Louden L., Gerhardt P. Porosity of the yeast cell wall and membrane. J Bacteriol. 1974 May;118(2):534–540. doi: 10.1128/jb.118.2.534-540.1974. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Srebotnik E., Jensen K. A., Jr, Hammel K. E. Fungal degradation of recalcitrant nonphenolic lignin structures without lignin peroxidase. Proc Natl Acad Sci U S A. 1994 Dec 20;91(26):12794–12797. doi: 10.1073/pnas.91.26.12794. [DOI] [PMC free article] [PubMed] [Google Scholar]