Abstract
A brown material, precipitable with ethanol, was formed during wheat straw and lignin degradation by liquid cultures of different species of Pleurotus. Fourier transform infrared spectroscopy and cross-polarization and magic-angle-spinning (sup13)C nuclear magnetic resonance spectroscopy showed that most of the precipitable material was formed from exopolysaccharide secreted by the fungus but it also contained an aromatic fraction. The results of acid hydrolysis, methylation analysis, and Smith degradation indicated that the major exopolysaccharide produced by these fungi is a (1(symbl)3)-(beta)-glucan branched at C-6 every two or three residues along the main chain. The presence of lignin or straw in the culture medium had little effect on the composition and structure of the extracellular polysaccharide. Cross-polarization and magic-angle-spinning (sup13)C nuclear magnetic resonance spectroscopy provided an estimation of the aromatic content of the lignin-polysaccharide complexes, assigning 20% of the total (sup13)C signal in the material recovered from cultures of Pleurotus eryngii in lignin medium to aromatic carbon. Analytical pyrolysis indicated that the aromatic fractions of the lignin-polysaccharide complexes were derived from lignin, since products characteristic of pyrolytic breakdown of H (p-hydroxyphenylpropane), G (guaiacylpropane), and S (syringylpropane) lignin units were identified. These complexes cannot be fractionated by treatment with polyvinylpyrrolidone or extraction with lignin solvents, suggesting that the two polymers were chemically linked. Moreover, differences in composition with respect to the original lignin indicated that this macromolecule was modified by the fungi during the process of formation of the lignin-polysaccharide complexes.
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Selected References
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- Gutiérrez A., Caramelo L., Prieto A., Martínez M. J., Martínez A. T. Anisaldehyde production and aryl-alcohol oxidase and dehydrogenase activities in ligninolytic fungi of the genus Pleurotus. Appl Environ Microbiol. 1994 Jun;60(6):1783–1788. doi: 10.1128/aem.60.6.1783-1788.1994. [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]
- Kondo R., Yamagami H., Sakai K. Xylosylation of Phenolic Hydroxyl Groups of the Monomeric Lignin Model Compounds 4-Methylguaiacol and Vanillyl Alcohol by Coriolus versicolor. Appl Environ Microbiol. 1993 Feb;59(2):438–441. doi: 10.1128/aem.59.2.438-441.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ruel K., Joseleau J. P. Involvement of an Extracellular Glucan Sheath during Degradation of Populus Wood by Phanerochaete chrysosporium. Appl Environ Microbiol. 1991 Feb;57(2):374–384. doi: 10.1128/aem.57.2.374-384.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Saitô H., Ohki T., Yoshioka Y., Fukuoka F. A 13C nuclear magnetic resonance study of a gel-forming branched (1 leads to 3)-beta-D-glucan, A3, from Pleurotus ostreatus (Fr.) Quél: determination of side-chains and conformation of the polymer-chain in relation to gel-structure. FEBS Lett. 1976 Sep 15;68(1):15–18. doi: 10.1016/0014-5793(76)80393-6. [DOI] [PubMed] [Google Scholar]