Assessment of saccharification efficacy in the cellulase system of the brown rot fungus Gloeophyllum trabeum

Jake Tewalt, Jonathan Schilling

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Brown rot fungi uniquely degrade wood by creating modifications thought to aid in the selective removal of polysaccharides by an incomplete cellulase suite. This naturally successful mechanism offers potential for current bioprocessing applications. To test the efficacy of brown rot cellulases, southern yellow pine wood blocks were first degraded by the brown rot fungus Gloeophyllum trabeum for 0, 2, 4, and 6 weeks. Characterization of the pine constituents revealed brown rot decay patterns, with selective polysaccharide removal as lignin compositions increased. G. trabeum liquid and solid state cellulase extracts, as well as a commercial Trichoderma reesei extract (Celluclast 1.5 L), were used to saccharify this pretreated material, using β-glucosidase amendment to remove limitation of cellobiose-to-glucose conversion. Conditions varied according to source and concentration of cellulase extract and to pH (3.0 vs. 4.8). Hydrolysis yields were maximized using solid state G. trabeum extracts at a pH of 4.8. However, the extent of glucose release was low and was not significantly altered when cellulase loading levels were increased threefold. Furthermore, Celluclast 1.5 L continually outperformed G. trabeum cellulase extracts, although extent of glucose release never exceeded 22.0%. Results suggest methodological advances for utilizing crude G. trabeum cellulases and imply that the suboptimal hydrolysis levels obtained with G. trabeum and Celluclast 1.5 L cellulases, even at high loading levels, may be due to brown rot modifications insufficiently distributed throughout the pretreated material.

Original languageEnglish (US)
Pages (from-to)1785-1793
Number of pages9
JournalApplied Microbiology and Biotechnology
Volume86
Issue number6
DOIs
StatePublished - May 2010

Bibliographical note

Funding Information:
Acknowledgments This work was made possible by a US Department of Energy (DOE) Biomass Research and Development Initiative grant # GO18088. The authors would also like to thank Dr. Charles Abbas from Archer Daniels Midland (ADM) Company for technical input, and Dr. Shona Duncan and Mr. Adam Norcutt for analytical support during the experimental process.

Keywords

  • Bioprocessing
  • Cellulase
  • Ethanol
  • Gloeophyllum trabeum

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