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Applied Microbiology and Biotechnology

, Volume 52, Issue 5, pp 689–697 | Cite as

Production of ligninolytic enzymes and synthetic lignin mineralization by the bird's nest fungus Cyathus stercoreus

  • A. Sethuraman
  • D. E. Akin
  • K.-E. L. Eriksson
ORIGINAL PAPER

Abstract

Production of ligninolytic enzymes and degradation of 14C-ring labeled synthetic lignin by the white-rot fungus Cyathus stercoreus ATCC 36910 were determined under a variety of conditions. The highest mineralization rate for 14C dehydrogenative polymerizates (DHP; 38% 14CO2 after 30 days) occurred with 1 mM ammonium tartrate as nitrogen source and 1% glucose as additional carbon source, but levels of extracellular laccase and manganese peroxidase (MnP) were low. In contrast, 10 mM ammonium tartrate with 1% glucose gave low mineralization rates (10% 14CO2 after 30 days) but higher levels of laccase and manganese peroxidase. Lignin peroxidase was not produced by C. stercoreus under any of the studied conditions. Mn(II) at 11 ppm gave a higher rate of 14C DHP mineralization than 0.3 or 40 ppm, but the highest manganese peroxidase level was obtained with Mn(II) at 40 ppm. Cultivation in aerated static flasks gave rise to higher levels of both laccase and manganese peroxidase compared to the levels in shake cultures. 3,4-Dimethoxycinnamic acid at 500 μM concentration was the most effective inducer of laccase of those tested. The purified laccase was a monomeric glycoprotein having an apparent molecular mass of 70 kDa, as determined by calibrated gel filtration chromatography. The pH optimum and isoelectric point of the purified laccase were 4.8 and 3.5, respectively. The N-terminal amino acid sequence of C. stercoreus laccase showed close homology to the N-terminal sequences determined from other basidiomycete laccases. Information on C. stercoreus, whose habitat and physiological requirements for lignin degradation differ from many other white-rot fungi, expands the possibilities for industrial application of biological systems for lignin degradation and removal in biopulping and biobleaching processes.

Keywords

Lignin Mineralization Rate Lignin Degradation Lignin Peroxidase Ligninolytic Enzyme 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • A. Sethuraman
    • 1
  • D. E. Akin
    • 2
  • K.-E. L. Eriksson
    • 1
  1. 1.Department of Biochemistry and Molecular Biology and Center for Biological Resource Recovery, University of Georgia, Athens, GA 30602, USAGE
  2. 2.Russell Research Center, Agricultural Research Service, United States Department of Agriculture, P. O. Box 5677, Athens, GA 30604, USA e-mail: deakin@qaru.ars.usda.gov Tel.: +1-706-546-3482 Fax: +1-706-546-3607US

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