Utilization of lignocellulosic polysaccharides Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/5q47rr655

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Lignocellulosic biomass represents a vast supply of fermentable carbohydrates and functional aromatic compounds. Conversion of lignocellulosics to ethanol and other useful products would be of widespread economical and environmental benefit. Better understanding of the behavior of different lignicellulosic feedstocks in fermentation protocols as well as catalytic activities involved in lignocellulosic depolymerization will further enhance the commercial viability of biomass-to-ethanol conversion processes. The relative toxicity of the combined non-xylose components in prehydrolysates derived from three different lignocellulosic biomass feedstocks (poplar, corn stover and switchgrass, or Panicum virgatum L.) was determined using a Pichia stipits fermentation assay. The relative toxicity of the prehydrolysates, in decreasing order, was poplar-derived prehydrolysates > switchgrass-derived prehydrolysates > corn stover-derived prehydrolysates. Ethanol yields averaged 74%, 83% and 88% of control values for poplar, switchgrass and corn stover prehydrolysates, respectively. Volumetric ethanol productivities (g ethanol l⁻¹ h⁻¹) averaged 32%, 70% and 102% of control values for poplar, switchgrass and corn stover prehydrolysates, respectively. Ethanol productivities correlated closely with acetate concentrations in the prehydrolysates; however, regression lines correlating acetate concentrations and ethanol productivities were found to be feedstock-dependent. Differences in the relative toxicity of xylose-rich prehydrolysates derived from woody and herbaceous feedstocks are likely due to the relative abundance of a variety of inhibitory compounds, e.g. acetate and aromatic comounds. Fourteen aromatic monomers present in prehydrolysates prepared from corn stover, switchgrass, and poplar were tentatively identified by comparison with published mass spectra. The concentrations of the aromatic monomers totaled 112, 141 and 247 mg(l)⁻¹ for corn stover, switchgrass and poplar prehydrolysates, respectively. The woody and herbaceous feedstocks differed in both amount and type of aromatic monomers. The cellulases of Trichoderma reesei are the most widely studied for use in the depolymerization of lignocellulosics. The Trichoderma cellobiohydrolases CBH1 and CBH2 are traditionally categorized as exo-acting cellulases. A simple individual-based model was created to explore the potential effects of native endo activity on substratevelocity profiles. The model results indicate that an enzyme with a small amount of endo activity will show an apparent substrate inhibition as substrate levels are increased. Actual hydrolysis studies using affinity chromatography-purified CBH2 preparations from three laboratories indicate that CBH2 has native endo activity, while CBH1 does not.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome, 256 Grayscale) using Scamax Scan+ V.1.0.32.10766 on a Scanmax 412CD by InoTec in PDF format. LuraDocument PDF Compressor V.5.8.71.50 used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2012-01-27T15:40:18Z (GMT) No. of bitstreams: 1 FENSKEJOHN1998.pdf: 1703344 bytes, checksum: 262fe4a1c9d8f87028f96bea4823395c (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2011-12-19T18:19:36Z (GMT) No. of bitstreams: 1 FENSKEJOHN1998.pdf: 1703344 bytes, checksum: 262fe4a1c9d8f87028f96bea4823395c (MD5)
  • description.provenance : Made available in DSpace on 2012-01-27T15:40:18Z (GMT). No. of bitstreams: 1 FENSKEJOHN1998.pdf: 1703344 bytes, checksum: 262fe4a1c9d8f87028f96bea4823395c (MD5) Previous issue date: 1998-06-30
  • description.provenance : Submitted by Erin Clark (ecscannerosu@gmail.com) on 2011-12-16T21:13:46Z No. of bitstreams: 1 FENSKEJOHN1998.pdf: 1703344 bytes, checksum: 262fe4a1c9d8f87028f96bea4823395c (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items