Abstract
Previous investigations have identified a quantitatively major intermediate of lignin degradation by Streptomyces viridosporus. The intermediate, a modified lignin polymer, acid-precipitable polymeric lignin (APPL), is released as a water-soluble catabolite and has been recovered in amounts equivalent to 30% of the lignin originally present in a corn stover lignocellulose substrate after degradation by this actinomycete. In the present work, APPLs were collected at various time intervals from cultures of two highly ligninolytic Streptomyces sp. strains, S. viridosporus T7A and S. badius 252, growing on corn stover lignocellulose. APPL production was measured over time, and the chemistry of APPLs produced by each organism after different time intervals was compared. Chemical characterizations included assays for lignin, carbohydrate, and ash contents, molecular weight distributions by gel permeation chromatography, and chemical degradation analyses by permanganate oxidation, acidolysis, and alkaline ester hydrolysis. Differences between the organisms were observed in the cultural conditions required for APPL production and in the time courses of APPL accumulation. S. viridosporus produced APPL in solid-state fermentation over a 6- to 8-week incubation period, whereas S. badius produced as much or more APPL, but only in liquid culture and over a 7- to 8-day incubation period. The chemistry of the APPLs produced also differed. S. viridosporus APPL was more lignin-like than that of S. badius and was slowly modified further over time, although no change in molecular weight distribution over time was observed. In contrast, S. badius APPL was less lignin-like and increased substantially in average molecular weight over time. Results indicated that differing mechanisms of lignin metabolism may exist in these two Streptomyces sp. strains. S. viridosporus APPL probably originates from the heart of the lignin and is released largely as the result of β-ether cleavage and other oxidative reactions. S. badius APPL probably originates in the same manner; however, after release as a water-soluble catabolite, lower-molecular-weight intermediates of lignin degradation are repolymerized with APPL in a reaction catalyzed by an extracellular phenol oxidase. The chemical analyses and the presence of extracellular phenol oxidase in S. badius, but not in S. viridosporus, support this conclusion.
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Selected References
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- Antai S. P., Crawford D. L. Degradation of softwood, hardwood, and grass lignocelluloses by two streptomyces strains. Appl Environ Microbiol. 1981 Aug;42(2):378–380. doi: 10.1128/aem.42.2.378-380.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bollag J. M., Sjoblad R. D., Liu S. Y. Characterization of an enzyme from Rhizoctonia praticola which polymerizes phenolic compounds. Can J Microbiol. 1979 Feb;25(2):229–233. doi: 10.1139/m79-035. [DOI] [PubMed] [Google Scholar]
- Crawford D. L., Pometto A. L., Crawford R. L. Lignin Degradation by Streptomyces viridosporus: Isolation and Characterization of a New Polymeric Lignin Degradation Intermediate. Appl Environ Microbiol. 1983 Mar;45(3):898–904. doi: 10.1128/aem.45.3.898-904.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lundquist K., Kirk T. K. Acid degradation of lignin. IV. Analysis of lignin acidolysis products by gas chromatography, using trimethylsilyl derivatives. Acta Chem Scand. 1971;25(3):889–894. doi: 10.3891/acta.chem.scand.25-0889. [DOI] [PubMed] [Google Scholar]
- Petroski R. J., Peczynska-Czoch W., Rosazza J. P. Analysis, Production, and Isolation of an Extracellular Laccase from Polyporus anceps. Appl Environ Microbiol. 1980 Dec;40(6):1003–1006. doi: 10.1128/aem.40.6.1003-1006.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Phelan M. B., Crawford D. L., Pometto A. L., 3rd Isolation of lignocellulose-decomposing actinomycetes and degradation of specifically 14C-labeled lignocelluloses by six selected Streptomyces strains. Can J Microbiol. 1979 Nov;25(11):1270–1276. doi: 10.1139/m79-200. [DOI] [PubMed] [Google Scholar]
- Pometto A. L., 3rd, Sutherland J. B., Crawford D. L. Streptomyces setonii: catabolism of vanillic acid via guaiacol and catechol. Can J Microbiol. 1981 Jun;27(6):636–638. doi: 10.1139/m81-097. [DOI] [PubMed] [Google Scholar]